mrvedit

Now that we know exactly when it slips, carlsonauto's suggestions are right on.

Aukai25

Hey guys I opened up my trans and I found a piece of a rubber seal in the 4th accumulator. Anyone know what this could be from? Please help! Thanks

carlsonauto

I would say that you have located a problem, Tear it the rest of the way apart and figure out where it came from. Did you take the servo apart? is your 4th servo stock or aftermarket? If its stock it doesnt have any rubber in it (except the cover o-ring) so thats most likely not where it came from. Find the rest of your rubber seal and you will find your problem.

Aukai25

I have a corvette servo we checked everything out and I was wondering if it could be from the last time. The last time the 1-2 accumulator seal was cut and flipped so I was wondering if it could be from that it has the same circumference and same width. And if I have the Transgo hd-2 kit and have the corvette servo do I use the red or white spring for the accum bushing valve? Thanks for all the help.

mrvedit

By "4th accumulator", do you mean the 3-4 accumulator underneath the separator plate? (Its opposite the 1-2 accumulator and a mirror of it with a piston and spring.)
That 3-4 accumulator piston has a rubber o-ring.
Or, as carlsonauto appears to assume, do you mean the 4th apply piston in the servo?

Carsonauto: Sonnax makes a servo seal kit that replaces that scarf-cut rings with o-rings. With that it is "theoretically" possible to find a rubber seal in the servo. (Sorry cannot find the part number now, but I have bought and used it.)
Also, I assume you are NOT suggesting that Aukai25 tear the entire trans apart, just the servo and accumulators, right?
Ted.

Aukai25

Ok here is what happened when I put everything back together. I took it for a test drive around the block I had the shifter in D. When I was going it shifts 1-2 then when going to 2-3 it just slips. Also tried to put the shifter in D3 and when I was going it shifts 1-2 then when it comes to the 2-3 it slips. The reason I think was because the band was to loose and we tightened it up and it felt much better but it still did the same thing. Do u guys think that I burnt the clutches already that's why it's slipping or could it be something else?

mrvedit

The band only affects the 1-2 (and later 3-4) shift. Therefore, if your 1-2 shift is good, then the band is good. When you shift to 3rd gear, the band is released.

Is this the same behavior as before, or is it now worse with 3rd gear also slipping?

Carsonauto and I are trying to determine if you have a problem (bad piston/seal) in either the 3/4 accumulator or in the servo.
The reason we are asking all these detailed questions is to determine if this can be fixed without removing the trans and rebuilding it.

BTW - With the Corvette servo use the white HD2 spring, but the difference is tiny and not your problem here.

carlsonauto

holy crap a lot has happened while I went out for dinner.. lol I am assuming that by 4th accumulator he means the accumulator in the case of the trans under the seperator plate. I also assume that he has checked that piston seal itself and it is intact. If the transmission was cleaned properly when rebuilt any parts of old seals would be gone. Therefore the "RUBBER" seal chunk has to have migrated from elsewhere. If the 4th servo is stock then it doesnt have any rubber seals that it could have damaged to migrate to the accumulator but if its a sonnax or superior servo then there is rubber in them and could have come from there. Yes I was suggesting that if he has the servo apart and the valve body off and has not yet found the problem then he most certainly needs to keep digging until he finds the problem. Either way if the rubber was left over from an improperly cleaned case or if its from a failed seal elsewhere, if it's this far apart and no issue is apparent there isn't much choice but to dig deeper... I am now suspecting that the 3-4 clutch has failed by what is being described. In my original post I asked questions about the experience level of the builder. The reasoning was if if the 3-4 backing and apply plates were damaged from a coned 3-4 clutch and reused the 3-4 clutch will burn up really quick even if everything else is just right... also a lot of old school builders like to set 3-4 clutch clearance too tight and toss the 5 sets of factory return springs that help the 3-4 release and stay released properly. Those two things alone will also burn up the 3-4 clutch quickly. Even quicker if the driver like lots of rpm in first and second gears..

Aukai25

ok so your saying that i should gut it out again and double check everything again. Do you think that i should just change the backing and apply plates? What 5 factory return springs are you talking about is that the one that transgo says not to put back? thanks

carlsonauto

If you have had it apart as far as you can go without tearing the whole thing apart and have not found the problem then I dont see any option other than taking it apart until you find the problem. I would guess that it will be fairly obvious as to where the issue is just make sure you find the actual cause. In other words if the 3-4 clutch is burnt up which I'm betting it is dont just replace the clutches and put it back together. You need to find out what caused the problem in the first place and fix it or you will be doing it again about 4 days after you put it back in.

mrvedit

Carsonauto is suggesting taking the trans apart to find where that rubber seal came from. For example it could be part of a seal from one of the pistons in the input drum; a torn seal will quickly cause a problem.
On the assumption you don't want to pull the trans again, I was trying to figure out what you can just done and if it had made it worse. If you can only removed the servo and the 3-4 accumulator, and now now it ALSO slips in 3rd, then I would check the servo carefully again. However, it it was slipping in 3rd and 4th when you started this tread, you have checked the servo and 3-4 accumulator, then it does sound like you will have to pull the trans and rebuild at least the input drum.

Carsonauto is referring to the five "3-4 release springs" in the input drum under the 3-4 backing plate. Did you install all the stiff Transgo springs? If not, then you want the 3-4 release springs installed. Personally I also install them and leave a few of the transgo springs out of the 3-4 spring cage, but I'm no expert on this.

Carsonauto and I are giving you very detailed posts while yours are very brief. It really should be the other way around so that we know exactly what you are doing and can help you better.

96lt4c4

iTrader: (5)

Your 3-4 clutch is toast and will need to be replaced, even a little slipping will burn the clutch discs. Did you reuse the old teflon sealing rings on the input drum or install new ones? You may have a problem there or torn a lip seal on the 3-4 clutch apply piston. For the acuumulator I reccomend installing Sonnax pinless pistons in the 1-2, 3-4 and forward accumulators. They are not that expensive and have double seals on them. I install them on every rebuild. I always leave out the 3-4 load release springs (per ATSG manual) in the 3-4 clutch and tighten the clearence up to about .040. I have never had a problem. I also install 8 clutches in the 3-4 clutch pack. The last one I built went into a lifted 93 Z71 and pulls a 6000 pound trailor everyday.

http://www.sonnax.com/system/announcement/77987-01K.pdf

http://www.sonnax.com/system/announcement/77998-03K.pdf


I know of 9 second drag cars that do not have the load release springs in them, for the 3-4 clutch.

carlsonauto

I am not going to argue with you but a 93 Z71 is rev limited at 5000 rpm. You can get away with no springs at that rpm even though I wouldnt. Its not worth the extra 3 lbs of pressure that you gain by leaving them out.

As far as the 9 second drag cars are concerned as long as you put the transgo return spring kit in you can in my experience toss the release springs and have no issues. If using stock springs throughout and no release springs you will most definitely centrifically apply the 3-4 clutch and burn it up. If you have figured out how to get away with no release springs and factory springs throughout then please share with me how to do it... I like to learn

Aukai25

Ok here's the question now I drove the truck around the block again and now the truck works. But when I drive it around for a little bit I slips from 2-3. Do u guys know what that could be and also what is the line pressures that it should be? Thanks Eryck

96lt4c4

iTrader: (5)

How bad is it slipping? Does it shift into 3rd at all? Does it flare shift...rev then go into gear?

Does not sound good, you are going to burn up the 3-4 clutch again.

carlsonauto

What did you do to it to make 3rd work better??

On any kind of a performance build I shoot for a minimum of 190 psi line pressure and usually a max of about 240-250 when maxed out. (the 240-250 is only on certain applications and takes special parts to make it live) At an idle in gear it should be in the 70-80 range or so depending on pr spring boost valve and tune. You can get max line by unhooking the electrical connector but that assumes that the electronics on your vehicle are functioning and the tune is correct. I prefer using a laptop or scan tool to manipulate epc current. I wouldnt like to see any less than 60 at any time and even thats pushing the low side pretty hard

mrvedit

Yes, you NEED to tell what you are doing. Rebuild the input drum or just fiddle with the accumulators?

Putting the shifter in reverse or blipping the throttle will come close to max line pressure. Putting it in reverse tests that the boost valve is working correctly. Blipping the throttle tests that the Pressure control solenoid is working correctly.

Ted.

Aukai25

ok the only thing that we did was check the 1-2 and 3-4 accumulator and changed the seals on it and also the accumulator on the side of the trans and changed the seals. i ordered the sonnax pin less 1-2 3-4 accumulator and pin less forward accumulator. thats all i did to the trans. also i seen on other forums that they said they get this when you drill the 2-3 feed hole to .101 (like the directions say from transgo) instead of the .093. they state that .093 is for firm shift and .101 is for full race. so just wondering if that could be the problem.

96lt4c4

iTrader: (5)

I do not reccomend drilling the holes in the plate that big. They shift way too hard. Are you reusing the stock plate? Does it have wear from the check *****? If the plate has any wear I always replace the plate with a new Transgo. They are thicker than stock, I also replace all 8 steel check ***** with plastic Torlon check ***** that will not wear the plate anymore. You are going to have to pull this thing out and take it back apart. I do not think you are going to fix it from under the car. I thnik your problem is either a torn lip seal or something wrong with the teflon rings on the input shaft. Make sure none of the solenoids have popped out of the valve body, missing clips. I have had this happen to a guy trying to build his own trans before. Left the clip off the 3-2 downshift solenoid.

I like to use this Sonnax Performance Pack instructions as a guide to drill the plate. They are a little more conservative.

http://www.sonnax.com/system/instruc...L60E-01-IN.pdf

Also not a big fan of the Transgo kit, Sonnax stuff is way better.

mrvedit

All really good advice from 96lt4c4.
The next time you have the valve body off, follow his instructions; the Transgo plate is under $25 and the Torlon ***** maybe $5. Make sure the gaskets are good too.
It is sounding more and more like there is an internal problem