Clutch Failure Questions

Inniswhe · 08-24-2010, 03:42 PM

Background

84 Carrera with 131K miles. I am not aware if the clutch has ever been touched.

I have had the car for about 3yrs and am slowly restoring it to first rate condition. I just got it back on the road 2 months ago after an 18 month layup . I did a complete glass out repaint that was very time consuming but worth it in the end as I have a very high quality finish, new headliner, all new gaskets/moldings/seals. Car is very tight and I planned on rebuilding the engine/tranny when that day comes.

I noticed after getting the car back on the road that the clutch was slipping on hard acceleration . I don't recall any slippage before the repaint. I hoped it would last this season and then this winter I would drop the engine/tranny and get it sorted as well as a tranny refresh (myself or outsourced).

Last friday on my way home from work on a rolling downshift from 2nd to 1st , heard a clunk and clutch/tranny started making noise, cannot fully disengage drive by depressing clutch pedal and when I hold the clutch it makes noise . Almost didn't get home as I put the car in neutral and couldn't get it back in first. Endured some grinding , got it in gear and got her home. Also the clutch pedal remains part way down when released.

Questions:

I assume that something let go/ broke in the clutch. Any idea what it sounds like?

Since I am worn out from the repaint , I think I am going to outsource the 915 refresh and clutch rebuild even though it is something I had hoped to tackle. I will take out the engine/tranny (first time doing this) Any idea how long this will take first time around removing the engine/tranny as a unit?

Looking for a good 915 mechanic is eastern Canada or New England - Suggestions ? I read that Gary Fairbanks is a good 915 mechanic in New England but if there is someone closer to PEI it would be nice.

Zeke · 08-24-2010, 03:58 PM

Had a flywheel bolt head break off and do pretty much what you are experiencing. Probably not any way you're not going to pull the motor and tranny on this even if it's something entirely different.

gregwils · gregwils's Garage

I agree with Milt that you should think about addressing the clutch before you make plans to refresh the 915. If you could do a rolling downshift from 2 to 1 in a 915 doesn't sound to me like you have issues unless there are other symptoms that you didn't list.

I did my clutch two years ago, it was my first drop. There are people that claim they can pull their motors in under three hours. I'm slow. I prefer to spend a few hours disconnecting everything, then coming back another day when I am fresh for the actual drop. Fix or six hours should be enough time. Wayne's book says ten hours, but I am guessing that might be in and out...not sure.

In my opinion it is more work to pull the motor than replace the clutch. Seriously, it's probably just another two or three hours to separate the trans, then swap out parts and bolt them back together. The money you save in labor you can spend on a throw out arm, shaft seals, cable, fix any oil leaks on the motor, new sensors, etc. You can even adjust the valves much more quickly while it's out. We all understand the frustration of getting a car on the road after a lengthy project only to have something else break. Hang in there.

To answer your other question, Gary Fairbanks has a great reputation.

Flat6pac · 08-25-2010, 05:37 PM

++ on Gary Fairbanks

Inniswhe · 08-26-2010, 10:31 AM

Regarding my thoughts to refresh the tranny. When I bought my car a few years ago it had a grind almost every time shifting 1st to 2nd.
I changed to Swepco gear oil, and replaced shifter bushings and it shifted much better, no grind as long as the shifts are fairly slow which as I understand it the way we must shift these 915 boxes. Every time I need to go into reverse, I still must put the car in 1st and ease out the clutch to match speeds things up before going into reverse. I am not sure if that is normal with a proper gearbox.

The box has 132K miles. I have read in these forums that a properly refreshed box by a good mechanic can result in significantly inproved shifting ( by 915 standards anyway) so I do want to get it done as some point as I improve this car overall. I also plan on rebuilding the engine to higher than stock specs when it's day comes. So I figure while I am in there to rebuild the clutch I might as well get the transmission done so when the future engine upgrades come the gearbox will be ready.

James Brown · James Brown's Garage

Reverse does not have syncros on the 915, it will always grind if not allowed to 'spin down' after pushing in on the clutch. This does sound like a clutch release arm. Eather way, dropping the engine is in your future.

Inniswhe · 08-26-2010, 04:12 PM

Trying to free up my weekend to tackle the removal part anyway. Once I get it separated I will decide what to do next. Reviewing engine drop threads and jacking techniques for the high angles required. I have a motorcycle jack so that will be used to lower the engine.

If I recall from the PPI I had done when I bought the car it indicated some wear was evident but not too bad for an 84 with 130K miles.

Ross

stevej37 · 08-26-2010, 05:10 PM

My 84 Carrera with about the same miles as yours, started doing the same thing this spring. Couldn't press the clutch far enough to get a gear...clutch pedal partway down. Checked my adjustment under the car and found out it was at the very end..no more adjustment left. Brought it in to the shop...was told the pedal assembly/pin was worn out and elongated. Two hours labor to fix it along with a new clutch cable and it's like new again. Owned the car for about 4 years and it has never shifted better than it does now. Must of been getting bad for quite a while. Might not be your problem...but worth checking.

Inniswhe · 08-27-2010, 04:08 AM

Sounds like I should have a look under the pedals before I do anything major however the fact that I can hear mechanical noise from the tranny when the clutch is depressed indicates the pedal is doing something.

I replaced my cable when and helper spring when I changed fluid after purchase. At that time I don't recall anything out of the ordinary at the pedals.

To the unexerienced porsche mechanic ie. me it sounds really sounds like something came apart in there ( maybe lining) . I wonder if when I press the clutch in now, pressure is no longer centered due to obstruction of some sort and the throw out bearing is making noise when I press in the pedal?

Will post an update when I get a look this weekend.

Inniswhe · 09-02-2010, 06:41 PM

Update:
I Pulled the engine/tranny on the weekend for the first time. It took about 8hrs total, was pretty straightforward. Compared to taking the entire car apart to repaint, replace headliner , etc. this was a piece of cake

I opened the clutch and found a failed pressure plate , several cracks see pictures. The throw out bearing is not aligned properly due to the pressure plate problems I believe. I believe this is the extent of the problem, comments ?

I am going to get the tranny rebuilt/refreshed and rebuild the clutch with all of the recommended parts. It will be a costly project as the clutch parts list adds up to a hefty figure when you replace all of the recommended components.

Does anyone know if it is necessary to have the engine main seal installation tool to place the seal properly ?

I need to determine what else I will do to the engine while it is out . I am thinking fix vacuum leaks, clean up, maybe install SSI heat exchangers as I want to do that down the road when the engine is due for a rebuild. Long term plan is to get significantly more power .