Since my Isuzu 5 speed died in my electric Fiero I've been considering using the auto. However I don't know how it will behave behind the electric motor. My concerns: 1. The electric motor doesn't need to idle, what will happen when I take off from a stop, will it bang as pressure builds up, will there be a substantial lag, or other problems? I could idle the motor but I'd rather not since that wastes energy. 2. Will I need to fake a throttle position signal to make it shift right? 3. Will the transmission be able to handle occasional revs to 7500 RPM? 4. What do I need to engage the lock up? Since the electric motor makes full torque from 1 RPM I'd probably want to lock up sooner rather than later. 5. What's the stall speed of the torque converter? What options are there? Lower is better with an electric motor for the above mentioned reason. 6. Any other possible issues?
1. If the input shaft isn't turning, there will be no hydraulic pressure to run the AT. When the pressure builds high enough the clutches that shift the tranny will lock up with a clunk. (Somewhat like when you put the car in gear) 2. The TH125C uses a mechanical input for the throttle position 3. It will shift before you get the revs up that high. 4. I really don't think you want to run the torque converter. Your range will drop. I can't see any advantage for running it. If you were to do the auto, I think you would have the TC locked up all the time. I would think the lock up would be a welded torque converter rather than using the Torque Converter Clutch (TCC).
I think you would be much better off with a 4 speed or 5 speed MT.
Yes, MT is much better and simpler, Don't even need a clutch for the motor, just couple the input shaft to the motor.
You can still get the automatic to work. I too suggest eliminating the torque converter. I would also put an external electro hydraulic pump on the line pressure tap to supply pressure before spinning up the drive motor. It will allow you to have the transmission clutched on first while the drive motor starts at 0 RPM's. An motor driven power steering pump would suffice.
Yes the other option is to drop the converter and go direct, which would save weight as well. For the pump I'd just go electric since my motor doesn't have a front shaft on it to drive a pump, plus direct electric pump keeps pressure to the transmission when the motor isn't turning. I kind of thought it might be nice to have the torque multiplication from the TC still in the system, and with the lockup I shouldn't take too much efficiency hit. On the other hand my electric motor is more efficient at higher RPMS so I probably want to do most of my driving in second, not third, so I probably want to manually shift it to keep it in second, and I assume the TC only locks up in third? If that's the case then I definitely need to drop the TC. Can I change the shift points so it doesn't shift until higher RPMs? My current manual setup was clutchless, but the regenerative braking on the motor makes speed shifting a very exact science with a narrow window in which to shift correctly, probably one of the reasons I killed second gear in the Isuzu.
I'm assuming that the automatic uses the same transmission mounts as the manuals, regardless of year and engine? Also that the axles for the automatic will fit the hubs on my 88 regardless of year it came out of?
Some of the comments are right on about getting rid of the torque converter. You probably don't need the addition torque by spinning the torque converter, most of the electric motor applications have a lot of low end torque to start with. You might also look into using a 4T60 none E transmission. It is all manually controlled. There is an adjustment for when to shift and there is also a throttle positon cable that actuates the down shift, which you might or might now want to use. If you just don't use the throttle position cable you could use it more like an auto/manual operation where you select what gear it is in after you start out.
If you want more information on how you adjust the 4T60 transmission, send a PM to olejoedad. He installed one of these in my wife's Fiero and it is really nice. With the 2.8 it gets above 32 mpg on the road.
I'm trying to keep this as simple as possible so if I do the auto trans I'll stick with the 125. Just trying to see if it's a bolt in swap if I have a donor car or if I'll need special parts.
I probbaly don't understand automatic transmissions well enough, cuz I always assumed the torque converter was the pump, and the trans shifted based on pressure levels rather than, say, by centrifical force or something like that. Thinking about it, I think it's purely assumption on my part. I just assume there's no point in having another pump inside when there's a big one already running all the time... If they work the way I thought they did, your idea won't work properly. It'll have pressure to run the internals, but it won't be enough or have the right amount of pressure at the right time. In which case, you would have wanted to use the torque converter and just make it so the motor runs for a few extra seconds as you stop, so it can complete downshifting and such. I'd think if it's already in the right gear when it starts up, there wouldnt be much clunking going on.
Someone who actually knows what goes on in there needs to pipe up.
Good luck with the idea. I know absolutely nothing about transmissions. I can change fluid and filter and adjust kickdown linkages. Anything past that and im lost.
I didn't know that much about automatics but learned a lot investigating this project. The pump is internal, driven by one of the splines inside the TC that engages the pump shaft, which is the smaller shaft in the picture. Circle track racers that run Powerglides use a direct drive coupler and eliminate the TC, but they don't have to worry about keeping the transmission pressurized at stop lights so they don't bother with an electric external pump.
So it wont have any problems shifting while locked up? I suppose, if someone got crafty enough, they might be able to spind the internal pump instead of using an external one. Hmm. Well, you've certainly got me interested. I wonder how efficient it will be, always being locked up. I was pondering an automatic trans/electric drive but didn't think it'd be worth the power loss, but this way might fix that.
This one I know the answer to...you don't need a clutch because the motor isn't trying to keep on spinning at a different speed from the trans. The synchros are enough to make the motor match the speed of whatever gear you're putting it into, the same way it makes the clutch disk spin to match before you let out on the clutch pedal. It takes a bit longer to shift though, becasue there's more mass for the synchro to rev-match. And of course you can put it into first/reverse(or any other gear) when stopped without a clutch because the motor isn't spinning at all.
Yes, but with one exception. My motor has regenerative braking, so when you let off the accel pedal to shift the motor very quickly slows down, so instead of taking longer to shift you have to shift really fast. When you get it right it's a much faster shift than with a clutch, when you get it wrong you get a lot of grinding and then you have to try and match motor speed to trans speed. The Isuzu didn't really like being speed shifted, hence the broken transmission. Most of the time I just used 2nd gear anyway which was good up to 65mph but occasionally I'd speed shift it if I wanted 1st for better acceleration.
So it wont have any problems shifting while locked up? I suppose, if someone got crafty enough, they might be able to spind the internal pump instead of using an external one. Hmm. Well, you've certainly got me interested. I wonder how efficient it will be, always being locked up. I was pondering an automatic trans/electric drive but didn't think it'd be worth the power loss, but this way might fix that.
Should be very efficient since there is no slip happening without the TC. I'm not sure how it will behave when shifting, only one way to find out
I think so. Looking at the pressure chart for the TH125 the lowest pressure during operation is 55psi, so I think 60psi will give me enough preliminary pressure until the motor starts spinning the main pump. The big concern is the GPM rating. If the trans needs more than the 2 GPM to keep pressure then the pump won't make any pressure, since pressure is resistance against flow.
Yes, but with one exception. My motor has regenerative braking, so when you let off the accel pedal to shift the motor very quickly slows down, so instead of taking longer to shift you have to shift really fast. When you get it right it's a much faster shift than with a clutch, when you get it wrong you get a lot of grinding and then you have to try and match motor speed to trans speed. The Isuzu didn't really like being speed shifted, hence the broken transmission. Most of the time I just used 2nd gear anyway which was good up to 65mph but occasionally I'd speed shift it if I wanted 1st for better acceleration.
Wont be an issue anymore with the automatic, but couldn't you program the controller not to alwywas be in regen mode and only be in regen when you've got your foot on the brake? or does it make that much difference to your milage having it on all the time? and what kind of motor are you running anyway, if I may ask?
Yes the controller can be reprogrammed to use a brake pressure transducer to activate regen, but having it on the A pedal allows single foot driving most of the time, which I prefer. I'm using an AC31 motor from HPEVS with a Curtis 1238-7501 120V 550Amp controller. HPEVS
Yes the controller can be reprogrammed to use a brake pressure transducer to activate regen, but having it on the A pedal allows single foot driving most of the time, which I prefer. I'm using an AC31 motor from HPEVS with a Curtis 1238-7501 120V 550Amp controller. HPEVS
Oooh, fancy. Most fiero setups I've seen are series wound motors. I'd love a setup like yours, but totally not worth it(at least not on my salary) for my driving needs. It'd take about 10 years to pay for itself!
[This message has been edited by Stubby79 (edited 10-31-2012).]
The shift arm on my transmission is definitely different, the ball stud that the cable attaches to is not part of the arm and the arm is longer. I can only assume the shift arm is from a different vehicle, or maybe an older Fiero? Anyway, I now have another shift arm with the ball stud in it so I'll use that.
When I got the parts off an automatic parts car I never thought to get the measurement between the throttle body and the bracket that holds the throttle and TV cables. I need to build a bracket that positions them the proper distance for correct cable action. If someone can measure the distance between the throttle body and the bracket as shown by the yellow lines in this pic I'd appreciate it.
Trying to figure out how much of the torque converter hub is needed to properly engage the seal in the transmission. Initially I thought I needed a bit of the flange to press against the seal, but the machinist I'm working with doesn't think so. I also noticed that the Powerglide coupler has no flange and is just a smooth shaft.
The flange would mean that if the adapter is not perfectly spaced the flange could put too much pressure on the seal. So does anyone know if the TC butts up against the seal and I need a bit of a shoulder or if all the sealing is done on the hub? Here is a pic to show what I'm talking about:
When I got the parts off an automatic parts car I never thought to get the measurement between the throttle body and the bracket that holds the throttle and TV cables. I need to build a bracket that positions them the proper distance for correct cable action. If someone can measure the distance between the throttle body and the bracket as shown by the yellow lines in this pic I'd appreciate it.
Still looking for this data if anyone can help out.
From what I have read the trans should shift OK with no hessitation as long as the external pump works. You will also need the TV cable to set line pressure for shifts according to pedal position. The only problem I see is decreased range as the external pump will consume power. I've always been fascinated by electric Fieros. One guy on this forum runs the 1/4 mile in the low 10's with his.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Powerlog manifold, Northstar TB, LS1 MAF, 3" Flotech Afterburner Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
From what I have read the trans should shift OK with no hessitation as long as the external pump works. You will also need the TV cable to set line pressure for shifts according to pedal position. The only problem I see is decreased range as the external pump will consume power. I've always been fascinated by electric Fieros. One guy on this forum runs the 1/4 mile in the low 10's with his.
I'm using the stock throttle body and TV cable, the TPS signal will be my throttle signal for the controller. The external pump should not affect range in any noticeable way since it should only run when I'm stopped and internal pressure leaks down below 60PSI. I'm hoping it won't come on at all for a momentary stop.
I am concerned that when I mounted it and checked it there is about 15 thousandths of runout. I don't have a dial indicator but bracing a dial caliper against a hard surface and checking the runout I get between 10 and 15 thousandths. The guy said it was true on the lathe but I've mounted the taper lock coupler on the motor twice and it still has the runout. When I check the taper lock hub base that runs true. Is this going to take out my seal prematurely, and if so what are my options to reduce the runout, other than starting over. Can targeted heating and cooling tweak it inline, or a press? It slides into the trans fine so the splines engage alright.
[This message has been edited by JRP3 (edited 11-29-2012).]
Doing some research on seal run out allowances it looks as if I'm pushing the parameters for acceptable tolerances. Page 16 of this PDF shows a max of .010 at 5K RPM for a 2 inch seal and .008 at 7K RPM. I did notice the outer diameter of the coupler is .006 larger than the TC hub, so I suppose if I can get it trued up by that much from the high side I'd be OK.