# Looking at this motor... What do you think?



## kennybobby (Aug 10, 2012)

NASA-tested!
https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19810020808.pdf


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## major (Apr 4, 2008)

Mschoen100 said:


> https://www.ebay.com/itm/PRESTOLITE...182649?hash=item366543e639:g:kSIAAOSw-9leXsxI
> 
> 
> Very interested in this motor. Anyone have an opinion?
> ...


Hi Mschoen,

I love that motor. I designed it, back about 1978 or so. For Jet Industries Electra Van. Small Subaru highway capable 4 passenger, 96V, 16 golf cart batteries and like the first mosfet controller for EVs (PMC I think). Jet Ind was in Austin, TX. Great motor in 7.2 inch diameter frame. Set up with factory brush advance, 4.5°. NASA did test it, see link from KB. They wired it opposite rotation from intended and no evidence they compensated for advance. So test results were not optimum. We did indeed verify 200 A continuous with forced air cooling.

After Prestolite production run and delivery, Jet switched to a GE 9" motor package with controller. Looks like seller ended up with excess inventory. Hell of a good price. She's a screamer at 100V but holds together. Could go higher voltage but limit to 6000 RPM. Even for a 40 year old motor, should be good to go right out of the box, with break in period. Careful of no load overspeed at full voltage. She'll accelerate like a banshee.

Nice find,
major


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## Mschoen100 (Jun 18, 2020)

That is so great to know! Who would've known that you would end up seeing these again! I will definitely jump on one then and let you know how she goes! I am putting it in my 1968 Fiat 850. Rear engine car so the motor would need to be counter-clockwise in rotation for drive, otherwise I will have many gears of reverse! ha! Also appropriate to have an era aged electric motor for a close in year car.

I do not plan to run this motor crazy, but as long as I can get to 65-70 mph comfortably to make the highway, I will be more than satisfied. Otherwise, this will be a Sunday cruiser for most of its life. No drag strips for me.

When you say 16 golf cart batteries I am assuming you mean the 6v size? I would like to use Nissan Leaf modules. I can actually fit 27 in the engine compartment above the motor. Perks of a low laying set up. That would give me just under 200v total. I Hope I can find a controller that can handle the 200 and bring it down to the 96 for frequent use without burning it up. 

What kind of controller did you say? I am new to this so the acronyms are tough sometimes haha. I also do not think I will be pushing 200A continuously, but I can easily hook up a temperature controlled fan to cool it if I do get to pushing that kind of amperage. Maybe I will though, still doing some math on these modules with the DC. I am no electrical person by any means, so knowing how to pick pieces that are strong enough is kinda hard for me. So, I do apologize for my ignorance on certain things!


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## Gigawatts (Aug 8, 2013)

At $180, that is super cheap for a new old stock 7 inch DC motor. It says C face. I assume that is smaller than the typical B face used on the Warp series and other 9 inch motors and the transmission adaptor plates for those.


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## Frank (Dec 6, 2008)

Is it a 4-brush motor?


Sent from my SM-T380 using Tapatalk


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## major (Apr 4, 2008)

Frank said:


> Is it a 4-brush motor?


No. 8 brushes, 1 × .55 inch face each. 33 bar comm. Brush area same as warp9 IIRC.

C face is 8.5" rabbit. It replaced Baldor 9". NASA doc has dimensions.
major


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## kennybobby (Aug 10, 2012)

@Mschoen, 

Do you know the gear ratio of the trans and differential, plus the tire size for your conversion? From that you can calculate the required motor RPM to reach 60-70 mph. 

Also what will be the weight of the car, and what is the aero drag coeff and frontal surface area? From that you can calculate the power required to maintain that speed.

Looking at the test curves, 200 Amps makes about 25 ft-lbs of torque.

96V and 200A is about 20kW or 25Hp input power, and with that it makes about 17Hp at about 4,500 RPM output.


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## Mschoen100 (Jun 18, 2020)

Well the car is a read engine, so that means I have a transaxle. The final drive gear ratio is 4.88:1 and top gear ratio is .96:1. It is a 5 speed manual, so I would probably keep it in 3rd gear which is a 1.96:1 ratio. As for the weight, the factory says 1600lbs but that includes the gas engine and a full gas tank. So I think it is safe to say that the car would weight about the same with all the modules, the motor(the motor is just over 100lbs), and all the other components. The tires are 5.5"x 13". I am not sure of the drag, but this car is super low to the ground and has a flat nose.

This is what it looks like. Not my car, but an example.
https://www.google.com/url?sa=i&url...ved=0CAIQjRxqFwoTCMDWxLuDmOoCFQAAAAAdAAAAABAM


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## Mschoen100 (Jun 18, 2020)

Just ran my numbers through an online calculator.

With a ratio of 1.96:1(that is third gear), tire size of 13" and wanting a speed of 70 mph would mean that my RPMs would be 3550. 

Seems pretty achievable.


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## Mschoen100 (Jun 18, 2020)

Also found a calculator for power to maintain speed.

Estimated coefficient of drag .31, front of car being 16 sqft, 1600lbs at 70 mph means that I need to have 15.5 HP to maintain that speed.

Also seems very achievable


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## kennybobby (Aug 10, 2012)

i found aero drag coefficient as 0.42 at this site:
https://www.automobile-catalog.com/car/1968/36575/fiat_850_sport_spider.html

Frontal surface area: 20 sq ft.

Might increase your numbers a bit, but likely still would work.


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## Mschoen100 (Jun 18, 2020)

I was trying to be optimistic here... ha! But thank you! I just don't know what kind of controller I would need for this kind of set up. I know that is a different topic area but since we are here I thought to ask. I would love to use an off the shelf unit. Something like his maybe?
https://www.cloudelectric.com/product-p/1221c-7402.htm


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## Mschoen100 (Jun 18, 2020)

A lot has happened since I posted here last. I do have a couple questions for @major though. I did purchase the Prestolite motor and is actually being delivered today! I wasn't expecting it for a week! I also got an evnetics solitron jr controller that I am very excited about. Now my question is, the controller asks for a proximity sensor. Obviously this motor doesn't have a post on both ends for a sensor to read from, so I thought to place it near the coupler in the bell housing on a bracket. Would you happen to know of a better place to mount it? Is there a way to add a post from the end? Since you were so involved with it's development I figured you would know best! Thanks!


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## brian_ (Feb 7, 2017)

Mschoen100 said:


> As for the weight, the factory says 1600lbs but that includes the gas engine and a full gas tank. So I think it is safe to say that the car would weight about the same with all the modules, the motor(the motor is just over 100lbs), and all the other components.


A conversion rarely comes out with a weight as low as the original, and especially not with enough battery for useful range. Occasionally the original engine is such a boat anchor that the conversion doesn't increase weight (a cast iron inline-six, for example), but that's rare, and the 850 engine should be light... it might not weigh much more than just the electric motor which replaces it. One 850 owner who removed the engine says it weighs about 150 pounds. The controller, wiring, and EV accessories (DC-DC converter, charger, BMS, etc) will weigh 50 pounds, so the motor plus that stuff is as heavy as the engine, and so every bit of battery weight beyond a tank of gas is an increase over the car's original weight.

I'm a bit surprised that an 850 Spider weighs as much as it does. I believe the 1600 pound specification (it's readily available online), but for such a small and basic car it seems heavy; a basic first-generation Honda CR-X is the same weight, in a larger car with almost double the engine displacement and 1980's construction and safety equipment. The 850 must have lots of cast iron components. It is likely handicapped by sharing chassis components with the larger body styles of the 850, which even included a 7-passenger van; on the plus side, that might mean that chassis components can handle the extra battery weight.


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## Mschoen100 (Jun 18, 2020)

That is a great insight. I never thought about it that way. It doesn't have a chassis per say, but the uni body has a massive X brace under the passenger compartment. The body panels are also thick compared to modern cars so I think that adds into the weight quite a bit.


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## Duncan (Dec 8, 2008)

1600 lbs is 727 kg - I don't want to rain on your picnic but that is actually very light - the old classic Minis were about 650 kg - so 727 kg is probably about right
My car which is very basic is 805 kg


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## Mschoen100 (Jun 18, 2020)

I can barely bump this thing and it rolls! I bench tested the motor yesterday and it was great! I posted it on my project's instagram. 850_ev_project if anyone wants to see and follow along!


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## Mschoen100 (Jun 18, 2020)

That's so cool! I didn't know they went into production. I received the motor and has to pop off the end of it to clean the surfaces. The ends of the connectors were stuck and had a loud noise. After cleaning it, things were much quieter. I have a video of the motor and trans tested together on Youtube if anyone is interested.


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## electro wrks (Mar 5, 2012)

Dude: that is a lot of movement! And noise! How did you line up your adapter plate? Most OEMs call for no more than 0.005" side to side misalignment in the ICE/ transmission set-up and the transmission input shaft needs to be carefully supported on its end(in your case there is a smooth round section for the pilot bearing to ride). The EV Gods don't grant you any waivers from having to maintain these tolerences and support.


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## kennybobby (Aug 10, 2012)

i agree, there appears to be too much misalignment. Part of the movement is the clutch which has those springs between the friction plate and the splined hub, so you can't use the spline hole as a fiducial marker for alignment--the springs get compressed with torsional loading of the hub and will move around to react the load. You might set up a dial indicator against the aluminum disk to measure the runout as you rotate the shaft by hand to get some idea of the magnitude.

Is the aluminum adapter a single machined piece or is it 2 pieces bolted together?

It might work for a short time if you just want to get it built and don't mind re-doing things later with some lessons learned, but realize that it will be very noisy and something will wear out and break fairly soon. 

Don't drive it on the highway and pull out in front of traffic or a big truck in case it lets go at the worst possible time. Building stuff is all part of getting experience but you don't want to die or kill someone.


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## Mschoen100 (Jun 18, 2020)

Thank you for the concern, and I do agree that they play is quite significant. It has also been loud considering the brushes were stuck to the end, causing them the rub odd. I have since this video cleaned that off making it much quieter. I do plan to run a dial along the edge of the plate to see what my play is. I am still quite far from finishing, so these things will get sorted. I do really appreciate everyone looking out for me!


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## electro wrks (Mar 5, 2012)

In spite of what you may think right now, most of us ARE looking out for you. I can't remember all of the many times I've gotten good ideas and had bad ideas corrected by the good people on this forum. In this case, the correct mating of the electric motor to the transmission, from the experience of a lot of other cases, many people have messed this up.

And, it is not something you can ignore, remove, or delete away!

I've been thinking about solutions for your situation. It's the kind of work I do: design, build, troubleshoot, and repair equipment and machinery. If you are interested in tapping into the 40+ years of experience I have( and others have on this forum) in this area, please let us know.

In this case, it may save you from destroying and having to replace, maybe multiple times, rare and expensive($2300!) transmissions. You're going to need that $ to pay for batteries and other equipment for your conversion.


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## Mschoen100 (Jun 18, 2020)

I have never said that I don’t appreciate the advice I get here and feedback. I’m not blowing it off and I certainly wouldn’t post here if I didn’t find what I got here to be constructive. If I didn’t want any advice I wouldn’t have bothered coming here.

you’ve already made a few comments on some of my videos on my process and how everything is “so wrong”. Instead of asking me to “do more homework” provide a solution. Easy to say something critical and not provide any potential solutions.

I ask because this is my first ever conversion. I value all that are here to welcome new EV conversion enthusiasts in their own projects. If I need to look at something I haven’t thought about, then I am all about taking that advice. Being critical of new learners isn’t a way to grow the community.


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## electro wrks (Mar 5, 2012)

Alright! Now we're getting somewhere. It sounds like you're concerned there is a problem with the way you set-up the mating of the motor/adapter plate to the transmission. So far, you have just plowed ahead and for the most part and ignored our concerns about this. At this point you probably are not going to believe much of what I suggest. And, I'm not going to waste my time, for now, with someone who childishly, in my opinion, deletes my comments on their videos just because I rattle their cage a little bit.

So, as I suggested on the one of the deleted comments, if you had taken the time to follow through on it: don't believe me. Talk to transmission repair shops or experienced mechanics about the potential problems from leaving out the alignment dowels (you call them "guide pins" in your videos # 6 at 5:45) between the motor/adapter plate and the transmission. And, also ask about not supporting the end of the transmission input shaft (no pilot bearing).

If you have done this homework(because that's what it is, and we all have to do it if we're going to be successful) and you understand the potential problem, by all means ask us if we can help.

You've done some great work here. The alignment issue between the motor/adapter plate and the transmission has turned out to be a very thorny problem with some first-time converters. Don't let this problem mess-up an otherwise great project.


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## brian_ (Feb 7, 2017)

I just watched the video linked in an earlier post (Episode 12), and I agree with earlier comments... there is an insane amount of radial runout in the adapter, and the comment about rounding out holes in the housing adapter plate to make things line up is disturbing. I also wonder why the input shaft has so much splined length showing when inserted into the clutch hub. The same general design, but re-done with precision, is probably workable. It wouldn't be the first time that the path to success included a couple steps back along the way.

Typically a transmission input shaft does depend on a pilot bearing in the flywheel for support, but some transaxle designs have a long input shaft which does not require this support. It's worth the trouble to understand what you have.


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## Mschoen100 (Jun 18, 2020)

I am sorry you think I deleted your comments, but I truly did not. I don't let a comment "rattle" me from learning. I tried to view your initial comments but they weren't there when I wanted to respond. Your second comment did with an "edited" note, so I am not sure what happened there. I don't block people from saying what they want to. 

I also have splined shaft showing since there is a smooth section at the end of the transmission shaft, so if I trimmed that excess off it would be completely in the coupler.

I do agree the movement is significant and should be addressed. My videos have been recorded previously (by about a month or so) from when they actually happened. I will plan on having a custom coupler made to have minimal movement. 

This is just part of the process to learn, no need for name calling after all!


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## brian_ (Feb 7, 2017)

Mschoen100 said:


> I also have splined shaft showing since there is a smooth section at the end of the transmission shaft, so if I trimmed that excess off it would be completely in the coupler.


If this shaft in an online parts listing is the input shaft for the 850 transaxle, it's decently long (which is good), but there is a huge length from the engine-side bearing location (the smooth part in the middle) to the shaft's clutch end (upper right in the photo), so it certainly should have support by a pilot bearing. In this conversion without a clutch, there is no actual pilot bearing required, as the motor and transmission shafts always rotate together (with the coupler), so the pilot bearing area of the shaft can just be a sliding fit into the coupler assembly.

Even if I have the wrong photo, that smooth section is almost certainly where there is supposed to be a pilot bearing; the 850 does use a pilot bearing.

What is stopping the shaft (without trimming) from inserting further? Could the aluminum plate of the adapter be drilled out for clearance (or better, machined to accept and support the shaft), or would the transmission shaft hit the motor shaft? The aluminum plate could just be thicker, with a bore for the shaft end, shifting the clutch hub toward the same transmission with the same thickness of housing adapter plate.


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## Mschoen100 (Jun 18, 2020)

So you are correct on the photo. That is what is in my transmission, and I will be running a clutchless system. What is stopping the transmission shaft from going further is like you stated, the shafts are hitting each other. If the smooth tip is shaved off, then the splined end could go further. There is about 75% of it in the coupler (though my concept works its no ideal) so I wasn't sure if I needed more grip. Once the splines pass the old friction plate there is an empty space. The friction plate is fully engaged as is, but if I wanted to get the motor and trans tighter together I could.


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## brian_ (Feb 7, 2017)

Mschoen100 said:


> So you are correct on the photo. That is what is in my transmission, and I will be running a clutchless system. What is stopping the transmission shaft from going further is like you stated, the shafts are hitting each other. If the smooth tip is shaved off, then the splined end could go further. There is about 75% of it in the coupler (though my concept works its no ideal) so I wasn't sure if I needed more grip. Once the splines pass the old friction plate there is an empty space. The friction plate is fully engaged as is, but if I wanted to get the motor and trans tighter together I could.


Okay, so you could make the adapter thicker to put more of the plain end of shaft in the coupler, but more importantly you could make the coupler so that the shaft slides into it without any more clearance than necessary to slide, and it will locate the shaft properly. 

I wouldn't want to cut off the end of a transmission shaft, and it isn't necessary.


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## Mschoen100 (Jun 18, 2020)

Thanks for that! Wouldn't be hard to have one made, especially one with a more centered adapter, so I have much less vibration down the road. Great advice.


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