Can I skim a 996 Turbo Flywheel?
Can I skim a 996 Turbo Flywheel?
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Discussion

JapFreak786

Original Poster:

1,820 posts

187 months

Saturday 9th June 2012
quotequote all
I need to replace the clutch on my 996 Turbo, and I'm sure the flywheel needs replacing/skimming as well
Now, i've done a search on several Porsche forums and either my searching skills suck lemon juice or there aren't any thread on it.

Can I skim a 996 turbo flywheel, or do I have to buy a new one??

Car's a 51 plate btw,higher mileage at 92k now but it's a great car to drive,clutch has been getting worse since I've had it the last 3 weeks so taking it off the road until payday to buy a new clutch.

If I can skim a flywheel,does anyone have a used flywheel I can buy and skim before I get the car onto the ramps?

Henry-F

4,791 posts

275 months

Saturday 9th June 2012
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The flywheel is what's known as a dual mass unit. In other words it allows some degree of twist or damping to take place. The amount of movement increases over time until the end stops take up the drive.

So it isn't just the flywheel surface you are concerned about. The danger is you re-face the surface only to have to open everything up again to replace the flywheel when the damping fails.

Not worth the risk. Let the person assess your flywheel and replace if necessary.

Henry smile

bobsan

495 posts

249 months

Saturday 9th June 2012
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JapFreak786 said:
I need to replace the clutch on my 996 Turbo, and I'm sure the flywheel needs replacing/skimming as well
is your clutch slipping ??

If not, the flywheel will be completely fine, only thing to ruin it is if clutch is down to rivets, has dug grooves in it and is slipping.

Henry-F

4,791 posts

275 months

Saturday 9th June 2012
quotequote all
bobsan said:
is your clutch slipping ??

If not, the flywheel will be completely fine, only thing to ruin it is if clutch is down to rivets, has dug grooves in it and is slipping.
How can you say that without inspecting the flywheel?

The friction surface could be worn and there might be too much rotation.

Have the flywheel inspected professionally by whoever is doing the clutch for you and be guided by them.

Henry smile

RatBoy M3CSL

1,490 posts

226 months

Saturday 9th June 2012
quotequote all
..As Henry says.. with a dual mass the rubber between the plates might be on the way out, and cause you more problems down the line if it's done a 92K miles, I would most likely change it while the cars in bits, it's a lot of work to take it to bits a 2nd time.. if there's too much slack in the damper it will become horrible to drive thro' gearchanges on/off power..

JapFreak786

Original Poster:

1,820 posts

187 months

Saturday 9th June 2012
quotequote all
sorry yes should have said that the clutch is slipping,quite badly now as well after a little play with a few friend's and their GTR's..

Look's like it'll be an expensive month next month for me then frown,i'll most likely do the work with a friend,who's first job was a Porsche technician,thanks for the info so far smile,anyone has any more input please do

So,just to be clear,I could in theory just skim the flywheel,even with it being dual mass?

VonSenger

2,465 posts

219 months

Saturday 9th June 2012
quotequote all
JapFreak786 said:
sorry yes should have said that the clutch is slipping,quite badly now as well after a little play with a few friend's and their GTR's..

Look's like it'll be an expensive month next month for me then frown,i'll most likely do the work with a friend,who's first job was a Porsche technician,thanks for the info so far smile,anyone has any more input please do

So,just to be clear,I could in theory just skim the flywheel,even with it being dual mass?
A worn flywheel has nothing to do with slippage, that'll be a worn clutch. A worn 996tt flywheel, as others have said, will have no dampening and thud upon take up, this'll be due to a split in the rubber between the two/dual plated flywheel, or, in your case (the former will be very obvious!) it will shudder in the initial pull away (sometimes very subtle). This shuddering is due to hot spots, when you take the clutch off this should be evident even if the shuddering isn't (raised blue areas). Im afraid skimming is a false economy if you are keeping the car, the dampening between the two/dual plates may split now or in thousands of miles time. After all the cost and effort of doing the clutch and skimming the flywheel, you may have completely wasted your time and money if it splits - a gamble. With 92k miles, i wouldnt, but certainly possible.


JapFreak786

Original Poster:

1,820 posts

187 months

Saturday 9th June 2012
quotequote all
thanks for that post,it does shudder when pulling away yes,i've used up the remaining petrol in the tank and the car's getting parked up now,been driving everywhere very carefully in the mean time since, don't like leaving petrol in the tank as I'm not sure how long the car will be parked and when it is driven again want to put "fresh" petrol in from the station

Guess it's new flywheel time as well then, wallet is going to take a right beating frown

RatBoy M3CSL

1,490 posts

226 months

Sunday 10th June 2012
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.. best part of a £2K job fitted with the VAT I'm afraid..

Edited by RatBoy M3CSL on Sunday 10th June 09:55

Magic919

14,560 posts

231 months

Sunday 10th June 2012
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Clutch kit and a flywheel should be about £600 each with the VAT.

Rockster

1,515 posts

190 months

Sunday 10th June 2012
quotequote all
JapFreak786 said:
sorry yes should have said that the clutch is slipping,quite badly now as well after a little play with a few friend's and their GTR's..

Look's like it'll be an expensive month next month for me then frown,i'll most likely do the work with a friend,who's first job was a Porsche technician,thanks for the info so far smile,anyone has any more input please do

So,just to be clear,I could in theory just skim the flywheel,even with it being dual mass?
Yes, the flywheel can be resurfaced if the FW is otherwise ok and the resurface won't bring the thing too thin.

There's a check to verify the dual mass feature is working properly. This test needs to be done. I do not know the details but the tech should. Then of course he has to evaluate the FW and deem it worthy of resurfacing.

Sincerely,

Rockster.

Henry-F

4,791 posts

275 months

Monday 11th June 2012
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Rockster said:
Yes, the flywheel can could potentially be resurfaced if the FW is otherwise ok and the resurface won't bring the thing too thin.

There's a check to verify the dual mass feature is working properly. This test needs to be done. I do not know the details but the tech should. Then of course he has to evaluate the FW and deem it worthy of resurfacing but given the nature of a dual mass flywheel such resurfacing isn't generally seen as good practice so I wouldn't bother going down that route as I suspect you will only end up replacing it shortly afterwards and by the time you've paid your labour to re-do the job and skimming cost originally you'd have been better off doing the job properly in the first instance

Sincerely,

Rockster.
Edited for accuracy.

Henry smile

RatBoy M3CSL

1,490 posts

226 months

Monday 11th June 2012
quotequote all
..as Henry says chap, you can do it, but you should be asking yourself if it's a good idea, or false economy in the longer term... I would say yes it is.. just change it while the cars in bits and do yourself a favour ..!

TISPKJ

3,780 posts

237 months

Monday 11th June 2012
quotequote all
Hi Mate ...

Check and see if it is the same as a mk1 GT3. I think it is.

If so I maybe able to help you as I have a 8000 mile clutch and flywheel for sale.

PM me if interested.

Regards

JapFreak786

Original Poster:

1,820 posts

187 months

Monday 11th June 2012
quotequote all
thanks for the advise again,i've given a few friends a call and i'll be able to buy myself a new clutch kit,and flywheel for £899!! So come pay day i'll be going down that route,unless I find out that I can use the same the kit from the user above,pending price I may go for that option,but if not it'll be a new clutch and flywheel smile

Bennachie

1,091 posts

181 months

Monday 11th June 2012
quotequote all
Whats all this about bonded rubber. Is the dual mass flywheel not the standard weighted mass and springs type units fitted to everything else that has a dual mass flywheel? As opposed to the bonded rubber anti-vibration damper on things such as crank pulleys.

Henry-F

4,791 posts

275 months

Monday 11th June 2012
quotequote all
My understanding is that the primary and secondary mass are controlled by internal springs as opposed to to bonded rubber. I must confess to never having pulled one apart but the construction is relatively simple in principle. The tricky part is getting the correct damping forces and handling higher loads from harsh acceleration.

Testing centres around assessing the ability of the secondary mass (which drives the gearbox via the clutch) to rotate against the primary mass which is bolted to the engine. There should be a 15mm or so movement with the flywheel returning its original position. Too much movement, not returning to the start position or no movement at all and there is a problem.

A skilled technician used to doing Porsche clutches will do this in their sleep.

Henry smile

Bennachie

1,091 posts

181 months

Monday 11th June 2012
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Thanks Henry, as I thought.

Rockster

1,515 posts

190 months

Tuesday 12th June 2012
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Henry-F said:
Edited for accuracy.

Henry smile
While you edited my post you subtracted accuracy. My post was accurate to begin with. All you did was add your misinformation combined with some kind of twisted bias.

I've talked to techs who say it is ok to resurface a dual mass FW. They do it for cars that come in for clutch jobs and they are not techs that hang out under a shade tree but highly trained/qualified techs who work at the various Porsche dealers I visit and do business with.

Sincerely,

Rockster.

RatBoy M3CSL

1,490 posts

226 months

Tuesday 12th June 2012
quotequote all
Rockster said:
While you edited my post you subtracted accuracy. My post was accurate to begin with. All you did was add your misinformation combined with some kind of twisted bias.

I've talked to techs who say it is ok to resurface a dual mass FW. They do it for cars that come in for clutch jobs and they are not techs that hang out under a shade tree but highly trained/qualified techs who work at the various Porsche dealers I visit and do business with.

Sincerely,

Rockster.
I think you're missing the point Rockster, from an engineering perspective it can be done yes, but is it worth doing..? you pay someone £100 to set it up and regrind the friction face on a 10 yr old 100K mile worn part full of springs that go weak with use, the cars in bits anyway, it's all on the floor, IMO there's no point not changing it, and risking having to take it all to bits a 2nd time...!