I removed the flywheel from my 70 LS5, clutch was chattering. I replaced the clutch when I did a frame off twenty years ago but foolishly tried to save money by skipping the flywheel resurface. Paying for that mistake now.

I see some hairline cracks on the surface here and there, not a lot of them but they're present. NAPA quoted $80 to resurface. Question is can a machinist tell if any cracking is present after resurfacing? NAPA offers a replacement for $120. I don't know where the replacement comes from, could be China. I generally prefer to recondition OEM parts. In this case I wonder about safety, whether a machinist could tell me if it's salvageable.
If not, is the NAPA product a good choice for a stock LS5?

Thoughts or experiences?

 

I would attempt the resurface small cost, if it fails and cracks are visible, get a replacement. if it cleans up of you have your original,
not some cheap made in china with recycled tin cans.
the machinist can check for cracks after it is machined.

 

That's what I'm concerned about. I'd rather keep the original flywheel rather than buy a new one of unknown quality. The cracks are a concern. If a machinist can verify the cracks are gone, great, I'll keep the original. Thanks.

 

I just did the same on the rebuild of my L-82. Resurfaced the OEM flywheel rather than go with a replacement but my OEM flywheel looked great-no grooves, discoloration, cracks...

 

I had the same clutch chattering when I got my 76. I took my flywheel to NAPA and had it resurfaced. They will remove only what is necessary to get rid of the cracks.

When you pick up your flywheel - get shims equal to the amount of material removed. Shims will go between the crank and flywheel to keep the flywheel surface in the original/stock position.

 

Great tip, I was wondering whether the change in dimension would have an effect on the linkage, etc.

 

I'm not a fan of 40 year old fly wheels with surface cracks in them. I have been blessed with the money to buy SFI rated items.

LS5's have moderate power and not high rpm. You could have yours machined and it will be much lighter. I had a 30 pound SFI 168 tooth 11 inch clutch shaved down to 22 pounds. Lighter flywheels make it more fun. I've since gone to a 10 pound 153 tooth aluminum.

The world is full of choices. Flywheels can be a lifetime long investment.

 

Your machinist should be able to check for cracks using magnaflux or fluorescent dye penetrant methods.

 

$80 sounds like a lot to cut a flywheel, I would check around. If you or anyone else is interested I have a genuine GM 454 flywheel that had a fresh cut then got wet, $95 plus postage although I think it might go USPS flat rate in a medium box for $12.

 

You will probably not find a GOOD quality replacement part for $100 or less. I would stay with the original, IF:

There are no chipped, damaged teeth on it;

The cracking appears to be at the surface and due to surface heating;

You feel confident in the machining capabilities of the NAPA store and personnel.

Otherwise, buy a new, QUALITY part...a lighter one would be better (but more expensive).

 

[QUOTEno Vette Go;1587736565]I had the same clutch chattering when I got my 76. I took my flywheel to NAPA and had it resurfaced. They will remove only what is necessary to get rid of the cracks.

When you pick up your flywheel - get shims equal to the amount of material removed. Shims will go between the crank and flywheel to keep the flywheel surface in the original/stock position.[/QUOTE]

I did not use any shims with the resurfaced flywheel and new clutch kit- balanced yes. Adjusted clutch free play and good to go.

 

NAPA quoted $121 for a replacement. I don't know where it comes from, assume China? $80 to resurface.

I could go with a steel flywheel from Hayes or some other aftermarket?

I got a funny look when I asked about shims, counter man never heard of them. Bottom line is their machinist said the cracks will still be there after machining. Said they shouldn't be a problem unless I plan to rev the engine very high. What's very high I don't know. It's a stock big block, can't go too high.

I hated to tear this car down again so I want to go with what gives me the best peace of mind without over spending.

 

The shims on the resurfaced flywheel reminds me of the discussion around measuring a cam button for my roller cam and the "black" magic of measuring pushrods for the roller cam-so much of this stuff is way overplayed….

 

I bought a RAM #1521 for $300 and it could not be mounted. The mounting holes were off just enough that 1 bolt could not be installed no matter how it was clocked. It's a decoration in my garage now. I had the OEM flywheel resurfaced locally for $30 and it works fine.

 

I just put a RAM HDX clutch kit-$350 on my 355 L-82 4 speed and it fit perfectly-no issues. My builder for the short block recommended RAM for my applications since he has used many of them with zero problems. Why didn't you just return your clutch?

 

When doing my 70 clutch I replaced everything using the OEM manufacturer LUK. I had the clutch disc, pressure plate and flywheel balanced as a unit by a machine shop. The machine shop will put a mark and dye to note how the units aligned as they were balanced.
Also check to make sure the ball stud is in good shape and that the throw out bearing is installed correctly.

Lastly, make sure the pilot busing is not magnetic. Most made today are magnetic, if only slightly. It should be a bronze (oilite), non magnetic bushing.

There is no way I would trust a 40 year old flywheel with even a hint of cracks IMHO.

You may also want to consider having the Muncie checked out while everything is out and rebuild the shifter.



Bill

 

A good machine shop will do a mag inspection (magnaflux is a trade mark) prior to surfacing; penetrant will not pick up any subsurface cracks which may be caused by metal smearing. You can use a 10x magnafying glass to check prior to the mag inspection yourself for surface indications; cracks will appear jagged although they may appear straight when doing a standard visual inspection with out magnification.
Make sure you check the gear on both the flywheel AND the starter.
Also, I agree; the price quoted for machining is pretty high.

 

Napa isn't the only place selling parts/service...also there is probably a minimum dimension after machining (like a brake rotor)...if the cracks are gone and it meets dimensional specs I would not be afraid to reinstall...Good Luck!

 

after market (autozone?) flywheel cost 79$; ship in 3-4 days

 

Good info, thanks. I see a LUK flywheel for $98.07, new. Is this indeed the OEM GM used? Price seems a bit low, made in China? I'm not looking to overspend, just cautious when the price seems to be too good.

I'll check the pilot bearing, appears to be a bronze alloy. It was installed sometime in the mid 80's or early 90's. I'd guess the car hasn't had more than 5K miles put on it since then. This car spent a lot of time from early 90's to just a few years ago apart, project was put on hold for several years.

I'm considering rebuilding the shifter while it's out.

The transmission had all bearings, seals, blocking rings, and shifter forks replaced in the early 90's, factory parts. It has a slight leak in the front, hard to tell where it's coming from or whether it may have been overfilled once. I know the counter gear shaft is a common leak area but don't see how oil from there would get into the bell housing. Maybe a gasket issue on the bearing retainer? Could be the nut is installed backwards though I'd expect it to leak much more heavily in that case.

Good to know, these clutches are significantly more expensive than the LUK units.

The counter man at NAPA called the machine shop while I was there. He was told the cracks will still be there after resurfacing, said unless I plan to run some high RPMs it would be OK. This may be so but it would probably bug me knowing they're still there. My take was it isn't likely they will be able to get rid of the cracks completely.

Yes, $80 appears to be quite high compared to prices I've heard others paying for this service. I've lost track of local machine shops I used to deal with years ago. Not sure what shops are around and who has a good reputation.