mikewmorley

Been driving myself crazy over the last few days, reading and re-reading most of the previous posts on the topic. My problem started a few weeks ago when I noticed a high-pitched whine when accelerating in 5th and 6th. It’s been into the shop on a couple of occasions and has had bearings etc replaced, but with no noticeable improvement. I then started reading previous threads on the subject (maybe should have done so sooner!).

I found Porsche PhDs’ advice very helpful, carried out the test, and think that the input shaft may well be twisted. A few questions…

Could a twisted shaft be responsible for the whining noise in 5th & 6th ?
Given the expense to remedy, is there a better cure than the standard ’97 shaft?
The problem became evident immediately following a clutch change; any connection or purely coincidental?

I wouldn’t describe my driving style as particularly aggressive, and rarely ‘hard launch’. I have participated in a couple of track days recently, but of course that mainly involves 2nd through 4th gears.

Any help and guidance would be greatly appreciated.

Jean

Mike,

I would think synchros before thinking main shaft if the problem is in 5th. In any case, the '97 shaft is slightly better than the '96 but I would not use that as a remedy, I bent one myself without great effort.

If you want to have a strong shaft you should go to a Guard Transmission billet shaft or similar, those are bulletproof. The repair is expensive though. If it is not a big deal and not really annoying, I would not change it. If you end up opening the box, upgrade your synchros to steel ones since you are tracking the car and check the differential, they tend to fail silently and become useless after a while.
I am not sure about this but the clutch change should not be the cause I guess. Nice avatar, that 996 is really struggling

mikewmorley

Thanks for the quick response Jean - taken on board. Are you coming over for the track day this Friday. And bringing the 705hp 993 TT with you?

Jean

Mike, you are welcome, you will get some much better opinions I am sure.

I cannot make it to Dubai unfortunately, I am trying to get the car ready to ship it to Bahrain, there is the Supercup race there, same day as the F1 race. The weather is starting to get hot, watch out for your gearbox wear and oil temps too (I assume you have an extra oil cooler).

Enjoy it and good luck!

PorschePhD

It could be part of the problem. Do you have the issue in 1st? The shafts bend on a regular basis. Most of the TTs that come in to the shop have the issue. I would say at least 75% are shot. You can go to a stronger shaft (GT2) style, but you will have to change the gears as the ratios on that shaft are different then stock. Typically whining is an issue with not enough play in the system and the gear running up track on the set gear. There has to be a specific amount of endplay in the tranny. When the shaft bends it removes the play and the gear does not run true to the set gear. You end up with a noise.

Hope this helps.

Jean

Stephen, are all the 993TT main shafts with built in 1st and 2nd? I heard some of them were not..Which shafts do you recommend?

Thank you.
Jean
p.s. good to see you here from time to time, you should visit us more often.

PorschePhD

Yes, all the TT shafts have the gears on them. I would use the PMS GTII shaft.

chris walrod

This is one of the measurements I did when I rebuilt Seege's 96TT gearbox. I measured the input shaft runout, which thankfully was only a few tenths of a thou.

Even though you note whine in upper gears, keep in mind that all gearsets are in mesh, just only one has power applied at one time. Knowing Seege's input shaft is straight, he still mentions a whine in his upper gears.

On my 1995 n/a 993, I get a slight whine in 5th gear only, but is much more noticeable when I installed a bolt-in roll bar. FWIW

Jean

Thanks Stephen, it might be the 993 Carrera then, not the TT..I guess you meant PHS II for the shaft.

Chris, could you please elaborate about the roll bar thing?

chris walrod

Sure thing. I really never noticed any gear whine in my car until the moment I installed a bolt-in DAS roll bar. No other interior or noise dampening components were removed, just a roll bar install. Me thinks the roll bar, even though it not being open ended, is acting like a tuning fork or the like. Basically amplifying chassis and engine noises. I also get to hear more of that great flat6 orchestra Does this make sense?

mikewmorley

Thanks for all the feedback and advice. I've had the best part of 4 years trouble free fun in the TT and want to get the fix right.

Jean

Chris, I thought it would be something along those lines and the fact that since you installed it, you felt safe and started driving like a maniac (in the good sense) So if I have a full roll cage I will be hearing the oil inside the engine?

Thanks!
Mike, Alex should be able to sort you out, in Bahrain there is a good mechanic as well, let me know if you need help.

mikewmorley

Jean, the cars with Alex now and I've passed on the feedback that I've received from the board. The gearbox is apart so guess I'm going to miss out on the track day at the Autodrome - the last of the season given the rising temperatures! Have to get some mods carried out before the new season starts - suspension as mentioned previously, and that secondary oil cooler!

Jean

Mike, you have 2 more working days to go, he should be able to fix it if he has the parts. Sorry to hear about that. There should be more events outside of the one organized by the P Club, you can always go and have fun. Otherwise you should come over to Bahrain, there is a good bunch of Porsche owners from Bahrain and Saudi.

chris walrod

Just driving a tick slower than my guardian angel flies I guess there is the factor of airspeed vs. ground speed.. Gotta recalculate that. I am in trouble if there is any head winds she is flying in