Shifting gets more difficult after a few miles? Heat-related?

gsxrken · gsxrken's Garage

My 1986 930 shifts like it always had when I first start out on a drive, but after a few miles and everything is up to temp it begins to get a bit more difficult to find a gear. No grinding at all, but I encounter some more resistance either selecting a gear, particularly 3rd, or getting out of a gear. I renewed the fluid from Kendall to Swepco with no noticeable change. Wevo shifter and Wevo coupler and known-to-be- good bushings.
Does it sound clutch related, even though it never grinds?
If it's heat related, which it seems to be since it develops over time, what component is expanding to such a degree that the shifting characteristics would be altered?

tdw28210 · tdw28210's Garage

Same thing happens in my '85. Have not addressed it yet, but I suspect the transmission mounts get softer with heat.

gsxrken · gsxrken's Garage

Quote:

Originally Posted by tdw28210

Same thing happens in my '85. Have not addressed it yet, but I suspect the transmission mounts get softer with heat.

That would be easy enough and my mounts are 30 years old now but I'd hate to spend the $200 the turbo mounts cost just to test your theory. It's your theory, YOU should test it and report back! ;-)

Rawknees'Turbo · 08-04-2017, 04:57 PM

Yo' Ken, if you decide to change the gearbox mounts (which are non-serviceable in OEM trim), I recommend Rebel Racing split bushings . . . they are in two halves (top and bottom) - the OEM are one piece, and you install them after burning the old ones out (or using a drill, press, etc., to remove them), since Porsche dumbly made the 930 support bar one piece (non removable bushing housings).

You can order them from his website, and they'll get to you in about a week (mine did, at least). There are two or so options for the "hardness"

of the bushings, and Clint recommends the softer option for the gearbox (which I think is 10% harder than stock).

Rawknees'Turbo · 05:37 PM

I also wanted to mention that when I removed the mount bolts and large washers, so I could actually see the original bushings on my 1987, the were completely tow'up from the flo'up with spiderweb cracking.

BUTT, I did not have the shifting symptoms you describe (gearbox has been overhauled, though $$$).

BSNMOE · 08-05-2017, 02:05 AM

Try adjusting clutch when car is really hot.

gsxrken · gsxrken's Garage

Thanks Ronnie- hadn't seen those Rebel split mounts. Last time I looked Wevo was the only game in town with that $250+ exchange or $150 bring-your-own-welder option.
I redid my suspension bushings with Clint; his stuff is worth the wait. I think I'll swap them just because 31 years is an eternity for any rubber bushing, they're reasonably priced, and there's a small chance it will address my OP. Thanks bro.

gsxrken · gsxrken's Garage

Also failed to mention I had Gary Fairbanks redo my box a few years and maybe only 20k miles ago. So while anything is possible, I doubt it's internal.

T77911S · 08-08-2017, 03:14 AM

I will be really surprised if this turns out to be mounts and not internal

David Goodman · 08-08-2017, 04:28 AM

Quote:

Originally Posted by gsxrken

Also failed to mention I had Gary Fairbanks redo my box a few years and maybe only 20k miles ago. So while anything is possible, I doubt it's internal.

Has it been doing it since it was redone? Don't be so sure it is not internal. He redid one of mine once and then had to go back in. The guy does make mistakes.

Which would have been fine except he blamed the problem on a "930 design flaw" and charged me for opening it back up.

gsxrken · gsxrken's Garage

Quote:

Originally Posted by David Goodman

Has it been doing it since it was redone? Don't be so sure it is not internal. He redid one of mine once and then had to go back in. The guy does make mistakes.

Which would have been fine except he blamed the problem on a "930 design flaw" and charged me for opening it back up.

Ouch. Even just the hassle of pulling it again would be frustrating. He's retired now in either case. Since I live local to CT, I drove over after he pulled it apart for a diagnosis... he showed me how it needed new syncros and a few other parts that he swapped for some used stuff he had in his inventory and charged me almost nothing for.
He was probably 75+ a few years ago.

bemmett · 01-15-2018, 02:09 PM

I'm curious if there was ever a resolution discovered for this issue?

I have a similar issue in my '87's G50 transmission. Shifts into first easily when cold, but after it heats up, becomes more difficult. Never any grinding at all, just more resistance getting into gear.

RSBob · RSBob's Garage

Had a similar issue and it happened to be thermal expansion of the clutch disk. Had it machined 3 1000ths and it solved the issue.

Tyson Schmidt · 01-16-2018, 11:55 AM

Also possible the pilot bearing drags when it gets hot. This will have the same symptom as a dragging clutch. Not fully releasing, which makes the synchro have to do more work.

bemmett · 01-17-2018, 07:08 AM

I'd hoped that maybe this was maybe symptomatic of just needing new bushings or new linkage, but everything suggested to date points to having to pull the transmission for further investigation.

Thanks for the responses!

Mahler9th · 01-18-2018, 07:37 AM

bemmett/Brian

I add that it might be a good idea to have your examined by one of our excellent NorCal shops-- there are quite a few possible answers, and shop tech might be able to help you zero in very quickly.

If you could use a recommendation for a good one nearest to where you live, I'd be happy to provide one.

I too am in the SF Bay Area.

bemmett · 01-18-2018, 12:28 PM

Mike,

Yeah, I know. I live near RMG (I'm a repeat customer) and work near JWE, so I'm definitely aware that we've got some fantastic local experts I can call upon.

I was just trying to see if there might be something small I could try on my own before having to call on them.

B

Mahler9th · 01-18-2018, 01:43 PM

Even something as simple as debris/dirt/carpet, et cetera under the clutch spring can cause what appear to be shifting issues and/or clutch release issues. At least that has been my experience with my 915.

My '75 is a race car so there is no carpeting. After every event I found all kinds of trash in the pedal box area. If I let it accumulate it can eventually foul the proper operation of the spring.

It can pay to have folks with accumulated knowledge and a "feel" for likely candidates do a test drive. Hopefully the OP got issue(s) sorted.

I don't have any experience working on G50 3.2's (14th last of these made tomorrow), but I expect many of the candidate culprits are the same or similar. RMG, like Tyson probably have some good starting points for troubleshooting things like this on street cars. Dan, Dan and Bob are awesome.

JWE can also do this type of work-- they are great friends and resources as well.

I think it might be hard to ID something thermal in this type of troubleshooting.

Nut/bolt and fluid level/condition checks might be some easy starting points in one's home garage.

Clutch cable tension and shifter bushing/linkage/coupler adjustment might also be easy things to check off before getting into more obscure areas.
Good luck!