Hooking a car automatic to a free turbine the wrong way

[turbochris]

I think this guy is going to cook his transmission. He hooked the free turbine right to the input shaft of the transmission and the hydraulic pump in the transmission is driven off the same shaft. So when it's in neutral, the input shaft spins and makes hydraulic pressure, but when he put it in gear, the input shaft should stop as it's directly hooked to the rear wheels and we're not moving yet. What I think will happen is the input shaft will begin to stop but he'll start to loose hydraulic pressure and the band that puts the transmission in gear will begin to slip. It will slip just enough to keep the pump slow enough to prevent it from going into gear.

If he takes it really easy he might get away with this for a while but he says he has a trans brake.

Am i missing something? I think he needs to run a small hydraulic pump off of N1 that runs all the time.

[racket]

Hi Chris

Yep , he's gunna have problems , the 4th gen Chrysler used a remote oil pump on the modified TorqueFlite "8" trans.

The 5th gen engine used a torque convertor as accessories were driven off N2 rather than N1 .

LOL, why wouldn't you want the "acceleration benefits" of having the torque convertor.

Cheers
John

[turbochris]

I tried to explain that all to him. He's building another car with a converter, I think that will work as long as the converter slips enough in gear to keep the pump spinning. Anyway, I told him to join our group. I fear he'll use the trans brake and who knows which way the car will go, I guess it depends on what slips first!

[enginewhisperer]

I know people do it this way with electric motors, and as you apply power the transmission spins up and starts moving the car.

Depending on the input shaft rpm it needs to generate line pressure, it might basically self regulate and give a smooth take off. The input shaft shouldn't stop because then the bands would release anyway - so there will be a controlled amount of slip - which may or may not be too much

I agree that the best way would be to run an external oil pump to maintain line pressure, and then you can treat it like a manual gearbox.