GP GT at the road track (trans leak?)

[eohrnberger]

With the addition of the GMPP Handling Kit, handling during cornering is much improved (you can see this here, here, here, and here - warning, each of these pictures is 300K, and it's being served across my cable modem - be patient). Cornering speeds appear to have been increased by 5 - 10 MPH with a very stable and reassuring feel. Threshold breaking technique was the focus of these session, as the proper setup and proper line techniques were learned in the May session.
Track conditions were good, and the temperature was mild, in the low to mid 70's, with low humidity for August in Michigan. The Waterford sportsman track is a 1.4 Mile road course with many different corners to challenge the driver.

The field was comprised of a number of BMW-M series, Porsche 911's 944's, and 928's, a Neon SRT/4, a Mini Cooper, and a Lingfelter Trans AM.

The first session was pretty tame, reacquainting myself with the track and the proper setup and line for each corner. The second session was much better, being able to carrying more speed into each corner. The third session was the best, really pushing the car to the limit in each corner, earning some praise from my instructor.

In order to prevent the transmission from continued hunting and down shifting from third to second, I kept it in second gear. This has the benefit of being able to use the transmission to slow down the car by just lifting off of the gas, as well as being in the correct gear for the acceleration after the turns apex rather than applying WOT and waiting for the PCM to catch up and down shift to second.

At the end of the third session, I parked in the paddock area and went and got a water. When I got back, I noticed a wet spot under the car. I backed the car away from the wet spot to see what it was. It looked and smelled like ATF . I turned the front wheels all the way to the left, to get a better look further under the car, and found that the left lower suspension arm was pretty well covered in thin layer of ATF fluid .

I checked the ATF level, but it was hard to tell as the part of the dip stick from the full marker to a full 1/2" higher had frothy ATF all over it. I didn't go out for the fourth session. I babied the car straight to the mechanic for an inspection. I needed to find out what was coming out, and why.

The mechanic is not a transmission specialist, but I figure that a trained eye looking at things is better than an un-trained eye. The mechanic said that it was ATF, and it was leaking form the top of the transmission, but he couldn't provide any more information than that. The ATF fluid was checked was at an acceptable level, and did not require topping off, which really surprised me, and makes me think that perhaps not that much fluid was lost.

There were at least three places on the track that I would imagine are hard on an automatic transmission. After the esses, there is a little hill up to another right hander, where the transmission wanted to downshift into first from second. Going up this hill would whined out the engine just short of redline just before it would shift. The second place is at the end of the back straight, where I was going between 75 and 80 MPH in second gear (still short of red line). The third place is the front straight, where you'd be going around 70 MPH in second gear.

I've set an appointment with a transmission shop for an inspection and estimate. I'm going to ask him specifically as to the whats and whys, and get a quote for repair. On the phone he said that since it's a leaker, he'll have to put it on the hoist, clean it all off, run the engine and see where the leak is coming from. He also said that if it's a seal, it may be a simple thing to fix, which I'm hoping for, but I'm not expecting that.

Regardless, I don't think that this car is the car that can handle the road track on a longer term basis. It's strange to me that stock Neon SRT/4's and Mini Coopers can, while the Grand Prix can't. WTF? Shouldn't every car be able to handle a little hard driving on the track in basically stock trim? Granted that teh automatic transmission is the weakest system, and the other cars has manual transmission, but still. It should be able to handle this. Shouldn't it?

[Ripn12s]

Cool pictures.

Maybe you have a bad oring or something on the axles. Was the leak on the driver side or pass side??

If your going to road race you should get a Qauife Differential. www.pfyc.com has them. Full time 2 wheels driving. According to the site they are great fro road racing.

Have u considered a aftermarkek PCM (DHP/INTENS)??

[eohrnberger]

Ripn12s,
The leak is on the drivers side and looks to be higher up on the transmission not down low. I'll find out more when I get a quote from the local transmission shop in the morning. I hope that it's not a serious or expensive problem, like maybe a simple seal that blew?

I also plan to ask specifically as to the why of the leak. I need to make sure that I clearly understand what action to took on the track that caused the leak, and not do it again.

I've been thinking about the Qauife differential, as well as the Intense Racing Gen 1 LSD (seems like the Qauife is only for the 4T65EHD, while I have a GT which I believe is a 4T65E). To my understanding, which is probably imperfect, LSDs are really important to prevent single wheel burn outs, as they'll over tax the gears in the differential and burn them up. At the road track, I've not been doing single wheel burn outs (no burn outs at all), but I can see where I'm loading the differential harder than normal when cornering really hard. I'll wager that's why a beefed up LSD is probably a good idea.

Do you think that the leak is related to a problem in the differential? I hope not, that sounds expensive!

I'm planning on a PCM replacement once I get past the 5/50 warranty. But not until then. If the tranny can't hold up now, adding more horses is only going to make it worse.

My main reason for posting was to let people know how much better you can corner with the GMPP kit. I really like it. It's not the same car as stock. Much more European in feel and response. Just can't say enough good stuff about it.

Thanks for responding.
Erik.

[Ripn12s]

Have u lowered the car?? That will help alot too I bet. After adding coilovers to my car cornering is so much more fun.

The Qauife is supposed to be good for road racing because it will help u in powering out of the coners not just for doing burnouts. You can upgrade to the HD. Check out INTENSE's site for that upgrade.

"In cornering, while accelerating out of a turn, the Quaife biases power to the outside wheel, reducing inside-wheel spin. This allows the driver to begin accelerating earlier, exiting the corner at a higher speed." - PFYC


I think the pcm will be help w/ the different shift points and downshits. Might make it easier to drive w/out the need to leave in 2nd all the time.

[eohrnberger]

While lowering the car would help a lot on the track, I'm afraid that it would make the car more of a "speeding ticket getter". I don't know if that's the 'look' that I'm after, and I'm concerned that it would make the ride on the road much harsher. I've seen a jucied up ricer with a fart can and a grab bar lowered, and when he went across the pot holes, his entire ride shook. That's really not something that I'm after.


I agree that the PCM would move the shift points around that would perhaps eliminate the 'hunting'. I'll bet that it would be crisper on the downshift as well, which would help on WOT. I just have to wait until the 5/50 is over before I go and do that.

Again, thanks for the ideas.

Erik.

[eohrnberger]

Well, I just got back from the transmission place, and it appears to be likely that I got the trans too hot on the track, and it just boiled over and spilled ATF out of the top vent. He said that normally this means a major failure of inside components. He cleaned all the excess fluid off of the underside of the car, and if it does not continue to drip, then it's OK. If it drips, it's not OK, and I'll have to end up doing something.

When I hinted that I was driving hard, he wanted to know how hard, and I had to admit that it was at the track. He pretty much told me that the transmission was not designed to hold up that kind of use, and that I'd better plan on a major rebuilds if I continue. Can any other road track drivers out there confirm this?

He took it for a road trip, and detected nothing unusual. He said that it felt pretty good, so I remain hopeful that no damage was done. But overheating would not be good, so if I'm serious about this car on the track, I wager that I'll have to add a trans cooler, and I've been thinking about the INTENSE™ 4T65E-HD Transaxle. I wonder if it would work in my GT if the final drive ratio were changed to the stock ratio. Anybody know?

I'll post again in the next few days and let you know how things end up.

Erik.