Clutch Gone?

benzor · 03-18-2015, 09:14 PM

I'm concerned I may have ruined my clutch.

Here's the evidence:

1) Rotating noise, only when car is moving. Intermittent, but most often between 1000-2000rpm. Often goes away when clutch pedal is depressed. Seems to be exacerbated by bumps in the road, which I found weird.

2) In 3rd and 4th on the highway, car runs too quickly to redline without the same pull as typically in 2nd gear.

3) I recently replaced the heater control valve with a metal one - it had been leaking. I'm concerned it dripped on the clutch, causing a failure.

Could I tell anything by looking in the clutch inspection window ?

petrolhead611 · 03-19-2015, 04:22 AM

Put parking brake on, try to pull away from rest in third gear.With a good clutch the car will stall before you've even completely removed your foot from the clutch pedal.

911tracker85 · 03-19-2015, 06:05 AM

Quote:

I recently replaced the heater control valve with a metal one - it had been leaking. I'm concerned it dripped on the clutch, causing a failure.

when I was installing a new clutch in my 951, as I was working on the bolt and ground at the top of the bell housing, had disconnected my HCV for access.

in the process, moved it and coolant went down the inspection hole on top the bell housing.

pulled the clutch and sure enough the clutch disc had a lot of coolant on it.

sent back to SPEC and they replaced for a very reasonable price.

I get varying reactions from people about if / how much damage coolant on the clutch disk can eventually cause. but I really dont want to do this again for a long time, so went ahead and replaced the contaminated disc.

I think petrolhead611 suggestion is a good one. assuming your emergency brake works and holds well, if the clutch slips with the emergency brake on, get ready for a real fun job.

Lapkritis · Lapkritis's Garage

Normal antifreeze contains a lubricant. If you have soaked your clutch with it then don't be afraid to follow in the same manner with brake parts cleaner.

911tracker85 · 03-19-2015, 11:23 AM

considered that, but this SPEC clutch has kevlar surface. called SPEC and they were pretty emphatic just cleaning with brake clean would shorten the life span.

this is a DE/track car, with a modified engine, so will take more abuse than a street car.

way too much of a job to risk the $100 they charged to replace the clutch disc, and having to do this again too soon.

and if coolant did get onto benzor's clutch disc, the petroleum in the coolant could contribute to slipping.

Lapkritis · Lapkritis's Garage

Bob,

If DE/Track only, maybe consider running water/water wetter only? This would prevent potentially spoiling a track as well...

$100 is cheap - very nice of them.

benzor · 03-19-2015, 06:13 PM

So I believe it failed the test. Parking brake holds well, third gear. I got almost to the top of clutch pedal travel before it stalled - most of the way.

Nothing I can do to extend temporarily (re: brake cleaner, water)?

John_AZ · 03-19-2015, 07:58 PM

AAA roadside assistance?

J_AZ

benzor · 03-19-2015, 08:20 PM

Ha! No, car is home, don't need AAA.

Lapkritis · Lapkritis's Garage

How long has it been doing this? In my opinion you can try water or a can of brake cleaner to try to extend as a last ditch effort. This would only work for a disc that is contaminated and still within spec with regard to wear. Worst case you're doing the clutch job anyway, right? Rather than dousing, try to aim at the disc... If patient, repeat a few times after driving a bit to loosen new contaminants each time.

Give plenty of drive time after cleaning for things to dry out. Unlike brakes for example, a clutch doesn't generate as much heat during operation to dry so quickly.

911tracker85 · 03-20-2015, 09:05 AM

Quote:

Bob,

If DE/Track only, maybe consider running water/water wetter only?

only problem is non-heated winter storage.

Ironically PCA requires owners of the early gen 911 GT3 to run water only, due the problem of those heater pipe popping out of the block. a guy I run with at DE had this happen a few years ago. the three cars right behind him all went of the end of the back straight at MidOhio and totalled them.

dougs951s · 03-20-2015, 09:10 AM

unfortunately, brake clean wont save the disc. If it got contaminated with coolant, its toast.

benzor · 03-20-2015, 09:15 AM

OK, thanks gentlemen. Putting the order in today, looks like a month's work worth of work at my pace. Really wishing I had put a 3 piece crossover pipe, given that I've already pulled it twice in the last year!

John_AZ · 03-20-2015, 09:39 AM

You might want to get a Harbor Freight Transmission jack.
450 lb. Low Lift Transmission Jack

With 20-25% off HF coupons very reasonable.

Member Corsepervita did a very detailed tutorial:
944 Forum - The crazy clutch tutorial (LOTS OF PICS!)

J_AZ

benzor · 03-20-2015, 09:46 AM

Very helpful as always John !

John_AZ · 03-20-2015, 10:27 AM

thx....and I would not cut out the bell housing by the reference sensors as some old posts suggested.

It will cause starting detonation kickback with the small turbo starters.
Porsche put out a memo:

John

911tracker85 · 03-20-2015, 12:46 PM

I followed the one on Clarke's Garage.

no pics but good step by step.

it is not until the end/reassembly section he mentions pulling the HCV/hose off the block for access to the top bell housing bolt and the grounds. after a while trying without removing that, gave up and pulled the HCV/hose. at the time, thought I had dumped all the coolant out when I pulled it.

he cautions to cover the bell housing holes to prevent dropping in bolts / debris during reassebly. I only stuffed some paper towel in, and the coolant just went right through.

my solution to that below. Alum HVAC duct tape. and left it in place when I was done.

I also elected to NOT NOTCH my senor holes. got to get in there to get to the top bell housing bolt and grounds anyway.

911tracker85 · 03-20-2015, 12:51 PM

not a tutorial, but here is the link to my build thread. covers the engine install, upgrades and then it gets into the clutch job.

good luck. clutch job took me 6 weeks in my 'spare time'. but lost over a week getting the replacement clutch disc.

my 951 DE/street build

benzor · 04-05-2015, 05:54 PM

Quick update on the prep:

- Jacked up as high as she'll go.

- Got the starter off, to measure current clutch. I'm at 24mm, which means it isn't at the wear limit. Hence the coolant spill theory.

- Bought all the parts, sitting in the garage, including the transmission jack, except for the RMS installation tool.

What's still puzzling me is why the clutch would make noise at idle when in neutral? Revolving sound, coming from clutch location under the car, not consistent.

I figured if the clutch surface was toast, when it is disengaged it should make zero noise regardless, correct?

mytrplseven · mytrplseven's Garage

Take a close look at the alminum TO bearing guide sleeve while you're in there. Also the smimming of the TO bearing so it's not too loose agains the pressure plate fingers.