DasCayman

Hello,
I have been searching for hours on the specifications for the G97.01 Synchronizer wear limit. I found it for my 987 Spyder but can't find it for my 2008 Carrera S. I am looking for something like this. The 6th gear in my Carrera S pops out of gear once the car is warmed up after an hour. Could anyone direct me to this synchronzier spec? Gears 1-2 have triple cone snychros, 3-4 have double cone, and 5-6 have single cone.

Thanks!

Bruce In Philly

2009 C2S 193k miles

Did you contact GBox? https://www.gboxweb.com/
or atlanta speedwerks https://www.atlspeedwerks.com/

Please post your journey here, some of us are having transmission issues. I have a jam getting into 1st and sometimes reverse.

Peace
Bruce in Philly (now Atlanta)

silver_tt

I thought you already rebuilt this gearbox a few months ago? I remember directing you to Stan Richardson at GBox who helped you with information. Stan would have all of this information you are looking for, it's generally not published........

DasCayman

I spoke with Stan who recommended a new shift fork. That turned out to not be the issue. I know he can only do so much over the phone, so I don’t feel any negative way about it. I sent him a few emails and phone calls to follow up for more guidance but never had any responses back.

I took it to a local shop - At Speed Services in MD. And…. It’s been a long process of mis-diagnoses and money wasted.

So now that I have the specs I’m going to check everything myself and make a video for others to learn from.

Thanks.

DasCayman

thank you. I spoke with Stan in the summer. He got me a really good first start at the fix but the trail ran cold with him. I can only bug that shop so many times with emails and phone calls for advice before accepting a cold shoulder.

I will fully document my issue and fix once it’s all sorted so others can be helped.

silver_tt

I am wishing you luck. I don't want to discourage you but working on gearboxes is different than wrenching on engines. Every major shop that knows what they are doing outsources this work and ships it to/from a place like GBox. You will definitely have your work cut out for you but I am pulling for you if you are somehow able to pull it off. The best wrenches I know wouldn't touch this job though.

DasCayman

Thank you. I usually throw in the towel and consult professionals when I've hit my knowledge or skill limit. Unfortunately when I've consulted these local independent Porsche shops I'm left with paying them $$ and I'm no better off than I was before I went there. My local Porsche shop was able to provide me this screen shot:

I'll still dig for more information and make a video on how to check this so others can do it at home.

silver_tt

Yes, if I had spoken with you before the fact I would have told you to save your money on local shops and drop the gearbox to ship it to Stan at GBox right away. My guess is that the cost is north of $5K but we have seen that even shops that claim to be reputable Porsche racing specialists have made all sorts of mistakes not even knowing the right parts to use.... eek

https://rennlist.com/forums/997-foru...ox-issues.html

I probably would have made the same mistake when I had this problem but was guided by a close friend who also ran a Porsche racing shop, but one that really is reputable. He's also the one that told me to never use anything but he OE fluid (he is a college educated chemist and it uses a specialized friction modifier), which Stan confirmed independently. When I asked my friend if I could send the gearbox to his stop to fix it he declined and told me the smart move was to send it to Stan/GBox.

You have some interesting content on your YouTube channel, I saw your gearbox video. The GT4 RS is one of my favorite cars, it looks like you went to Germany to buy it and pick it up. My wife is German and I have thought about doing the same. We have a lot of the same interests, I see you like espresso too. I just bought the Rancilio Silvia Pro X. Had the Silvia for the last 15 years but gave it to my father after his last trip to Europe and had the realization that it's easy to make good espresso (duh).

Happy holidays

PatrickBateman

I used OE PTX in my gearbox and had a grind when the weather was under 40* F until the motor had warmed up for 60 seconds.

Changed it out for motul gear 300 and both the grind when cold and notchiness are gone. GT3 guys have a getrag but they also use motul.

I was skeptical, but had little to lose. I am happy I gave motul a shot and understand I may be the anomaly.

BTW- My local Porsche dealer doesn’t keep the OE fluid on hand as they rarely do any trans services (OE interval is 120K miles) and they said the large containers of fluid expire before they can use it, so they will use motul or a similarly avail fluid whenever they do.

silver_tt

Thank you for the information. I will provide full disclosure that my gearbox was a Getrag from my 996TT track car. I do not know the exact fluid the previous owner used because he lied and took it out of the records but I do know for sure that it was not the OE fluid. It was almost $5K for the gearbox repair, and that was 10 years ago, and that was also not including my cost to drop the gearbox, which is not that hard, and the shipping/insurance to/from Boulder, CO.
https://rennlist.com/forums/997-foru...l#post18044273

I talked to Stan several times during the course of the repair and Maggie always put him on the phone when I asked but I kept it short and to the point. They are both very nice people and Stan was good to work with. He was very clear to only use the OE fluid in this gearbox and he told DasCayman the same. It's possible you could get away with something other than OE fluid but the chemistries and specifications of these oils are highly specific so there is some risk to it. Most OEMs say that the fluid is "lifetime" but they define a lifetime as the time period until it's not their problem anymore. I usually change my ATF/gear oils and the filter every 75K miles, it's a lot cheaper than having work done on it.

carguy999

What filter do you need to change?

silver_tt

Good morning. Usually manual gearboxes don't have a filter and automatic transmissions do (sometimes they have more than one). So the Getrag I am talking about doesn't have a filter but a PDK would.

carguy999

Ok good haha. I changed my trans fluid (to the often recommended PTX) and didn't change any filter so you had me spooked

silver_tt

haha no problem, sorry about that. I should have been more clear.

Smart move going with the PTX. Once bitten twice shy for me. Still hurts looking at that bill haha.....

DasCayman

Solved. I was able to find the spec after exhaustive digging. This applies for the 997.1 6 Speed

5/6 Synchronizer wear spec:



4th gear Synchronizer wear spec:

3rd gear Synchronizer wear spec:


1st/2nd gear Synchronizer wear spec:


My last question will be why we can or cannot measure this gap while everything is still on the shaft?? This is a picture from my transmission:



Hope this helps someone in the future. With my car, it ONLY pops out of gear once the car is driven for more than an hour... or once the transmission is warmed up/ hot. I suspect that the synchronizer gap is very small when cold and once it warms up this gap becomes even smaller. The thermal coefficient of expansion of the brass synchronizer is 18.5 e^-6 mm/mm*C and steel gear is 13 e^-6 mm/mm*C. So the brass synchronizer expands at 1.4x the expansion of the steel gear per delta temperature increase. As the transmission warms up this gap "A" becomes small enough that there is no longer an interference fit between the synchronizer and the steel gear cone so it just spins freely. This is my suspicion but I will confirm once I take the gearbox out again.

Here is a good explanation for others: