Darin Morgan

Never asked for help on this board before but I really need it now!

A friend and I recently purchased a complete rebuild kit with the Alto Red Eagle double bonded clutches and Alto steals. I was the first to rebuild and after wards I encountered a problem. When you first start the car, put it in drive and take off, multiple clutch packs ratchet ( engage and disengage) about five to seven times with an addible clicking sound (when heard from outside the car). You can then drive the car around all day with out this happening but as soon as you shut the car off and let it sit for about five minutes it will do it again on initial take off. I thought it was my shitty rebuild effort so I took it to a pro and he went through it. On inspection he said I had done nothing wrong and the rebuild was fine. My friend just got done with his rebuild using the same kit and now has the same problem. We have both messed around with different tunes and volume presets trying to eliminate the problem. You can see in the first part of the log where it is locking up and releasing various clutch packs

Anyone have any insight?


transmission.txt is a .cfg file change extension. (why cant I upload a .cfg file?)

zgp

The 6spd GM transmissions obviously have very complex controls. What you may be experiencing is the Controls learning or calculating the fill volume for the individual clutches. Since you have change the coefficient of adhesion by upgrading the friction material and changing the clutch travel, the clutch pack my be rattling during this start up. IMO.

Darin Morgan

I see what you mean but if this is so, I wonder how many times it must do this to re-calc the fill volume and fluid transfer parameters? Its done this about 45 times and does not decrease or increase in intensity nor do the characteristics of the shudder or the number of hits change. Have you ever seen anything or experienced anything like this?

Is there a "re-learn" type procedure the dealer could do with a tech-II?

zgp

There is a learn that a dealer can do with the Tech 2. As for how many times it does this. The transmission is constantly updating the adapt values, it has to calculate them every time a shift is made. It will also do it on Start up to check clutch prefill and fill volume. It is basically needs to determine how much oil drained from the clutch during ignition shut down. Then the tcm knows what the prefill volume is and the fill volumes is for the oncoming clutch.
Other then that wild explanation you might just have loose clutch pack that rattle on start up.

Darin Morgan

Thanks for your insight. The clutch packs are at the minimum of .040 to .045. I have the 4-5 at .038. Went through them five times to make sure I had them right. Used feeler gauges and checked at the ring. I think I will see if a re-learn can be done.

ramaircjm

iTrader: (4)

Give Mike Kurtz at Century Transmission a call (I think he's still a supporting vendor here) as I'm thinking you may have somehow installed them wrong.

I've been running those clutches in my A6 since September of last year and have never had any noise problems or needed to do a relearn.

Darin Morgan

I have talked to Mike before but not about this. I will give him a call.

Darin Morgan

In case anyone comes across this problem, here is the solution.

The stock clutch clearances are .045 to .065 normally. Because the double bonded clutches have a much higher coefficient of friction they need more area between them to set up a hydrodynamic wedge. The 6L80 transmission will cycle through the solenoids on first start and if the clutches are to tight, the car will jerk VIOLENTLY 6-7 times when first started and put in drive. Installing the clutches with .080+ clearances on ALL clutch packs will eliminate this problem and give the pressure purge clearance to eliminate air from the orifices but not apply the clutches violently 6-7 times.
In order to accomplish this clearance you must precision grind the clutch backing plate. Other wise you wont be able to get the clearance to .080+.
The real kicker here is, the directions tell you to put them at .045-.065!

Special thanks to Mike at Century Transmissions for lending his expertise and getting me out of this jam.