Finally got the clutch changed on the M5......

[Clevy]

Originally Posted By: Jarlaxle
Double-clutching a downshift is pretty simple: press clutch, shift to neutral, release clutch. Blip throttle to raise RPM's, press clutch, trans in lower gear. That's how I shift.


Thank you for explaining it to me.

 

[djb]

Originally Posted By: OVERKILL

These ones don't wear out, the auto adjustment mechanism starts to stick/fail at that age, and that causes partial engagement along with other issues.


It's a hydraulic clutch actuator, which is inherently self adjusting. There isn't an auto-adjustment mechanism (mechanical contraptions which *are* balky). The output cylinder range is enough to compensate for the wear until the clutch disk is so thin that the diaphragm spring can't apply enough pressure. Sometimes the spring holds until friction material is gone and metal-on-metal contact doesn't provide friction.

The only thing that usually sticks and causes clutch wear is the disk riding on the splines, which must be lightly lubricated with special grease that resists water and doesn't gather friction material dust. The hydraulic part of the system fails when the fluid isn't changed, but failure prevent disengaging the clutch rather than wearing it out.

 

[TallPaul]

Originally Posted By: cchase
Some people love to ... sit on hills holding the car with the clutch.

You don't mean slipping the clutch with it in gear to hold position on a hill, do you?

Surely you mean like some do at a red light where they sit with the clutch pedal fully depressed and in gear.

 

[TallPaul]

Originally Posted By: Jarlaxle
Double-clutching a downshift is pretty simple: press clutch, shift to neutral, release clutch. Blip throttle to raise RPM's, press clutch, trans in lower gear. That's how I shift.
Never done it and my trannies have lasted just fine. Last truck had the Mazda M5OD with about 175,000 miles on it and was shifting beautifully when I sold it. Never rev matched either. My '84 F150 went some 300,000 miles with the original tranny and never double clutched. Only time I typically rev match is downshifting into first at higher speeds, say about 15 mph or higher. I see no point in double clutching (at least not for my driving needs), but to waste time and over complicate driving. Not going to do it just to add to clutch life either. Typically get 100,000 miles out of a clutch.

 

[SteveSRT8]

Originally Posted By: HTSS_TR
Originally Posted By: mechanicx
See this is why I don't understand why some people think manuals are more reliable and cheaper to fix than an automatic. Manuals often need a clutch work and that's not cheap especially on FWD cars. The gearbox internally can wear out/fail too. I remember on an '86 RX7 you couldn't buy a new transmission. You had to buy all the parts, $3k retail back then and that did not include the clutch parts or any labor. Automatics could usually be rebuilt for a couple hundred dollars in parts but there was some labor involved. I've had plenty of automatics go 150K+ miles with just one fluid change.

I agree.

The Auto Trans in my 300+k miles LS400 didn't need any work other than changing ATF every 60-80k miles, the Auto Trans in my 140+k miles in my E430 had one ATF change at 80+k miles and will do another in about 30-40k miles.

The S2000 only comes with MT so I prepare to pay for the clutch job in the near future, so far it didn't show any sign of problem yet.



So BMW parts and labor are expensive. No news there. A stealership tried to hose a client. Not news either. They'd steal from their own Mom if they thought they could!

I've had many manuals and in very strong cars, never had a clutch go less than 150k miles even with track use. I would be pleased that a car like Overkill's with a high performance drivetrain would go that far. Not bad at all.

That said, a manual's advantages are only born out with a good DRIVER. This is why we used to devalue used cars with a stick, it depends who's driving!

 

[Jarlaxle]

Originally Posted By: Clevy
Originally Posted By: Jarlaxle
Double-clutching a downshift is pretty simple: press clutch, shift to neutral, release clutch. Blip throttle to raise RPM's, press clutch, trans in lower gear. That's how I shift.


Thank you for explaining it to me.


No problem! Now try it with a non-synchronized 13-speed.

 

[Jarlaxle]

Originally Posted By: TallPaul
Originally Posted By: Jarlaxle
Double-clutching a downshift is pretty simple: press clutch, shift to neutral, release clutch. Blip throttle to raise RPM's, press clutch, trans in lower gear. That's how I shift.
Never done it and my trannies have lasted just fine. Last truck had the Mazda M5OD with about 175,000 miles on it and was shifting beautifully when I sold it. Never rev matched either. My '84 F150 went some 300,000 miles with the original tranny and never double clutched. Only time I typically rev match is downshifting into first at higher speeds, say about 15 mph or higher. I see no point in double clutching (at least not for my driving needs), but to waste time and over complicate driving. Not going to do it just to add to clutch life either. Typically get 100,000 miles out of a clutch.


I replaced the OE clutch in my 1992 F-350 with just short of 300,000 miles. The LUK heavy-duty in the F-550 ramp truck I drove went over 250,000 miles (OE went ~180K, was replaced due to a bad DMF.) Driven properly, a clutch will last most of the service life of the vehicle.

 

[SteveSRT8]

"Driven Properly" is a HUGE qualification.

My bet is less than ten percent of us know how to drive an un-synchronized gearbox, and even fewer know the subtleties of rev matching, heel and toe, etc.

 

[supton]

Originally Posted By: Tegger
Originally Posted By: A_Harman
You must be a very smooth driver. Not many people can get 250k miles on a clutch.


I got 255,000 miles on the original clutch in my Integra.

And even then the only reason I took it in to get replaced was because I was having difficulty getting the shifter into 2nd gear (there was a good reason for that which had nothing to do with me, and was discovered after the transmission was removed). The clutch was not slipping at all at that point, and my mechanic estimated that it might have gone another 10K miles before it was down to the rivets on both sides. Got 147K on the new clutch right now, and I've only had to adjust it a few times.

The clutch job cost $800 all told; Hondas are cheap to run, unlike some status models.


You know how the clutch disc has most of it raised up, then little grooves in it? Kinda like water run off areas, or whatever? Yeah, on mine--those grooves were all still there, lots of the raised area, nowhere near the rivets.

[I suspect a 45 mile highway commute has something to do with that--274kmiles in 9 years, zero city traffic, etc.]

 

[Tegger]

Originally Posted By: OVERKILL
Double-clutching is unnecessary with a synchronized transmission. All you need to do to minimize clutch wear is rev-match, which is what I do via a blip of the throttle on a gear change to bring the revs up to match the lower gear before engaging.

That's true, but double-clutching does save quite a lot of wear on the synchros as well.

 

[dwcopple]

Originally Posted By: OVERKILL
Come on, the car is 12 years old and hasn't really cost much to own up until this job,
haven't you only owned it around one year though? I'd be PO'd.

 

[Pop_Rivit]

Originally Posted By: OVERKILL
And my wallet is ~$2600.00 lighter.


Ouch. I've never owned a car that I've had to sink that much money in repairs over it's entire lifetime, not to mention in one singe repair.

And I hope I never own a car that costs such a ridiculous amount just to keep it roadworthy.

 

[supton]

I'd hope not to either. But I have, and that's life. Repairing has been cheaper than replacing. Altogether different sort of vehicle though; mine is a high mpg commuter--but like the OP I'm sure both brings smiles to our faces while driving.

 

[Jarlaxle]

Originally Posted By: Pop_Rivit
Originally Posted By: OVERKILL
And my wallet is ~$2600.00 lighter.


Ouch. I've never owned a car that I've had to sink that much money in repairs over it's entire lifetime, not to mention in one singe repair.

And I hope I never own a car that costs such a ridiculous amount just to keep it roadworthy.


No kidding! Even a full trans job-including a rear main seal & flexplate-on my first LT1 Caprice was only about $1400.

 

[OVERKILL]

Originally Posted By: djb
Originally Posted By: OVERKILL

These ones don't wear out, the auto adjustment mechanism starts to stick/fail at that age, and that causes partial engagement along with other issues.


It's a hydraulic clutch actuator, which is inherently self adjusting. There isn't an auto-adjustment mechanism (mechanical contraptions which *are* balky). The output cylinder range is enough to compensate for the wear until the clutch disk is so thin that the diaphragm spring can't apply enough pressure. Sometimes the spring holds until friction material is gone and metal-on-metal contact doesn't provide friction.

The only thing that usually sticks and causes clutch wear is the disk riding on the splines, which must be lightly lubricated with special grease that resists water and doesn't gather friction material dust. The hydraulic part of the system fails when the fluid isn't changed, but failure prevent disengaging the clutch rather than wearing it out.





This is the information I'm going by:

Quote:
the original BMW (LUK-manufactured) clutch in the V8 models has a new "SAC" (Self Adjusting Clutch) design. This new mechanism built into the pressure plate is supposed to keep the clutch pedal engagement point the same as the clutch wears... but in all reality, it's a case of "an answer to a question that nobody was asking." They have added a layer of complexity and feedback isolation, filling a need that didn't need filling - it is not too often that anybody notices that their clutch engagement point as moved 1/2" over 50K miles.

The SAC mechanism itself causes problems; it over- or under-adjusts the pressure plate and therefore causes the clutch to slip or burn out prematurely. They are also known to shift, causing the pressure plate release fingers to slip off the plate, keeping 1/3 of the pressure plate engaged at all times. Bottom line is that the only fix is a complete clutch job, and your dealer is likely to claim "driver abuse". We have seen it happen too many times.

The SAC mechanism may not give a clean release like a standard clutch. Instead of just two sets of springs, there is an adjuster mechanism that makes engagement feel mushy or slow.

 

[OVERKILL]

Originally Posted By: Tegger
Originally Posted By: OVERKILL
Double-clutching is unnecessary with a synchronized transmission. All you need to do to minimize clutch wear is rev-match, which is what I do via a blip of the throttle on a gear change to bring the revs up to match the lower gear before engaging.

That's true, but double-clutching does save quite a lot of wear on the synchros as well.


I've never worn out a set of sychro's. I killed 3rd and 4th in my Mustang on the original tranny at somewhere close to 300,000Km, with an engine making 100HP more than stock. Launched it on some MT ET Streets, hooked hard and twisted the yoke (not the original one to the car, it was on an aluminum D/S I had fitted), which shifted the guts of the tranny (T-5.... not a strong gearbox anyway) 1/2" inside and killed the two gears. The synchro's looked fine upon tear-down, despite the massive abuse that transmission saw.

 

[OVERKILL]

Originally Posted By: dwcopple
Originally Posted By: OVERKILL
Come on, the car is 12 years old and hasn't really cost much to own up until this job,
haven't you only owned it around one year though? I'd be PO'd.


Had this been unexpected, yes, I'd be PO'd. However, I knew the clutch was OE when I bought the car. I was also aware that it was already past the mileage they usually start to fail at, so when it started to slip, I wasn't really surprised and just started to budget for replacing it.

The bigger shocker what what I got charged for changing the RMS. I think the clutch replacement cost was reasonable. Not so for the RMS change.

 

[OVERKILL]

Originally Posted By: Pop_Rivit
Originally Posted By: OVERKILL
And my wallet is ~$2600.00 lighter.


Ouch. I've never owned a car that I've had to sink that much money in repairs over it's entire lifetime, not to mention in one singe repair.

And I hope I never own a car that costs such a ridiculous amount just to keep it roadworthy.


You should try owning an airplane

They make bills like this look like coffee change. We have two of them at work.

As I said very early on when I bought this car, you have to pay to play. My original post on this thread wasn't a complaint with respect to the cost of ownership of this car, which, as of Thursday, has jumped up a fair bit. I felt I got taken over the RMS repair, but I was also glad that they were able to complete both repairs on such short notice. So therein lies the rub. Pleased, yet feeling a bit screwed at the same time.

I don't complain about gas prices, never have, never will. I drive what I choose to drive, and accept the costs associated with that decision. I'm not saddling myself with debt or lease payments, so driving a nice 400HP car that may be a bit older, but is paid for and may require the odd expensive repair is, to me, chalked up to the ownership of such a vehicle. I spent much more money on my Mustang on upgrades than I've spent on this car in repairs. So there is some relativity there as well.

 

[OVERKILL]

Originally Posted By: Jarlaxle
Originally Posted By: Pop_Rivit
Originally Posted By: OVERKILL
And my wallet is ~$2600.00 lighter.


Ouch. I've never owned a car that I've had to sink that much money in repairs over it's entire lifetime, not to mention in one singe repair.

And I hope I never own a car that costs such a ridiculous amount just to keep it roadworthy.


No kidding! Even a full trans job-including a rear main seal & flexplate-on my first LT1 Caprice was only about $1400.


I did the clutch (Centerforce Dual Friction $250 on E-bay), had the flywheel machined ($80.00) and replaced the RMS ($10.00 and some screws + vice-grips) in my driveway on my back. The whole job was under $400.00.

Had I the time, I could have tackled this job myself and been out probably around $800.00 in parts total. But I didn't, so it wasn't.

 

[KrisZ]

Some of the lamenting here is truly funny. This is a BMW and on top of the it's an M5. Why would anyone be surprised at the price tag and on top of that generalize this situation to other manual transmission cars is beyond me.

If anybody wants to compare apples to apples, they should look at the price tag for the automated manual tranny found on current M5s and compare it to the manual variant.