996 2nd gear pop out Gear and Synchro damage.

I was wondering if someone could explain the 2nd gear pop out that ultimately leads to damaging 2nd gear. I am working on an 02 996 and I have the gearbox out and the nose cone off. 2nd gear is pretty wasted and I would like to replace the necessary parts to fix 2nd gear and keep it from popping out so it doesn�t get destroyed again. Any help is greatly appreciated.

Gear popping out of gear is normally a sign of excessive wear on the syncro ring, and syncro hub. How many miles and what kind of use did this gearbox get? Do you have any pictures of the synchro ring and the dog teeth?

I�m guessing 2nd gear was damaged more by trying to slam it from 1st to 2nd than popping out?

Can you post pictures of the 2nd gear and the syncros/ selector rings, etc that is associated with it?

175k miles. I�m not sure how it had been driven. What�s the most cost effective long lasting repair? Thanks.

Duke , how hard is it to get the nose cone off, I'd like to inspect mine whilst it's out the car, how do you get the shift lever off??

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Look it up on YouTube. There is a really good multi episode video showing how to take it all apart but besides that, just do a search here, there are at least 2 threads on this with detailed pictures. I've added some when I took mine apart.

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Besides that synchro ring and maybe some other small parts in that selector ring, you will need to replace that gear with a new one. Check YouTube for the video and the couple of threads here for the procedure. what shape is the pinon gear bearing in?

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For someone who has never taken a transmission apart....what am I supposed to see in this picture that tells me the 2nd gear is trashed?

If you zoom in on the picture you will see the top teeth that engage 2nd gear are all worn off. How hard it is to get the gears off to replace the damaged parts? Will I be able to use standard pullers or do they take special pullers? Thanks.

@DukeTJ8 agree, teeth are trashed, odds are the brass syncros and steel cones (the grippy surface on the face) need to be replaced too. Gears come off with a regular 3 arm puller, but you need a big one!! @Porschetech3 has talked about an issue with shimming of the gear stack that Porsche struggled with that led to 2nd gear popout issues, at least in early transmissions. There are at least three bandaid solutions available to mask a second gear pop-out, but I understand that the proper fix is to properly re-shim the gear stack. Not a project for the faint of heart!

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You see the small teeth just above the big one? the top of them is chewed up. They sort of supposed to look the the small teeth above those ones. The big teeth are the actual 2nd gear but the little ones above it, that are chewed up, are what works with the sychro ring when the 2nd gear needs to match the speed during gear change.

If I just replace the damaged gears and synchros will I still have the 2nd gear pop out problem? How long will it last before it starts to happen again?

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Thanks....that was real helpful...now that I see it, seems obvious ...this is what I love about the forum....learn so much from you guys.

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IMHO, you will most likely still have the pop-out, but it's hard to say without being there. The worn teeth can impact engagement since the points are to ease engagement. I don't know if (or to what extent) the cause pop out, since once the sleeve is engaged, there is a positive lock up between the shaft and gears (at least as I recall from fixing my 2nd gear grinding issue). Like I said above, there are at least three bandaids. They are the G-Box detent, the CMS shift arrestor, or a ball bearing "spacer" in the stock detent. But they are all are workarounds that mask the real issue. People much smarter than me tell me that pop out can be caused by the gear stack being shimmed wrong (...so I read, no personal expertise).

One will find it very tricky to keep track of all the parts and reassembly. I would check with GBox about a rebuild or a rebuilt unit. http://www.gboxweb.com/

Or, you could just buy a rebuilt transmission from GBox with their proprietary upgrades and be done with it.

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And that`s exactly what you want to do when the economy is collapsing.

Great thanks!

At 175,000 miles, the gearbox has lived a good life. It's time for a rebuild. I agree that the gear set is toast. The pitting is the sure sign. It would be very surprising to me if the second gear is the only one with issues during a rebuild.

I agree it�s probably due for a rebuild. I would really like to know more about the 2nd gear pop out. I would hate to rebuild it just to have it still pop out of 2nd. I doubt that it does this from the factory all the way through the warranty period. Does anyone specifically know what causes the pop out to start? Worn synchros, worn gears, detent issues, abusive driving...

I hope this isn't too harsh for you, but I'd highly recommend some searching here on Rennlist and reading historical posts, as well as spending a little time with Google. This is not a new issue, and lots of smart people have posted all kinds of great information about the topic that it'd be worthwhile to dig up, rather than trying to rehash it here. Do the research, then ask any unanswered questions. Here is one particularly informative post from a former Porsche Master Technician that is active on this board: https://rennlist.com/forums/996-foru...l#post15000899 " As for 2nd gear grinding it can occure for two reasons, one being the syncro not letting the slide engage the dog teeth on the loose 2nd gear , or the slide engaged, but then pops out slightly causing the grind.Sometimes it is hard to tell which is happening. 2nd gear gets the most abuse, and the factory admittently got the positioning of the 2nd gear ideal position off by 0.015. The factory fix for pop -out is to adjust the shim stack to move the second gear 0.015 further forward allowing the slide to engage further. The g-box detent allows further engagement of ALL the gears , but this isn't a problem. The CMS (California Motorsports) has a modified shift arrester that does the same thing but only to 2nd, 4th, and 6th gear , and requires the rear case to be removed to install. The loose 2nd gear "dog teeth" are "V" shaped to allow fast and easy engagement. every time a grind occures, the tip of the V is ground or rounded. If too much of the Dog teeth are ground off the slide will no longer stay engaged and/or be very difficult to engage. "

I have watched about every YouTube video that I could find about this problem. Thanks for the info about Porsche having the second gear out of the correct position. So even if 2nd gear is not in the correct position but everything is new and the synchros/dog teeth aren�t worn the shift sleeve will engage correctly. If the synchros were worn or you have hard shifting into 2nd the dog teeth get ground down and they won�t stay engaged. My plan is to replace 2nd gear, the synchro, and the shift sleeve. At that point I will install the gbox detent to get the shift sleeve to get a better engagement. Please correct me if I�m wrong or you see a problem with my plan. Thanks.

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I am not a Porsche fan boy, but I find it hard to blame the factory design for something that has gone 175,000 miles before it � pops out.

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Sounds like a good plan, go for it!

I just got the car and it had this problem. I�m not sure when it first started or how it was driven. I�m not knocking the design. I just wanted to figure out what exactly was going on so I could figure out how to fix it.

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This has been going on for a very long time with this transmission. It didn't just happen 5K miles ago. Most of the time when the first signs of an issue starting to show, the driver will start to adapt their shifting habits to keep the problem from getting worse. They they will start doing other things to drag it on like, change the oil, change the engine and transmission mounts and so on. AND only after all this they will start excepting that this is a problem and just live with it until the car becomes undrivable or they sell it and becomes the next owner's problem. This includes not using 2nd gear at all. Just rev the engine a little higher in 1st and they shift directly into 3rd. You can nurse a transmission with an issue like this for 50K before it becomes undrivabel.

Maybe off topic but I have to share - I had a 05 997S I bought with 20k miles back in 2012 and 2nd gear would pop out occasionally. I recall it was a fairly common issue. Seems Porsche didn�t get around too quickly to address the issue. My .02.