buzztt

if anyone has or has had this issue they should definately read this

http://www.6speedonline.com/forums/9...ctionable.html

good luck

mooty

this is usually a turbo gear box issue. not often in GT3.
AFAIK, PCNA replaced the gearboxes?

iLLM3

Never had this issue in my GT2, had it in my ex 996TT, weird!

KOAN

I am having my transmission GT3) repaired as we write, because of difficulty making the 3-2 shift. Apparently, there is a sleeve of some sort that becomes mushroomed, and makes shifting difficult, and also can damage 2nd gear and syncro. My mechanic ( P-dealership) says it is the 3rd he has seen. I am not the first owner, and the car has 30k mi. My car is off warranty, but covered by an extended warranty. Although I track my car, I shift very carefully, and apparently this flaw cannot be manifested by "driving hard". Is the TT and the GT3 transmission the same?

Kailua

More than you probably want to know:

The TT and GT3 are almost identical, but the tiny synchro teeth on 1st and 2nd gears (that first came out in the 993 6-speed) differ slightly between the two. The TT has asymmetrical teeth on 2nd and 3rd, which supposedly allow smoother shifting ... both up (2nd to 3rd shift) and down (3rd into 2nd shift), while the GT3 has symmetrical teeth (similar to the difference between early and late 915 1st gear synchro teeth).

Whether this slight design difference is behind the pop-out issue is debatable. It is more likely the higher horsepower of the TT wearing the tiny tooth flanks more quickly (than the NA version) that is the cause.

When I say "tiny" synchro teeth, I mean a LOT smaller than those found in the earlier G50 5-speed. The change was to accomodate the more modern 3-piece synchronizer arrangement, but in the opinion of many, the "bad" aspects of this change greatly outweigh the "good". Not only is the total surface area of the driven tooth flanks greatly reduced (which relates directly to the pop-out issue, as the parts wear), but since the teeth are EB welded on, it is not a simple matter to renew worn synchro teeth, as it was on previous Porsche 911 models. Worn synchro teeth on either 1st or 2nd gear typically lead to replacement of both gears and mainshaft at any dealership, as Porsche has not made the idlers available separately with the TT as they have with some other models. (And of course the shift sleeve / guide assembly is the other component that must be changed when the idler's synchro teeth wear out.)

swbatte

That's a heck of a first post.
My only complaint with shifting a GT3, is from 2 - 3, it's a stiff and not very smooth shift. I have a Cup shift kit coming from Germany, and hope it helps.

KOAN

Kailau,

Thanks. That is great info. I'd like to see it to see if the design is the reason for my problem, or if it was abused by a previous owner.

Juha G

Not me though...

Sorry to hear about the problem Chuck. It was a good thing you got that extended warranty. It was well worth it!


While I had the car (from 14k to 28k?), I had the shifter cables replaced, and I remember the 2nd gear being hard to get in. Which leads me to believe somebody has been hard on the shifter.
While I tracked the car, I never abused it. My theory is that how fast you change gears has nothing to do with how fast you are around the track. Hence I never felt the need to smash the gears.

I can though imagine that the first or the second owner of the car who bith only drove it on the street, could've abused the gear box (drag racing or some other stupid things).

Hope you get is solved and fixed soon!

KOAN

Juha,

I'm certain it wasn't you. There were at least 3 other (brief) previous owners. Maybe one learned to drive a stick with this...or never learned.

Kailua

This is a very common problem for any car that has been tracked. The lower the 2nd gear ratio, the heavier the idler gear and the harder the job is for the synchronizer assembly to slow the spinning gear.

Steel synchros help a bit, but the real solution would be a hybrid kit utilizing the earlier G50 5-speed components. As a matter of fact, I've heard of this being done. The money saved from not having to use the outrageously expensive 6-speed steel synchros on 1st & 2nd almost pays for the hybrid conversion, with virtually the same shifting performance and special ratios to boot.

va122

The cup shift kit helps, you'll love the rifle bolt shifting action. I'm assuming you got the cables too. they are the most important part. you can get them from PMNA like i did.

swbatte

Yes - my tech is ordering everything from Porsche Motorsports in Germany and has collected all the parts - I'll specifically ask about the cables to! thanks!

eab3@bellsouth.net

It was my understanding that the outside of the gears themselves are always engaged and meshing but freely spinning on their respective input and output shafts. It was the operating sleeve, when the shift lever is moved, that locked a gear on the particular shaft. The teeth on the operating sleeve matched up with corresponding teeth on the inside of the gear to engage. The synchro, when engaged, started spinning the gear to match the speed of the spinning shaft. The older 911 transmissions had a rough, split ring synchro that as it wore, became smooth and less able to spin the gear resulting in crunch. When fullt engaged, the synchro was compressed which provided a spring pressure to help keep the gear engaged. A worn synchro exerted less pressure resulting in ocasionally popping out of gear when transitioning between acceleration and deceleration.

I'm not quite sure how the newer transmissions accomplish this.

LVDell

What a baseless and nonempirical statement.

Kailua

You're correct. It wasn't what I meant to say at all. Correction: The problem is rather common among cars that have been tracked ... far more common than among street cars.

I've studied literally dozens of these damaged gears beneath a microscope.