76' 915 trans problem.

jrod · 09-12-2008, 02:34 PM

hello, I have a 76' 911S w/over 100,000 that pops out of 1st and reverse and makes a grinding noise when i let the clutch out normal. But if i "pop" the clutch no problem at all drives nice shifts nice exc.. i have adjusted the clutch and the shift coupler and rebuilt the pedal cluster. I can also start it

in 1st gear fine and won't pop out. i have a chiltons manual which i think the clutch adjustment segment is weak. any tips or advise would be great thanks!!

Flieger · Flieger's Garage

Sounds like worn syncro hub teeth - necessitating a rebuild and lots of "while you are in there" refresh work

Disclaimer: I am not an expert and have not worked on transaxles.

surfdwn · surfdwn's Garage

I had a similar problem with a 915. It turned out to be s severely worn synchro hub. I did the work myself and the transmission was great afterwards. Expect to replace a lot of bits and pieces "while you're in there."

David Nolen
'70 911T

robert walsh · 09-12-2008, 06:14 PM

replace the clutch cable and helper spring, detialed here in the tech forum, the cable is probably frayed or twisted inside the cable housing, change out the clevis bush at the same time, pretty easy once you understand how to do it, took me 2 hours but made a dramtic change in clutch operation. The adjustment takes a few attempts but get it as close to spec as possible, do it before getting into a clutch or tranny synchro's. I bet the cable is binding up due to the frayed in wires being twisted, less than $200 diy, it worked wonders for mine. Good luck. It takes patience and small hands, PM me if you need help.

jrod · 09-12-2008, 07:25 PM

thank you all for the info. I will replace the cable, spring and bushings first before diving into the tranny.

dentist90 · dentist90's Garage

If it crunches going into 1st and pops out of gear most likely the synchro ring is worn out. The synchro ring is primarily responsible for holding the gear.
Grinding while you let the clutch out slowly? Hmmm, maybe TO bearing is worn out too? It would grind while holding the clutch pedal down as well.

jrod · 09-13-2008, 06:23 AM

it only grinds right after it pops out and until i make sure it is back in neutral. almost like it's half in and half out...... weird. but if i pop the clutch, away i go w/ no problems until i completly stop. upshift fine ,down shift fine, no grinding going into any gears.

robert walsh · 09-13-2008, 07:35 AM

I'm not sure you have the helper spring under the tranny on your model, but trust me if you do replace it, it for sure replace the cable, very simple, it sounds like your clutch is not fully engaging on slow (normal) pedal release, if you pop it, the cable will pull through, slow release causes it to bind up inside. Just went through it and wayne pretty much said change out the parts above first because regardless of the problem you'll change them when you fix a bigger problem anyway. A fellow posted how he installed an entire new clutch kit and still had the same issue only to, then, replace cable + spring to have it resolved.

dentist90 · dentist90's Garage

Reverse usually isn't a problem as far as popping out. It is not synchronized and held in place by detents. Perhaps just a linkage adjustment. I doubt it has anything to do with the clutch itself (unless it grinds going into reverse). I'm thinking that when you let the clutch out fast there is enough pressure on the hub dog teeth to prevent them slipping apart (for example, try pulling the shifter out of 3rd while accelerating and when coasting. It's much more difficult while drive torque is on the gears). If it ever pops out of 1st (or any gear) after coasting and accelerating again it is a worn synchro ring.

Check your linkage adjustment first, just in case you are not fully engaging these gears.