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/luk-04-113/year/1990/make/chevrolet/model/corvette/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]

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%20Web/articles/Clutch%20Replacement%20Options%20in%202019.pdf

H
:cheers:

[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]

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
:cheers:

[Weeberone]

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

[A26B]

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%20Web/articles/Clutch%20Replacement%20Options%20in%202019.pdf

H
:cheers:

Hans,
You mentioned "the flywheel has a "cup" designed into the surface. Several months ago, I was inspecting several OE DMF's. All still have the machine tooling marks present. I found that they had about 0.005" ~ 0.006" "dish" or "cup" as you prefer, down towards the center. Do you mind telling me where you derived your statement? I have been hesitant to sell either of these flywheels and your comment is the first I have heard of this.

I read Marc's document from the link you posted. He mentions the pressure plate having an 0.008" cup, but nothing about the flywheel.

Thanks,
Jerry

[Ccmano]

Hans,
You mentioned "the flywheel has a "cup" designed into the surface. Several months ago, I was inspecting several OE DMF's. All still have the machine tooling marks present. I found that they had about 0.005" ~ 0.006" "dish" or "cup" as you prefer, down towards the center. Do you mind telling me where you derived your statement? I have been hesitant to sell either of these flywheels and your comment is the first I have heard of this.

I read Marc's document from the link you posted. He mentions the pressure plate having an 0.008" cup, but nothing about the flywheel.

Thanks,
Jerry

Jerry,
Haibecks article quoted here does have that statement. He says the flywheel has a “cup” of 0.010”. Page 4 under the paragraph that leads with “Inspection of the Dualmass Flywheel “
H
:cheers:

[A26B]

Jerry,
Haibecks article quoted here does have that statement. He says the flywheel has a “cup” of 0.010”. Page 4 under the paragraph that leads with “Inspection of the Dualmass Flywheel “
H
:cheers:

Your are absolutely right! I only read the first page & thought that was the entirety of it. I will have to ask Marc where he obtained the flywheel cup information.

[Weeberone]

Have any of you ever attempted to replace a clutch with the car on jack stands? There's no real surprises here, are there? just a heavy transmission.
Remove exhaust, remove C-beam and drive shaft, remove transmission (hard part), remove bell housing and you're there?
I do have a service manual, but sometimes others experiences can be even more helpful.

[Ccmano]

Have any of you ever attempted to replace a clutch with the car on jack stands? There's no real surprises here, are there? just a heavy transmission.
Remove exhaust, remove C-beam and drive shaft, remove transmission (hard part), remove bell housing and you're there?
I do have a service manual, but sometimes others experiences can be even more helpful.

With a decent transmission jack it’s very doable on Jack stands. I’ve done several. The C-beam can be trickier due to the limited working room. It’s really pretty straight forward. The trans is very heavy ~150lbs. So doing the old drop on to your chest is not recommended. Don’t forget to support the engine, once the C-beam is out there nothing holding the back of the engine.
H
:cheers:

[Paul Workman]

With a decent transmission jack it’s very doable on Jack stands. I’ve done several. The C-beam can be trickier due to the limited working room. It’s really pretty straight forward. The trans is very heavy ~150lbs. So doing the old drop on to your chest in not recommended. Don’t forget to support the engine, once the C-beam is out there nothing holding the back of the engine.
H
:cheers:

Point of interest, IOW, another way to skin a cat?

Before I removed the ZF trans (on my 95 LT1 car) I asked Bill Boudreau (ZFdoc) about a transmission jack; where to buy and what to buy, etc.

Bill told me he doesn't use one. Instead, he puts the cup of the floor jack at the balance point under the trans and that's all he said he ever uses. (Wha-wha-whaaat???)

So, I tried it and he was right! I pulled the trans, installed a new one (in the 95 LT1 car), and I have pulled the trans on the Z a couple of times now...easy peasy. Yup! The monster will balance sweetly on the cup of the floor jack like a ballerina on tippy toes, and roll right out or back under the car all the while riding on the cup of the floor jack. And, as Bill said, he prefers to do it that way b/c he can align the angle of the trans with the clutch more easily. Well, I'll have to take his word on that, cuz I've never used a trans jack. But, the plain ol' floor jack worked like he said on 3 different occasions.

And, then there's Lee Gaffgan... Some years back Lee posted a video of him installing a ZF trans by himself while standing under his Z on a hoist. Lee bent over and picked the trans up off the floor, then "bench pressed" it head-high, and proceeded to stab it into the bell housing!:jawdrop:

The only question I had was, why didn't I think of that?? .....yeah, right!!

But, back to the clutch thing for a minute:

I've replaced the clutch disc twice on the Veleo (OE) clutches on two different cars, and once after swapping in a Fidanza FW. On no occasion did I resurface the FW - left it untouched (surface was not scored/damaged, only fine surface wear lines). Break-in (following Marc Haibeck's suggestion) ( simply babied the clutch for the first 500 miles to let the disc conform to its new surroundings (and the cup of the Veleo PP): never had a problem in 20k miles, even after the few passes at a drag strip.

YMMV!:)

[WARP TEN]

For the record, Marc Haibeck does not have a lift in his shop. He and Bob do everything under the cars with them on jackstands. --Bob

[Paul Workman]

For the record, Marc Haibeck does not have a lift in his shop. He and Bob do everything under the cars with them on jackstands. --Bob

And....I'm not sure Marc has to use jackstands either! :sign10:

[WARP TEN]

And....I'm not sure Marc has to use jackstands either! :sign10:

Well Paul, we tried to fatten him up yesterday at lunch but I think you are right--he can still slide under without using jack stands!-Bob

[Weeberone]

So I attempted to order the shims needed in order to use the Centerforce clutch disk as recommended in the Marc Haibeck article. I ordered from McMaster-Carr figuring they would be a stand up company as also recommended in Marc's article. This is the response I got for trying to order 6 shims to Jupiter's moon known as Canada:

"Hi Chris,



Due to the cost and complexity of shipping our products to Canada, we are only able to accept orders from businesses and schools. We’ve canceled your order. If this material is not for personal use, please resubmit your order online using the business or school name.



Jennifer

330-995-5989"

hmmm. Six shims. Pretty complex. I guess I'll source these locally.

[Weeberone]

Does anyone want to help me procure this shims? I can’t seem to find any locally and everywhere online either won’t ship to Canada or wants to charge me $50 for shipping.


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[Weeberone]

Does the roller bearing pilot bushing require any special lubrication, or does it just go in as is?

[Paul Workman]

Does the roller bearing pilot bushing require any special lubrication, or does it just go in as is?

I would defer to the manufacture of bearing for advice. That said, the bronze bushing with the flutes is recommended by many over the roller bearing pilot.

I suggest you ask Marc Haibeck for his recommendation, as Marc sees or has seen more of those ZR-1 clutches than practically anybody. (But, for what it is worth, I have the roller bearing pilot installed in my car - for the past 9-10 years and 40k miles. But, maybe I should mention that I avoid holding the clutch pedal down when idling, e.g., at a stop light, etc., which I think reduces wear and tear on that bearing.) ;)

[Weeberone]

Opinions on this clutch? Particularly the surface of the flywheel and pressure plate.
https://uploads.tapatalk-cdn.com/20200308/62e94c8508962c01f330b97dc955517f.jpghttps://uploads.tapatalk-cdn.com/20200308/810d04d986afb64f43efbe10a617f967.jpghttps://uploads.tapatalk-cdn.com/20200308/13960549cdac3261750850f812713133.jpghttps://uploads.tapatalk-cdn.com/20200308/4669953865bd57aacb408c7c32ce95d1.jpghttps://uploads.tapatalk-cdn.com/20200308/ad093d58630d5713295acf4bdf00098c.jpg


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[Ccmano]

The flywheel looks pretty normal. The pressure plate is suspect, showing a somewhat normal look on the outside and different look on the inside. Measure them per the specs in the article from Marc Haibeck. As a matter of fact I would run that photo of the PP by Marc and see what he says. Make sure there are no gouges or pits. Doesn’t look like it. If they check out I would scour with a scotchbrite pad to get gloss off and reuse them. The disc looks like it’s about done, getting thin at the outer edges. I would replace the disc. Cleanup the throw out bearing and make sure it runs smoothly. They are sealed bearings. They’re either good or they’re not. Grease the center lightly with hi temp grease where it fits to the input shaft. Install an new pilot bearing, flutted brass or roller bearing, opinions differ of which is best. I like the flutted brass.
H
:cheers:

[Weeberone]

The flywheel looks pretty normal. The pressure plate is suspect, showing a somewhat normal look on the outside and different look on the inside. Measure them per the specs in the article from Marc Haibeck. As a matter of fact I would run that photo of the PP by Marc and see what he says. Make sure there are no gouges or pits. Doesn’t look like it. If they check out I would scour with a scotchbrite pad to get gloss off and reuse them. The disc looks like it’s about done, getting thin at the outer edges. I would replace the disc. Cleanup the throw out bearing and make sure it runs smoothly. They are sealed bearings. They’re either good or they’re not. Grease the center lightly with hi temp grease where it fits to the input shaft. Install an new pilot bearing, flutted brass or roller bearing, opinions differ of which is best. I like the flutted brass.

H

:cheers:



Thanks for the input. I have a new Centerforce disk as per MH’s clutch article. I also have a roller bearing pilot bearing. Just waiting for a tool to pull it out.

The pressure plate and flywheel don’t have any pits or gouges, just that coloring, which I needed some input if it was normal or not. I’ll hit it with the scotch brite and see what it looks like.

I’m hoping just the disk is needed.


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[Paul Workman]

Thanks for the input. I have a new Centerforce disk as per MH’s clutch article. I also have a roller bearing pilot bearing. Just waiting for a tool to pull it out.

The pressure plate and flywheel don’t have any pits or gouges, just that coloring, which I needed some input if it was normal or not. I’ll hit it with the scotch brite and see what it looks like.

I’m hoping just the disk is needed.


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As for the puller, you can "rent" it at AutoZone, and return it and get your deposit back. OR, you can keep it and just forfeit the deposit. And, if you intend to keep the tool, let them know ahead of time and they'll issue you an brand new tool as your "rental". I've got several nice tools that way!

[jss06c6]

They look pretty good to me, I've seen far worse. Bill Boudreau takes in rebuildable clutch discs, yours is definitely rebuildable.

He also has a machine shop that he personally certified to resurface the DM. I've had one done by Bill, perfect, like new. He can also disassemble the Valeo PP for rebuild I believe..

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