G50 transmission problem
06-17-2008, 12:07 PM
#1
Rennlist Member
Thread Starter
G50 transmission problem
Hey guys, unfortunately I need some G50 transmission help…
There are two tracks (Putnam and CMP) where I need to haul it down to 2nd gear in tight turns. I noticed back in April (at Putnam) that I was having a little grinding when upshifting from 2nd (at/in redline) to 3rd. I didn’t think too much of it and thought maybe it was because I wasn’t getting the car 100% straight before shifting (which obviously is sometimes really hard to do).
This past weekend (at CMP) it became much worse (I use 2nd gear in three spots there).
I thought, again, that maybe I wasn’t letting the car get straight enough before shifting but then I went out of my way to get straightened out and it would still PAINFULLY grind on the upshift.
There is NO grinding when DOWNshifting from 4th to 3rd (I heal/toe). And there is NO grinding during “normal” driving or in any other gear. It’s also seems to get worse the longer the session goes on.
A Porsche mechanic (but admitted non-expert in G50 transmissions) was paddocked next to me this weekend and this was his differential diagnosis: 3rd gear synchro overheating?? Bad carrier bearing?? Bad brass 3rd gear dog teeth?? I have VERY limited knowledge about what this stuff is…
Some background: the car is an ’87 911 and has 165,000 miles on it. To my knowledge, the tranny has never been rebuilt. The tranny fluid is brand new (Mobile 1). The clutch has less than 10,000 miles on it.
Another interesting fact to consider: Sunday afternoon, I was talking to a guy in my group with a 964… and he said he was having the EXACT same problem when upshifting into 3rd after Turn 14 (I don’t think he uses 2nd anywhere else)…
What do you all think is the problem and what is the best/easiest solution?? Thanks a LOT!
Jack
There are two tracks (Putnam and CMP) where I need to haul it down to 2nd gear in tight turns. I noticed back in April (at Putnam) that I was having a little grinding when upshifting from 2nd (at/in redline) to 3rd. I didn’t think too much of it and thought maybe it was because I wasn’t getting the car 100% straight before shifting (which obviously is sometimes really hard to do).
This past weekend (at CMP) it became much worse (I use 2nd gear in three spots there).
I thought, again, that maybe I wasn’t letting the car get straight enough before shifting but then I went out of my way to get straightened out and it would still PAINFULLY grind on the upshift.
There is NO grinding when DOWNshifting from 4th to 3rd (I heal/toe). And there is NO grinding during “normal” driving or in any other gear. It’s also seems to get worse the longer the session goes on.
A Porsche mechanic (but admitted non-expert in G50 transmissions) was paddocked next to me this weekend and this was his differential diagnosis: 3rd gear synchro overheating?? Bad carrier bearing?? Bad brass 3rd gear dog teeth?? I have VERY limited knowledge about what this stuff is…
Some background: the car is an ’87 911 and has 165,000 miles on it. To my knowledge, the tranny has never been rebuilt. The tranny fluid is brand new (Mobile 1). The clutch has less than 10,000 miles on it.
Another interesting fact to consider: Sunday afternoon, I was talking to a guy in my group with a 964… and he said he was having the EXACT same problem when upshifting into 3rd after Turn 14 (I don’t think he uses 2nd anywhere else)…
What do you all think is the problem and what is the best/easiest solution?? Thanks a LOT!
Jack
