993 Clutch Adjustment

ahklein · ahklein's Garage

I recently purchased a 1995 993 with 117K miles. I have many of the service records and it appears to have been regularly serviced by a Porsche racing shop. My clutch works fine, but it "grabs" very high. Once engaged, it does not slip. Can this be adjusted? Also, when the car is hot, I notice the clutch pedal feels "loose." the records indicate it was flushed 2 years ago with racing brake fluid. I am planning to flush the brake system soon, as I feel this could be the culprit.

Any thoughts??

Thank you

RedCoupe · 03-11-2016, 03:45 PM

If the 993 clutch system is like the 964, there isn't a normal clutch adjustment for the hydraulic clutch system. I think you're on the right track with the flushing and bleeding as the clutch system shares brake fluid with the brake system. However, the slave cylinder will have to be accessed and bled to be sure to get old fluid out and remove any air.

TMc993 · 03-11-2016, 06:13 PM

As stated by RedCoupe, there is no adjustment on the clutch of a 993. The clutch on a 993 normally does "catch" at a point that is quite high on the pedal arc. Bleeding, although a good idea, probably won't change that significantly.

I'd be interested in knowing what you mean when you say the clutch pedal feels "loose" when the car is hot...What does "loose" mean?

Also, since you have service records, do you know how many miles the current clutch and pressure plate have on them?

ahklein · ahklein's Garage

When I say "loose,: I mean that the clutch pedal falls to the floor easily, without much pressure. I do not have any records which demonstrate a new clutch, or any engine drop. Is that possible? 120K miles?

TMc993 · 03-12-2016, 04:54 AM

Anything is possible, but it's not likely. The original 993 clutches typically last 50-70K miles. If your 993 does have its original clutch assembly and slave cylinder, then you're most likely overdue for replacement.

The pedal dropping is typical of a slave cylinder problem. I would start by bleeding that system per RedCoupe's suggestion.

Drisump · Drisump's Garage

In my experience, as a clutch wears the pedal action does move higher up the pedal arc. Does the clutch exhibit signs of slippage? In a fried clutch, when trying to climb a hill in a higher gear than you would normally use, it would usually show signs of slippage. The mileage you quote is quite high if it is the original clutch. My car needed a clutch when I bought it @70k miles....and when I dropped the tranny I found that the clutch wasn't the original either! I can't say that I've noticed that the pedal action on my RS clutch is high on the pedal arc versus most other cars but the pedal action of the new clutch was far more progressive.....not at all like my 915 equipped 3.2 LOL. Cheers

TMc993 · 03-12-2016, 07:57 AM

Quote:

Originally Posted by Drisump

In my experience, as a clutch wears the pedal action does move higher up the pedal arc. Does the clutch exhibit signs of slippage? In a fried clutch, when trying to climb a hill in a higher gear than you would normally use, it would usually show signs of slippage.

Agree on both points.

When the clutch went bad on my 993, the pedal engagement point moved higher and higher on the pedal arc and there was slippage on gear change, particularly at WOT.

When the master and slave cylinders started going bad about 40K miles later, the clutch action was notchy and unpredictable due to inconsistent hydraulic pressure in the system.

I think you have some diagnosing to do.

ahklein · ahklein's Garage

Just drove the car today and am convinced the clutch is starting to slip. On a twisty uphill in 2nd gear, shifted from 2nd to third at 6000 RPM, revs didn't drop right away. Could air in the system cause slipping? I note that when warm, the clutch pedal "sticks." It does not pop back up as it should. I believe this could be due to air in the system or a bad/leaking master cylinder?

ahklein · ahklein's Garage

I just went through the service records and found no engine drop or clutch work. The prior owner kept great records. He was a mature owner who drove it all over the West, with documented trips to Pebble Beach, Tucson, Lake Powell, even Mexico from his home in Santa Fe. The car had frequent oil changes, Transaxle fluid changes, and brake flushes with ATE Super Gold. Most of the work was done by "Rex Goes Racing" in Santa Fe. New Bilsteins were documented, along with several sets of tires. Since it appears that this car was "babied" with no track use and many long trips, I believe it may be the original clutch. At any rate, I think it is time to drop the engine, replace the clutch, replace the torn engine soundproofing, and tackle some of the leaking cam towers and valve covers.

While I am there......What should I do?

This is an original paint car which I plan to keep and drive. The engine feels strong, does not smoke, freely revs and uses a quart of oil every 1500 miles.

Any insight is appreciated

bazar01 · bazar01's Garage

Quote:

Originally Posted by ahklein

Just drove the car today and am convinced the clutch is starting to slip. On a twisty uphill in 2nd gear, shifted from 2nd to third at 6000 RPM, revs didn't drop right away. Could air in the system cause slipping? I note that when warm, the clutch pedal "sticks." It does not pop back up as it should. I believe this could be due to air in the system or a bad/leaking master cylinder?

No.

Air in the system usually shows up as very hard to shift or won't go into gear because the clutch is not releasing.

At 117k miles, plan on replacing the clutch/PP/DMF.

johnsjmc · 03-12-2016, 12:26 PM

I had a 1995 993 and changed the clutch at 115000 mi. It was definitely still the original clutch (The 1994 ink stamp was still visible on the pressure plate. .The dual mass flywheel also still passed inspection. I only dropped it because the input shaft splines were rusty and cause the clutch to drag slightly ). the clutch was close to the rivets but not quite .

TMc993 · 03-12-2016, 12:43 PM

Quote:

Originally Posted by ahklein

While I am there......What should I do?

It's not my money but in addition to what you listed, I'd replace the clutch slave cylinder (because it is so difficult to access with the transmission in the car), the spark plug wires if they're in less than excellent condition, the spark plugs if they're even moderately close to the end of their life cycle, power steering pump belt, and every little vacuum tube and flexible hose that cannot be easily accessed with the engine in the car. It might be a good idea to compare the service records you have to the 120K mile service items for the drivetrain and see if there's anything else that is coming due that would be easier done with the engine out of the car.

ahklein · ahklein's Garage

Thank you. All good insurance. I replaced the spark plug wires last year and it was a PITA! I do not have a 120K service listed, just the 60K.

Anyone know what should be done at 120K vs 60?

What spark plugs are recommended?

johnsjmc · 02:43 PM

add upper and lower valve cover gaskets and the rubber washers on the cam chain housing bolts are usually leaking by that mileage. You will be surprized by the power steering belt. It will look like new but I changed it anyway. the clutch slave cylinder and it,s flex hose also the needle bearings and seals on the throwout cross shaft. Rear main seal behind flywheel is a good idea too.
Plugs ,the forward upper ones are very hard with the engine in and easy with it out. If keeping the car then might as well do the distributor drive belt and check the oil pressure sender unit and crankcase vent on top for leakage

ahklein · ahklein's Garage

If the A/C is on and I am revving it high, sometimes I feel an odd vibration. Anything else should I replace?

johnsjmc · 03-12-2016, 04:01 PM

Look at the two fan belts and check your motor mounts for sag. The rear ones are hydraulic and they will sag with age

ahklein · ahklein's Garage

Well, dropped the engine and here is the clutch. Looks like it is time to replace. Anyone know how to interpret these markings? Is this an original clutch? While I am in there.....Let's just say lots of parts have been ordered......

johnsjmc · 03-21-2016, 05:14 PM

I found a small ink date stamp on my pressure plate but not the disc

ahklein · ahklein's Garage

My car was manufactured 2/16/95. Could this be the date stamp for Jan 95?

earossi · 04-01-2016, 03:48 PM

I agree with everything that has been recommended so far. Use common sense. Given the age of our cars, and the difficulty of servicing the engine while in the car, I would replace anything that has rubber in it since you are at retirement life of most rubber parts. Especially all the rubber vacuum lines.

You should also consider replacing the flywheel at this point. The price of dual mass flywheels has dropped, and the rubber in the original wheel has got to be close to failure. I would not recommend going down the slope and installing a LWF. The LWF saves a little weight, but the revability of the engine does not change much and with a LWF, you will hear all the gear rattle from your tranny at idle. That's why Porsche went to the DMF.....to isolate such noises from the cockpit. I know this since I just changed back from the LWF to the DMF on my car. And, if you do remove the flywheel, its cheap insurance to replace the rear main seal at this time.

As stated earlier, installation of the clutch slave cylinder is very easy with the powertrain out of the car....and a PITA when installed.

Lastly, with over 100K miles on the car, you are nearly at end of life on the valve guides for the engine. I'm surprised at your statement of 1500 miles to a quart of oil, if the guides had not been done earlier. You should also consider doing a leak down test on the engine while out of the car to assess the overall condition of your valves.