Yet another 915 issue

[brighton911]

I'm fairly new to the Porsche world, had my 86 911 for a year now. I wish I could find a gal that felt as good as this car! Anyway, my issue is about 65% of the time, the 3 to 4 and the 5 to 4 shift offers resistance into fourth - but never grinds. By resistance I mean you have to exert a fair force or give up and skip forth all together. The strange part (to me) is the other 35% of the time, it shifts perfectly. All other gears are great-both upshifting and down. I have done all the usual stuff, shift coupler bushings, rod support bushing, JWest shifter (love it) and a new clutch cable and Swepco oil in it. Clutch has about 8000 on it. I did get service records with the car but there is no record of transmission work on the car, just the clutch. I have looked at a number of the 915 transmission forums and I am amazed how all the Pelicanites join in to help. I plan on taking the transmission apart this winter to find out what is up but thought I would first solicit any advice from the members. Thanks!

[RWebb]

Originally Posted by brighton911

I... about 65% of the time, the 3 to 4 and the 5 to 4 shift offers resistance into fourth - but never grinds. By resistance I mean you have to exert a fair force or give up and skip 4th all together.

I used to have a gal EXACTLY like that.


usually, it is harder in the lower gears...

does it happen when there any bumps in the road?
cornering?

also have you inspected the shift linkage at both ends?

[brighton911]

Thanks for your reply. The hard shift into forth is independent of bumps, acceleration, deceleration etc. I should have mentioned I did replace all motor and transmission mount to eliminate that possibility. I have not checked out the linkage at the transmission end, tell me where to look.

[RWebb]

pull the triangular cover in the rear

you'll need to d some searches on this site - lots of detailed post

eliminate the easy stuff first....

[john walker's workshop]

sounds like a minor coupler adjustment would fix it, provided the coupler bushings are still good.

[Peter Zimmermann]

From my experience most "one gear glitches" are usually a synchro related issue. Without records it's not possible to determine if the trans has had repair work done, but your symptom sounds an awful lot like someone put a new synchro ring on 4th gear, but re-used the 3/4 slider. That can cause a sometimes good shift, sometimes bad shift.

Is it possible for you to go under the car and see if the center housing and nose cover of the trans are cleaner than the diff housing? This would indicate a partial disassembly for a prior synchro repair. Of course, the entire unit being very clean would also be a tip-off that someone had been in there.

BTW, the same symptom can be caused by a new synchro ring that was installed out of spec (I measure every one, and I've found some "out-of-the-box" that were not in spec).

[dimeified]

Originally Posted by brighton911

I'm fairly new to the Porsche world, had my 86 911 for a year now. I wish I could find a gal that felt as good as this car!

Stick a flesh-light in the tailpipe. Problem solved.

[Flat6pac]

I would check the helper spring and lever on the end of the clutch cable at thetrans. If the large lever is binding from lack of lube on the verticle shaft you ll get all kinds of weird shifting because you dont get a good disengagement of the clutch

[brighton911]

Thanks for all the answers including the one that made me laugh. The transmission looks pretty clean but maybe it was cleaned when the clutch work was performed. Certainly no problem to pull the small cover on the transmission and make sure all is well there. I didn't mention the shift cup was new too so linkage problems should not be an issue.
John, you mentioned maybe an adjustment, what method do you suggest keeping in mind I have the JWest shifter. The clutch helper spring is new and the clutch action is always spot on. Thanks to all for the support.

[Peter Zimmermann]

Originally Posted by brighton911

Thanks for all the answers including the one that made me laugh. The transmission looks pretty clean but maybe it was cleaned when the clutch work was performed. Certainly no problem to pull the small cover on the transmission and make sure all is well there. I didn't mention the shift cup was new too so linkage problems should not be an issue.
John, you mentioned maybe an adjustment, what method do you suggest keeping in mind I have the JWest shifter. The clutch helper spring is new and the clutch action is always spot on. Thanks to all for the support.

The 915 trans stays in the car during clutch work, and would be very difficult to clean as thoroughly as it should be done during trans repairs. If it's clean it's probably been worked on, How many miles are on your car?

[john walker's workshop]

coupler adjustment procedure: in neutral, loosen the nut/bolt on the rear of the shift rod, at the coupler. then center the shift handle, front to rear, in the shift tower, and hold the handle firmly to the left. then while you're doing that with one hand, reach back and turn the coupler to the right all the way and tighten the nut/bolt. that should do it. the shift handle with it's little lockout ear should now be able to go directly to the right without hanging up on anything in the process. do a minor front/rear adjustment if it does.
__________________

[brighton911]

Greeting Went for a long drive today and shifted that poor car about 1000 times. Speed, load do not seem to have any effect on shift difficulties. No grinding ever!
Here's the latest:
1 to 2 always more effort that it should be - probably medium low
2 to 1 perfect
2 to 3 perfect
3 to 2 perfect
3 to 4 30% time perfect 70% time there is medium to high effort
4 to 3 fine
5 to 4 30% time perfect 70% time med to high effort

Does it make sense to have effort on the 1 to 2 but none for 3 to 2?

SEE NEXT POST FOR MORE TEXT

Attached are two pictures on the shift guide. Some wear on the fork - opinions?

[brighton911]

Part two

So up on the hoist to drain the oil and pull the guide plate. Funny thing, when I changed to Swepco recently, I was happy to see very minor filing fuzz on the magnet. The Swepco has only been in about 300 miles and same amount of filings on the magnet. Obviously something is up. I did shift a lot today.
John, I used the same method you quoted for the coupler adjustment. This condition was the same with the stock shifter and JWest too.
The transmission and engine have the same amount of dirt ( not much really) so no recent evidence of work done.
Thanks to everyone again for taking the time to pick your brains guys. I think I have a winter project coming up.

[brighton911]

Forgot to answer a couple of questions posed by readers. The mileage on the car is 103,500 and the clutch helper spring is fairly new. Clutch action is smooth every time with full release and easy first and reverse selection every time as well.