davith

iTrader: (9)

I have an 99T/A with about 87K on it and as about 1K miles ago it started slipping in overdrive only after driving above 65mph for over 45mins? It is also leaking a small amount of fluid when parked and moving. Other then that it shifts great, even chirps the 1-2 shift, any ideas what the cause could be? I bought the car used so I do not know the history however it looked to be all stock when I bought it at 80K?

I also should throw in the trans was low on fluid when I purchased it causing it to bounce off the Rev limiter on the 2-3 shift. I added more fluid and now it shifts fine.

performabuilt

iTrader: (25)

Are you sure its slipping in 4th gear and its not actually coming out of lockup or slipping in lockup Generally unless its been tuned out actual slipping more than a couple hundred RPM in fourth gear would set a code for compinet slipping ?

Gilbert@Ace Racing

Do you have any way to log the event you described? It is highly possible that the converter clutch is slipping due to excessive wear in the the valvetrain or fatigue in the converter itself. Does the car shutter or just seems to lose power?

When this takes place, can you say for sure that the transmission is slipping? Here is something to think about, in 4th gear the 3/4 clutches and the 2/4 band are applied. So, it only makes sense that if it were actually slipping due to excessive soft parts wear then other gear ranges would be affected. What is the fluid condition?

Next time you are experiencing this, hold the throttle very steady and then slowly, gently apply pressure to the brake pedal. Then watch your tachometer for a change and see if you can feel the converter clutch disengage and engage with the brake switch input.

Get back to us and we'll see if we can help you determine a good course of action.

g

davith

iTrader: (9)

No System check lights have came on. I am not sure if it is the trans or converter it does not shutter or buck the RPM’s just start to raise about 200-400RPM as if something is slipping for 2-3 seconds then it catches and then drop if I hold the gas pedal steady. The last time it did it I gave it a little gas when slipping and it shot up by about 2000RPM but then I would let off and give it gas and it would catch again. Or I could cause it to downshift and it would grab. It would work fine under 65mph but it did it right around 70MPH. It only does it after driving in overdrive for an extended time and it only slips in overdrive. The fluid looks good however I may have over filled by about one quart about 4 months ago and it started leaking about 2 months ago.

Gilbert@Ace Racing

Yep, sounds like it is slipping to me!

Have you replaced the filter?

g

davith

iTrader: (9)

Thanks for the info, I have not touched the filter since owning the car, I will change it tomorrow and see what the fluid in the pan looks like.

Gilbert@Ace Racing

Well it is worth a look. See the reason I suggested the filter is that it seems to do ok and then just slip it's *** off, then ok again. Point is, I bet you could lean on it pretty hard cold and it not act up.

The reason is if the filter is clogged, or getting clogged as it is running then after it is shut down the debris can falla way from the filter overnight. But... get back to us when you get a look at it. A few picks of the pan when it comes down will be worth a whole bunch!

g

jimmyblue

iTrader: (11)

I found worse TCC slip when hot and that can turn into a
"runaway" situation (lockup clutch slip makes more heat
than unlocked). I think thinner fluid doesn't apply as much
force at the end of the line where it matters, for the same
(commanded) head pressure. I would start a trip with the
TCC just being "wimpy" and end with it slipping at level
cruise, then unlock (P1870) until key-off / key-on reset it.

Codes may not set until you remain in slip for a little while
or across multiple incidents. Though you might see immature
P1870 or like that even with the light not set.

Lockup clutch pressure modulates a lot with throttle and with
learning so it can be pretty variable.

Nothing wrong with attending to hygeine first, then if it persists
you want to scan for immature slip codes etc.

2000RPM worth of flare is a lot for a stock converter lockup /
unlock to show. May be you got a "bonus". Might have the
inspection cover off and see what color the converter is. Stock
is bare metal. Aftermarket are all (that I know of) painted.

Gilbert@Ace Racing

I too suspect a TCC issue, but there is a significant flare here that implies otherwise.

g

performabuilt

iTrader: (25)

2000 rpm is to much for converter are you sure its not down shifting thats really to much for even a down shift to 3rd

Roarin_8

iTrader: (5)

Check the tailshaft near the transmission bushing and make sure that it isn't cracked. (Use a flashlight) You could have a small hairline crack there that would explain the fluid loss which would also mean that your bushing is shot and needs to be replaced.

davith

iTrader: (9)

I changed the fluid and filter last night and it looked terrible! It was as black as motor oil. I did not see any metal shavings or chucks of anything in it. I drove it about an 1hour home on the expressway after the install with no issues? I could not find any cracks and have not seen anymore fluid leak after the pan gasket change. I will post or send out some pic’s of the pan once I get them loaded from my buddy’s digi camera.

davith

iTrader: (9)

Here are some pic's. I wonder how much longer this trans is going to last? It seems to be working fine again for the moment...

http://s95.photobucket.com/albums/l1...ff/Trans%20Am/

Roarin_8

iTrader: (5)

Yuck....

performabuilt

iTrader: (25)

Man dude that looks really bad I would definatley start saving for a transmission put one on layway or just buy one, Your gonna need one very soon from the looks of those pics.

Gilbert@Ace Racing

Well that is unfortunate. I suspected there was a clutch failure and the fluid condition verifies that. The reason it would have a good 1/2 shift is that the 2/4 band is applied during that upshift, apparently it is working well enough to bite hard. The clutches affected in your unit are going to be the 3/4 clutches. That is why you were seeing slippage at highway speeds, or when you were in overdrive. It is highly possible that the 3/4 clutches were hurt the few times it hit the rev limiter on 2/3 upshifts. It does not take much to glaze those clutches and they go downhill very, very fast.

It is good that you serviced the unit, but in cases like this by removing the old fluid sometimes transmissions that are weak do not last very long. The reason is the old fluid has particulates that aid in the application of the damaged or worn clutches. That is not to say yours will quit pulling all together anytime soon... rather I would suggest that you put a plan together now for replacing the transmission and torque converter. The reason for the converter replacement is that the converter clutch will quite possibly be compromised as well.

If you would like to discuss some options feel free to give me a call today, I will be in the shop most of the day. Again, I think it is time to put a plan in place for a replacement transmission... or have your unit rebuilt.

We would be happy to work with you, all you need to do is call!

Good Luck with it either way!

g

davith

iTrader: (9)

I will start making call's to get a plan in place, and get that high stall conveter and trans on back up......

Thanks for the help guys I will be giving you a call!