Forward clutch piston Aluminum VS. Steel?

[dalesteraz]

Is there any benefit to using one or the other?
The GM diagrams are also confusing on the friction/steel/wave configuration for each.
Any opinions or input would be appreciated!

 

[KL Mallender]

Forward clutch piston use really boils down to what drum assembly you are using, drums with steel piston have a bleed capsule in the drum itself, drums with aluminum pistons have the bleed in the piston, they also have different sized holes in the shaft itself, steel piston drums have a smaller feed hole.
Bewarned, using the wrong piston(or drum without a capsule/bleed) will cause the clutch to centrifically apply in Park\Neutral causing damage to friction plates.
GM implemented the double wave plates into the 200-4R and the FWD 125C in attempt to cushion the engagement and reduce the driveshaft "Clunk", sounded more like a "Snap" in the 125C.


Kevin.

 

[dalesteraz]

Thanks for that info Kevin,I see the difference, I was real close to assembling with the two mixed up!!

 

[KL Mallender]

Glad you caught it before reassembly and installation, your forward frictions are breathing easier, lol

Steel piston in a no-bleed drum causes drag in park/neutral(almost like brake torqueing) but only lasts until smoke from dipstick tube is emitted.
Aluminum piston into a bleed drum usually causes a very soft/delayed forward engagement with stock line pressures(50-75 psi)
Either mismatch will need to be R&R'd to correct problem, if not found during orginal rebuild.

Kevin.