904 clutches and frictions

Pulled the trans down further.

Steels:

Some of the frictions seemed gritty to the touch when i ran my fingers over them.

Frictions

Been slipping. The gritty frictions means they have been over heated.

I replied to your PM with other possibilities.

Is your kickdown fitted and working correctly, if not you can have that sort of damage in days.

Kickdown was fitted and working to the best of my knowledge

Detent could be out of adjustment, cut seal, worn pump causing low presure. Check everything.

First check line pressure with a gauge, it must be right to specs. Remember if it has a shift kit, call the maker and find out what they recommend. The other issue is overlap. With a chrysler trans the 2nd gear band must release and then the high clutch is applied. So you always have a brief time when the band and clutch are both applied at the same time, the timing of this event is critical to keep the trans clutches or band from burning. Band apply lever ratio, band adjustment, valvebody modifications like orfice size in the plate, line pressure, all control this event. Thats why sometimes when you buy a shift kit, or valvebody they may recommend a differant apply lever ratio, or band adjustment.

Doesn't look that much out of the ordinary. How long had it been together? what kind of power. What valve body? May be time to step up to Altos, Kolenes and and a 5th friction.
Doug

I 2nd the overlap possibility

Trans was built to take 450 HP. Valve body new and was the trans builders modded unit. I haven't pulled it apart to see what he used but will do next.

4.2 lever and when I returned the box the Trans builder said the adjustment looked fine.

Trans was built in 2012 but has only done about 1K miles and 5 street meets 21 passes in total at our local track.

Now for more pics, direct drum steels on the left:

Frictions comparison

Any chance it was simply run low on fluid?

Not likely at all.

Here is where it gets interesting. I spoke to my machinist about my problem and said he knows another racer who bought a box from the same guy and then had problems with it he couldn't get right. I'm sure he said it had a line pressure problem which A&A helped to sort out. I'll try and talk to the guy and find out what it was.

I'm going to do the Fairbanks stage 3 kit and manualize it.

So if I have this correct it is the the direct clutch, not the high/reverse clutch that is burnt. To me this is either loss of pressure in the direct clutch feed circuit or some type of mechanical bind with the direct clutch piston. This clutch is stationary applied and shouldn't slip at this power level.
Doug

Which clutch pack was it? Are those the frictions that came out of the trans? I assume the frictions on the right came out of the same drum? Everyone's assuming a high gear failure.

Both sets of friction came out of the same trans.

Are they not the same clutches and steels for both drums?

“Most” of the time the rear clutch pack has smooth frictions while the front clutch pack has waffle or grooved frictions.

Which frictions came out of your front drum and which out of the rear drum?

Forward clutch plates are .063. High plates are .087, and they are interchangeable.. Most of the time forward plates are used in both drums which allows you to use 5 in the high drum with a different snap ring, thin steels and/or by machining the pressure plate. Factory forward plates were usually smooth with a hi friction material since it just needed to hold. Measure them. Plates on the right look like high gear plates out of rebuild kit. With a performance/race unit, we just use the good plates in both drums.

I would have thought the corresponding frictions would look worse after seeing the steels.

I think the burnt ones came out of the direct drum. But not 100% certain as i didn't take any pics but only from memory.

"Direct" and "High/Reverse" are same thing, the front clutch; this is what happens when people use non-Mopar terminology.

The factory simply calls the clutches front and rear but when people use the GM/Ford terms "forward", "direct", high/reverse" it causes confusion.

Stepping down off soapbox.