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  #11  
Old 07-15-2012, 10:34 PM
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onegreenev onegreenev is online now
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Default Re: Planning 1968 Chevy Corvair

The Corvair is like the VW Bug. You have a transaxle so you really have no choice but to retain your original transmission. You can however have it re-geared to better suit a fat DC Series motor. The Corvair is heavy. 2500LBS. You do have a choice of transmissions. I am not fully sure how the trans attaches to the axle but it is not conventional. direct drive is not an option.

Good choice.

http://www.evalbum.com/3304/
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  #12  
Old 07-16-2012, 01:19 AM
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Default Re: Planning 1968 Chevy Corvair

Electric motors have tremendous ability, but have some limits. Both AC and DC have those limits.

1-A motor alone without a transmission is a tough cookie to do. It needs the proper gearing, a large pack and excellent cooling.

2-A motor alone can be geared for acceleration, but will have a low top speed because it runs out of RPM. It can be geared for cruise speed, but will draw a huge current getting there and will need good cooling.

3- Cars like the Tesla can be single speed because they are geared for decent acceleration and low current draw. They also can do 12,000RPMs to get a decent cruise speed. These motors are expensive.

EXAMPLE: My car has 7.80-1 in low and 6.14-1 in high gear. With a 32" tall tire gives me 55-60 in low and 105-110 in high gear. I can get by with this set up because of a good pack and my car weighs about 2,200#.

Yes, your car would be really cool with a powerglide. With the torque converter removed, a direct drive coupler made and an external charge pump installed, it would be unique.

Yes, you could use 1 large controller for two DC motors. But you would need a HUGE pack to support it and you would still have the gearing issue,(low current draw and low speed operation...or high current draw and decent cruise speed?)

YES, direct drive is possible by replacing the trans with a I.R.S. type diff. (corvette) and retaining the corvair suspension. But, not desirable in My opinion.

Miz

Last edited by mizlplix; 07-16-2012 at 05:16 AM.
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  #13  
Old 07-16-2012, 04:50 AM
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Default Re: Planning 1968 Chevy Corvair

Quote:
Originally Posted by Xrayguru View Post
Hello all.

I am picking up a 68 Corvair this weekend and it currently has no drive train what so ever. I thought electric would be a great way to go. It is a rear wheel driven car and the motor is normally in the rear. I am not sure if I should go two motors in the back independent or connected or just one. Does it need a rear end? Transmission? Would like some ideas from some people on what they would do. My range would need to be a minimum of 40 miles which is round trip to work. I am good at electrical wiring and mechanical. Good at fabrication also. Was thinking of using an AC motor and possibly Regenerative Braking if possible. Other than that I am not sure what else would be a good fit for my project. The car stock weight is 2500lbs roughly but with all drivetrain out I am estimating it to weigh 1900 pounds. Any suggestions anyone???
Have you considered an Emrax Motor? Very light weight at 26lbs,
Peak power (1 minute) is 80kw which is 108 hp.
Power (2 minutes) is 50kw which is 68hp.
Continuous power is 30kw which is 40.8hp.
Exterior dimensions is like less than 4" in length and it is less than 10" in diameter.
More details at http://www.enstroj.si/Electric-produ...ax-motors.html

It is an AC motor so can have Regenerative Braking (if controller supports it). Someone in my Electric Car Club bought a few of these motors and they are quite compact.
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  #14  
Old 07-16-2012, 09:59 AM
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Default Re: Planning 1968 Chevy Corvair

Quote:
Originally Posted by mizlplix View Post
EXAMPLE: My car has 7.80-1 in low and 6.14-1 in high gear. With a 32" tall tire gives me 55-60 in low and 105-110 in high gear.
Miz
Not to go off topic, but are you sure about that low gear ratio, Miz?

If you have a 1.82:1 1st in your glide, that's 11.17 final in low, which would line up better with your reported speeds in gears.

Just guessing, but I don't think a 1.82 first PG/3.89 rear is deep enough gearing for this heavy a car, which would be only a 7.35:1 final drive in low. To go deeper is going to cost real money for non-standard ratios, where the stock Saginaw 3sp is cheap and offers a better spread with the deepest stock differential.

Since the Corvair is going to be at least 50% heavier than your A-bone, the Saginaw 3 speed is probably a better spread with the deepest 3.89 Corvair diff. I'm not sure what ratios are now available for the Corvair 3 speed used, (stock spread was 3.50/1.99/1) but that stock box combined with the optional stock deep diff (versus the more common 3.27 or 3.55) would provide three apparently useful drive ratios, (13.61:1, 7.74:1 and 3.89:1) especially with the stock tire height of 24.5". The more common and cheaper 3.55 Corvair differential gears might be an even better choice...

Last edited by TomA; 07-16-2012 at 10:16 AM. Reason: Clarity
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  #15  
Old 07-16-2012, 10:57 AM
Xrayguru Xrayguru is offline
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Default Re: Planning 1968 Chevy Corvair

I have been reading up on the PG and would like to use that. Not having a torque converter sounds interesting. I would like more info on that if you have it. I also want to machine up some aluminum half shafts to lighten things up a bit. I also heard you can get the rear and front hood in fiberglass which would also help on weight. what DC motor would be a good fit for the PG/Corvair?
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  #16  
Old 07-16-2012, 11:14 AM
Xrayguru Xrayguru is offline
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Default Re: Planning 1968 Chevy Corvair

If I was going to do the corvette rear it would have been with the suspension as I would gain disc brakes. Do you have a design for using a DC motor direct coupled with the PG? Is there such a thing as an external charge pump? That would have the same effect as a torque converter? Miz do you have a Corvair project?
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  #17  
Old 07-16-2012, 03:43 PM
TomA TomA is offline
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Default Re: Planning 1968 Chevy Corvair

Xrayguru, you would really benefit from reading Miz' build thread:

http://www.diyelectriccar.com/forums...ild-59659.html

It might take you a couple of days, but its a terrific example of a carefully planned and executed build, and what happens along the way.

You need more people to weigh in on gearing, but I just don't think the Powerglide is going to work for you, because you can't get sufficiently deep gears for the differential.

Looking into it a little, there's more to the Saginaw 3 speeds in these cars than I thought. The early ones with the deep first gear don't have first gear synchros, so you are going to have to figure some things out, but there are choices. Join corsa.org and check out their forums. You'll get lots of help on everything from parts selection and sourcing to shedding weight there. BTW, their international meet is in Sturbridge, MA in two weeks.
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  #18  
Old 07-16-2012, 10:53 PM
Xrayguru Xrayguru is offline
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Default Re: Planning 1968 Chevy Corvair

I have read all of Miz's thread and would like to say he has done a wonderful job and shows that anything is possible with time and money. Not forgetting determination. I did learn quite a bit from his epilogue and know also from him doing his project there is some things you just have to do for yourself in person to get the answer/results you need. I first will be contacting my insurance agency to see if I can get insured. That will be my defining green light. I then will complete the body and find a rear differential and power glide. Hopefully that all will be done by next year and then see what options best fit my needs. I would like to pull the max range out of my car but would settle for a work commuter.
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  #19  
Old 07-17-2012, 12:12 AM
TomA TomA is offline
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Default Re: Planning 1968 Chevy Corvair

I think if you go with a stock PG and any stock diff, your drive ratios will be 7:08 in low and 3.89:1 in high, or 6.46 in low and 3.55 in high, all of which is really too tall, but I'll stop saying it now.

To make that work well in a car over 2500lbs that seats 5, you're probably going to need an 11" motor, 1400-2000A liquid cooled controller, and a big turbo blower to cool the motor. Even 200Ah prismatic cells will be overstressed at the amperages you'll routinely see, so you'll have to supplement them with some A123 cells to absorb the transient current loads. Everything is getting heavier fast because of the high amperage requirement, aggravating the problem, and multiplying the costs.

You'll also be making some monster torque in this configuration, stressing your direct-driven nested 'vair PG input shafts, which may not be up to it, particularly if you don't seriously slow the rate of power onset in the controller. Lastly, since you won't have any damping between the motor and the transmission, road shock (like wheel hop while going over a shabby rail road crossing under brisk acceleration) may well snap the transmission shafts when fully laden.

Enough of my precautionary concerns! Everybody should build what they want, by all means, and with the right amount of care and money it could work well- even the hard way. More and deeper gears would be so much easier, though...
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  #20  
Old 07-17-2012, 12:24 AM
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Default Re: Planning 1968 Chevy Corvair

Sorry, that was a lot of conclusions without any reasoning. Here's what I really mean:

The torque converter in the Powerglide isn't just a fluid clutch, its also torque multiplier. That's why the 'glide can use taller and fewer gears with the same motors as other stock Corvairs. When you remove the torque converter, you now need to generate a lot more torque in the motor to get the same performance.

The transmission isn't designed to accept that much torque without the dampening effect of the fluid clutch, (TC) so its input shaft will be stressed much more by the higher, and especially the instantaneous torque your electric motor dishes out, both when you stomp on the throttle and from transient on-off traction situations.

The Powerglide is a neat EV transmission, but it isn't a panacea, and with the compromised input system of the Corvair configuration, in a heavy car with a relatively tall differential, I don't think its a good choice.

Last edited by TomA; 07-17-2012 at 12:29 AM. Reason: Clarity...
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