Flywheel Machining Question

[Bass Junky]

hey ppls.

Here's a quick question for those who know some stuff about clutches.

When a flywheel is machined, how much of the face is skimmed?

Looking at both my standard and Ogura flywheel, I can see the section where the clutch face rubs/grips against.

I can also see the dowel pin locators. and the bolting pattern.

Are the dowel pins removed for machining?

The next question, is this.

when machining the face of the flywheel, is the whole thing machined, or just the section when the friction material rubs/grips the flywheel?

The reason I ask is because I have just had the Exedy 8 button sprung centre thing fitted, and I'm concerned about it's lightness.

I deduct that if only the section that rubs/grips the friction material is machined, then the relationship between the clutch disk and the flywheel is then different by the amount of material skimmed off the flywheel.

Does that make sense?

All help appreciated.

[blind_elk]

What do you mean by "lightness"? Are you referring to how easy it is to depress the clutch pedal? If so, then that is related to the spring tension and leverage ratio of the "fingers" on the pressure plate vs the clamping pressure of the pressure plate.

I believe they only machine microns from the surface where the driven plate contacts the flywheel. So the loss of material would be insignificant relative to the thickness of the driven plate (your 8-button thing)

[shanef]

From what i believe and have personally seen, the dowells are removed prior to machining and the WHOLE face is machined. if only part of the flywheel is machined, then there will be a 'step' in the flywheel, this causing uneven clamping/loading properties affecting the clutch operation in a negative mannar

[shanef]

this is a pic of my 32gtr flywheel. it's had 1 hr use after it was machined and a 5puck brass button clutch was fitted. notice the wear area of the clutch face, and the hatching outside that area from when it was machined.

[mad082]

they usually only take off a 'thou' or 2, depending on how badly worn it is.. from memory there is 40 'thou' to a millimeter, but i could be wrong, but i know there is a fair few.

[SteveL]

The dowels are removed and the whole surface machined. The amount removed depends on the depth of the wear damage. There will be a factory recommended max amount to be machined off and with cast iron flywheels its best to be a little cautious

[turboedsloth]

40 thou is .1mm. they remove the dowels and machine the surface where the actual clutch plate runs. as per the complaint about the Exedy 8 puck cushioned clutch, there built to be light like that. thats wat makes them so good. i install these and they are a very good unit.

[SteveL]

40 thou is .1mm

No, 40 thou (0.040") is approximately 1mm.

Actually 1mm = 0.03937007874"

[turboedsloth]

my bad i put the . in front

[SteveL]

my bad i put the . in front

Yeh, figured it was a typo, it's all good