003 Automatic transmission problem

[Multi69s]

Currently I am going through an auto transmission from a 74 - 412 (I have done full rebuilds before). The owner bought it from a salvage yard and installed it in his SB. He took it for a test drive and all seemed fine, then the transmission locked up. He took it to a shop and the 2nd gear band had broken. The shop replaced the band (verified) and supposedly replace the seals. However, the trans will now only go in 1st and reverse. The owner took it back twice, but with no results (he is now suing).

I disassembled the trans, and as far as the main internals, I have not seen anything that is really wrong. However, when I removed the transfer and separator plate, I discovered a couple of problems.

The first thing that I noticed was that the 6mm pressure relief valve looked like it had been hammering into the separator plate. It is so bad that the steel of the plate has actually mushroomed up between 1/64-1/32.

The other problem that I have found is in the transfer plate itself. In the transfer plate there is another 6mm ball that sits on a spring. However, it was not installed correctly. Instead of the spring being installed vertically, I found that the spring was installed laying on its side and it deformed the spring.

I have 3 different manuals for the automatics, and none of them show what the purpose of the check valve in the transfer plate is.

So I am trying to pick your brains. What would cause the hammering effect of the 6mm pressure relief valve, and was is the purpose of the 6mm valve in the transfer plate, and could they be related?

Thank you for taking the time to read this

[mr horsepower]

place some pics please
so i can help you out

gr henri

[Multi69s]

Ok.

Here is the link to the pictures.

https://www.facebook.com/media/set/?set ... 78ba96aee1

Any Ideas what would have caused this type of wear. The car has been sitting for at least 10 years with a thrown rod. Any ideas what the check ball in the transfer plate would do? Would the incorrectly installed spring and or the separator plate wear explain the not shifting issue. Since the 1st post, I have disassembled and cleaned the Governor (looked fine) and disassembled the valve body. It also seemed fine and all of the springs checked out to the correct uninstalled height.

Last, should I spot surface the area at the pressure relief check ball to get a flat surface, or would that make things worse?

Thanks

[raygreenwood]

Sorry it took a long time getting back to this. The "peening" around the hole is actually vibrational wear....I am betting.
If the spring was missing or improperly installed the ball simply rattled and spun around the edge of the separator plate....probably at cylinder firing rpm. It would not take long to to roll the edge.

If it was having shifting problems....and you had a check ball messed up it was probably bleeding off main pressure. I have worked on a lot of these autos over the years when I owned them but I wont pretend to know the valve body routing.

Ray

[Multi69s]

Well, I cleaned up the rolled edge by spot surfacing it with a polishing stone I mounted in a mill. Corrected the spring problem in the transfer plate and reassembled, but still not shifting right. However, when I reassembled, the clutches, servos and accumulator went together far to easily. The shop had said they put in new seals, but only charged $30 for the parts. On the other transmissions that I have rebuilt, new seals are generally rather difficult to install, these just fell in. We tested the transmission, and it did the same thing. I really believe that the shop did not change out the seals. I through my gauges on it, and it passed the idle test, but failed miserably in the drive and reverse stall tests.

As a side note, I have a chart for the springs in the main valve body. I disassembled the valve body and all of the parts were in the correct order and the springs all matched the free length and coil count in the chart. I also disassembled the governor and cleaned it, and didn't see any problems there. So at this point, I believe that the shop did not replace the seals.

What would your opinion on this be Ray

Thanks

[raygreenwood]

Unless they just had the seals laying around.....I find it hard to fathom they they were able to get ALL the seals these days for $30.
It sounds like the seals or certain seals did not get replaced.....or if they did replace the seals and they WERE laying around for years.....that could be the problem as well. Just like brake system parts....more than a, couple of years on the shelf depending on how they are stored is not good.

So.....main pressure is correct at idle but fails under load. So obviously its leaking internally somewhere. You note that you removed and cleaned the governer. Did you replace its shaft seal? Also you note that the transmission had locked up on the original owner. What was the reason for the lock up? Was it the failed brake band jammed.....or something else?

The reason I point to potential thoughts about the governor is that the modulator valve operation is heavily influenced by the pressure from the governor. As I noted....I am no expert on these boxes at the valve body level.

As for what the ball check valve does.....the closest circuit it the valve body to thst check ball is direct and reverse clutch valve ball check. But that is in the valve body. Remember that the purpose of the transfer plate is as a set of passages to link various areas of the valve body to other areas.
The check ball in the transfer plate is either limiting pressure into or out od direct/reverse clutch in the valve body....but the question is from where or to where the passages in the transfer are linking to.
If all the plunger valves are intact and moving in the valve body, installed in the right direction and have the correct springs.....and stall pressures are not correct and you have shifting issues.....as I noted....you are probably leaking internally. The most obvious areas to me would be intermal leakage at the seperator plate if it was damaged....or in the shift pressure accumulator pistons....because they require physical rubber seals that can bypass.


Ray

[Multi69s]

No I did not replace any seals, and as mentioned, they just sort of fell into place without much effort. I remember in the past, that some of those seals really seemed to be a bear to install into their bores when new. So I am probably looking at getting a master rebuild kit, and changing everything out. I know that the governor plays a large part in the shifting, but do you think a bad seal there would create that much havoc. Either way, it should be included in the kit.

As regards to the brake band. The owner stated that the transmission operated fine around the block, then locked up. The tranny shop told him that the second gear break band had broken in two. I confirmed that it was new.

[raygreenwood]

Yes...if the accumulator pistons with new o-rings
Seals just seem to fall into the bores....that could be a problem. They need to be able to seal to absorb and hold pressure. Ray