I've copied this from the other thread for detailed description. And my mileage was a bit off as I was writting from memory. This describes it more accurately;

I've had my gear box rebuilt by a clown 3 years ago. My main shaft bearings failed. This is standard on tuned cars. After the rebuild I've developed second gear pop out which I never had on the original gear box. Damn! The clown then fited the detent (upon my research) and the pop out went away. However, after 15k miles my gear box was screwed again due to incorrect tolerances used by my clown rebuilder. Bearings were noisy again. I've then taken my car to the Porsche racing specialist in Munich / Germany who is "God" in gearboxes rebuilds and is closely linked to the factory. The workshop rebuilt my gearbox and handed me back the gbox modified detent. I was surprised and asked him why? He told me that the modified detent is absolutely NOT the way to go. It places a tension onto something (forgot what) and causes wear of that item which on the long run ruins it and makes next rebuild substantially more expensive. The key is a proper rebuild of the gearbox with proper tolerances. If workshop is clueless your gearbox won't last modified detent or not. Just telling my story. So, no detent for me just a solid workshop who will from now on change my main shaft bearings every 100k miles. ;-). Ps. I've done 25k miles since the second rebuild and have zero pop outs or issues.

 

The problem is that dealer would not repair the gearbox. They used to but no more. I guess this is due to unsuccessful rebuilds even by the main dealers in the past. It is now replace item only. The way I researched it; initially some cars had problems. Under warranty boxes were replaced. Porsche then changed specs (different shimmy sizes). After that all was well providing re-builder knows about the changes.

 

first of all. one should never NEED a detent. they're a POS . secondly, if you hadn't ( not YOU terminator, but rather "you'" generically! ) had not rounded the ******* thing in the first place it would ( as steve has, as well as myself, have pointed out! ) never been in need of a "shift arrester"or a detent which is essentially stopping it from where it wants to go, owing to the MIStolerances inherent in the INHERENT FLAWED design! not the AMMENDED ONE! so those gadgets and gizmos are trying to "arrest", diminish, "lessen" the "issue" without addressing its CAUSE! this is key!

by virtue of the "damage"! we are talking millimeters as all shim tolerances that need micrometers to measure don't need to be "wrong" by "much'!

couple the foregoing with the use of "triple cone synchros'" which are what was used so as to allow for a smoother shift! hell, our boxes actually have a synchro for REVERSE!... then you'll have a much deeper understanding into what caus(ed) the issue design wise in the first place! you'll begin to understand that trade off's porsche made for this car when designing it, they wanted a "pretend race car for a banker", and that's pretty much what is! as one who has made a whole bunch of compromises to make it more competitive at the sacrifice of "street ability", but most that begin down that slope say, ( **** it!!, why didn't i just begin with a gt2/3?!? ) well cost, obviously! but than we've put that money back in it to make it more gt2/3 like in the first place! irony anyone??

all the detent or shift arrester for 200 bucks is gonna do? is buy you some time to put off the event and ultimate "proper" repair you'll need to do ONCE to forever have your gear stack properly placed and aligned. no 200$ part is going to accomplish that. so it's a band aid, basically.

any/all competent porshc gearbox g50 rebuilders KNOW all this, and even know what minor mistakes i am making in the dissertations of mine lol. they're just too busy correctly re-shimming g50 boxes to correct the minor errors in my explanations LOL

all kiddin aside, i was taken into the confidence of the master tech that did all 4 years of work on my car at this d'ship as he felt my pain and KNEW he was ( as he was advised duh..lol..) to treat me like a mushroom and feed me BS and keep me in the blind

every once in awhile you get one that says "hey, this isn't a weekend wannabe racerboy banker" he's just a guy,... paid good money for a warrantied and relatively new turbo and a multi BILLION$$ corp is trying to **** him around. let's see what we can do to mitigate some of that standard operating procedure, just a bit. being "fair" with one out of a 100 ain't gonna kill "us" LOL

 

I have to carefully read your posts not to feel somewhat attacked unfairly. I just bought this turbo. It came with the issue having already been addressed by the (non-Porsche) dealer I purchased it from.
I discussed this issue with my dealership (Penske in Scottsdale) who has given me a bid to remove, correct as need be and re-install the trans. They stated they absolutely stand behind the work and will warrantee their work. That's about all I can ask for.
I certainly am learning that theses "cheaper fixes" may or may not work and can easily cause longer term issues. I haven't experienced the dealer claiming a total tranny replacement is the only answer. If the dealer says they can and will fix it and warrantee the work, I don't see how I can go wrong.

 

ok, i think if you read my posts however many times you'll find no attack of you personally. but i do know a bit about the 2nd gear pop out situation and am only too happy to share.

perhaps you mean my "bedside manner". yeah, i'm sure that could be improved

any shop can guarantee their work and there are laws demanding they do so in most states iirc? but you'd know stuff like that as easily as i would!

but porsche themselves would absolutely guarantee their internal or otherwise work on a gearbox from start to finish. i believe it's 2 years parts and 12/24 on labor.

i'm a "dry" read, i think? is what your sensing. certainly nothing personal.

BTW!! tranny "replacement is aboslutely NOT the solution. only the 1/2 mainshaft parts and synchros ( a 2nd, more than likely ) gear if damaged, possible not probable! ) etc are necessary for repair of 2nd gear pop out. i could link you to a complete SET that contains most everything needed, as well as shops that would be half the price of a porsche shop. again, either would guarantee either of "their" work! parts and labor. but not ALL shops would be capable of properly rebuilding the trans or repairing the second gear popout situation. this is MUCH easier than a full gearbox repair.

 

Thanks. It probably is just bedside manner but no problem here. With over 7000 posts you are certainly entitled to be a bit short from time to time. All the facts seem to fall into place once we get past the claims of "quick fixes".
The difference between facts and opinions run high on these blogs. I know that. At least you are responsive and fair. What is it they about "opinions?" Everybody has one... LOL
You have been helpful. The volume of dialog on this subject would have shaken out the truth after a few years, one would expect. I've owned other Porsche turbo cars and never had this issue so I'm learning by test of fire.
Not taking it personally. Thanks for saying that...

Still NO Substitute!

 

I disagree slightly with the detent/arrester comments. The detents simply adds extra pressure on what I will refer to as the shift arrester. The stock gearbox has a part that looks almost identical to the CMS shift arrester (though with a different cam profile). I will refer to this stock part as the "shift arrester" and refer to the aftermarket part as the "CMS shift arrester".

The "shift arrester" determines how far the shift rod moves. The shift rod then acts on the individual gear shift rods, which in turn move the shift forks, which engages the dog rings (guide sleeves).

The detent simply puts more pressure on the cam of the shift arrester, trying to hold it in gear. This part does nothing to change the amount of motion/travel of the guide sleeve. However the extra pressure could wear out the shift arrester cam profile, causing issues in the future (this is theoretical, because I doubt the pressure is being increased significantly enough). This is also why the detent won't fix the 2nd gear pop out once it starts (typically).

The CMS shift arrester has a different cam profile, which changes the amount of motion/travel of the shift rod. The result should be a more complete engagement of 2nd gear (all gears for that matter).

My guess is Porsche used the new shim specs to re-position the 1st/2nd gear guide sleeve to more fully engage the 2nd gear dog ring. This effectively accomplishes the same result as the CMS shift arrester. I have the stock shift arrester at home and will post a picture tonight (though it looks exactly like the CMS shift arrester).

Hopefully the diagram below will help.

Later, Steve

 

the above sure helps more than my blathering on and on..and what they say about pics = a 1000 words is as true as what dappainta says about opinions being like ..well, we all know how that one ends. yeah, my goal here is twofold help/be helped, and kill time, and there's my 7000k post count for ya! time on ones hands.

as to the pic just provided and explanations above they are helpful, and although i was ( at the time! ) told that the re-shimming had to to with changing where fourth gear ends up sitting/being placed in the gear "stack placement". whether that's true or i imagined it, i cannot remember with any certainty. but that's what i was told. it was a lot to absorb i can assure you given my lack of technical understanding. up until that point in my life i had never inspected a g50 gearbox firsthand so i had NO idea what i was or was not looking at. i'm not technically based by any means, am somewhat of an auto didact and i'm speaking here from a severely challenged and addled memory. but no incorrect info would ever be intentionally shared.

the explanation as to why the shift arrester is the far better and potentially longer term solution, absent a trans rebuild, well that makes sense too. i was merely told to avoid the detent at any/all costs so i didn't pay much if any attention as to "why", since i knew i was having my gearbox rebuilt by porsche.

 

I was told that the only weak point in our gearboxes are the main shaft bearings. The rest is bulletproof. I was told no mater what at about 100k street miles they will fail. In my case this was correct as my bearings failed few miles shy of that. But what pisses me off is that there is a whole bunch of clowns out there who feel qualified to rebuild these boxes and fail miserably. I found such a ******. Usually, the upshot is pop-outs and shot bearings again. Then there is all this talk about the detent as preventative measure. Why would detent be a preventative measure? My car had 0 pop-outs since new up to 100k miles. And it's tuned. Only after one of these clowns was let loose in my gearbox did I experience pop-outs. All I can speak is for my case but with a proper rebuilder you don't need detent. Just my 2 cents. I hope I helped someone with my case.

 

You are in stride with the rest of us here. The ***-monkeys who claim to be Porsche transmission GURU's should be called out anytime their work is inferior. My earlier comments of dealer repair and warranted work is my only real choice. Too bad I didn't learn all this $400 and three weeks ago. Oh well education and especially Porsche education, can be costly. We know that.

 

you guys are both dead on right. anyone tells you you NEED a "detent" or whatever is full of sh*t, or simply an amatuer. if it NEEDED one, PORSCHE would've made one lol

 

Below are a few pictures.

This is the stock detent (a bad angle, but the only picture I had).






This would be replaced by the GBox Detent.





Here are a few pictures of the stock shift arrester.








Here's the CMS shift arrester.







Hope this helps,
Steve

 

I have my court day on the 28th this month as I have sued the clown. He denied he screwed up immediately. It will be a difficult case to prove as he is denying he did anything wrong. Of course he would. Clowns will always be clowns. It will all come down to the expert witness. I hope he will understand and gave evidence accordingly as I have provided him with all of the gearbox data available.

 

had no idea your issues had progressed to such an adversarial state. find a porsche master tech. slip him 20 quid for the ( now 10+ year old ) updated shim spec sheet(s) (though they are usually now only retrievable from their bench top computers/pet screens, tsb files etc ) so ya may may have to go a lil "007" on him lol ) from porsche which your clown clearly was never in possesion of, and good luck on the hearing!

 

I had my tech do this. the ideal 'boost' is not the full diameter of the bearing, but a mm or so less, so he used the specified bearing plus a crush washer. As a result, my shifts in and out of 2nd have stiffened and I have not experienced the occasional decel pop out I had previously. Very happy with this inexpensive fix.