915 hard to shift into gear when hot?

Tim L · 09-27-2002, 08:10 AM

When at the track and the transmission is very hot it's hard to shift into gear with the motor running, like the clutch is dragging some. What can cause this? Could this be a bad pilot bearing? There is less than 4k on a new clutch and rebuilt transmission. Once the car is moving the shifting gets better. I changed the transmission fluid thinking that could be the problem but didn't help.

Thanks

Tim
84 3.2

Elombard · 09-27-2002, 08:23 AM

Could it be the clutch needs to be adjusted a little more?

Mine has a similar problem (73 915 though) Think the through out arm has started to spring. I am droping the motor this weekends to look.

Good luck

Shawzy · 09-27-2002, 08:41 AM

Trouble shifting when hot?

That's weird. I am not an expert by any means and so therefore my opinions are my own and not based on experience!

I just rebuilt by 915 and so i trying to think of why you are experiencing this. as far as i know, a bad bearing would not create intermitant shifting problems. and you should hear the bearing whining away if it's bad i would think (maybe try a mechanic stethoscope on trans with the engine running - i think a high pitched whine is a bad bearing)

Hot trans - you using swepco 201? it behaves wonderfully when hot, and disperses heat better than others apparently. it also doesn't get aerated as much when whipped around, which allows for better lubing. an external trans oil cooler can be added, but i don't know if that's necessary. i.e. the 915 should be fine at the track as is.

Simple but have you checked clutch adjustment? another thing - when you replaced clutch, did you replace release fork?? I had one crack on me that would get worse with driving. of course if the fork was bad, shifting would be difficult hot or cold.

when hot, how does it go into reverse? if you have trouble getting her into reverse i would think that's clutch for sure.

when you shut the engine down and the tran is hot, can you shift throught the gears no prob?

shifting problems in my mind boil down to clutch and synchros. since your trans was just rebuilt, synchros should be fine (dog teeth, rings, enegizers, sliders, etc).

has this problem been there from the day of the rebuild on? or did it just appear?

we need johnnie walker here!!

other guys will be able to correct my above statements accordingly, i'm just thinking out loud.

good luck - i'm interested to know the future solution!

Early_S_Man · 09-27-2002, 09:03 AM

Adjust your clutch towards minimum freeplay spec. You probably have it adjusted for disengagement near the floor, and are never truly fully disengaging. Once you have adequate actuation travel, you can try adjusting the cable one turn at a time for more freeplay, but you need to be wary of 1st gear difficulty or reverse grinding at a standstill, and reduce the freeplay when difficulty is encountered!

Tim L · 09-27-2002, 09:32 AM

When it's hot and hart to shift into any gear, reverse grinds. I had to shut the car off to shift into reverse. The clutch engages about half way up so I think it's adjusted correctly but I will recheck it tonight.

Tim L · 09-29-2002, 01:50 PM

When I went to readjust the clutch I found that there was sand under the peddle cluster and the clutch wasn't returning all the way. I vacuumed out the sand and readjusted the clutch to spec. and I'm off to the track. I'll let you know how it works when it gets hot.

Thanks,

Tim

Shawzy · 09-30-2002, 07:20 AM

Sand, eh?

I hope that was it!

I was thinking over the weekend about the hot vs. cold thing. Maybe your clutch was only disengaging partially - enough so that when cold, grinding didn't occur. With the clutch nice and hot, maybe parts expanded enough to not disengage things much at all, and therefore grinding resulted.

In any case, resetting the clutch to spec should clear it up I would think...

Tim L · 10-02-2002, 05:06 AM

Ok. I'm back from the track. After about 100 mi when everything was hot the same problem occurred, so I tightened the clutch cable tighter than spec. that didn't help. I had to start it in gear then once I was moving matched the revs to shift. The second day the problem got worse for the next 200 mi. and started to shudder when starting out. Then mysteriously totally disappeared while the transmission was really hot. So now I have no clue I guess I should open it up when I get a chance.

Tim

Shawzy · 09:37 AM

That is bizzare.

The fact that the problem is dependant on heat baffles me. Adjusting the clutch doesn't help any as you say.

I think pulling the tranny off and taking a good look at the clutch kit, release bearing and fork is your only option unless someone else can suggest something.

This is silly but I assume the trans is topped up with oil? I.e.not loosing any? i know you refilled but it might be worth checking before you drop the engine.

The thing the bothers me is your reverse grinding. that implies clutch and clutch only in my mind. if synchros etc. were screwed, it wouldn't shift well in any situation.

Release bearing:
You said your clutch was replaced. Any chance they forgot to put the thrust washer on the release bearing? This is a wild guess, but if they only put on the circlip it may allow too much play, or worst case, be able to slip through the diaphragm spring essientially making the clutch useless! Not sure if the circlip would even provide any resistance on the spring, so this is def a wild guess.

Maybe talk to the mechanic who did the job to verify parts replaced, etc. Did you use an aftermarket clutch? Friend of mine just got burned by a dealer on her Jetta who charged her for a VW clutch but installed an aftermarket. Not to rock the boat of course...

I'm afraid you are looking at an engine drop - confident you have clutch issue, but we'll see.

Please keep us up on any findings!!

scottb · 10-02-2002, 10:05 AM

When was the last time you replaced the shifter and coupler bushings, and adjusted the coupler?

barlowdo · 10-02-2002, 10:28 AM

I had/have the same problem with a 901 trans. I found that the front shift seal was leaking into the tunnel which lowered the amout of fluid in the trans causing it to shift very hard into gear after a 40 minute drive. It worked great when cold.

There could be other reasons for trans to heat up other than low oil. Maybe a vent problem or internal wear that is prematurely heating up the fluid.

Good Luck,

Don

Tim L · 10-02-2002, 11:32 AM

I think it's a problem with the clutch not the transmission. At its worst point just before the problem went away the car would actually move forward when in first gear and the clutch peddle to the floor, then shudder when engaged. I replaced the clutch myself and used a Sachs with all new parts. My theory is the clutch or pressure plate warps when hot, or something got in there somehow causing friction when the clutch is disengaged, like track rubber. The weird part is I drove another 100 mi on the track after the problem went away. So I'm not going to drop the engine until the problem occurs again.

Thanks,

Tim

pete911 · 10-02-2002, 12:29 PM

I had the exact same symptons with my car. I just dropped the engine for a different prblem and looked at the clutch. What I found was that the input shaft of the tranny was marred (a little eaten up, not much) I think this was my problem. Even though the clutch was depressed the input shaft was still turning due to the friction between the input shaft and the pilot bearing. I ended up using emory cloth to clean up the input shaft, and put a new pilot bearing in. I just did all this last week. On the street I have no problem now. I'll be at the Glen next week and will see how it is after some hot laps. This problem manifested itself last year after some very fast laps at the track by the way.

Pete

Dana_Drury · 10-03-2002, 04:28 AM

Did you lube your pilot bearing? I have heard that the pilot bearing can almost weld itself to the input shaft if it isn't lubricated properly..

Tim L · 10-03-2002, 04:43 AM

Yes, I did lube it with high pressure molly grease but didn't replace it. I think this could be the problem. I was told that these make noise when they go bad but I don't know if this is true.

Thanks

Tim

Dana_Drury · 10-03-2002, 04:48 AM

You should always replace the pilot bearing when doing a clutch job...

Tim L · 10-03-2002, 05:48 AM

So now you tell me! I wonder why they don't include it with the clutch Kits.

Tim

pete911 · 10-03-2002, 05:58 AM

I doubt that the pilot bearing makes any noise that you would be able to hear. The throwout bearing on the other hand makes noise when it is bad.

Pete

Tim L · 10-03-2002, 07:35 AM

So now you tell me! I wonder why they don't include it with the clutch Kits.

Tim

Early_S_Man · 10-03-2002, 07:44 AM

Tim,

No doubt it WAS a clutch problem when you encountered the creeping with pedal down all the way!