Read all the hits from searches and I fear the worse...

My main shaft gearbox bearing was shot. I had it taken apart and fixed (about 6 months ago). I have also changed all the synchros to be on the safe side. Rebuilder told me all gears are fine.

Now twice, I’ve had a dreaded 2nd gear pop out. First time I thought maybe a sloppy shift, now I am getting concerned. Both times it happened on hard acceleration up the hill when car unloads / loads and perhaps when I back off acceleration in high rpm. Is it possible it is the shifting cables? If not if I go back to the rebuilder and exercise my warranty, what do I tell him? What did he do wrong?

Otherwise car shifts flawlessly. I tried the test; accelerating in 2nd gear all the way to 6K rpm, then off gas whilst coasting in second back to zero. I did this both uphill and downhill and the gear does not pop out. Opinions please…

 

It won't always happen. If it has popped out since the rebuild, 2nd gear is indeed jacked. You should have put in a detent while you rebuilt. Are you still warrantied on the rebuild? If so, make the guy rebuild again and don't forget the detent.

My car pops out to, but I just hold the lever anytime I'm in second so it doesn't pop out.

 

the "gears" can be fine while 2nd gear's synchro's may not be. since it's the dogring that gets rounded and that's on the triple cone synchro setup porsche deemed reasonable to saddle us with in the name of providing a very staid shifting mechanism, it seems. therein lies the problem, and yes, going UPhill i was also able to replicate the problem. but only once, usually it's downhill under load, 2nd gear.

the problem with most "older" rebuilds is that unless care was given to the tolerances and actual gear stack placement of ( iirc 4th gear in the gear stack ) which slightly alters where second gear positions ( this using shims to change the tolerances per porsche materials ) then the conditions that contribute to the inherent weakness in the original build are far more likely to exhibit themselves.

given that it's only happened a couple of times, you MAY find some measure of relief using the gbox detent, worst case, you'll need to either rebuild 1/2nd etc,.. or..

keep your right hand ( or would that be your left hand in UK?! ha ) on the shift while under load in 2nd. esp going downhill. it never goes away, much like intermittent spoiler issues. this is on par with those, in that you could conceivably drive forever without fixing it,.. but why. it sucks.

good luck

 

Before I go complain to the rebuilder, what are the chances that when the gearbox was taken out and the new gearbox mounts were fitted, that the cable tension was disturbed? How do I check that the shifter cables are tensioned properly. I have short shifter fitted.

 

my best guess? the cables have nothing to do with the popping out, so i'd say chances are low. i have an ssk also, and can tell when a cable isn't linked right. this ain't that. sorry.

bottom line: if they rebuilt anything back to original stock specs.. WITHOUT taking into account porsche's own ( possibly begrudging ) admission that their original tolerances helped bring about this issue..

then it is prone to failure again. i only know all this as a dealership rebuilt mine for this and had to rebuild it again, within 6 months, and i NEVER.. missed a shift.

it was then we ( me, the tech/pcna whomever ) all collectively researched the updates tsb's, whatever from porsche and got the right shims installed, rebuilt again etc. all good thereafter. was a pita nonetheless, as they should have done it right from jump. one would think. i'm afraid you may be facing what i have in the past. although without factory support. ack.

 

Damn!

But if the synchros are new, and the gears have no wear (he checked it all) where could the builder go wrong? I don't get it.

Also, as he will go for a drive he will wonder what I am talking about as then car won't misbehave!

 

of course. car never exhibits the problems while our tech's are in the car ha. but seriously. the issue has to do with the gear stack placement. pure n simple. most techs until they have dealt specifically with this issue repeatedly will not know anything other than porsche's original factory fix which is to build it back to stock spec.. rarely with any mention of this "newer" info, ...that once is found, will get into deeper detail about the "reshimming" which changes by millimeters the eventual position of second gear in the stack. again, if my tech who was a pcar master tech at the biggest dealership in LA didn't know about the "updated" info vis a vis shims etc, then it's no real reflection on your guy, that he didn't ( doesn't?) know about it either.

find the info from porsche re this issue. it exists, as i've seen it. good luck, i feel your pain.

 

Given that all my gearbox parts are not worn, that I have new synchros, that it only happened to me three times without any grinding noises; the problem appears to be the assembly tolerances when my tech was putting it all back together. I guess i will go with gbox detent fix. I have a question though, what is it that gbox detent does. I presume as spring remains the same it must be longer hence applying more pressure onto the dog ring in order to keep the gear engaged to prevent a pop out. Also it must be working on all gears. Is this correct? Anyone know exactly how it works? Thanks.

 

Some would have us believe the issue with the 996 turbos jumping out of second gear is a "Porsche product flaw issue" and that 20% of those affected can not be repaired without custom gear work.
We're told... "After a proper replacement of the second gear and syncros to correct the jump out issue, the trans may still jump out of gear."
This kinda sounds like a backdoor excuse for not fully correcting (all) the possible issues while the transmission is out and apart.
Have you experienced this and what was your outcome?

 

first it isn't a product flaw as much as it a "design flaw". that said, if one or ANYone never misses a shift or otherwise unintentionally and inadvertently rounds the 2nd gear dogring portion of the 2nd gear synchromesh, then the problem might theoretically never have had to occur. EVER occur.

it all begins with ONE bad shift. if not you? then someone else. the design flaw ( if "it" can even be "fairly" called that! )? has to do with the fact the the shim tolerances were so tight/close.. pick a word ) in the EARLIER iterations ( '01/02's mainly ) that had the they shimmed it with a bit more tolerance ( read margin for error ) which would've "slightly" but decently altered where fourth gear sits in the gear stack placement which is what the RESHIMMING solution that PORSCHE devised came from then the propensity for it to happen ( mostly again ) to the 01/02's and it would ( and never would've PRE existed...)

it is also not coincidental we rarely hear of this happening beyond MY 02 but i suppose it's possible, it's the same G50 BOX.

as to your point about a gearbox rebuilder not reshimming it according to the NEWER revised specs ( from "roughly" MY '02 onward, ( which coincides nicely with about the time that Porsche dealerships stopped even trying to admit that "no issues exists with our g50 gearboxes in the 996 porsche turbo!".)

believe me when i say this was their "COMPANY LINE" ( ask me how i know this?? )

first it isn't a product flaw as much as it a "design flaw". that said, if one or ANYone never misses a shift or otherwise unintentionally and inadvertently rounds the 2nd gear dogring portion of the 2nd gear synchromesh, then the problem might theoretically never have had to occur. EVER occur.

it all begins with ONE bad shift. if not you? then someone else. the design flaw ( if "it" can even be "fairly" called that! )? has to do with the fact the the shim tolerances were so tight/close.. pick a word ) in the EARLIER iterations ( '01/02's mainly ) that had the they shimmed it with a bit more tolerance ( read margin for error ) which would've "slightly" but decently altered where fourth gear sits in the gear stack placement which is what the RESHIMMING solution that PORSCHE devised came from then the propensity for it to happen ( mostly again ) to the 01/02's would not PRE exist...thats why they eventually "came clean" too many occurrences for it to be them calling it a "coincidence or "gee, never heard of that one before!! :"

they tried it all.

 

Give this a try. I havnt done this tio may car yet but it's on the list.

https://www.6speedonline.com/forums/...n-do-pics.html

 

there's also a cms shift arrester that is highly recommended

http://californiamotorsports.net/pro...shift-arrester

 

The detent will not help once you have the second gear popout.

 

I definitely feel this is an assembly spec issue. As '02996ttx50 stated, you will probably never have an issue if you never grind a gear. It's amazing how overly sensitive this gearbox is to any wear on the dog ring teeth.

Almost everyone grinds a gear from time to time in the life of a car and it never causes pop out issues. I believe the dog ring doesn't engage fully on second gear, which makes it super sensitive when there is any wear. I'm hoping the CMS shift arrester I installed will fix this issue.

I drove a Supra for to 135,000 miles without any pop out issues and this car had thousands of roadcourse miles and probably close to 50 drag-strip passes on it. I also have a 2001 M3 with over 200,000 miles on it, with no transmission issues. This car also have several thousand roadcourse miles on it. Both of these cars use a Getrag transmission.

I do believe cars with cable shifters (like the 996) have a much higher rate of ground gears, especially if your trying to may quick shifts.

Later, Steve

 

Too bad you had to rebuild more than once to get to the right guy. But you confirm my growing belief that failures to effect proper repairs can't be blamed on a "Porsche Design" issue. How often do we opt for the extra cost of actually fixing issues as opposed to spending $ "trying to fix them". The dealership is looking more and more like the best choice for me all the time.