Clutch "flare"

[Weeberone]

Hi, my 1990 has what a GM service technician called a flare. He drove the car up a slight hill in fourth gear at about 1200rpm and applied moderate gas. The clutch seemed to slip a little and the rpm increased a couple hundred rpm as the car got up to speed and then held fine. This is unusual as the clutch works great in all other conditions including extreme acceleration from a standing start.
My question is; does the entire clutch need to be replaced, meaning flywheel, disk and pressure plate, or just, say, the disk etc?
Any help would be appreciated.

[kluketic]

Sounds like the clutch needs to be replaced. Knowing how many miles are on the car, and hard its been driven might be helpful but may not make any difference. I believe these are hydraulic throwout bearings, so probably no adjustment possible there.
If it were my car I would replace the clutch, pressure plate and throwout bearing as a unit, as i believe most would recommend.
Flywheel, if not scored, could just be resurfaced. Some may advocate replacing the flywheel with a high performance unit while your doing the clutch. No big advantage to this unless you're looking to ring every bit of power out of the car you can.

[Flyman 27]

The only work that should be done to the flywheel is a mild application of scotchbright pads. You do NOT want to "resurface" a dual mass flywheel.
The little shavings can easily get into the working parts of the flywheel and then it is a boat anchor.
About 18 months ago I was going to Mark's to swap my clutch. The flywheel had been "resurfaced" and there were chips in the mechanism, which was evident by turning the wheel & hearing the grinding of little chips.
Mark said this was common in flywheels that had been machined.
I had 2 flywheels that were bad for this reason.
I ended up using an old rusty flywheel from a friend (thanks Paul!). It cleaned up nicely with a little scotchbright.

[Weeberone]

If the flywheel is ok and just needs a little scotch brite, then only the other components could be replaced? Any opinions on this set up?

https://www.summitracing.com/parts/l.../submodel/zr-1

[kluketic]

By"resurfacing" I didn't necessarily mean turning it. But I would definitely check the flywheel for warpage with a dial indicator.
I have no experience with Summit's clutch kit offering.

[Ccmano]

Originally Posted by kluketic

By"resurfacing" I didn't necessarily mean turning it. But I would definitely check the flywheel for warpage with a dial indicator.
I have no experience with Summit's clutch kit offering.

Keep in mind the flywheel has a “cup” designed into the surface.

Best article on the subject by Mark Haibeck

http://www.zr1specialist.com/HAT%20W...0in%202019.pdf

H

[Weeberone]

Thanks! That article is exactly the information I’m looking for.

How does one determine the difference between needing just a new friction disk and needing a new flywheel and pressure plate too?

[oldpro]

I would consult Bill Boudreau on your clutch / flywheel to pen . I believe he knows someone who can resurface the flywheel and can share what problems you may rein into buying a aftermarket . He deals with this on a daily basis his ph 602 319 6575 he is also known as zf doc

[Ccmano]

Originally Posted by Weeberone

Thanks! That article is exactly the information I’m looking for.

How does one determine the difference between needing just a new friction disk and needing a new flywheel and pressure plate too?

Some of that info is in the article. Generally, the flywheel will have three possible issues, wear to the mating surface, hot spotting of the matting surface (dime and larger size blue smears) due to “high performance driving’ and excessive play between the “masses” as defined in the article. Similarly the pressure plate will show wear but also to the interface between the fingers of spring and the TO bearing. Over 100k miles the finger springs would be suspect for fatigue but theres no way to tell. Many cars go well past 100k on the original clutch pack.

Dittos on www.ZFDoc.com Bill Boudreau.

H

[Weeberone]

Awesome. Thanks for all the info. I guess I’ll know more once I actually remove it.