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Drivetrain: My biggest question right now is whether or not to use the stock tranny. I really like the idea of direct drive and the advertised Hyper9 specs seem to suggest it would work (as well as several threads on here). Is this reasonable or should just run the stock tranny for the near future?
Can you fit the HyPer 9 into the transmission tunnel, where the transmission is now, without structural modification? If you can, the gain of space in the original engine location for battery modules would be a significant advantage; however, if it doesn't fit there and has to be forward of the firewall then saving some weight would be the only benefit and you will be limited in torque to the wheels by not being able to use a lower gear.

For those that have done direct drive with the Hyper9, how is performance?
At this time, I think you'll be lucky to find anyone who has even completed a HyPer 9 build, let alone one without a transmission and in a car of comparable size to the Spitfire for a useful comparison.
 

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The conversion:
Car: 1976 Triumph Spitfire 1500 (running!) with 3.89:1 final drive
Have you seen any of the Spitfire conversions in the DIY Electric Car Garage? The Garage has been non-functional for a while, but pages are available from the Wayback Machine. Here are a few:
If you're interested, there are more and I can extend this list.
 

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From what I've read, I expect that the Hyper9 will fit about 9in back into the transmission tunnel. I haven't removed the old engine/tranny yet, so I can't say for sure. That said, I could easily modify the transmission tunnel if it was worth it.
Getting the motor right out of the engine space would be nice, but all of the Spitfire builds that I've seen retain the transmission. The tunnel itself is one thing, but I would wonder about clearance between the frame rails. With the motor dimensions available, and the car in the garage, it should be easy to check.

Any suggestions on BMS or what I should be looking for?
Not my area, but I'm sure you'll get suggestions, widely varying in approach. ;)
 

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I've seen several of them, but I haven't been through the garage (it not working explains why I haven't found it!). I've read through Molten's thread twice as well several others that showed up when I searched "triumph" or "spitfire".

I've also looked on EVAlbum.com where there are ~12 spitfires. The common trend I've seen is LiFePO4 "brick" batteries and DC motors. I think this is mostly because they were done before AC was common and Lithium was put in production vehicles, but I could be missing something.
Yes, the longer list of Spitfires in the Garage here shows a trend over time from lead-acid, to individual LiFePO4 prismatic cells, and just starting into salvaged production EV modules. Similarly, older builds are all DC, and some newer builds are AC induction (while DC builds continue); aftermarket AC PM motors had not appeared until this project, and I haven't seen any salvaged production EV motors or drive units yet.
 

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Rather than assembling a longer list of previous Spitfire projects, I'll attach my spreadsheet as a PDF file. I would just put it in this post as a table, but vBulletin (at least as implemented in this forum) doesn't do tables.

And in case anyone is wondering why I have this spreadsheet already lying around... what brought me to this forum is that we have a Triumph Spitfire with a dead engine. I have an extensive list of potential engines to swap in, but an EV conversion was another option. It may still happen, someday...
 

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I'm very interested in Bottomfeeder's Sparkfire. It looks like the only one that's known to have went direct drive. I just found the thread and hope to get through it tonight.
Good catch - I had forgotten about that one that eventually eliminated the transmission. The story of his switch to "direct drive" was in a post in another build thread (Planning a new ev from a triumph spitfire - post #16). It was a late change, and I don't think it appears in his build own thread at all.

Sparkfire appears twice in my spreadsheet, to represent the initial and later versions.

Any other nuggets of insight?
My conclusion was that the Spitfire is an antiquated and flawed but fun package. Everything in it can be improved, but if you go down that route you have built a new and different car, so why start with a Spitfire? For instance, by the time the suspension is fixed and structure is improved it might as well be a Miata... and just buying a Miata would be cheaper and easier. The optimal compromise for me would be a powertrain replacement with as little effect on the rest of the car as possible, which means a transition between new stuff and old at either the input to the final drive, or the input to the transmission. What follows from that is that there is no point in trying to produce more torque than a well-prepared original Spit would have... not much more than 82 lb-ft into the stock transmission, or the corresponding stock non-U.S. input to final drive of 287 lbf-ft | 389 N-m @ 860 rpm shaft speed (first gear @ 3000 rpm engine speed). I also have little desire to do bodywork, so battery packaging into existing spaces would be a major issue and would lead to a moderate range... especially since I would refuse to stack cells in the nose or tail, to avoid ruining the vehicle dynamics.

But hey, that's just my thinking, and I haven't built it yet. :D
 

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As for you comments on the spitfire in general, I completely agree and I think you hit the nail on head about some of my concerns. I chose the spit because of the styling and availability. I paid $2500 for a running spitfire with a clean body. I worry about the rear suspension, but at the same time my only intent is to use this to turn heads and drive the 12 miles each way to work. I'm not looking for crazy performance and I don't ever plan to run autocross with it. I just want it to be fun to scoot around town in. This also lets me get away with an approx 10kwh pack, which at ~250wh/mi, should give me a 30-40mi range.
That all seems reasonable to me. I would add that running an autocross (assuming you mean a pavement autoslalom, not a rallycross type thing!) is reasonable, too, since the "swing spring" design of the later Spitfire suspension calms down the swing-axle silliness. As long as you limit the torque to a reasonable level, pushing it around a course shouldn't be a problem for the car.

While searching to confirm that the 1976 would have the swing spring, I ran across an online discussion in which a Spitfire owner was proposing rear spring changes (to an earlier variant). A wise participant noted this:
The thing about a Spitfire is by the time you're putting down enough power and have enough traction that the spring rate is a concern, you have much more important things to worry about, like the differential, u-joints and axles.
This goes well with my thinking, that keeping the power - and the tires - reasonable means that you don't really need to worry about a lot of other things, in both drivetrain and suspension.

Going with the Hyper 9, I do worry about blowing up the final drive/tranny. I'm almost certain it would destroy the tranny if I let it loose. That's another reason why I'm leaning toward going straight to direct drive. It looks like the final drive should be able to handle the 1:1 ratio torque (173ft-lb advertised peak vs your stated 287ft-lb stock load). Using the tranny may actually be bad in that regard as it would also allow over-stressing of the final drive in lower gears.
You could program the controller to limit the current (and thus torque to the transmission and subsequently the final drive), which wouldn't take full advantage of the motor at low shaft speed, but wouldn't change high speed operation. Eliminating the transmission is an obvious solution, which wasn't so desirable with typical 9" DC motors but more feasible with the HyPer 9; however, it is effectively like driving in 4th gear all the time, while the final drive could withstand 3rd or even 2nd.

I did some more looking at the Hyper 9 specs and I think direct drive should work nicely. I sacrifice a little efficiency at low speed (<~20mph) but that seems to be the only significant detriment.

Hyper 9 curves: http://www.go-ev.com/PDFs/HyPer_9_120V_Performance.pdf
Losing the lower gears means losing the resulting torque multiplication and the ability to keep the motor in a more efficient speed range... which as you say only matters significantly at lower speeds.

If you run higher voltage, you have the option of using the HyPer 9HV, which (if given enough voltage) can provide a broader range of speeds over which full power is available. On the other hand, given the stock tire diameter (22.8" and 914 rev/mile for a 155SR13), and a final drive ratio of 3.89:1, a mile per minute (60 mph) would be 3555 rpm... so maybe all of the area of power improvement would be at speeds you'll never drive anyway without a transmission or other reduction gear.

I think this is the core of the single-speed problem: with enough voltage a modern motor can work well over a wide range of speeds, but the range is likely to extend up to 8,000 to 12,000 rpm. That means one ratio is fine, but it should be a much greater ratio than a typical final drive contains; in fact, production EVs all use two reduction stages to get the desired overall ratio. There is one production EV motor which was designed to work with a ratio similar to the Spitfire's 3.89:1, and that's in the Chevrolet Spark EV. Unfortunately, that's not the most common EV motor, it might be difficult to run with a readily available inverter (and the stock inverter would require hacking), and it's large in diameter. A HyPer 9 is a more practical choice, even though its speed range doesn't match the available gearing well.

The other really effective fix to the motor/gearing mismatch is to add simple fixed reduction gear to the back of the motor, instead of the multi-speed transmission. This can make a relatively small motor effective, by matching its speed range to the operating speed range of the car. Unfortunately, that's not a trivial bit of hardware: the only one I'm aware of is the ev-TorqueBox, which is a bit of overkill and not cheap (US$3500).
 

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As with other modern motors, there are performance graphs for the HyPer 9 showing output over the full speed range of the motor, given various supply voltage limits.

For the same supplier's brushed DC equivalent (WarP 9 or another size), Netgain provides only those silly charts resulting from clamping a brake on a spinning motor, so there is only (questionable) data from free-spinning speed down to something near the torque peak. Is there any useful source of objective data for the torque (or power) output of a "forklift" motor over the speed range which is actually used in a car? Or do people just assume that the torque and current from stall to peak torque speed are constant at the peak values?
 

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Another reason why I've leaned toward the Hyper 9 is it is IP67 rated according to EVWest's page. But now that I look at literature on go-ev.com I'm not seeing any such claim. The only thing I've found is IP54 (limited dust intrusion). If it is in-fact IP67 then that will help a ton, because I am certainly concerned about moisture under the vehicle.
The HyPer 9 motor is made for Netgain by SME; Netgain is just the distributor (although EV West lists them as manufacturer). It is one of their "SRIPM" series. SME's web page for this product is a bit general, and I don't see any indication of the IP code rating, but you could ask them.

The more I look, the more I find wrong on EVWest's page for the Hyper 9. The motor curves they show do not match anything that I've found in other literature.
The more links in the communication chain, the greater the errors...

The motor performance graph shown by EVWest appears to be from Netgain, but is for 64.5 volts RMS at the motor or 96 V DC supply, which doesn't match the EVWest package description (of 120 V); it doesn't even look quite like the 96 V grapsh published on Netgain's website. The shape suggests to me that it might be for the HV motor, but it's not labelled that way and Netgain only publishes 120 V and higher for the HV. SME does not publish details for the specific motor which they supply to Netgain.
 

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Brian,

What you state is all that I've been able to find as well. At best I've been able to dig up a stall torque. Nothing about max RPM, efficiency, etc.
Efficiency is one of the data items in the performance charts for Netgain's brushed DC motors, but only for the speed range of the test. They only publish data for 72 volts supply voltage, but here it is in what I find to be a more useful form... but it's the same data as their graphs so it still doesn't cover most of the working speed range of the motor.
 

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I did just think of one other question on going direct drive. Will I need to allow for axial play between the motor and final drive? If I understand correctly, the TransWarp 9 has a slip-yoke spline for the U-Joint output to allow for some axial play. Will I need to devise something like this? I was hoping to just mount one of these below on the motor shaft and just hook directly to a custom length drive shaft. Allowing axial play will definitely be a challenge, but should be doable if needed. I'm just not sure if it's actually needed!

http://www.evwest.com/catalog/product_info.php?cPath=44&products_id=428
There will be some movement of the final drive in its mounting bushings, so there needs to be either some axial freedom in a component of the shaft, or some longitudinal compliance in the motor mounts. Vehicles always handle this in the shaft (not by having the shaft shift the engine and transmission), and I wouldn't to depend on motor mount compliance, for the sake of the motor bearings.

EV West may be counting on that compliance, or assuming that there is a plunging or slipping section of the shaft. Allowing the transmission output yoke stub to plunge is common, and what the TransWarP motors are set up to do; however, in some propeller shafts there is a slip joint (splined and sliding section of the shaft), especially in the rear section of a two-piece shaft (which has a support bearing midway between the transmission and the axle). The most straightforward way to avoid problems would be to use a slipping section of shaft with that fixed yoke on the motor.
 

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A sliding spline drive shaft sounds like the ticket for sure. Axial loading the drive shaft is just going to wear out U-joints.
I agree, but the rear suspension of a Spitfire carries all of the lateral load through the axle shaft U-joints... which seems to work.

Looking real quick online it looks like some Triumph drive shafts are the sliding-spline type. I'll have to see what mine has when I start pulling it apart.
I didn't even notice if our Spitfire has a sliding section; if it does, the problem is solved. :)

Worst case I think I'll just have to find a sliding spline drive shaft from a different vehicle that is the correct length. I still have no idea where the shaft of my motor is going to end up in the transmission tunnel.
Or get one made up, with the appropriate yokes; it's a routine service from driveline specialty shops.
 

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See attached first-version of adapter plates with diff (I've modified them slightly from this) Rear plate, Top Spring plate, and forward plate, which all pick up existing Spitfire mounting locations.
Good work. :)

The big thing is whether you decide to stay with the existing swing spring setup. If so, you must use the Datsun 510 diff which is exactly the same casing as Subaru diff, (not sure of ratio options) however the difference is the Datsun510 has bolt in stub axles which are required for the lateral load from the swing spring half shaft design. Adapter flanges required can bolt straight onto existing half shafts. The subaru/forester diffs use CV splined shafts held in with snap ring and can not take any lateral load.
I know a guy who is an almost obsessive 510 enthusiast, who has built many of them, with friends. As I recall he said a while ago that they now use Subaru diffs, because the Datsun hardware is now rare. That will vary by location, of course.
 
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