limiting flexplate flex

[jstein]

Being a racer I have had failures of the flexplate. All very dangerous to health. I assume that the higher pressues in a racing automatic pushed the convertor forward to the point it made contact with the starter. When a "button" was placed between the crank and convertor thrust bearing problems appeared. Do the pressures need to be this high? Is the convertor any more efficient at higher pressure or we wasting power driving the pump. Any ideas or cures welcome.

 

[Metalguy]

Dump the converter and run a Crowerglide (triple disc centrifugal clutch)-that is' *if* you have enough HP to require something like that.

 

[GregLocock]

For a given geometry the turbine can only react higher torques by running higher pressures. These increase the distortion of the housing, so I'd guess that's the root cause of your flex plate problem. Can you add a doubler to the torque converter housing to stiffen it?

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[Fabrico]

Your problem could be something else. The hydraulic pressure in a transmission pump is not really very high, therefore neither could the pressure applied forwardly on the torque convertor. There is a thing called torque convertor balloning. It is often misconstrued, misused, and mis-believed. But the fact is that a torque convertor under great strain or RPM can and will change shape and get fatter from front and rear. That is why there are several companies making billet front covers (front half of convertor). Some are for diesel applications. A place called The Convertor Shop (TCS) and Banks Performance are just a couple.

 

[curlyhiro]

Balloning could be a problem but, most tranmssions have the input pressure at approx. 40p.s.i. and a requlator valve controls that. I've found most flex plate brakage due to crank shaft movement. In you case, I would check the torque converter pilot to see the it matches the pilot in the crankshaft. If the pilot are of different size, you've found the problem.