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I'm considering a lightweight flywheel and want to know my options. I don't want to get anything TOO extreme, but I do want something to make my lower gears snappier since a lot of my driving rarely requires stopping and I am usually at speeds where I can jump down gears to pass slow cars, I feel I will see an increase in performance. How likely isit that an aluminum flywheel will explode (or whatever it is called?). What would be the ebst route to go?


I was going to try and get the UUC kit, but at this point my financial situation prohibits me from getting it.
 

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Drew:

I am going the UUC route shortly. From what I have read, and understand I expect the following:

1: A heavier flywheel smooths things out a bit. It is more forgiving when the gas/clutch application isn't perfect. The heavier rotational mass allow one to be sloppier with the gas.

(The flywheel's stored kinetic energy is delivered when the clutch is engaged, if you didn't have enough gas applied when engaging, the flywheel makes up for it --OR-- if you have too much gas applied, the neck snap is greater due to the extra energy from the flywheel and the engine).

2: The added rotatonal mass requires torque to spin, so less accelleration. A lighter flywheel will require more attention to the gas/clutch foot dance.

3: Inversely, expect a small decrease in downshifting stopping power. Less mass to turn with the lighter flywheel = less resistance to change.

4: At cruising velocity, there will be no apparent difference between the two.

5: Throttle response should be improved.

6: Downshifting and mashing the gas should improve.

7: A well made aluminum flywheel should not explode.

My $0.02 worth.
 

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DrewKeen said:
I'm considering a lightweight flywheel and want to know my options. I don't want to get anything TOO extreme, but I do want something to make my lower gears snappier since a lot of my driving rarely requires stopping and I am usually at speeds where I can jump down gears to pass slow cars, I feel I will see an increase in performance. How likely isit that an aluminum flywheel will explode (or whatever it is called?). What would be the ebst route to go?


I was going to try and get the UUC kit, but at this point my financial situation prohibits me from getting it.
In my opinion, it is too costly to install a 9-5/8" clutch because recurring labor and material charges are going to empty your wallet and result in long term heart burn. A proper OEM clutch costs almost $1200 in parts alone (kit + flywheel) and the labor is an easy $600 bringing you close to $2K for a defective design. An aluminum, lightweight flywheel in combination with a 9-5/8" clutch is the appropriate setup for a performance M3, not a V8 M5. Powerful, heavy V8 cars need a 10-1/2" or 11" clutch to provide reasonable durability & this is far more important than optimal flywheel weight.
 

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Of course the 605 hp carrera gt uses a motor cycle type clutch...weighing under 7 lbs...Proving size don't matter unless you are trying to comensate :)




Now the same size with a better material and all this would be irelavant. the 11" 850 csi clutch is just compensation because no one wants to make somthing new.
 

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Jayson said:
Of course the 605 hp carrera gt uses a motor cycle type clutch...weighing under 7 lbs...Proving size don't matter........ :)

In practice, size matters if you are obligated to run "single disk" type automotive clutch. Nobody manufactures a proven multi-disk street clutch for M5.

A multi-disk clutch multiplies swept area by the disk count, which indeed allows a smaller diameter with the same effective swept area. Unfortunately they are unable to absorb much heat from extended slippage (street traffic jamb etc) unless they are immersed in a cooling fluid, as in a motorcycle crankcase. Heavy cars that see lots of stop and go traffic need a clutch assembly that can provide smooth engagement & absorb lots of heat.
 
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