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I took the motor in to an electric motor shop, and they popped the hub off as easy as opening a pickle jar! They didnt even need to heat it up. They would have been willing to do it for free, so I was back on track for just a morning spent driving around and some beer money for the very helpful guys down at Advance Electric Motors.
:)

I had measured the critical distance as 21.2mm when I took the motor apart - now I am getting 22.3mm. How precise should I strive to be here?
I would only be concerned if this causes the transmission input shaft to bottom out in the adapter.

It seems like it is generally recommended to have the flywheel resurfaced anytime you have it out of the vehicle, anyway, so should I have it shaved down by about a mm to get closer to my original value? Also, is there any value in having them mill off extra weight, like the gear teeth, for example? I might also put in a new clutch disc, as the one in there is getting pretty close to needing replacement (I think).
Since a clutch lasts at least half the life of a car, I've never replaced a clutch disk more than once... and not resurfaced the flywheel except in the one case that we were also lightening the flywheel.

Also, is there any value in having them mill off extra weight, like the gear teeth, for example?
Yes, although it's certainly not necessary when you have a clutch. Flywheels exist primarily to add rotational inertia; mounting the clutch is secondary. Flywheel inertia smooths out the pulses of an engine, and makes it easier to start off from a standstill without stalling; neither of these applies to an electric motor. Flywheel inertia just stores kinetic energy, making the car behave as if it were a bit more massive when changing speed.

Even with an engine the flywheel is routinely far heavier than it needs to be: I had half the weight taken out of our Honda's flywheel when preparing it for competition, and it still wasn't rough or hard to drive after that.

The ring gear is commonly a shrink-fit on the flywheel - in that case, it can be removed without machining work, and makes a significant contribution to interia.
 

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Discussion Starter · #82 ·
I would only be concerned if this causes the transmission input shaft to bottom out in the adapter.
I am measuring the gap on the engine/adapter plate side, so since the distance has gotten larger I am assuming the tip of the transmission input shaft will have less engagement if anything, right? I am starting to think I might just plan on assembling everything as-is. I am not really going to be using the clutch very much anyway, so it should be fine at least to get this project rolling.
 

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I am measuring the gap on the engine/adapter plate side, so since the distance has gotten larger I am assuming the tip of the transmission input shaft will have less engagement if anything, right? I am starting to think I might just plan on assembling everything as-is. I am not really going to be using the clutch very much anyway, so it should be fine at least to get this project rolling.
I apparently misunderstood what you were measuring, but if the flywheel and transmission are further apart than intended then I wouldn't worry about one millimetre. The engagement of the input shaft into the pilot bearing, input shaft spline space available for the clutch hub to slide on, and clutch fork travel required disengage the clutch will all be affected... and none should care about that one millimetre.
 

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Discussion Starter · #84 ·
A picture is worth a thousand words. Two thousand words if, like me, you dont really know what you are talking about :)



I measured distance A, from the front face of the flywheel. That gap got bigger, so the whole flywheel is now about 1mm closer to the trans. I see now that my last response probably didnt make any sense, as I was thinking that moving the flywheel would somehow hold the input shaft back, which it wont.

So your original point is valid, the shaft will insert an extra mm, but there is quite a bit of clearance from the back end of the pilot bushing to the shaft of the electric motor. I will measure that depth and compare it to the length of the pilot shaft on the trans - but I think it will be fine.

I borrowed an alignment tool, and started getting the flywheel put back together. I inspected the ring gear more closely, which did reveal that it was press fit on. There is a lip on the top surface - the ring presses on the from the rear, so from above it looks like the teeth are machined into the actual flywheel. I used a torch to gently heat it, and it tapped right off. It will save me a little weight out at the very edge of the flywheel, and get rid of all the sharp edges, so seemed like a good idea.

I am just about ready to mate the two halves together to be hoisted in. I will probably have to wait until next week for the install when I have an extra set of hands (and feet) to get it in place and bleed the clutch. Thanks for all the help with the "car stuff," I am looking forward to being back in my element with the last of the wiring!
 

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Discussion Starter · #85 ·
The flywheel is all assembled now

I was able to simply pick the transmission up, and just set it down on the motor, so it was really pretty easy to get them together. Its now ready for installation!

I forgot to check the shaft clearance, but since it went on there, I am guessing it did not cause a problem :). Oh yeah, and I did eventually hear back from the motor supplier. They said that the motor can be supported only from the face, as long as the transmission is mounted in such a way that it can resist rotation. They also said that it was not a problem to mount the back end, and even sell a clamping band that looks like a much less crude version of what I built.

As the guy building the custom mini with a hyper 9 system pointed out, the CAN EV adapter plates seems to turn the motor to a weird orientation - I would have preferred it have had the wiring at the 12 o-clock position. Also, If you mount the controller above the motor, the 3 phase wiring studs are reversed from the motor, so the cables need to cross over each other. Seems almost like the intended position for the controller was behind the motor.
 

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Oh yeah, and I did eventually hear back from the motor supplier. They said that the motor can be supported only from the face, as long as the transmission is mounted in such a way that it can resist rotation.
A clamped-on support won't help with torque - all of that must be done by whatever is bolted to the motor's mounting face. In this case, the rotational constraint (torque reaction) is provided by the cradle and the engine mounts, which is fine, although I'll note that the torque is the motor torque multiplied by the gear ratio of whatever gear the transmission is in - it's substantial.

The cradle isn't really designed for torque - ideally it would be better with diagonal braces on each side of the cradle, to lower on the adapter plate. Sorry, I should have mentioned that before it was painted...
 

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Discussion Starter · #87 ·
The cradle isn't really designed
Haha, its sure not :)

I had not realized that the gear ratio would multiply the torque, but I guess that makes sense. The motor is rated for 173 ft-lbs, and if I plan on driving it in third gear, the ratio is 1.67 (I think). So thats about 290 ft lbs, which is acting around an approx 7" radius, So there should be 168lbs of force acting on the cradle, or 84lbs per side. First gear would obviously be a lot more, putting almost 300lbs per side - but doesnt this assume full throttle?

As far as fortifying the structure goes, there isnt a bolt hole farther down the adapter plate, that is the lowest one. Since I am not really capable of designing it to resist some given force anyway, I am pretty much limited to trial and error. If I see broken welds, I will simply have to redo it, I suppose.
 

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I had not realized that the gear ratio would multiply the torque, but I guess that makes sense. The motor is rated for 173 ft-lbs, and if I plan on driving it in third gear, the ratio is 1.67 (I think). So thats about 290 ft lbs, which is acting around an approx 7" radius, So there should be 168lbs of force acting on the cradle, or 84lbs per side. First gear would obviously be a lot more, putting almost 300lbs per side - but doesnt this assume full throttle?
Close... if you're driving a shaft (or turning a wrench) you use the radius and get 290 lb-ft of torque divided by (7/12) ft of lever length or 498 lb of force; if the motor and transmission were mounted by bearings around the input and output shafts and all that kept the case from spinning around was an anchor 7 inches from the shaft centreline this would apply and there would be almost 500 pounds of force on that anchor, tangentially.

In this case you are supporting from two points so if they are 14" apart that's 290 lb-ft of torque divided by (14/12) ft lever length, or 249 lb of vertical force on each side (one side in addition to that mount's share of the weight, on the other side pushing up against the weight). Yes, first gear would be about double the torque (depending on your gearing).

Yes, that's all at maximum motor torque, which you will only see at low motor speed and full accelerator setting. You should be able to set a lower current limit in the controller if this is too much for your structure; ideally there would be a current limit for each gear but of course the controller won't have this and doesn't know your gear selection anyway.

Motor mounts are no joke. 😮 Have you ever seen a drag racer (with live beam rear axle and suspension, not a rail dragster or funny car or anything with independent suspension on the driven wheels) twist as it lifts the front end at the start? That's all reaction to transmission output shaft torque, transmitted through the engine mounts, then the vehicle structure, then the rear suspension. They routinely lift one front wheel off the ground and unweight the opposite corner rear tire enough that without a locked differential that tire spins.

As far as fortifying the structure goes, there isnt a bolt hole farther down the adapter plate, that is the lowest one. Since I am not really capable of designing it to resist some given force anyway, I am pretty much limited to trial and error. If I see broken welds, I will simply have to redo it, I suppose.
That's not surprising, since there is only engine block to bolt into from roughly the crank height and up. The alternative is to brace upward - it doesn't matter which way you go. Basically, those small triangular gussets on each side should just be larger, spanning the whole height between the two bolts used on each side, and extending horizontally as far as practical.

The cast aluminum adapter plate is pretty substantial, so even though there is no bolt to the transmission near the bottom a brace could still go to the plate.

Of course most people build their transmission and motor mounts with little understanding of the forces involved, and seem to generally get away with it. :)
 

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Discussion Starter · #89 · (Edited)
Yeah, I suspect it works just because of how incredibly strong steel is. I started looking up some numbers, not so much to prove anything, as to satisfy my own curiosity. So starting at the bolts on the motor mount:

5/8" Grade 5 bolt: 23,000lbs of shear strength (times 4, because there are 2 planes on each side.

One mounting tab welded to the square tube: 1.25" of weld on each side(x2), 0.125" wide and 60,000 psi tensile strength: 18,750 lbs

The square tube I am not so sure about, but it is 5" in circumfrence, and .095" thick, so it has a cross section of .475 inches. If its yield strength is 36000psi, that would take 17,000lbs for it to start deforming?

Obviously, there are going to be some big forces acting on this frame, but I am starting to suspect that the transmission would give out before the frame did. This motor is actually about 25% (?) stronger in terms of torque, is that going to be an issue I should think about?
 

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The square tube I am not so sure about, but it is 5" in circumfrence, and .095" thick, so it has a cross section of .475 inches. If its yield strength is 36000psi, that would take 17,000lbs for it to start deforming?
In straight tension, yes, but this is a bending problem. You can easily break a small stick of wood by bending it, even though you can't pull it apart.
 

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Obviously, there are going to be some big forces acting on this frame, but I am starting to suspect that the transmission would give out before the frame did. This motor is actually about 25% (?) stronger in terms of torque, is that going to be an issue I should think about?
Yes, transmissions are normally rated in terms of input torque... but it's probably not a problem at this level, and you're not going to sustain maximum torque for very long.
 

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Yeah, you're confusing the tensile strength with the bending strength. Which is what we're looking for here. Simple flanged mounting points are usually are made of much thicker material than the wall thickness of the tubes they are attached to. There are typically more bending forces on and movement of the flanges than on the walls of the attached tubing. The walls of the tubing are typically further away from the neutral axis of the tension and compression forces -so less bending forces on and movement of the tubing. The gussets, as you have added, can help. As brian wrote, yours look a bit weak.

As one alternative design, what about using lengths of angle iron that pick up all three transmission plate attachment bolts, on the passenger and driver sides of the adapter plate. It looks they line up well enough so the angle iron doesn't have to be too wide. Are you using 1 1/4" square tubing? Use 2" X 2" angle iron. Maybe 2 1/2" X 2 1/2", if needed. Face the angle iron out so there is easier access to the plate attachment bolts. Use angle iron with a flange thickness 2-3 times the square tube wall thickness. Say, 1/4" minimum thickness. Some gussets between the tubing and the flange of the angle iron, similar to what you have done, would also be a good idea.
 

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Discussion Starter · #93 ·
Yeah, actually designing something like this is likely way out reach of your average do-it-yourselfer. I realize that beam deflection is going to be a whole other beast (I did use a much lower value than the tensile strength, which is likely closer to 80,000psi?) Another quick search did turn up a deflection calculator:
I plugged in 1.25" steel tube of .095" with a beam length of 20" (its maybe about 10" from the plate to the motor mount) and a load of 1000lbs (full torque in 1st gear, and then some for good measure) with the ends fixed. The deflection would be about 0.0143 inches. All of this is very speculative, and does not take into account the fact that the angle iron will also be resisting the bending force, or that there is a beam going between the two arms at the front.

The gussets and the plates are made of 3/16, so they are fairly sturdy, if somewhat undersized

I will say that I am feeling pretty confident in the design. Its probably not very optimized, but it contains an awful lot of steel :). I dont think it could fail catastrophically, and it should be fairly easy to keep an eye on it for any signs of fatigue.
 

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Discussion Starter · #94 ·
Okay, the guy who was going to give me a hand got delayed at an appointment at the DMV (shocking, right?) but I did manage to hoist the motor and trans in myself. The stupid gear-shift lever is annoying, and the motor mount bolts needed a little persuading to line up.

I ran out of time, so I have a few loose ends to wrap up. I am going to double check that my drive-shaft angles are passable, top off the oil, and fish out the nut that I dropped inside the frame somewhere. I plugged the clutch back in, but I am not sure how to test and see if it is working without someone else there. I need to bleed it too.

Anyhow, there will be a bunch of wiring to do now, which will be a nice change of pace. I am tempering my expectations of "I could be driving this thing in X more work days!" Partly because it always seems to take 2X days longer than I thought, and also because I guess with Covid, the delay in getting registration and plates from the DMV is something like 18 WEEKS. I have tried to call and talk to someone about what I will need to do to get it street legal, but the hour hold time has put me off. I might just get a trip permit and drive it like that for a while, I guess they are not enforcing expired trip permits. Might not help if I dont have plates, though? I dont know. Hopefully by summer things will be settling down.
 

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I love that motor - it's so small compared to an ICE engine.
Sure. But the battery (which does the real work of converting stored energy to something useful) is so large and heavy compared to a fuel tank. It really doesn't make sense to think of an electric motor as a direct replacement for an engine; the combination of battery and motor is almost comparable to the combination of fuel tank and engine.
 

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Discussion Starter · #97 ·
the combination of battery and motor is almost comparable to the combination of fuel tank and engine.
Man, you are really going after the concept of equivalence of late, did you just finish reading everything ever written about logic, or something? :D

But yeah, the engine bay feels cavernous with the ICE (and all its hangers on) gone. It will get a little more cluttered as I finish up the last components, but it will leave lots of room to turn a wrench. One project I am going to try and tackle is removing the entire front suspension for an overhaul. The rubber on the control arm bushings looks pretty cracked, and all of it could probably stand to benefit from being sandblasted and repainted.

When I got the truck, there were some tattered remains of some sort of splash-guards that covered the gaps under the fenders. I have been trying to find replacements, but without much luck. Are they called Gap Guards, maybe? And can I make my own? The guy at the motor shop mentioned something about the bearings not being sealed, so I am thinking I am going to try and make some sort of shroud to keep the back end of the motor from getting splashed.
 

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Discussion Starter · #98 ·
I got a little work done on my high voltage stuff today, and it is starting to come together.

I cut the conduits to length for my main power leads, and have spray painted them orange. Once they are dry I can get the 2/0 cable run back to my main contactors. Up front the big contactor is for the controller, and then 4 smaller ones will run the cabin heat, DC-DC, precharge circuit, and coolant heater. All the high voltage negative wiring is split off into the smaller box on the side. I was hoping to be able to keep all the wiring nice and neat, but I suspect its going to turn into kind of a rats nest when all is said and done.

Got the clutch bled today too - the fluid was very dark, so I wound up cleaning out the reservoir and flushing quite a bit through to try and clean it up some.

Anyway, lots of fiddly wiring to do now, but I will keep chipping away at it... I need to sit down and read over the manual for the X144 controller and figure out which of the wires I will need, and which ones I can ignore for now. Its a rather daunting looking wiring harness!
 

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Discussion Starter · #99 ·

Main leads are in place, so I am wired up as far as the controller now. I still need to make the engine leads, and then I can start in on the big controller wiring harness. There will be a bunch of detail work to do, so I suspect this next part is going to take longer than I think. Still, It feels like the end may be in sight. I am excited to get my controller fired up so that I can finally see these tires move under their own power!
 

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Discussion Starter · #100 ·

Made my motor leads today - I am annoyed by the way the controller is laid out. I wish they had swapped the layout so that the leads were not all twisted up. Maybe there is a technical reason to do it this way? It seems like it makes the logical configuration of having the controller above the motor harder to wire up neatly.

I pulled my high voltage wiring for the DC-DC converter, and the coolant heater (which is not installed yet). I realized today that I have the wrong size of fuses for my fuse-blocks, so I will need to get the right ones ordered before I can test anything.

I also checked and labeled all the wires coming out of the main harness - someone had mentioned they got one with a few mixed up colors. Everything checked out, though, and it is looking a bit more manageable with all the wires I am not going to use set aside. I have probably at least another mornings worth of wiring to do, but then I will be ready to bring the controller online.
 
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