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The Reasons why Automatic Gearboxes WILL Work with EV's & how to do it..

212K views 532 replies 84 participants last post by  poprock 
#1 · (Edited)
Who am I?
A gearhead like you are. I now make a living in technology but am a certified journeyman mechanic as well. I'm in my mid-fifties and old enough to know when I'm beat and how to capitalize on other peoples work as well as their mistakes. I currently do racecar fabrication and I drive as well during those hours that Corp. America does not have her hooks in me. Like many gearheads, I have more projects than time.. When I crossed the boundary into my 50's I realized that I was burning hours on the sofa in front of the idiot box that I'd never recover. So I guess now I've traded seats and now spend at least some of that time in front of my PC whilst enriching myself on the Internet. During my years turning wrenches - I've been through many automatic transmissions. Of course I was baptised by fire when thrown into the deep end with a Turbo-400 from a pickup truck was assigned to me. (worked like a charm thank you).. I've a thorough understanding of these myterious slush boxes and have grown to both love and hate each one of them equally.
I've had a dream since I was 10 years old to build a series hybrid. Yes over 4.5 decades ago. It was then that my Grand Pa (a brilliant engineer) and I sat down at the rail yards and he taught me how the "new" Diesel Locomotives worked.
It was that principle that I wanted to use (in essence) in the creation of my own EV. Start out building and refining the car as an EV and adding Waste-oil diesel generator to the mix for a range extender.
I have my own Mill and Lathe and, of course, welders.
Enough about me..

I've read through nearly 30 pages of YES YOU CAN and NO YOU CAN'T on the "other" thread.. I've addressed some of those issues here (if you can stand reading that much)..

I'd ask one thing of the participants to this thread -
Please keep on topic. Those of you that want to say how rediculous the idea is - please see other thread.

On with the show....
I see many people touting the line - "Well if you wanted a standard - why didn't you start out with one, that's what you're making your automatic into anyways!" Guys - read the PROs below - that's why..

PROs -
- Automatic is lighter
- Automatic does have "ParK" selector - Go ahead and use the parking brake on a Northern car that's 15 years old - You'll be calling a tow to the shop to un-freeze your rusted cables.
- Automatics are less intimidating to people that have never driven a std
- Many really good prospective donors have been passed up due to their transmission
- Conversion to a stick requires not only the transmission but retrofitting the shifter from auto to std.

Addressing the Green-ness -
- Automatic trans fluid can be recycled along with regular motor oil.
- ATF can be burned for heat very efficiently with super low emissions (it's done frequently up north here).
- Volume of ATF required is dramatically reduced over what's required with a torque convertor.
- Fire potential of the ATF? yes it will burn but you can pour it on a hot exhaust manifold and it will not ignite. It needs to be vaporized first just like diesel fuel or gasoline for that matter. I also think that the potential for fire and explosion is far greater from batteries not put inside of protective casings with crush-zones around them.

Various Notes made during the consumption of the "other" thread -
- Idling the traction motor to maintain pressure is out of the question in my estimation. Keep reading for more..
- Pressure leakage internally is minimal with a transmission in good condition. I've seen a transmission maintain pressure for as long as 30 minutes.
- Slippage on start-up - I don't think this is as big of a problem as some have stated it to be. Point in fact, you do want "some" slippage between shifts and startup due to the high levels of torque in the electric motor at lower RPM. Slippage and the torque convertor (not needed here) are where the vast majority of heat is created in an automatic trans.
- Most transmissions made since 1984 are controlled by the ECU or ETC (I-E Electronically controlled).
The interface to control it can be made quite simply since the actual control inputs to the transmission are binary (on or off). I would suggest that shifting of the transmission still be kept manual with a 4 positions controlled by the shifter. 2nd gear, Neutral, 4th gear (highest 1:1 rather than an OD) and Reverse. If you want to retain fully automatic controls, you could do that as well but with a higher degree of complexity.

If you have a transmission that's a bit of an internal bleeder - you could either overhaul it with new seals and gaskets or add an external accumulator. The Accumulator would have a low pressure switch to engage external pump motor to build pressure to a specific level (40 PSI would be enough). Depending upon the weight of the vehicle, you'll need between 40 and 100 PSI to keep clutch packs engaged without slipping. If you want to hot-rod it, you better be looking for pressures double that.

Speaking of Clutch Packs - I don't know of any automatic transmission shipped in a car that has bands any longer. They all use clutch packs now days. Clutch packs have far more friction / surface area than do bands so they require less pressure to operate properly.

Regeneration: Yes, the wheels will backfeed torque through the transmission to capitalize on Regen if using the AC drive system and appropriate controller(s).

Additional issues to be taken into consideration -
The input shaft of the standard transmission locates between the Pilot bearing and the front bearing of the transmission. This would have to be taken into consideration while making an adapter. This noted - the adapter will need to drive the pump of the transmission and be locked to the input shaft of the trans.

Let's have fun!
 
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#57 ·
I've gotten myself confused, I guess, trying to relate torque curves between ICE and EM and the correct timing of shifting gears.

Generally, you stomp on the gas in an ICE and an AT will kick down to a lower gear thereby allowing a higher RPM where the ICE will provide more torque.

An EM is exactly the opposite, and shifting to a lower gear would give you higher RPM but LESS torque. Below is an example curve if you look at the line labeled "RPM".



So if your EV is cruising along in one gear with the motor turning 5000 RPM already, and you need passing power, where do you get it ? Not from a lower gear, because that would mean over-revving the motor. You need a higher gear so the motor can run at the lower RPM/higher torque, right ? Except that is going to lower the ratio through the trans and to the wheels, giving more motor torque but less torque at the wheels.

It seems like the speed-based, and TPS-based shift pattern of an AT computer is going to do exactly the wrong thing when you stomp on the accelerator. It expects an engine to be turning at a lazy RPM of 800 - 1500 and for there to be plenty of room to downshift and access more torque up at higher RPM.
 
#58 ·
What I haven't seen mentioned in this thread so far is that the torque converter does more than simply allow slippage when the car is stopped and the engine is running. The TC also multiplies torque as long as there is a significant difference in speed between the impeller (attached to the engine shaft) and the turbine (attached to the transmission shaft).

The transmission shaft actually "sees" more torque than the engine is producing. Unfortunately, I have no idea how MUCH more torque the TC usually imparts. Granted we might have more torque from an electric motor at low RPM than the original engine was producing, but without the TC, will we have enough ?

Big-Foot: Isn't there a valid reason to keep the TC for its multiplication of torque at low speed launch, even if we do have a short delay while pressure builds due to lack of motor idling ? Or even using an Accumulator to eliminate the delay ?

Other than the weight savings and the smaller overall package size, I'm not clear on why we'd want to eliminate the TC. If we start with an AT that is usually mated to engines with peak torque of 300 lb-ft (at 5000RPM), and mate it to an electric motor with 100 lb-ft right from zero RPM, is it possible the AT input shaft will actually "see" more torque from the electric motor than it would have from the engine -- because of the the TC multiplying effect ? Will we break the AT internals by leaving the TC in place ?
 
#63 ·
Guys - all great work here!!! Let's keep it going!!

What I haven't seen mentioned in this thread so far is that the torque converter does more than simply allow slippage when the car is stopped and the engine is running. The TC also multiplies torque as long as there is a significant difference in speed between the impeller (attached to the engine shaft) and the turbine (attached to the transmission shaft).

The transmission shaft actually "sees" more torque than the engine is producing. Unfortunately, I have no idea how MUCH more torque the TC usually imparts. Granted we might have more torque from an electric motor at low RPM than the original engine was producing, but without the TC, will we have enough ?

Big-Foot: Isn't there a valid reason to keep the TC for its multiplication of torque at low speed launch, even if we do have a short delay while pressure builds due to lack of motor idling ? Or even using an Accumulator to eliminate the delay ?

Other than the weight savings and the smaller overall package size, I'm not clear on why we'd want to eliminate the TC. If we start with an AT that is usually mated to engines with peak torque of 300 lb-ft (at 5000RPM), and mate it to an electric motor with 100 lb-ft right from zero RPM, is it possible the AT input shaft will actually "see" more torque from the electric motor than it would have from the engine -- because of the the TC multiplying effect ? Will we break the AT internals by leaving the TC in place ?
Since the late 60's when we had the switch pitch torque converters, they really don't do "much" in terms of the multiplication of torque.. After reading some of the other posts I was reminded of how the stall speed of a converter is raised or lowered depending upon how much torque is being input to it initially. Now that's not to say that the given stall speed would change in any one particular installation - rather the stall speed of a given converter would change between motors/engines of different torque specs.
So - lets say that the stall speed is 1500 RPM for a 7" motor, it may well be 2000 RPM for an 8" and 2500 RPM for a 9" motor..

So - the real reason / rationale of the TC today is not to multiply the available torque, but to allow the ICE to move itself up into the RPM range that is starts making enough torque to move the load (GVW) of the vehicle.
TC's (and gear ratios) are carefully matched to the designed use of the vehicle and the ICE that's propelling it.

So to the point of passing a vehicle when you need more power and your EM is already pulling at it's peak RPM of 5,000 - you would actually need a higher gear (lower numerically) to reduce the RPM of the EM into the range of it's higher torque value with greater margin to it's higher RPM.
EG - shift from 3rd to 4th gear to reduce your RPM from 5,000 to 4,000..
While the available torque may not change, you have another 1,000 RPM to accelerate with.

Bottom line is this: Automatic transmissions with their torque converters are not designed nor optimized for use with electric motors that break all the rules of ICE engines in terms of RPM -vs- Torque.

This is the way I see it anyway..

Thought:
If TC's were multiplying torque with any degree of efficiency - I think we would see torque converters in literally all of the 70-100k behemouth trucks traveling the highways today. Instead we see them with very large standard transmissions almost all of the time.
 
#60 ·
I wouldn't worry about it. My Auto Tranny had 243,000 miles when I converted it to an EV and it's fine. While the motor can provide ridiculous amounts of torque, I seriously doubt any controller (besides a Zilla) could even provide the current needed for those gear-stripping torques.
 
#61 ·
I found this at answers.com:

"In a hydraulic torque converter, efficiency depends intimately on the angles at which the fluid enters and leaves the blades of the several parts. Because these angles change appreciably over the operating range, k varies, being by definition zero when the output is stalled, although output torque at stall may be three times engine torque for a single-stage converter and five times engine torque for a three-stage converter. Depending on its input absorption characteristics, the hydraulic torque converter tends to pull down the engine speed toward the speed at which the engine develops maximum torque when the load pulls down the converter output speed toward stall."


So ... up to 5x motor torque ? With an engine, that is only multiplying a small portion of its peak torque because the TC is doing this when the engine is at low RPM and then this multiplication effect diminishes as the engine torque increases. But with an electric motor, the motor's peak torque is the torque that is being multiplied.

PS. I'm trying to find specs on various transaxles that are FWD for a longitudinal mount engine. (Transverse mountings always have unequal-length halfshafts, which means torque-steer, and reduced suspension travel.) One example would be the 42LE Chrysler transmissions used in the Intrepids. That transaxle is a compact package and relatively light weight -- but has a poor reliability reputation. Anybody have any other suggestions for longitudinal FWD, light weight, small package ATs ? I have this notion of trying to build something like the GM skateboard -- flat chassis with motor and low-profile tranny and batteries all mounted within the "board", keeping a very low CG. So weight and size of the tranny is important, and leaving out the TC would allow a smaller package.
 
#65 ·
I found this at answers.com:

PS. I'm trying to find specs on various transaxles that are FWD for a longitudinal mount engine. (Transverse mountings always have unequal-length halfshafts, which means torque-steer, and reduced suspension travel.) One example would be the 42LE Chrysler transmissions used in the Intrepids. That transaxle is a compact package and relatively light weight -- but has a poor reliability reputation. Anybody have any other suggestions for longitudinal FWD, light weight, small package ATs ? I have this notion of trying to build something like the GM skateboard -- flat chassis with motor and low-profile tranny and batteries all mounted within the "board", keeping a very low CG. So weight and size of the tranny is important, and leaving out the TC would allow a smaller package.

I understand that torque multiplication is only 1.1 X, but can't recollect source. senoir moments suck.

for tranny: have you considered Audii's from say the late 70's or early 80's? Basically a bug tranny but mounted backwards (engine in front) with equal length shafts and steering couplers. Probably 6 to 8 bolts holding everything in. both flavors, but don't go for the two speeds since they are kinda weak. guessing bug people can rebuild em, maybe not.
 
#68 ·
That AC motor torque curve is much easier to read than the one I posted for a NetGain Warp motor. It shows exactly why I think the programmed shift behavior of an automatic transmission is completely wrong when mated to an electric motor.

As in Big-Foot's starting post for this thread, it seems like allowing completely automatic shifting is going to be pretty tricky. "Manually" selecting "D1","D2","D3" should be simple as long as you have a Tachometer on the dash. Otherwise, we'll have to defeat most of the sensor-driven shifting the AT wants to do.
 
#69 ·
Piotrsko: "have you considered Audii's from say the late 70's or early 80's? Basically a bug tranny but mounted backwards (engine in front) with equal length shafts and steering couplers."

I was hoping to stay more recent than 70'/80's, but I remember looking at the Audi 5000 which is used in many mid-engine kitcar builds as a cheaper alternative to the Porsche G50. What auto tranny numbers would you suggest I research for light weight and small profile ? A guy just started a thread on his conversion of an Audi TT Quatro and it sounds like that tranny needs a lot of computer control and wheelslip sensor feedback, etc. And that is for a manual 6-speed.

Of course, there are also the Subaru FWD versions -- mounting to those boxer engines requires longitudinal mounting, I think. I have no idea what they weigh, though.
 
#70 ·
If looking for a RWD trans I have an idea, but it would require some fabrication and experimentation.

A General Motors TH350 3 speed auto trans uses a vacuum modulator to control the shift, which makes the decision to shift based on engine vacuum. When this modulator is defective, the transmission will not shift until it reaches the max speed to shift regardless of throttle input, indicating that the more vacuum the modulator sees, the lower the shift point.

One of these transmissions might work, but you'd have to have a way to simulate engine vacuum. A way to do this would be with a vacuum pump, a solenoid to bleed vacuum, and a throttle position sensor to control the opening of the solenoid. With no vacuum (WOT on an ICE) the vacuum modulator on the trans sees no vacuum, thus holds the shift to the max shift speed that the trans is set up for. This is a mechanical shift point set inside the trans, but that's as far as I can go on that as I've never actually been inside one. Under partial load, the trans will shift at a lower RPM, as the modulator will see partial vacuum. The more vacuum the modulator sees, the lower the shift point. There is a set screw inside the modulator that can adjust how much vacuum is needed to induce a shift in relation to input shaft speed. There is also a kickdown cable attached that will force a downshift when floored in 3rd gear to pull it down to a lower gear.

So, you should be able to use a vacuum pump to make the vacuum, a solenoid to induce a variable amount of vacuum bleed, and a TPS to control how much bleed is needed. You might also need some feedback from the trans on what gear it's in to adjust the bleed, because you'd not want to have the upshift and downshift at the exact same level of vacuum because that would cause gear hunting. I think this might be addressed mechanically inside the trans as well though.

Hope this helps.
 
#71 · (Edited)
can't say as to what model being that I was wandering around in a junk yard at the time looking for VW CV joints. Did notice the case was almost exactly the same as the 3 spd auto bug tranny. No hook-ups for anything computer. I am guessing about 150 to 200 lbs installed since I can pick one up singlehanded. That is the limits of my knowledge here. definitely cheap however, $50 a copy at the time.

OH yeah: they don't require a TC to run tranny. the TC is only for clutch simulation.
 
#72 · (Edited)
Somebody earlier mentioned that the actual control signals to solenoid packs on modern ATs are pretty simple, and Qer mentioned that he might be able to add this programmable shifting functionality into the browser control interface he is building for Tesseract's new controller. Even simpler than fooling with vacuum source controls.

The motor controller really might be the perfect place for it. Qer doesn't need to reinvent a TCU because an AT's shifting behavior including kickdown is much more complex than what is needed for an electric motor. An AT mated to an electric motor simply needs to know what the vehicle speed is and what the gear ratios available are in order to pick the right gear -- kickdown is not desirable due to the torque falloff at higher motor speeds, so it is just a matter of picking the gear that lets the motor run most efficiently at that vehicle speed.

In fact, if the interface for controlling solenoid packs can be made generic enough, this could be a real selling point for Tesseract's controller -- it would be the ONLY controller that really works well to create a good mating between AT and electric motors.

In my personal quest for the smallest package size of AT units, does anybody know offhand which transmissions have separate bell housings -- so if a TC is not used, the profile of that tranny can be very short ? By "short" I mean vertical height.
 
#75 ·
Somebody earlier mentioned that the actual control signals to solenoid packs on modern ATs are pretty simple...
The motor controller really might be the perfect place for it. Qer doesn't need to reinvent a TCU because an AT's shifting behavior including kickdown is much more complex than what is needed for an electric motor. An AT mated to an electric motor simply needs to know what the vehicle speed is and what the gear ratios available are in order to pick the right gear -- kickdown is not desirable due to the torque falloff at higher motor speeds, so it is just a matter of picking the gear that lets the motor run most efficiently at that vehicle speed.
I'm primarily a GM RWD guy, from the performance side of it, so I can't comment on other brands or FWD, but...

EFI Live makes a program (750 bucks) that will speak to a lot of GM FWD, RWD and 4WD vehicles. This program also manages the auto transmission completely, allowing you to program it in more detail than even a Tech 2. That program shows that the transmissions are controlled by engine RPM and by speed, so you'd need a TPS signal, a VSS signal and an engine RPM signal to control it. But, it might be possible to control it just by speed which would eliminate the need for an RPM input. I have a copy of this program at home, I'll try to remember to bring it up at home and see what all can be done with it.

One bad thing, EFI Live requires a separate license for each PCM it controls, or you can buy a blanket license for a particular make. In this case, once a program were designed to work properly, someone could buy a group license (think they are 2 grand or so) then program them for anyone running a GM transmission. The group license would be for a family of vehicle, here is a list of the vehicles supported.

A second problem, is that GM as of late has been putting all their computer controlled gear onto a CAN bus. So, you'd either have to build a CAN network in your car or figure out specifically what vehicles are both manageable by EFI live and don't use a CAN bus.

In my personal quest for the smallest package size of AT units, does anybody know offhand which transmissions have separate bell housings -- so if a TC is not used, the profile of that tranny can be very short ? By "short" I mean vertical height.
GM RWD autos have 2 piece bell housings after I think 1997, and I'm pretty sure that Ford RWD autos do as well since Ford engines have different designs on their engines. A GM trans stands about a foot, maybe 14 inches tall at the closest point to the bell. Beyond that, I don't know. On the FWD transmissions, since they are pretty small to begin with, and there are only so many ways a FWD transmission can fit, it shouldn't be too hard to modify any vehicle to accept a GM transmission from one of the supported vehicles.
 
#73 ·
150 to 200 lbs would actually be quite heavy. A VW beetle manual trans only weighs 65 lbs. A Honda Civic auto tranny weighs about 135 lbs. A PowerGlide auto tranny can weigh as little as 45 lbs -- of course, that isn't a transaxle so the rear-end weight must be figured too.

Big-Foot mentioned one advantage of auto tranny's was being lighter than manual tranny's in many cases. Is it possible I'll find FWD transaxles under 100 lbs w/o torque converter ?
 
#74 ·
both questions: solenoids can be triggered by the presence of 12 v at about a couple of amps. sequencing can be sometimes the problem, BUT any kind of simple circuit would be able to control most auto's. Pressure sensor or two, couple of 555 timers, a pi circuit for frequency control and some sort of current switching.{very simplified, but used to illustrate}

Sorry, like I said, I was in a junk yard. this was the whole front end less engine and tires sitting there. I picked it up. My personal max at the time for dead lifting was about 275 lbs. this was just somewhere left handed to look.
 
#78 ·
OK, brought the program into work with me this time. On the transmission, EFI Live can tune:

General
* Parameters - Set the gear ratios in the trans, and when the WOT shift tables come into play
* Shift Stabilization Ratios - Predictive values for torque management

Shift at VSS
* Upshift tables
XX Part throttle tables - Controls what speed a part throttle upshift occurs, speed xs TPS
XX Manual hold gear - Controls what speed the transmission will upshift at even if held in one gear
* Downshift tables
XX Part throttle tables - Controls what speed a part throttle downshift occurs, speed xs TPS
XX Manual downshift - Controls the maximum vehicle speed the transmission will allow a downshift for even if the lever is manually moved to a lower gear

Shift at RPM
* Upshift
XX Parameters - Controls the maximum engine RPM the engine can go before an upshift is made under WOT

Throttle Kickdown
* Throttle kickdown - Controls when the transmission will "kick into passing gear" determined by TPS vs engaged gear

Desired Shift Times
* Shift times Determines how fast a shift will be executed depending on engine torque delivered

TCC
* Parameters - Allows you to control whether the torque converter locks on an upshift
* Apply - Determines at what speed the torque converter will lock up, by gear
* Release - Determines at what speed the torque converter will unlock, by speed or TPS
* Pressure - Allows you to determine TCC pressure apply and slip rate (newer GM torque converters have predetermined slip, which makes a smoother transition from locked to unlocked; TCC lockup no longer feels like an extra gear)

Trans Pressures - Allows you to adjust transmission line pressure by various parameters

Torque Reduction - Implemented by GM to allow a weak transmission to live behind a powerful engine by retarding engine power right before a shift, adjusted as a percentage of torque delivered. Also has an abuse parameter set.

CARS/CAGS - Not sure what this one is.

The program can also adjust things like rear end ratios, tire sizes, ect, according to what your EV may have on it that the PCM needs to know about.

There's also a diagnostic section where you can turn DTC fault enablers on and off, so the PCM won't recognise faults that you don't want to see. This would allow you to turn the engine sensors all off, so that when using the PCM with an EV you can use the Check Engine Light to determine faults in the stuff you are using, without seeing the light on because something you aren't using is no longer there.

Another neat thing about the PCM, it can be set to turn a fan on and off according to temp, so using one of these PCMs to control your transmission gives you the ability to set a backup fan to keep the EM from overheating, without running a power robbing fan when the motor ISN'T overheating.

There's also a function on there that allows you to control how the tach works, so if you used a GM crankshaft sensor setup (24X reluctor) on the EM (wouldn't be hard to stick on the end of the EM shaft) you'd be able to use it to run a tach.

Hope this helps out with using an electric trans like a GM 4L60E in an EV.
 
#79 ·
In my honest opinion, just like an automatic DOES NOT get better mileage than a stick... so in electrical vehicles I find the same principle to apply. An automatic may work for whoever, but the question is simply when you are trying for maximum efficiency it is wiser to go standard transmission. An NO it isn't because some of us have enough trying to get our head around the building of an EV... I gutted my front-end and converted my Toyota (clutch, tranny, drive axles and shock towers,.. and put in a standard. (of course I ditched anything and everything related to the conveyance of gasoline, exhaust or what ever was ICE as I was at it...:p)
I didn't find any 'slack' in the standard transmission it is just go or don't... hit the foot-feeter on your slushbox I bet you will notice a 'whir' of the engine prior to engagement of the gear...
Now this is all just my opinion and experience.;)
 
#80 · (Edited)
In my honest opinion, just like an automatic DOES NOT get better mileage than a stick... so in electrical vehicles I find the same principle to apply. An automatic may work for whoever, but the question is simply when you are trying for maximum efficiency it is wiser to go standard transmission. An NO it isn't because some of us have enough trying to get our head around the building of an EV... I gutted my front-end and converted my Toyota (clutch, tranny, drive axles and shock towers,.. and put in a standard. (of course I ditched anything and everything related to the conveyance of gasoline, exhaust or what ever was ICE as I was at it...:p)
I didn't find any 'slack' in the standard transmission it is just go or don't... hit the foot-feeter on your slushbox I bet you will notice a 'whir' of the engine prior to engagement of the gear...
Now this is all just my opinion and experience.;)
to all,

I repeat my earlier to the nay sayers;
People who choose an automatic transmission generally do it knowing that there WILL BE a performance price for the convieience of an automatic.

It's no different with EV's or an ICE. If you want the automatic, you go into it knowing you will pay a price.

For those hobbiest who want to squeeze out the last erg of power for that last inch of distance, a manual or direct drive may be best (the jury is still out).

The problem is that some of these techno wonders that have been built require a bit of time (got to rent a flight simulator) to learn how to drive and verge on the edge of unsafe. E.g. skinny, hard tires at the limit of GVW, with the weight bias all bas akwards. This is fine for those who want it and are willing to live with it, but the average Joe just wants to get in, turn the switch and go.

For those who, within current battery and motor technology, can bulid/buy a vehicle that will go their needed distance and who want a silent, convieient, just get in and drive EV, an automatic may be the better way.

There is room for both. and who knows, the people working with automatics MAY just find that magic bullet that helps us all.

One REALLY BIG reason for this thread is that the vast majority of vehicles built over the last few years are automatics. If the hobby conversion people and the performance people want a modern, good handleing, safe, comfortable vehicle they may just HAVE to go Auto.

For those of us looking for the last bit of performance, being ECO friendly is nice, but remember the first electrics were mostly luxury vehicles. People just built/bought the vehicle and battery that did the job they needed done. We all should do the same, build what fits your need, trading usefull information from both sides of the coin.

Just my thoughts.
 
#81 ·
Actually, there are a couple of autos on the market that are rated for damn near the same mileage as the stick version of the same car. The difference is 1-2MPG at most. Personally I'd rather have a stickshift but the 'ol lady can't drive them and refuses to learn, so I have to work around that.
 
#82 · (Edited)
Actually, there are a couple of autos on the market that are rated for damn near the same mileage as the stick version of the same car. The difference is 1-2MPG at most. Personally I'd rather have a stickshift but the 'ol lady can't drive them and refuses to learn, so I have to work around that.
Telco
You sound like the guy they developed the dual shaft, sequential autosticks for. I'm not talking about an auto stick mod to an automatic.

This is a real automated sequential manual gearbox. Put it in drive and the computer shifts for her. You get in hit sport and it's instant formula 1 paddle shifted sequential fun.

You owe youself a drive in one of these things.

By the way you can find them at your local VW store for one place. I think VW calls it DSG for dual shaft sequential gearbox.

It has two shafts with alternate gears e.g. 1st, 3rd and 5th on one and 2nd, 4th and 6th on the other. Each shaft has a motorcycle type hydraulically operated multi disc basket clutch, they alternate back and forth. They are a real trip.
 
#86 ·
I love this thread and will review all posts tonight after work. I too have noticed the soundness of the concept. As a controls and integration type I want an pump, AC motor, and VFD that is independent of the traction motor. A pressure sensor on the transmission fed through a A to D converter allows me to integrate pressure control into a feed back loop to the pump motor VFD. The pressure regulators in the transmission would then be redundant and in some cases could be rendered inert. Logical linkage to the u-P controlling the main AC drive allow pumping losses to be minimized big-time.
The torque converter is an uneeded weight and can be easily deleted. Back in the day drag race transmissions used a manual clutch with a simple drive clip that drove the front pump with dogs that hooked over the clutch pressure plate levers. (ClutchFlight)
The TH-200 in my donor vehicle has a steep low gear allowing me to use a smaller, lighter invertor duty rated main traction motor with a free running speed of about 3,500 RPM when driven with 60 Hz. These AC motors are most efficient when driven at or near 60 Hz. The automatic allows this efficiency to be realized. Many of these motors are available in a C-face mounting configuration making the fabrication of a bell-housing mounting adaptor easy for the average machinist. By cutting a port in the bell housing one can drive the pump with a timing belt to the pump drive motor with very low losses.
Some of you have read my other posts advocating the use of a Parallax Propeller chip to control an EV. The cog laydown for this application would be as follows: Cog 0-supervisory (driver inputs and road speed), cogs 1 through 6- main traction motor IGBT control, cog 7-transmission pump motor speed/pressure control. There you have it!
 
#89 ·
fugdabug,
with all due respect to a fellow EV enthusiast I don't follow the logic of coming into the thread dedicated on how to do an auto conversion with obvious predisposition against it. If you don't like it and don't want it, fine, post in the thread below where people discuss why NOT to do an auto conversion. How does anything you said in this thread help people who want to do an auto conversion? Do you honestly think we are stupid enough to have made this decision without weighing all our options?

Yes, forum is all about back and forth communications like you said, but there is certain behavior code where you don't come in like a bear in a china shop into someone else's conversations. Pretty much the only thing you contributed in this thread is that auto is less efficient than manual, duh, we already knew that, its been said by thread starter right from the beginning. Its not about efficiency of auto vs stick at all... its about using auto transaxle as efficient as possible WHILE achieving other primary goals.

Sorry, I really tried to stay away from making this comment, but just couldn't keep my mouth shut anymore :)
 
#96 · (Edited)
Hi, I'm new here (used to be over at the yahoo diy EV group) and I've read only the first 50 posts in this thread so excuse me if I repeat a question. The only ATs I'm familiar with is the old iron Powerglide in my '55 BelAir, the newer alu Powerglide, the TH350 and the TH400.

The latter three requires a vacuum signal from the intake manifold, without it the trans never upshifts. Can any AT be used or just some types that don't require a vacuum signal?
 
#98 · (Edited)
Really I don't see the real need for a torque converter either. The main purpose for a torque converter is to allow an ICE to run when the vehicle isn't moving. It's not a requirement for an electric motor which can spin freely with no power applied and does not have to run when the vehicle is stopped. In other words, the torque converter is required for the ICE, not the transmission. The only reason the torque converter drives the tranny pump is packaging, since the ICE requires it anyway they made the TC run the pump. You can actually modify an auto to use a direct drive from the engine to the tranny pump by reworking the fluid passages a bit, in fact I'm pretty sure that torque converter adapters like this are already made even though I don't have a source. It would be better to build an auto EV with electric accessories rather than to use the EM to drive the factory ICE accessories anyway, or at least run the ICE accessories off a separate drive motor.

El Rayo, a transmission that uses vacuum modulation would just need a way to duplicate the vacuum in order to operate properly. It shouldn't be too hard to use a vacuum pump to provide the vacuum, then use a throttle position sensor to control a vacuum bleed solenoid. On a vacuum modulated transmission, the more vacuum is applied the lower the shift point. The vacuumm modulator (at least on a TH350) is controlled via a set screw inside the vacuum line port so the shift point vs vacuum inputcan be adjusted, and a linear bleed solenoid would allow you to control the shift point with the vehicle throttle. It would take some calibration to make it work correctly, but it's very doable.
 
#99 · (Edited)
It would be better to build an auto EV with electric accessories rather than to use the EM to drive the factory ICE accessories anyway, or at least run the ICE accessories off a separate drive motor.
Absolutely agree with your statement, it would be better not to have TC and run accessories off a separate motor. The question is how much better? How can we quantify the cost and efficiency difference between these two approaches and then look at the bottom line and say, this was really worth the trouble, or not ?

I am really playing devil's advocate here, don't get me wrong. This is my second EV, in my first EV I used electric PS pump and gave up the AC because it was a convertible roadster. I know how much energy the PS pump takes and have pretty good idea how much energy AC takes, and losses associated with belts and pulleys, etc. If you really lay down a good plan on how to drive these accessories with separate motor, then consider the cost, complexity and additional weight of everything you have to add to make it work, also don't forget that room is very limited and 1-2 Hp electric motor is not that small. Then you look at all of this from the distance and you start thinking, maybe, just maybe, I should have just used the main motor?

As for TC, the only reason I kept it other than my decision to idle the motor, is that I am not the machinist and not transmission expert, and don't have any friends who are. I don't have means to adapt EM to tranny without significant investment, and I am not comfortable with major deviation from OEM fluid path and volume, since I don't know possible long term consequenses of such mod. I'm sure in racing world all these things are possible and easy, but they probably don't use same transmission for 10 years without major overhauls, but I am building a commuter car and intend not to fix it anytime soon.

Sorry for long winded post, all these things somehow make sense to me, but I will be the first one to come back here and admit what an idiot I am when my EV fails miserably to meet my expectations :D . Also, I am not trying to convince anyone to follow my path, in fact I would love to see all these other ideas implemented in other EVs so we can compare our results.
 
#100 · (Edited)
Well, I suggested using an electric motor to drive ICE accessories because it's been done. A better way, although more costly would be electric accessories to begin with. I wouldn't think there would be that much of a difference on cost, but there would be a huge difference in battery costs when the power needed to run accessories part time is compared to the power needed to run inefficient ICE accessories off the main drive motor.

On the torque converter: The shell of the converter connects to the engine and the transmission pump. The input shaft of the transmission connects to the internal vane inside the converter, only. There's no physical connection between these parts. When the engine spins the shell, the fluid inside will spin with it, which pushes on the vanes inside the TC, which spins the input shaft of the transmission. To convert the torque converter over, you would have to split the shell, then cut the input shaft connection off the vane assembly. This would need to be welded to the shell of the converter so that the shell of the converter spins the input shaft of the converter. Next, since you no longer need all that fluid for the engine to spin the input shaft, the body of the torque converter is no longer needed. So, you can build an adapter to connect the EM to the modified input shaft. The unit will also need to be sealed so that fluid will not leak between the modified torque converter and the transmission. So long as fluid can circulate between the modified TC and the input shaft, the transmission will have no idea that there is not a torque converter present anymore, so the transmission will need no modification. The only negative, is that the EM will need to spin a bit before the car takes off, so there will be some lag between throttle and movement. This is because the transmission will still need the fluid to be pressurized before the tranny guts start working. But, as the torque converter is the major source of heat in the transmission, removing it means everything will work cooler. You might not even need a fluid cooler anymore. Once the piece is finished, it would be an excellent idea to balance the unit. You also have to pay attention to centering the input shaft to the shell.

NP with the devil's advocacy, it's a lot better to poke holes in a theory with words than to wait till you've invested time and money to find out something that doesn't work. It's a lot easier to fix a problem with a pencil than a welder.
 
#101 ·
Howdy All,

Thought I would step back in for a while with some positive and negitive comments.

I myself would run without a torque converter and use an auxilarry pump that runs only at dead stops to maintain pressure. Early on there was talk of using an accumulator to do this but there is one thing that was never covered. Where does the fluid from the accumulator go that is used to maintain pressure until the pump starts running again. A three quart accumulator could put enough extra fluid in the pan to flood the body and cause foaming when the trans shafts starts turning and splashing around. Foam is a NO-NO in an auto (ask me how I know).

There was also mention that the transmission might hold pressure by itself. I don't know about the very newest transmissions, but older transmission clutches had bleed off check valves in the clutch body that dumped pressure to allow faster clutch release. If anyone knows about the newer transmissions, now is the time to inform us about them. I would be interested in how they dump pressure for clutch release myself. (getting lazy in my old age and not keeping up like I used to)

Telco it's much easier then you think to make a coupler. Check with TCI tranmissions and some others race transmission builders, they make converterless couplers for powerglides and others transmissions. Circle track racers use adapters that completly eliminate the TC. One reason they use these converted transmissions is an automatic can be lighter and stronger than a manual, when properley set up. (before every one screams, I did say PROPERLY SET UP).

Now some positive comments on reasons for keeping the TC. As dimitri says, it's a lot easier to keep it in the trans even though it is heavy. Then just idle the motor at stops, You would need to find out what rpm/voltage/amprage combination it takes to keep the trans under pressure and give a slight creep on flat ground. Then you would make/modify/design and build a control unit to supply that power with a fully released throttle. The trick here is to minimise TC slipage on take off by engageing the TC clutch as soon as you can when coming "Off Idle" and do this without overloading the TC clutch with too much torque form the motor. This will eliminate a lot of the comments about power wasting slushboxes. With the properly timed, positive, fast shifting found in automatics it might even equal surpass the maunal in OVERALL efficency.

Maybe one really nice feature to keeping the TC is hill climbing. (You all check me on this, maybe my logic is faulty.) I think that as the motor loads down and before a transmission downshift if you release the TC clutch and let the TC go back into slippage mode (Torque Multiplication) turning rpm into torque. The motor would speed up into a more efficient rpm range and you would still get the torque needed to climb the hill without pulling big amps and heating everything up. What do you all think, am I on to something or am I all wet?

I can think of a number of ways to use the TC clutch in regen and the TC and pump for hill retardation and motor overspeed control. I bet you all can think of a lot more ways to do other things.

Turn what are thought to be negitives of an auto into positives. I'm very impressed with how you have all run with the transmission ECM programing and blending it into EV control needs.

Keep it up, I'm haveing a ton of fun watching you guys develope this stuff.
 
#102 ·
Then just idle the motor at stops, You would need to find out what rpm/voltage/amprage combination it takes to keep the trans under pressure and give a slight creep on flat ground.
Why do you need to create creep? That seems just like wasted energy. Why not just give enough RPM's to keep enough pressure to eliminate transmission lag when you hit the throttle?
 
#104 ·
Rather than "creep" requiring the brake to be applied and the TC to slip, couldn't we accomplish the same thing by a trigger attached to the brake "fully released" position ? If resting your foot on the brake pedal stopped the motor, but taking your foot off the pedal immediately powered the motor just enough to prevent the vehicle from rolling backward or forward ? This should be a simple function to build into a controller -- increase amps as long as vehicle transmission is in gear and the motor is being forced to turn the wrong direction, until the motor is getting enough power to hold the vehicle in position.

I had to qualify that "direction" part since the other scary situation is when you are trying to reverse up a slope. I don't know about other states, but in California, if you meet another vehicle on a steep single-lane road, the vehicle headed downhill is the one that must reverse to allow the other guy to come through. Pretty scary footwork with a manual transmission, but a piece of cake with an auto that "creeps" enough to hold vehicle position even before you get your foot over to the accelerator pedal.
 
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