Built AOD/4R70W - slipping in 3rd on dyno

[OVERKILL]

A buddy of mine was over today to tell me about his "epic fail" on the dyno today getting his car tuned.

He put the trans in about 2 years ago, but due to the changes made to the engine (lowered the compression...etc) he put very few miles on it after converting it to automatic from standard. He needed to get it in and get the tune changed to deal with the issues that resulted from these modifications.

Transmission is an AOD with aftermarket bands, increased # of clutches, one-piece OD shaft, 4R70W gears, Lentech valve body...etc. Converter is an aftermarket unit good for way more power than he is making and locks in around 3K.

Fluid used was AMSOIL ATF.

Had it on the rollers and at ~370RWHP and 3,700RPM in 3rd it started slipping badly. Car previously made 525RWHP at around 6K when it was standard.

He's thinking the fluid may have been "too slick". The instructions that came with the valve body said to use Mercon V.

I thought an easy test would be to swap it out for some type F and see if the problem goes away

As he now needs to pull the transmission and take it to a shop to get 3rd fixed otherwise.

Any thoughts?

 

[TooManyWheels]

I think I remember reading that the aftermarket Kevlar bands don't always work that well, if that is what he has. The other obvious thing would be the servo, but that is usually one of the first things changed on an AOD.

 

[Colt45ws]

Direct is a clutch though. Only reverse and OD are band. What kind of clutch plates were used? Factory 4R70?

 

[OVERKILL]

Originally Posted By: Colt45ws
Direct is a clutch though. Only reverse and OD are band. What kind of clutch plates were used? Factory 4R70?


No, aftermarket ones, and more of them. Do you want me to find out the name?

 

[Colt45ws]

Yes.

 

[OVERKILL]

Originally Posted By: Colt45ws
Yes.


Alto Red's. Apparently, they are the problem.

 

[SteveSRT8]

Seen this one before. Your fluid must be compatible with the band/clutch material. Also there should be a line pressure spec as well.

He may need to remove and replace all the friction parts now. Just a bit of slippage can toast it with a strong engine.

Sad.

 

[Colt45ws]

Originally Posted By: OVERK1LL
Originally Posted By: Colt45ws
Yes.


Alto Red's. Apparently, they are the problem.


Jerry Wroblewski, AODE/4R70 engineer, recommends factory clutches even up though and above 650RWHP. Just more of them along with proper changes in the VB.

 

[SteveSRT8]

I learned the same thing with my GM hot rods. The factory clutches and such are good to big numbers if the line pressure is correct.