[grayballs]

I got the 'Twins'

http://i195.photobucket.com/albums/z...MVC-003S-1.jpg

re-assembled today, so I guess it's time to start a build thread. I've been working at making parts for about 6-8 months, but with my work schedule, it just ain't been happening.
The plan is for a twin motored (one driving each front axel), twin controller Geo. The donor is a '95 Metro that is next to perfect, except for the tranny.
Most of the tear-out is complete, so on to the 'tramsmission', if you can call it that. I'm building a direct drive unit, using gearbelts at about 4 1/2 to 1 reduction. Hopefully that will put me in the 50+ mph range @ 3800 rpm.

http://i195.photobucket.com/albums/z...MVC-005S-1.jpg

The bolts extending from the tail shaft are for the tach pick-up that is yet to be installed. The plan is to try to use pulse driven tachs with shift lites to operate a control relay in the event of a broken or slippped belt. After searching the forum, I found what I thought were the parts I needed, but when I contacted the manufacturer, I was told that I needed at least 36 teeth to generate the pulse. I think maybe I don't understand everything I need to know, here. If any of you care to share a similar solution, with part descriptions, I would appreciate it.

Ross

[vpoppv]

I will follow this project closely!!! Those are some really beautiful motors...

[dtbaker]

so..... WHY are you going with direct drive to each wheel? Just to get more HP?

Do you have any monitoring/control between the motors to compensate for slightly diferent speeds? How about if one wheel breaks loose? I just would be pretty concerned about 'torque steer' if one motor is pulling and the other loses traction....

[grayballs]

Originally Posted by dtbaker

so..... WHY are you going with direct drive to each wheel? Just to get more HP?

Do you have any monitoring/control between the motors to compensate for slightly diferent speeds? How about if one wheel breaks loose? I just would be pretty concerned about 'torque steer' if one motor is pulling and the other loses traction....

No monitoring,,, I just don't think that torque steer is going to be a major issue,,, or turning corners at slow speed,,,, my thoughts are that the less loaded motor will just turn faster. I may get some real surprises, here,,,, and just in case, I have a plan 'B'. My initial idea is to provide total redundancy, in case of component failure,,, one could still limp home. If my idea fails, I figure to wire the pack in series (144v), wire the motors in series (they then act as a limited slip diff.), new controller, and so much for redundancy.
I have seen so many threads on this forum, asking about the possibility of this approach, I decided it was time to give it a try. I think the idea has merit and since most of the expensive parts I had laying around,,,,, (still need batteries),,, you get the idea.

[Salty9]

I have considered a similar drive system and wondered if proportional control could be used with the angle of the steering wheel used as input.

[dtbaker]

interesting concept for sure.... I'll be following along. I am thinking that the one-speed gearing is going to give some pretty sluggish acceleration, but perhaps w/ 144v and the dual motors you'll be ok.

I am not familiar with those motors, what is the rated torque/hp at 144v?
What batteries are you planning for 144v? You must be planning to sacrifice the rear passenger/cargo area completely?

[grayballs]

Originally Posted by dtbaker

I am not familiar with those motors, what is the rated torque/hp at 144v?
What batteries are you planning for 144v? You must be planning to sacrifice the rear passenger/cargo area completely?

They are 6.7" ADC's,,, about 8 hp cont.@ 72v,,,, 22 hp momentary. I'm guessing there won't be any issue getting this thing moving.

I'm planning for LiPo4,,, 2 paralell packs of 160 - 180 ah each, depending on what I can afford at the time. No back seat,,, this is going to be a 2-holer commuter,,, the batteries taking the space where the seat and tank used to be,, maybe a package shelf over them

[grayballs]

I got some time, today, so I decided to try to run in the brushes on my motors. At 12v they are drawing 14.3 a and running 2272 rpm. After an hour they are getting very quiet. Not having done this, before, I guess I didn't know exactly what to expect,,, still don't know how long it will take to fully seat the brushes. Any ideas?

http://i195.photobucket.com/albums/z...MVC-009S-1.jpg

The picture also shows some of the buss that I came across, today. I'm guessing I scored about 110# total,,, some of it up 7' long,,,, all in all, a great day

[grayballs]

Started the 'transmission' parts, today. mostly playing and shedding weight.
http://i195.photobucket.com/albums/z...MVC-001S-1.jpg
The one on the left is the stock hub, as it comes from the manufacturer. It weighs in at 12 lbs. 13.6 oz.
http://i195.photobucket.com/albums/z...MVC-013S-1.jpg
This is after some playing. The cast hub was cut out and replaced with a 1/2" 6061T6 plate and then attacked with the mill.
Now that the programming is done, the other is just time,,,, it would be quicker if we knew something about optimizing the tool path (soon enough, I guess). The drive hubs are roughed out and splined, ready for final, then trial assembly.
Case next,,, I hope-

[grayballs]

Yesterday was a good day, production wise. We got the drive hubs made and test fit.

I had no luck finding a broach to cut the splines for the hubs so we took a different approach. The splined gears were removed from the differential and the teeth were ground off, then machined to size. We then silver soldered the splines into the hub and for good measure (translate that as I chickened out) ran a tig bead around the end. 'Back into the lathe to finish sizing and into the mill for the bolt circle. I was surprised how many steps were required, but very happy with the finished product.


Last picture shows the assembly waiting for bearings and housing,,,,, next week, I hope