Replace Clutch Disc BUT KEEP OLD PRESSURE PLATE ??

[pc100porsche]

Hello there,
I'm looking to purchase an 88 Carrera.
The car has had a new Clutch Disc fitted, But the Pressure Plate was retained as it was "supposedly"still serviceable.
This seems odd to me BUT I'm wondering if it is a "normal" situation or not ?

The clutch work was done by a highly respected p shop, as well as another $5k on other things (but I know they were asked to save $$ where ever they could).

[john walker's workshop]

potentially fine. if it works and doesn't shudder, i wouldn't worry about it for 80K or so.

[herman maire]

I am sure others will disagree but I would have no problems reusing the original pressure plate. It can handle more HP than what your engine is probably putting out . I would however put a new throw out bearing.... reusing the old throw out bearing would not be too smart.

[Joe Bob]

What is your 'test' criteria for a pressure plate? What are the signs of a 'bad' plate?

I have my ideas but would prefer to have the pros speak up.

[Jesse16]

I wouldn't worry either, keep all and forget about it. I put in a new clutch and lightly used PP and all is fine.

[aigel]

This may be a sign that the owner liked to cut corners and only spent the minimum. While it may be fine on the pressure plate, where else was this approach practiced on the car - possibly without good mechanic's advice?

I really don't think it is a prudent to put a new clutch without replacing all components. You are out $1500 on R&R and skip a $500 part that makes the difference between all being new and a mixed bag? Again, that tells me something about the PO's attitude.

Just my two cents.

G

[Flieger]

$500 is a lot. Pressure plate is a spring and metal surface like a flywheel. Not a piece of friction material. I guess you replace your flywheels every clutch job too? Why not the whole transmission?

[aigel]

Originally Posted by Flieger

$500 is a lot. Pressure plate is a spring and metal surface like a flywheel. Not a piece of friction material. I guess you replace your flywheels every clutch job too? Why not the whole transmission?

$500 is not a lot if you just paid your mechanic $1500 for R&R. If you lack $500 to do it right, you shouldn't own a 911.

I have never replaced a clutch without replacing all the components on any of my cars, even beaters. The pressure plate will no wear by friction but indirectly from heat. The springs soften from repeated heat cycles. Do you know how many heat cycles at what temperature your clutch received? How many are too many for the PP to retain sufficient stiffness?

Saving $500 while it is all out and easy to replace is what I call "dumb cheap". There is a reason clutches are sold in "kits". If you DIY and like to spend time on your back, it may be a different story even though you may wear out your brand new disk with a weak plate not putting enough force on it.

Of course, this is all JMHO. I still would buy that car if it was nice, but as I said, would worry about other corners cut.

G

[diabolical]

Originally Posted by john walker's workshop

potentially fine. if it works and doesn't shudder, i wouldn't worry about it for 80K or so.

Could you (or anyone else) please clarify why it would shudder if the pressure plate was reused?

Thanks

[Flieger]

Originally Posted by aigel

$500 is not a lot if you just paid your mechanic $1500 for R&R. If you lack $500 to do it right, you shouldn't own a 911.

I have never replaced a clutch without replacing all the components on any of my cars, even beaters. The pressure plate will no wear by friction but indirectly from heat. The springs soften from repeated heat cycles. Do you know how many heat cycles at what temperature your clutch received? How many are too many for the PP to retain sufficient stiffness?

Saving $500 while it is all out and easy to replace is what I call "dumb cheap". There is a reason clutches are sold in "kits". If you DIY and like to spend time on your back, it may be a different story even though you may wear out your brand new disk with a weak plate not putting enough force on it.

Of course, this is all JMHO. I still would buy that car if it was nice, but as I said, would worry about other corners cut.

G

A clutch should never produce enough heat to affect the heat treatment of the metal. That would set fire to the organic material long before the springiness would be lost. If you are shifting properly and using the handbrake at a stop there should not be that much heat produced. I just don't see how it wears out. Flywheels get hot spots but that is when the clutch slips. Otherwise they slowly wear down (or are machined down) past the wear limit.

And I still say $500 is a significant amount of money. It could buy ~5 hours labor. It is 33.3% of the cost of R&R you proposed.

[56 nomad]

[QUOTE=aigel;6825504]$500 is not If you lack $500 to do it right, you shouldn't own a 911.

not meaning to hijack this thread

this is not necessarily about the clutch pressure plate issue but a general attitude relating to porsche ownership.... i have heard this before from my previous mechanic, i had a stiff clutch pedal low to the floor and very hard to engage the mechanic said i needed a new clutch , cable, helper spring and should probably do the pedal assembly bushings "while we were at it".

it "needed" a lot of parts as well as several thousand dollars to "do it right". when i questioned the work i got the "if you cant afford it , you shouldn't own it" attitude..had i done what was "needed" to do it right i would have been out a few grand .

after getting on the board i discovered i might need to "adjust" the clutch cable free play, about 1 hr of my time , in the driveway and it was fixed. it was a simple cable adjustment nothing more.

in my opinion its not a matter of ones ability to "afford", but simply a matter of whether or not it is necessary (porshe guys sometimes get hosed) ...if its not necessary why do it?

the reality is a Porsche is simply a car..albeit a great car, but still a car and i don't feel i am any better than the next guy because i own it.

by the way i would reuse the pressre plate (and have many times) as long as its not warped or burned.

really jm2c so take it for what its worth, ben

[Flieger]

Well said.

[timmy2]

I would re-use it, but then again I re-used my alusils with no problems. Opinons will vary on many choices for replacing parts that have a serviceable and measureable life span.
I utilize the RCM philosophy at work and it has rubbed of on me at home. (RCM= reliability centered maintenance)
In my industry we used to do time based complete teardowns of equipment to find nothing wrong. We now use diagnostics, the number of operations and stress events to trigger this work. Parts are only replaced when they have served their useful life or have reached wear limits.

My son's '88 Toyota gets a new pressure plate with clutch soon, only because it was $65 for the kit! If we could get prices like that for our cars, then there would be no question.

[T77911S]

i had to change my tranny in my E30 not long ago. i put the old stuff back in but i lightly sanded both the flywheel and Pplate. they both had some light burn marks from getting hot. from what i understand, those can cause clutch chadder. i used 220 with a flat sanding stick i use for bodywork so i sanded it evenly. if it has grooves, you should reconsider your options

[jimrs2000]

I changed the friction plate and throwout bearing two years ago when I rebuilt the transmission, so far so good.

I seem to remember "back in the day" that there were limits for pressure plate wear, although I agree with most that it's the spring pressure that is most likely the reason why the pressure plate would not be reusable, mine had around 70k on it when I changed the friction plate, I am now just about to go through 100k.

It seems to have just become the norm now to swap out the pressure plate without really knowing why you are doing it.

I work in the Aero Engine industry and we see the same mentality there, when an engine comes off wing early to have a failure fixed there is a whole list of stuff people want to do to the engine "while i'm in there". My take is that if you were happy to leave it on wing and go flying then you shouldnt be "fixing" it whilst its in the shop, the components are designed to go for a full life why change them half way through.

The same goes for our P cars, components were designed for a certain life.

Just my 10 cents.

[yelcab1]

I have kept the old pressure plates a few times with no adverse results. 15 years ago when you could get a PP, clutch disc, TO bearing package for $300, it was a no brainer to change it. Now, not so much.

[KTL]

I disagree that a clutch should never get too hot such that it gets "hot-spotted", but that its more common on the flywheel. The clutch friction surface (it is indeed a friction surface, it's just like one side of a brake rotor- the other side is the flywheel) acts no differently than the flywheel, other than it moves in/out. It still contacts the clutch disc just like the flywheel does and has the opportunity to get very hot if slippage occurs.

People who take their cars to the track and don't do a good job of matching RPM on downshifts can hot spot their clutch surface if they really abuse/slip the clutch.

I'm of the opinion that the clutch can be reused. Clutches can be rebuilt with a new friction surface/pressure plate, or the old surface can be lightly resurfaced similar to what is done with flywheels.

I agree $500 is a lot of money and if the clutch is in good condition, I see no reason not to reuse it. The Sachs clutches are really robust. The cast metal housings, be it iron or aluminum alloy, are really strong and the spring fingers are really durable.

I would agree that the release bearing is a good while you're in there because it is something that is always being loaded & spun, regardless of whether the clutch is being disengaged whether it is engaged/at rest.

[Joe Bob]

When my 915 puked it's guts, I replaced the disc because I had an extra laying around.....and I admit it, I had abused it. The PP had no discernible issues and since I was the driver, knew it did not have chatter.

My question...which still hasn't been answered.....how do 'others' make that decision? In other words, someone who has never driven the car....not like I have ever seen a spring rate on these things.

[KTL]

Guys that rebuild them like Kennedy will put them on the scale and bench-test the amount of poundage needed to operate it. If they find that the operational load is significantly diminished, the spring fingers are fatigued and it's done.

You also have to inspect the drive straps to make sure they're not cracked. These are the straps that connect the pressure/friction contact surface to the main housing and allow it to move but also stay aligned in the housing.

Most DIY people just look at the condition of the friction surface for heavy grooving and hot spots/discoloration. The clutch can certainly be a crap shoot if you're just looking at it. Ideally you'd like to be able to load it, so you can see how the pressure plate behaves. Some clutches are really old and if sitting for a long time can get quite rusty, since the pressure plate is iron.

[Canuck_Targa]

With all due respect I think there is allot of generalizing as to if the pressure plates should be reused. To say that they "should never be reused" or "not a problem to reuse it", I recently redid my clutch and reused the pressure plate, only after inspection and clean-up. If you have the mechanical ability to replace the clutch yourself, you most likely have the ability to determine if the pressure plate is able to be reused or if it needs replacing. If you are having a shop do the work, I really hope the shop you are using has the same ability to determine this also (which the original poster indicated). Truth be told my 911 is one of the cheaper car I own to maintain, one because I can do all the work myself and get the parts from great places like Pelican Parts. I have a VW Touareg that costs me more in maintenance than my 911, one because of all the electronics and two the parts are as much or more than parts for the 911.
I really dislike the phrase "If you can't afford to repair and maintain a Porsche, you shouldn't own one".
The OP stated that his car was in for $5k+ of work at a highly respected shop, so maintenance does not seem to be an issue, and if they are telling me the pressure plate looks fine to reuse and save him $500 on the bill why not, thats $500 more gas money to drive it once it is done.