Need some advise from the gurus here. Couple of weeks ago at the track I suddenly could no long shift the car in the 3rd and 4 gear if I was downshifting and even 2nd was very hard. If I drove nice and rit was fine, but as soon as I got on the gas and hit the regular 8K rpm on a couple a gears, it would stop down shifting when I got on the brakes hard. Kind of the same feeling you get when taking a right hand turn hard and it won't shift up from 2nd to 3rd. So I got off the track, let the car cool down and then tried it again about an hour later. Warmed up the gearbox real nice and slow, never getting up over 6K rpm and the car shifted fine. After 2-3 laps I finally started stepping on it and immediately I experienced the same problem. Could not downshift from 4 to 3 or from 3-2. Refused to force the gears so I got off the track again. Drove the car home that night for 100 miles without issue but of course I don't drive at 8K rpm on the street.
I dropped the car off on Thursday at dealer and suggested motor mounts and/or transmission mounts and/or possible the cable mount on top of the transmission that supposedly has a tendency to come loose but all checked out. The dealer cannot find any issue and of course it is difficult to re create this problem on the street. In addition the shifting on the street even at normal speeds has gotten really notchy compared to normal as if something is loose with the cables and it does not go into the right gear. Dealer has asked Porsche Motor for advise, but in the meanwhile, I'm here for advise and am desperate since 48 hours of Sebring starts in 3 days

 

So, we can rule out transmission and motor mounts for sure?

 

As far as they say

 

So what changes after 6K RPM, I can only come up with the same problem of the typical 2-3 shift in a corner that torques the engine and transmission, so I would think there lies the problem..

anyone?

 

"In addition the shifting on the street even at normal speeds has gotten really notchy compared to normal as if something is loose with the cables and it does not go into the right gear"

So something has moved and it moves more under heaving G-loading and torque. I can't see any of the mounts remaining in play once you slow down to street speeds so it has to be the relationship between the shifter and the engine. I think that you're correct in your assumption that the cables or a related adjustment are the cause.
Alternatively how about the clutch master cylinder? I hear that they can be troublesome and if you do not have enough release bearing travel a partially engaged disc can cause all of the above problems.

 

Leigh, I had thought about the pressure plate innitially, but the clutch engages fully and car does not move at all if in gear but clutch depressed. Braman states that the RS linkage on top of the transmission is not the same as the regular Gt3 ?.

It does definitely have something to do with being "under torque or under G's", which is why I keep thinking something is moving. But the notchyness now has me thinking something with the shifter itself ??

 

A good guess is the shift linkage if it is external. the cable can stretch a bit and the minor adjustment under load can affect it.

 

Erik,

Pop the shifter boot off and see if the bushings on the pivot points are loose. If it is anything like the 996GT3 OEM shifter the plastic bushings do go bad.

Peter

 

I have a few shift linkages in my toolbox just in case it happens. The plastic linkages are flimsy. Mike

 

I have similar problem but going from 2-3 gear up the straight of Laguna Seca before turn 2. 1/2 of the time the gears will grind when I try to shift from 2-3 pass 6K RPM. What the !@#$

I am not turning and the only thing I can think of is torque from high RPM? Bad motor mount, shift link mechanism or shift cable?? No problem going from 3-4 gear and no problem on the street from 2-3 and 3-4

 

How much mileage on these cars? My bet is it's clutch related (assuming the easy stuff like cables check out) because it's related to multiple gears and these clutches do take a beating. Have you bled/checked the clutch hydraulics?

 

mikymu, your issue is different and well known, even on brand new cars. In order to shift from 2-3 at high rpm and high lateral loads, give your hand a 1/2 second pause in neutral and let the shifter naturally find 3rd gear. It will go right in and once you get used to it, it will become second nature. Whatever you do, don't force it, the more you relax, the more the gearbox works with you instead of against you.

 

I know they looked at Erik's clutch when they last fixed his RMS and it looked like new.
I assume at that time they bled/checked the clutch hydraulics? That was only about 6 months to 1 year and a few thousand miles ago....

 

Okay guys I think I shed some light on this. You get the car over 6K after the gearbox is heated and it does not want to shift accurately. Then you back off and get the sense that it is still shifting notchy. Do I have the symptoms correct?

If so then here is the deal, you have worn out synchronizers, I think. The reason that you notice it more in the higher RPM Band is due to the addtional heat generated trying to slow or speed up the gears. You will notice that it gets a bit harder to shift into any gear from a downshift more so then an upshift as you are asking the lower gear to speed up, which is harder then catching a taller gear on the syncho.

Nothing for it but to rebuild your gearbox. I would upgrade your 3rd gear - 5th gear synchronizers with fresh steel units, and you should be fine.

I realize that this is not what you would like to hear, but this is what I think it is. You might benefit for a days worth of running if you move to a more viscious gearoil, as if you're running with synthetic, it may be too slick for the synchronizers could be causing some issues there.

I look forward to hearing if this assessment is correct, so please let me know, and feel free to contact me with any part needs, or if you would like us to rebuild your gearbox. That is what we specialize in.

I hope that this helps,

Erik Johnson
GBox Performance Transaxles
(303) 440-8899 work
(303) 895-4828 cell

 

- I was going to say the same thing as ^^^^ above
- I didn't want to be the one to bring it up but that is what it sounds like to me
- I've had this issue with high hp turbo cars and syncros and what you described basically nails the initial symptoms
- street driving is also a key (i.e. you can drive around the problem)
- you are better to cure the problem now than start grinding the teeth of the gears (this is major money)
- fresh syncros as stated above is the fix (if this is the problem)

- I have unfortunately just heard this same story from another owner and suggested this was likely the issue (nice to have Erik from GBox confirm my suspicion)
- I do not know Erik or GBox but clearly he knows more than me

- hope this isn't your issue and it is a cable or other - but it doesn't sound like it

- a local race shop (that has done this before) is your best bet
- not a hard operation
- parts should be reasonable
- not sure about number of hours

- How many track miles do you have on the car?


Paul