Flywheel surfacing questions

[warmonger]

Some questions for you service tech and engineer types:

Does anyone know for sure what the distance between the SVT flywheel friction surface and the mounting surface for the pressure plate is?

If anyone has a new SVT flywheel accessible can they measure that distance accurately for us so we have it as a reference?

Does anyone ever have both surfaces milled equally?

It is my thought that the distance between these two points should remain fixed so that the clamp pressure of the pressure plate is basically the same. I found out that most machine shops only do the single surfacing of the friction area and don't touch the pressure plate mounting area. The only thing I can think of is if this distance increases significantly it would almost be the same as having the disk wear down and the pressure plate has to move farther to accomodate that.

So if you start with it further away, could this lead to slippage when the disk is more worn?
How far can you mill before this becomes a problem?

[Big Jim]

I haven't had a look at the Duratec manual trans flywheel, but if it is a stepped flywheel the two surfaces MUST be machined equally. Any machine shop that does otherwise doesn't know what they are doing.

[todras]

Ditto. X11111

[todras]

When you consider a new clutch it's MOST important to check the clutch face on the flywheel.If it's anything like the one in the pic it needs machining.Please also note that on a 2.5/V6 flywheel it has a recessed design so if you machine say 50 thou off off surface 'X' then the SAME amount must be removed from 'Y'....OK,'Y' you ask?...The distance between the disc mount face and the pressure plate mount face MUST REMAIN CONSTANT.If you don't machine 'Y' you have reduced the clamping force that the clutch pressure plate will have on the disc.The 'red mark' distance or recess measurement must remain the same as in a new flywheel.The dowels MUST be removed for this,a good m/c shop will have the correct puller to remove them.If the surface has burn marks it must be resurfaced or the new clutch will not bed and has a high risk of slip.Flywheels do not warp(neither do rotors!),but the hot spots/burn marks cause hard/soft areas in the material.This variation in hardness affects the coeff of fiction of the flywheel.As in rotors,99% of 'so called 'warped rotors ' are not warped at all but have 'hard spots' that cause a variation in friction and give the 'pulsing pedal' feel.Same on a clutch.A new disc needs a fresh even area of flywheel material to bed and give an overall even level of friction to.Got to get off that uneven(hardness/burnt) skin of metal...Easy eh!!!

Some serious bluing.

[warmonger]

When you consider a new clutch it's MOST important to check the clutch face on the flywheel.If it's anything like the one in the pic it needs machining.Please also note that on a 2.5/V6 flywheel it has a recessed design so if you machine say 50 thou off off surface 'X' then the SAME amount must be removed from 'Y'....OK,'Y' you ask?...The distance between the disc mount face and the pressure plate mount face MUST REMAIN CONSTANT.If you don't machine 'Y' you have reduced the clamping force that the clutch pressure plate will have on the disc.The 'red mark' distance or recess measurement must remain the same as in a new flywheel.The dowels MUST be removed for this,a good m/c shop will have the correct puller to remove them.If the surface has burn marks it must be resurfaced or the new clutch will not bed and has a high risk of slip.Flywheels do not warp(neither do rotors!),but the hot spots/burn marks cause hard/soft areas in the material.This variation in hardness affects the coeff of fiction of the flywheel.As in rotors,99% of 'so called 'warped rotors ' are not warped at all but have 'hard spots' that cause a variation in friction and give the 'pulsing pedal' feel.Same on a clutch.A new disc needs a fresh even area of flywheel material to bed and give an overall even level of friction to.Got to get off that uneven(hardness/burnt) skin of metal...Easy eh!!!

Some serious bluing.

Thanks Todd and tell Terry thanks as well. I thought this was the case considering the physical operation of a clutch but I never delved into it and I though it was best to ask.
I'd questioned some machine shops but they must not be very good and were not very knowledgeable about it. I just did a job for a guy and I told the shop to pull the pins and surface both levels anyway. Glad I did.

[todras]

I didn't even know it was a question honestly. I thought it was a given. The last guy I did a FW for I took the FW to Napa. I asked if they had the proper pins after it had been resurfaced and they replied yes. Damn I hate podunk machine shops.

[warmonger]

I didn't even know it was a question honestly. I thought it was a given. The last guy I did a FW for I took the FW to Napa. I asked if they had the proper pins after it had been resurfaced and they replied yes. Damn I hate podunk machine shops.

Yeah, n/s! But then look at my sig and see where I have to live right now! lol
This is why it took me so long to organize the brake group buy too; finding capable places was hard.