Dual mass flywheel should not be machined....
10-03-2006, 06:42 PM
#1
Burning Brakes
Thread Starter
Dual mass flywheel should not be machined....
Do you know why a dual mass flywheel can not be machined.
When it is time to change a clutch it is recomended that the flywheel should be resurfaced and even so the clutch will last longer.
What technical reason prevents dual mass flywheels to be resurfaced?
If done what can go wrong?
When it is time to change a clutch it is recomended that the flywheel should be resurfaced and even so the clutch will last longer.
What technical reason prevents dual mass flywheels to be resurfaced?
If done what can go wrong?
10-03-2006, 07:16 PM
#2
Team Owner
There has been a lot of urban legend here, but this is what I have been able to cull together as to why:
1) space... the dimentions within the clutch assembly are so close, that taking off some of the material will ruin the clutches action.
2) durability... the DM is only good to about 120k miles, TOPS. So what is the point of doing this at 100k miles, only to have to do it again in 20k more?
That's it. If the clutch is being replaced, there is a test to check deflection on the dual mass. However, if it's close to the standard, I would replace.
Check out this option: Clutch Conversion.
One addition - you need to match balance your flywheel to the new SMFW.
1) space... the dimentions within the clutch assembly are so close, that taking off some of the material will ruin the clutches action.
2) durability... the DM is only good to about 120k miles, TOPS. So what is the point of doing this at 100k miles, only to have to do it again in 20k more?
That's it. If the clutch is being replaced, there is a test to check deflection on the dual mass. However, if it's close to the standard, I would replace.
Check out this option: Clutch Conversion.
One addition - you need to match balance your flywheel to the new SMFW.
10-04-2006, 11:07 AM
#3
Heel & Toe
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Originally Posted by bogus
One addition - you need to match balance your flywheel to the new SMFW.
i bought a alluminium FW (SPEC) Do i have to do something ?
i heard the gear chattering when clutch engaged and a little vibration at high RPM(5500/6000) or high speed (+120mph) About the vibration, is it reliable ?
10-04-2006, 12:25 PM
#5
Team Owner
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St. Jude Donor '08-'09
Originally Posted by GS#0677
What do you mean by "match balance your flywheel to the new SMFW" ?
i bought a alluminium FW (SPEC) Do i have to do something ?
i heard the gear chattering when clutch engaged and a little vibration at high RPM(5500/6000) or high speed (+120mph) About the vibration, is it reliable ?
i bought a alluminium FW (SPEC) Do i have to do something ?
i heard the gear chattering when clutch engaged and a little vibration at high RPM(5500/6000) or high speed (+120mph) About the vibration, is it reliable ?
Thats fine. its normal. its called clutch chatter. All ZF6 trannies with a single mass do it.
I also have a spec single mass flywheel and clutch in mine
10-04-2006, 12:54 PM
#6
Melting Slicks
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Location: Phoenix, Arizona Corvette: Blk '96 LT4 Coupe
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Originally Posted by Kinkajou
Do you know why a dual mass flywheel can not be machined.
When it is time to change a clutch it is recomended that the flywheel should be resurfaced and even so the clutch will last longer.
What technical reason prevents dual mass flywheels to be resurfaced?
If done what can go wrong?
When it is time to change a clutch it is recomended that the flywheel should be resurfaced and even so the clutch will last longer.
What technical reason prevents dual mass flywheels to be resurfaced?
If done what can go wrong?
10-04-2006, 02:10 PM
#7
Team Owner
Originally Posted by JEFNLSA
Check out this LINK
the bottom line - there are differences between the way the BWM clutch works and the Corvette clutch works...
I stand by my statements above.
The reason? TORQUE... your average BMW I6 does not have the torque that a L98 or LT1 has.
10-04-2006, 02:11 PM
#8
Team Owner
Originally Posted by arkangel81
hhmmmm boise transmission machined my dm flywheel so far no problems, been over a year.... was it unethical for them to do this?
only 80,000 miles on my 1990
only 80,000 miles on my 1990When I replaced my clutch at 92k miles, I went through hell with SPEC, and ended up putting the stock clutch back in with my existing DMFW.
At 120k, I could feel bad things happening in there... very bad...
So I replaced the clutch again, this time with a Fidenza and clutch assembly from Carolina Clutch.
When I got to the DM, I was able to deflect the outer mass about 1", in either direction - BY HAND. this is so far out of spec, it ain't even funny. I don't race, so don't be surprised if this happens to your DM by about 120k miles.
Last edited by bogus; 10-04-2006 at 02:13 PM.
10-04-2006, 02:18 PM
#9
Team Owner
Originally Posted by GS#0677
What do you mean by "match balance your flywheel to the new SMFW" ?
i bought a alluminium FW (SPEC) Do i have to do something ?
i heard the gear chattering when clutch engaged and a little vibration at high RPM(5500/6000) or high speed (+120mph) About the vibration, is it reliable ?
i bought a alluminium FW (SPEC) Do i have to do something ?
i heard the gear chattering when clutch engaged and a little vibration at high RPM(5500/6000) or high speed (+120mph) About the vibration, is it reliable ?
To match balance, it requires the old and new flywheels be put on a machine. They are installed in such a way that they are 180* out of phase. they are spun to a specific (or varied) RPM (not sure which) and the weights are added to the new SMFW, much like tire weights.
The weight should be welded on.
The DMFW has small holes in its parameter, these holes accept small weights that are used to fine tune and replicate the balance.
I hope this clarifies problem/issue a bit.
10-04-2006, 02:31 PM
#10
Melting Slicks
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Originally Posted by bogus
Hib posted that crap over here a few months ago.
the bottom line - there are differences between the way the BWM clutch works and the Corvette clutch works...
I stand by my statements above.
The reason? TORQUE... your average BMW I6 does not have the torque that a L98 or LT1 has.
the bottom line - there are differences between the way the BWM clutch works and the Corvette clutch works...
I stand by my statements above.
The reason? TORQUE... your average BMW I6 does not have the torque that a L98 or LT1 has.
Regardless of your opinion of Hib's revelation, you can't deny that he knows quite a bit about "our" cars.
10-04-2006, 03:23 PM
#12
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thanks bogus for your help 
i'm gonna try to find a machinery shop in france to do this special work!!
An other question why when you buy a SMFW in aluminium, do the dealer doesn't specify this ?
thanks
i'm gonna try to find a machinery shop in france to do this special work!!
An other question why when you buy a SMFW in aluminium, do the dealer doesn't specify this ?
thanks
10-04-2006, 04:47 PM
#13
Team Owner
they seem to think that the base balance of the SM is good enough... if that was the case, GM would not have had to go to these lengths to balance them completely.
