Baffling clutch issue (3rd clutch in 30k KM)

awdbandito · 08:56 AM

This is long, but strange. Let me get the galleries input here:

I purchased a '77 911 last year and it was my first Porsche, and the only 911 I had ever driven.The garage I had do a PPI just happened to employ the mechanic who had maintained the car since 94. The car came with a lot of receipts and documentation. The mechanic told me I was probably due for a clutch because the pedal was very heavy. He said the pressure plate gets old and stiff. This transmission also needed some attention because the 2nd and 3rd synchros were definately worn. I ordered a SACHS clutch kit from an online retailer and took the clutch and car in to the shop in February. They pulled the motor, rebuilt the transmission, installed the new clutch kit, new clutch cable, new clutch fork, and fully rebuilt the pedal box with bronze bushings. The pedal was now very light and engaged close to the floor. Upon leaving I noticed that the pedal did not fully return to its top position after depressing it. I could grab the pedal and it would travel another inch before stopping. I thought that it had something to do with the design, and payed no attention to it. After a couple hundred miles of easy driving I began to be more agressive. On two occasions of agressive driving I noticed that I could smell clutch(not bad, but present) and I figured it was slightly out of adjustment after being broken in. I returned to the shop that did the work to have the clutch adjusted a bit. When they got the car up on the lift, the cable has started to mushroom a bit, and the pressure plate is stiff again. They attributed it to getting too hot because it must have been slipping. Their first inclination is that I got a bad clutch out of the box and something was wrong with the pressure plate. They can't warranty this type of work because I brought the part in myself. They could take it all apart but I would be liable for the labor charges if they do determine it is a bad part and not a mistake in the installation.

Edit to add: The clutch was not slipping at all and would grab great when I purchased the car. I only replaced the clutch because the pedal was heavy and I was told that I needed a new clutch to remedy this "problem". It was better to fix it sooner than later because of the wear on other items that the heavy pedal could cause.

I spoke with my distributor and Sachs(ZF) will warranty the parts. I just need to remove them and they send them off for testing to see if it was a bad part or an installation error. If it was a bad part they replace it.

I started going through the history on this car and this is what I found.

Clutch replaced in 1997 at 140k KM.
Clutch replaced again in 2000 at 149k KM. All parts including fork
I bought the car in 2008 with 153,600km on it.
Clutch replaced again in 2009 with 158k km because of heavy pedal and mechanic recommendation.
Now suddenly I have the heavy pedal/stiff pressure plate issue creeping back in less than 1k km.

Because this car is on its 3rd clutch in 30k km I really don't think that I got a bad clutch.
The only common factors are that the same mechanic has done all 3 clutch jobs, and the car is the same.

Can anybody think of a mechanical issue that would be causing this?

MURF · 04-27-2009, 08:41 AM

Sounds like an improper cable setup..the air gap is set first on short lever..then the 15mm's on cable housing are adjusted to bring the pedal up to the top. Too little air gap or not readjusting the clutch after break in can cause slippage

Goth · 04-27-2009, 09:26 AM

+1 on what MURF says about the gap. The gap goes away as the clutch wears. If you don't have a gap, the clutch will slip and burn.

Also, Is the amount of wear on the clutch disk even on both sides? If not, I would suspect the disk is not sliding freely. Like when an installer does not lightly grease the trans input shaft splines, or, when the splines are nicked/damaged.

MURF · 04-27-2009, 09:30 AM

2nd that ..with that many clutches on same car you have an installer error..try some one new!!

awdbandito · 09:44 AM

I have no idea what kind of shape the old disk and everything was in when it came out. I am now curious though.

I don't have the cash to have them pull it all again to look at it after the costs in February coupled with wedding costs (I'm getting married in Aug!!). I just brought the trend in clutches to the shops attention this morning, so we'll see what they have to say.

If nothing else I'll drop the motor and trans in a couple months to look at it myself. It is just frustrating to dish out that kind of $$$ to only have related problems. I wish that I had purchased the clutch kit through them now, even though it was significantly more than what I paid going straight to a distributor.

dad911 · 04-27-2009, 11:05 AM

The only common factors are that the same mechanic has done all 3 clutch jobs, and the car is the same.

Time for a new mechanic.

awdbandito · 12:10 PM

Quote:

Originally Posted by dad911

The only common factors are that the same mechanic has done all 3 clutch jobs, and the car is the same.

Time for a new mechanic.

I don't want to make that leap just yet. I'm just trying to figure out what might cause this. I really don't think that I got a bad clutch from the distributor after looking at the big picture, but am not in a financial position to 'put my money where my mouth is' if I do get hit with the cost of an engine drop. Even if it wasn't some fluke installation error or hardware failure and we find another problem that wasn't found the first time, I can't handle that hit right now. Thats why I was trying to do everything that I thought I needed in February before I bought a ring and started planning a wedding.

ljowdy · 04-27-2009, 01:45 PM

Call off the wedding, most end in divorce. If you do, then you can sink more "love" into the car

dshepp806 · dshepp806's Garage

I often wonder (worry?) about "walking in with my parts" to my wrench. Never walked in with such as yours'....yet often wondered what one would "get into" should a problem occur with (possibly) the parts......mmmmmmm............

just may be who (and how) the work's getting done....not sure there. Dad911 may be very well right....

Can't contribute on the mechanicals,..for I fear a G50.

Vicariously,...I live through your trials, watching,...learning..

Best of luck,

Doyle

pozee · 04-27-2009, 02:23 PM

I know I'm stating the obvious and certainly don't want to judge anyone, but, your wrench's proficiency at clutch repairs on the 901/915 is suspect.

There has got to be a critical step that is being left out (adjustment or whatever).

Although not a clutch/trans expert, I can definitely say that the frequency of new clutches in your car is absolutely abnormal.

Find another shop.

awdbandito · 04-27-2009, 02:56 PM

Quote:

Originally Posted by ljowdy

Call off the wedding, most end in divorce. If you do, then you can sink more "love" into the car

I can't sink the kind of 'love' into my car that I sink into my finacee'

Quote:

Originally Posted by dshepp806

I often wonder (worry?) about "walking in with my parts" to my wrench. Never walked in with such as yours'....yet often wondered what one would "get into" should a problem occur with (possibly) the parts......mmmmmmm............
Vicariously,...I live through your trials, watching,...learning..
Best of luck,
Doyle

I normally do all my own work but this car intimidated me. The golden plated porsche and all, so I thought I should trust a professional to the work. These guys have done several items for me so far: replace a distributor and a starter. I've had the car for a year now and I've replaced a fuel pump, accumulator, shift bushings and small stuff but I thought I should leave the bigger items up to somebody that had experience on a Porsche. It needed a transmission rebuild so I thought that I would just get the clutch done at the same time. I took my clutch kit and sport engine/trans mounts in and had them do it while rebuilding the transmission. I would NEVER recommend taking your own parts in to a shop now. It can just put everybody in a sticky situation. If I had just had them order the clutch I would be fine right now. The clutch return spring in the pedal box makes a racket, so I'm wondering if maybe it is bad, or the omega spring is shot. From what I can tell they would both make a difference in the stiff pedal. After the clutch was adjusted the other day I believe the slipping is gone.

Rumble-Bee · Rumble-Bee's Garage

Quote:

Originally Posted by dad911

The only common factors are that the same mechanic has done all 3 clutch jobs, and the car is the same.

Time for a new mechanic.

I agree...

This guy has probably overlooked something. Something really suspicious here is that the fork is being replaced so often. Do you have a floor board on the driver side? It is vital to protecting your clutch. It has an adjustable clutch stop that prevents the pedal from traveling so far that forks bend and things break. If your floorboard clutch stop is missing, out of adjustment, or falling apart -- then I would blame this on the mechaninc who worked on the clutch 3 times and never checked the floorboard.

KNS · 04-27-2009, 07:22 PM

Similar problem: You mention that after a while the clutch action became light and engaged near the floor. What would that be an indication of...? I know of a car with a similar problem, two clutches in a short amount of time, clutch grabs near the floor with a light pedal. Don't mean to hijack the thead but it sounded familiar.

awdbandito · 04:52 AM

Quote:

Originally Posted by GDuchanin

I agree...

This guy has probably overlooked something. Something really suspicious here is that the fork is being replaced so often. Do you have a floor board on the driver side? It is vital to protecting your clutch. It has an adjustable clutch stop that prevents the pedal from traveling so far that forks bend and things break. If your floorboard clutch stop is missing, out of adjustment, or falling apart -- then I would blame this on the mechaninc who worked on the clutch 3 times and never checked the floorboard.

I do have a floorboard on the driver side, and I pulled it last night just to look around the pedal box. On the underside of the floorboard is a metal bracket. This metal bracket looks as if it should have a rubber bumpstop on it, but it doesn't. You can see where the top of the clutch pedal has been hitting this metal bracket. If the clutch pedal travels its full stroke it impacts this piece of metal that looks like it should have a bumpstop, and the piece of metal is bolted to the back side of the floor board. I also see a little rubber bumpstop down in/on the pedal box itself. When the clutch pedal is in its normal up position it rests on this bumpstop.

The garage rebuilt my pedal box at the same time they did this clutch and transmission, so I'll have to say they definately overlooked the bump stop. Whether this is the root of the problem, I'm not sure yet, but they definately overlooked it.

So, if the pedal doesn't hit the bump stop, you run the risk of putting a lot of unnecessary force on the cable and fork. Potentially bending the fork. Then if the fork is bent it is not acting to give the correct mechanical advantage when operating the pressure plate, thus giving a heavy pedal and leading one to think that the pressure plate is stiffening up.

Is this correct?

Rumble-Bee · Rumble-Bee's Garage

That would be my guess. It sounds like the clutch will have to come out again. If the fork is bent or cracked again I would say there's definitely too much clutch pedal travel. The fact that it now stops on the metal tab is not really helpfull to diagnose anything -- your clutch is screwed up now and the fork maybe bent. What needs to be done is replace the bad parts at the transmission and then make sure that clutch pedal is being stopped by the floorboard tab well before the fork bottoms out. Also make sure that the floorboard is solid -- Iv'e seen a few that were so old that they would flex and not have a real stopping point. On my car the floorboard also has an adjustable stop for the accelerator (I have broken 2 accelerator links from the pedal cluster due to floorboard also). The idea there is the same: you should not be able to overstress the throttle linkage by mashing on the pedal.

Rumble-Bee · Rumble-Bee's Garage

I see you also have a TR-6. I've owned a TR-6 and TR-250 in the past. My goal is to have a 911 for speed and a TR-6 for... well... just... well... just because I dig them. Mechanical nightmares... they are. Seventeen mut&^$^%#*f(*&9ng nuts and bols to connect the engine to the trans -- and somehow Porsche does that with just 4. And every one of them only has 3 of the four differential mounts connected because the fourth broke off. I came up with a good work-around for the diff mount -- it got rid of the annoying rattle-squeak in the back.

awdbandito · 05-04-2009, 08:30 AM

I'm taking the car in tomorow morning to have them pull the motor out for diagnosis. I told them the clutch stop theory and the service advisor seemed to agree that 1. it might have caused the problem, and 2. they probably should have caught that when rebuilding the pedal box and all.

The floor board is very solid. It had a bit of delamination of the layers occuring at the very front left edge, so I fixed that with wood glue and heavy clamps. It looks great now. I thought about throwing some sealant on it to prevent future moisture damage. Anybody do this?

Thanks for the help on this George. My TR-6 is currently sitting in the garage getting ready for some body work and paint, then comes the reassembly process. I was driving up my driveway and hit a bump and the two front seat mounts pulled through the floorpan. I am fixing a broken diff mount at the same time. I never had a rattle/squeak, just a thunk thunk as I engaged the drivetrain.
I'll be calling you tonight, I've been out of town since last week and haven't had a chance.
Thanks again.

awdbandito · 05-06-2009, 08:52 AM

Update - The engine was pulled and everything broken back down. Low and behold, a bad clutch fork. The mechanic says that the clutch stop didn't matter and that the assembly wasn't over traveling. He says we must have just gotten a bad fork.

He also said the reason this car has had so many clutches is because the previous owner wasn't too good at driving a manual.

I'll keep my thoughts to myself.

Rumble-Bee · Rumble-Bee's Garage

Big surprise!!! Another bad fork. You should never have to replace forks unless the clutch travel is too far and the fork is being bent because it is being pushed on when it can't go any further. The chances of getting a defective fork after you already replaced 2 is astronomical. In your previous post the service manager seemed to agree that the stop may have caused the problem. Now it sounds like they are trying to weasle out of it now that your car is apart. I guess it's OK if they weasle out of taking the blame as long as they actually fix the problem this time (except for the previous time that you paid to have it done way before it should be due). When you get it back check the pedal movement for yourself before you drive it. Make sure that the stop is being engaged. I'm sure that even this mechanic who says that isn't the problem will make sure it's OK (unless he's a complete idiot).

awdbandito · 05-06-2009, 12:38 PM

Well, they are replacing the mushroomed clutch cable and the fork, but they are telling me the flywheel and clutch disk are OK. I asked them to take pictures of the flywheel and to take a pic of a micrometer measuring the disk material but they weren't sure they had a camera, so I'm going to stop in tomorrow and just verify everything and take pictures.
They are insistant that the fork was bad, but I feel like a mechanical problem, IE-the missing clutch stop, caused the fork to bend. I would feel much better if the mechanic admitted that the clutch stop is needed and he overlooked something, but he is standing by his diagnosis, which makes me lose faith in their work.
His reasoning for all of the clutch replacements bothers me too. The previous owner didn't know how to drive a manual very well???? If that were the case then the flywheel should be pretty glazed at each of these clutch jobs, but they have never serviced it according to the maintenance records.
They are going to install the stop for me and adjust to 25mm of travel. It is just frustrating. This is a perfect example of why I don't like to use mechanics and just do most of my work myself.