If you saw black in the pan, after the dyno test..I'll bet it had issues then. The "street" clutch discs I use are red Altos..same with the bands, but the forward clutch could have a light tan, or dark metallic grey look to them if they used stock replacement stuff. You raise the issue with the builder before it was ever installed, so his reaction (I woudl think) should be fairly supportive. good luck with it..it's amazing how an outside source can make you want to dump the car. Just walk away for a while..that helps for me...

Ok, now I got it open, you guys where right, the rear clutch retainer is totally gone!
It totally burned the clutches, the steels are also bend from the heat, the clutch retainer itself also shows heat signs! Also the beleville spring got scratches and so does also the front planetary assembly on the teeth a little bit.
BOTH sealing gaskets of the piston (inner and outter) are partly destroyed. I found parts of the piston seal in the clutches!
I just checked quickly the band adjustment with the "snug" method: front band got around 2.5 turns, rear band I got around 4 turns!!
The rear band also looks a little bit used! You can see the fine lines in the band, BUT on a few spots they are gone... this band was also used more than normal, but not burned or so! That would also explain the 4 turns of the rear band!
That transmission is supposed to have alto red eagle racing clutches and red lined bands. The rear band is solid and ORANGE and the front is flex and ORANGE! I always had black and solid front bands on my other tranmissions, why is this one flex and orange? Aren't Kevlar bands black?
Anyway, it's orange, so are the front clutches (they look like new!) and the rear clutches, as much as I can tell since they are burned up pretty bad! So this few black parts I saw in the pan BEFORE I installed this tranmission are 95% sure sealing gasket from the rear clutch retainer piston, or what do you think? Or do I have Kevlar parts?
I mean, I got the first time this reverse problem after 15miles driving and that trans never saw more than 140F!
It just makes me sick that I had to remove this trans a 4th time, the torque converter is again full of dirt (I paid last time 300$ to send that back to the USA to open it, inspect, clean, weld and send back to me), I got again back pain AND working today on the car and lowering the car on the lift I hit something and that bend me the whole lower quarter!!!!!! I mean, it's more than just a few broken parts, it just makes me sick!
I want to know WHY that happened and IF this parts I saw in the pan before I installed it could have been the piston sealing parts!
This valve body is by the way a modified (not by me!) VB that shifts stronger. Could a bad VB cause something like that?!
Otherwise the other parts look fine, the front clutch retainer also thank god! Sprag also...

Here are the pictures:

http://home.tiscalinet.ch/6o4o/727

thank you for any help guys... really appreciate that!

Judging from the pictures, the root cause of the failure was the plastic spacer ring in the rear clutch; when this spacer failed it allowed the piston to travel too far and pop out of its bore. When the piston leaves the bore the rubber lip seals expand and prevent it from returning, then the fluid pressure blows the seals apart. The lack of apply pressure causes the clutch discs to burn up. The plastic spacer ring is not a good choice for performance units, it should be replaced with an earlier steel spacer.

It also appears that there is a mismatch of parts in the rear clutch, a late piston was used with an early Belleville sppring, this might have contributed to the failure since the early Belleville is not as robust as the later version, especially when subjected to raised line pressure.

The color of the front band and clutches is red and they appear to be quality parts.

The pic shows the difference in the Belleville springs, the late type is on the left:

Thank you John...

What plastic spacer ring do you mean? There where the clutches and at the bottom the spacer ring is out of metal, as far as I know. But below the wave ring was sealing rubber, probably from the piston... or was there maybe a plastic spacer that is gone now?

Yes, the rear clutch retainer seems to be a late model (got a 3 tab washer + 2nd washer), the belleville spring is an early one, yes!

I will ask on the line pressure, but I said I want firm shifts... don't know if maybe the belleville was to weak? That would explain the scratches on it?! That the piston pushed the bellevile spring to much and it started to touch the planetary gears? Is that possible or how do you explain those scratches?

In one of the pics you have a red arrow pointing to a ragged piece, this appears to be the plastic spacer between the Belleville and the wavy snap ring, plastic was used from the early seventies on.

The pic shows the different style spacers, at right is black plastic, next is white plastric, next is continuous loop steel (the best) and far left is split steel.

I checked the ring, it's steel, not plastic! This plastic you see on the picture is just a big piece of piston seal. I then put it on the side of the piston, you can see it on the piston picture. It fits right there, so it's piston seal.

But I still have a few questions:

1. This black little pieces (0.08-0.1" long) that I found in the trans oilpan before I installed it, could those have been already piston seal or are they really from the kevlar parts? (if I have any?) I just didn't check if they where soft, but they had this size and where black. My bands&clutches are orange?
Can a 727 shift, get the right pressure, although the piston is already a little bit broken? Or how did it pass the dyno test?

2. Can the converter be the reason for this? As said, it was cut open, inspected, cleaned & welded again.

3. Can dirt in the oil be reason for this? I cleaned all lines and cooler as said. The VB filter is also supposed to hold back bigger parts, isn't it?
I mean, can dirt in the VB be the reason for that? Maybe it had a malfunction?

4. Why is the belleville spring scratched? How could this happen?

5. Why is the rear band used? (4x on the adjusting screw!) Does it have to do, that the clutches didn't release?

6. Do I have to send again that converter back to Dynamic to clean & inspect or is it enough if I fill in fresh ATF and drain it trough the drain plug on the converter?

thank you very much for all the great help!

*popp*

The Belleville spring has always been a problematic part in the 727, even when all the surrounding parts are in good condition the Belleville can be overstressed to the point that it will allow the piston to leave its bore. The early style Belleville with the longer internal "fingers" is more susceptible to failure and is iffy when used in a performance unit.

In your case it could have failed at any time after a dyno test. Debris or the converter won't cause the Belleville to fail. The Belleville and piston are scratched because they traveled past their intended limits and contacted spinning parts.

The black residue is probably a combination of ground up rubber and friction material from the burnt up rear clutch discs.

The filter should have prevented any major debris from reaching the converter, a good flushing with clean fluid would be a good idea.

The rear band appears to be in good condition, I have no clue as to why it was adjusted at 4 turns out; ask your builder.

In short, the source of this transmission failure appears to be the Belleville spring; a combination of the wrong part being used and the possibility it was already well used and the increased pressure from the shift kit mods over stressed it.

This is a great post! I took the recent TorqueFlite A-727 book out to see what it said about the Belleville spring because I don't remember anything about strength being mentioned as John Kunkel pointed out. And I was right it wasn't mentioned. But here is an excerpt of what was mentioned:

"Unlike the front clutch pack, the rear uses a Belleville spring to return the piston upon release. The Belleville spring was changed in 1974 to improve the neutral to drive shift. At the same time the height of the piston was increased. THESE PARTS DO NOT INTERCHANGE WITH PRIOR MODELS."

If John Kunkel is correct and you have a later piston and early Belleville, and since they don't interchange, could this be the reason for failure? (I know Kunkel alluded to this). Sounds like the builder may owe you another 727!

Quote:

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"Unlike the front clutch pack, the rear uses a Belleville spring to return the piston upon release. The Belleville spring was changed in 1974 to improve the neutral to drive shift. At the same time the height of the piston was increased. THESE PARTS DO NOT INTERCHANGE WITH PRIOR MODELS."

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Sorry , but that is not true. Yes you can use the late piston with and early spring. I do it all the time. Even Chrysler in 2000 went back to the early style belleville spring on all the 46REs / 48REs transmissions. When useing a #374 late stlye piston with an early Belleville spring you can set the clearance between the piston and the spring down to .003 - .010, then set the clutch pack clearance at .030-.035 , this will keep the piston from coming out too far and still apply the clutches fully


You can NOT use a #212 early piston with an late Belleville spring, this is what the hand book should say.

I'm glad I read this. I'm rebuilding a trans this weekend and when cleaning everything I found the plastic spacer to be in bad condition. I checked the box of '66 trans parts I have and it had the steel welded spacer. The belville spring in the '66 trans seem to be lighter in weight than the later model one and it was cracked too.

Did you say you used Type F fluid, as in Ford? Aren't you supposed to use Dexron in a 727? Maybe it doesn't make any difference, but when I worked at a gas station they made a big deal about using the right stuff so I always assumed it was pretty critical.