Clutch Wear

[MannyA]

I have a boxster 2.5 (1999) - I have had it for a couple of months and aside from a few teething problems it has been a joy.

I have a trip planned in May which will take me from London to Paris then Paris to the Nurburgring and home, some 1200 odd miles in total

It has 64,000 miles on the clock and is still on the original clutch!!! Other than a heavyish pedal the clutch is fine, not slipping, not juddering and managed a recent track day no problems.

I am a bit nervous about setting off on a 1200 mile trip witha 64K mile old clutch though, is there an inspection cover or similar on the box that would allow a specialist to see the thickness of the linings and general condition of the clutch?

Otherwise I may have to just replace it for peace of mind :cursing:

[Chris_in_NH]

i have twice that mileage on my original clutch. no worries. enjoy your trip! ;)

[MannyA]

i have twice that mileage on my original clutch. no worries. enjoy your trip! ;)

Wow, thats a quality clutch!

has helped put my mind at ease.

[Tool Pants]

is there an inspection cover or similar on the box that would allow a specialist to see the thickness of the linings and general condition of the clutch?

On some vehicles there is. But not on a Boxster.

[986Jim]

is there an inspection cover or similar on the box that would allow a specialist to see the thickness of the linings and general condition of the clutch?

On some vehicles there is. But not on a Boxster.

Sure there is!

When you drive does it slip? no? clutch is fine enjoy.

[MannyA]

is there an inspection cover or similar on the box that would allow a specialist to see the thickness of the linings and general condition of the clutch?

On some vehicles there is. But not on a Boxster.

Sure there is!

When you drive does it slip? no? clutch is fine enjoy.

Thanks for responses, will chance it then, if clutch goes pop on my trip I will obvoiusly be back to split the cost of cancelled hotels etc with you all :thumbup: :lol:

[986Jim]

Unless a spring pops out of the disc or the fingers on the pressure plate break it will not go "pop".

When a clutch wears out what will happen is at low rpm in 5th gear if you floor it going up a hill, it will start to slip and rpm will go up but the car will not accelerate. Whats happening is the clutch and flywheel are moving at different speeds (the same as when your releasing the clutch from a light) and it will start to slowly polish and basically smoke the clutch. Once 5th starts slipping all the time, 4th will start next, and then 3rd etc till your slipping no matter when and how lightly you push the clutch.

One you slip in 5th it would take about 2-3k miles for it to start to slip down into 3rd where the car wouldn't be drivable easily anymore. If that starts to happen you will have much advanced warning that something is about to go.

[MannyA]

Unless a spring pops out of the disc or the fingers on the pressure plate break it will not go "pop".

When a clutch wears out what will happen is at low rpm in 5th gear if you floor it going up a hill, it will start to slip and rpm will go up but the car will not accelerate. Whats happening is the clutch and flywheel are moving at different speeds (the same as when your releasing the clutch from a light) and it will start to slowly polish and basically smoke the clutch. Once 5th starts slipping all the time, 4th will start next, and then 3rd etc till your slipping no matter when and how lightly you push the clutch.

One you slip in 5th it would take about 2-3k miles for it to start to slip down into 3rd where the car wouldn't be drivable easily anymore. If that starts to happen you will have much advanced warning that something is about to go.

Going "pop" is a UK expression, I appreciate it is likely to start slipping first, I was just hoping that there was an inspection cover so I could take a look at the clutch as I dont want it to ruin my trip.

[rushrevisited]

Unless a spring pops out of the disc or the fingers on the pressure plate break it will not go "pop".

When a clutch wears out what will happen is at low rpm in 5th gear if you floor it going up a hill, it will start to slip and rpm will go up but the car will not accelerate. Whats happening is the clutch and flywheel are moving at different speeds (the same as when your releasing the clutch from a light) and it will start to slowly polish and basically smoke the clutch. Once 5th starts slipping all the time, 4th will start next, and then 3rd etc till your slipping no matter when and how lightly you push the clutch.

One you slip in 5th it would take about 2-3k miles for it to start to slip down into 3rd where the car wouldn't be drivable easily anymore. If that starts to happen you will have much advanced warning that something is about to go.

This is really excellent information. I have wondered on my 2001 as well. I will try uphill in 5th and see once in a while (51,000 miles).

I will say though, on checking the amount of clutch left, when I took mine in for service at the dealer, I asked them to check and they said there is a tiny indicator hole that you can look in or put a tool in to measure - said about 30% left on mine. Not sure if they were full of it or honest but that was what they said...

[Paul Fraser]

Jim, I take it if the clutch has started slipping then your DMF is toast by then as well...?

[LuisR]

Other than a heavyish pedal the clutch is fine

I also have a 2002 Boxster S (US spec) and I have noticed how my clutch is a lot harder than my friends '03 Boxster S. What causes the clutch pedal to be so hard on earlier Boxsters. Can I change my clutch to the '03 spec ???

Thanks

Anyone!!!!!!

Edited March 29, 2007 by LuisR

[LuisR]

Other than a heavyish pedal the clutch is fine

I also have a 2002 Boxster S (US spec) and I have noticed how my clutch is a lot harder than my friends '03 Boxster S. What causes the clutch pedal to be so hard on earlier Boxsters. Can I change my clutch to the '03 spec ???

Thanks

Anyone!!!!!!

Anybody here knows the difference between the clutch system on 2002 - 2004 Boxsters??????

[986Jim]

Jim, I take it if the clutch has started slipping then your DMF is toast by then as well...?

No not really it will just glaze it over. They just turn the flywheel the same as rotors and slap on a new pressure plate and disc and your all good.

[rushrevisited]

Jim, I take it if the clutch has started slipping then your DMF is toast by then as well...?

No not really it will just glaze it over. They just turn the flywheel the same as rotors and slap on a new pressure plate and disc and your all good.

Jim,

What causes a flywheel to go out of balance and cause a vibration at a certain RPM range? Especially considering no clutch slip or anything - any ideas?

[986Jim]

Jim, I take it if the clutch has started slipping then your DMF is toast by then as well...?

No not really it will just glaze it over. They just turn the flywheel the same as rotors and slap on a new pressure plate and disc and your all good.

Jim,

What causes a flywheel to go out of balance and cause a vibration at a certain RPM range? Especially considering no clutch slip or anything - any ideas?

This generally doesn't happen. OEM motors are not balanced from the factory, by that I mean the crank is but no other part of the rotating assembly is. Generally on a race motor the crank, rods and pistons are all balanced. The machinist will grind off small parts of metal on each to make them all weigh the same. You don’t need to full balance a motor unless you have serious hp or serious RPM. Some may argue that OEM motors are balanced but in a race motor where everything is exact, that is balanced, what OEM does doesn’t really compare.

Basically what that huge run-on sentence is saying is that it's not balanced from factory but is close enough that it you should never feel it. If it goes out of balance then something seriously has gone wrong with it. Either it has been surfaced too much and too much material is gone, surfaced incorrectly so it's thinner on one side than the other.

During the machining process there are two ways of doing it. Most common is putting it on a machine that keeps the flywheel still and a machine goes around it and plains the top or fly cuts it. The other way I have seen is on a lathe. Most flywheels have a step which is the height different between the surface the clutch rides on vs. the side where the basket of the pressure plate bolts to. If you machine one you must machine the other so they distance between the two is always constant. If you were only to machine the surface of the flywheel where the clutch touches then it would create a larger gap inside the clutch as eventually it would be totally flat with no "step" at all. If any of this is done improperly it will put the flywheel out of balance.

There are two ways of balancing an engine. Either zero balanced inside the motor so you just zero balance the flywheel so everything is fully balanced regardless if it's together or not. The other way is called the Detroit way where the flywheel is balanced offsetting the balance of the engine so when appart the engine and flywheel are not balanced, but together they are balanced. Most import engines and race engines are all zero balanced incase something happens to the flywheel you can just zero another one and put it on vs. balancing the whole rotating assembly again.

Typically your flywheel should never go out of balance if it's all OEM and has not been machined. If it feels like it has, generally it's the pulley on the other side of the engine that runs all the accessories. Most pulleys have a rubber balancer or harmonic dampener inside of them. If this rubber rips or starts to rip it will cause the balance of the pulley to go oblong and get out of balance. Eventually the rubber rips all the way around and the pulley rips into two pieces sending belts flying all over the place. It has to be pretty bad for this to happen. Looking in my Bentley I can't tell if a Boxster has a two piece pulley or not, I have never pulled one off so I'm not sure..

Most of what I'm referring to here is all import race car based not really Porsche information so if any doesn't apply here that’s why. It's more general info for inquiring minds.

[rushrevisited]

Jim, I take it if the clutch has started slipping then your DMF is toast by then as well...?

No not really it will just glaze it over. They just turn the flywheel the same as rotors and slap on a new pressure plate and disc and your all good.

Jim,

What causes a flywheel to go out of balance and cause a vibration at a certain RPM range? Especially considering no clutch slip or anything - any ideas?

This generally doesn't happen. OEM motors are not balanced from the factory, by that I mean the crank is but no other part of the rotating assembly is. Generally on a race motor the crank, rods and pistons are all balanced. The machinist will grind off small parts of metal on each to make them all weigh the same. You don’t need to full balance a motor unless you have serious hp or serious RPM. Some may argue that OEM motors are balanced but in a race motor where everything is exact, that is balanced, what OEM does doesn’t really compare.

Basically what that huge run-on sentence is saying is that it's not balanced from factory but is close enough that it you should never feel it. If it goes out of balance then something seriously has gone wrong with it. Either it has been surfaced too much and too much material is gone, surfaced incorrectly so it's thinner on one side than the other.

During the machining process there are two ways of doing it. Most common is putting it on a machine that keeps the flywheel still and a machine goes around it and plains the top or fly cuts it. The other way I have seen is on a lathe. Most flywheels have a step which is the height different between the surface the clutch rides on vs. the side where the basket of the pressure plate bolts to. If you machine one you must machine the other so they distance between the two is always constant. If you were only to machine the surface of the flywheel where the clutch touches then it would create a larger gap inside the clutch as eventually it would be totally flat with no "step" at all. If any of this is done improperly it will put the flywheel out of balance.

There are two ways of balancing an engine. Either zero balanced inside the motor so you just zero balance the flywheel so everything is fully balanced regardless if it's together or not. The other way is called the Detroit way where the flywheel is balanced offsetting the balance of the engine so when appart the engine and flywheel are not balanced, but together they are balanced. Most import engines and race engines are all zero balanced incase something happens to the flywheel you can just zero another one and put it on vs. balancing the whole rotating assembly again.

Typically your flywheel should never go out of balance if it's all OEM and has not been machined. If it feels like it has, generally it's the pulley on the other side of the engine that runs all the accessories. Most pulleys have a rubber balancer or harmonic dampener inside of them. If this rubber rips or starts to rip it will cause the balance of the pulley to go oblong and get out of balance. Eventually the rubber rips all the way around and the pulley rips into two pieces sending belts flying all over the place. It has to be pretty bad for this to happen. Looking in my Bentley I can't tell if a Boxster has a two piece pulley or not, I have never pulled one off so I'm not sure..

Most of what I'm referring to here is all import race car based not really Porsche information so if any doesn't apply here that’s why. It's more general info for inquiring minds.

Awesome info - thank you very much Jim!

This is an original dual mass flywheel on my Boxster, so it has not been machined or anything... I am just hesitant to spend the kind of money it will take to replace it without knowing exactly why it is out of balance... $900 for the flywheel alone, of course not including labor...

Has anyone else here had their OEM flywheel go out of balance?