3v0

hey guys!

i got a free used spec SC75A (at least i think it is) from the guy i bought the ls1 from. but it looks like some machining (circle around the bolt holes) was done to it and it has cracks radially from the bolt holes outwards. i can feel the cracks with my fingernails like on a worn bearing. he never got around to install it, hell ne didn even unwrap it from the box it has been shipped in. only a cardboard box from a scale. what do you think?









thank you in advance!

SPEC-01

iTrader: (2)

Our parts have our part number machined into them (SC75A or SC75S) and have for a number of years. That flywheel appears to be a Fidanza unit. Additionally, it appears that this part has been previously installed. I have not seen a flywheel crack like this but I would not install it with cracks in the crank flange.

NVR_SPDS

iTrader: (39)

Recycle that bitch, its worthless as a flywheel. Its definitly been used, and was surfaced who knows how many times. I wouldnt trust it for a second anywhere near my engine/transmission.

lizeec

iTrader: (57)

Is it junk? Yes! But to the local aluminum can recycler it's worth it's weight in aluminum but that's about it. The flywheel is not a part you want to cheap out on because when it fails it usually will damage alot of other parts with it and some of those might be your body parts.

3v0

thank you all for your input. funny that there is a spec sticker on it since it really looks more like a fidanza one like this right here:



but mine is flat from the crank flange out up to the friction plate. why would anyone machine that flat and rob it of it's stoutness..

The_One

iTrader: (6)

Why take a chance with something that can explode?

Paperweight at best.

raven154

iTrader: (14)

Are you sure its not dried locktight or similar that got slung out? They dont look like cracks to me but then again, its always hard to tell without seeing it first hand. And to the person that said it was surfaced, that really makes no sense. You dont resurface aluminum flywheels.

I would get some carb or brake cleaner and clean it up before I jumped to any conclusions. If you can still see/feel the cracks after that, then I would toss it.

NVR_SPDS

iTrader: (39)

Care to explain why the flywheel has clearly been installed and run, yet has zero signs of heat checks, or anything else on the friction surface?

rickyzZ28

iTrader: (28)

I was thinking the same thing. If you look at it it looks as though the lines in the flywheel go straight out to a little pool of the same stuff an the edge that spun out. Again I can't verify this, but I would try and get it cleaned up to make sure they are cracks.

SPEC-01

iTrader: (2)

That is not a "SPEC" sticker but a SFI certification sticker which typically ready spec1.1. I suppose that the "cracks" could be loctite but as mentioned this is hard to see in pics. When described as cracks by the OP I figured he had a better perspective then we do via pictures.

raven154

iTrader: (14)

You do realize that the friction surface is replaceable? You can't surface one because the fiction plate is recessed into the flywheel. To cut the friction surface you would also cut the aluminum and possibly the heads of all the counter sunk screws that keeps it attached to the flywheel.

To me it looks like it was replaced with a new friction surface and never used.

NVR_SPDS

iTrader: (39)

Yes, I know they are replaceable, and just because they are, doesnt mean someone will. Your probably right, its just that me having worked in a machine shop, it wouldnt take long at all to cut that surface down, without touching the aluminum, or the heads of the bolts.. It wouldnt take a whole lot to clean up the surface.

SPEC-01

iTrader: (2)

By changing the friction surface depth and leaving the mounting surface untouched you will affect geometry. It would be like having a clutch disc that is worn thin as a result of use. This means less clutch life and a greater potential for premature slippage. That is why these flywheels have a replacable friction surface. Just replace the FPK and you will be fine.

guppymech

iTrader: (7)

Clean the area around the bolt holes where the 'cracks' are and then take it to a engine shop or your local small airport where there are mechanics and have them Dye Penetrant inspect it for cracks in those areas. This is a simple inspection that any local FBO (fixed base operation) mechanic will be able to do. Here is a complete kit Grainger sells.
http://www.grainger.com/Grainger/SPO...4&ci_sku=3WU63

guppymech

iTrader: (7)

Those lines that appear to be cracks, if they were indeed cracks would originate in the bore of the bolt holes and would propagate outward from there. The lines just appear to be on the surface and they do not intersect the bolt hole. You can try sanding the crack line with some green scotchbrite or 600 grit sandpaper, if the surface is cracked it will still be visable after you sand the surface. If it is just surface debris you will be able to sand/clean it away very easily.

karpetcm

iTrader: (2)

Its a fidanza flywheel. Definitly would not resurface them since you can buy a surface rebuild kit for around 80 bucks and thats what your suppose to do with those anyway. Clean it up and see what it actually is, wether its a crack or not. If the surface has been used you can replace it and if it doesnt have any cracks its up to you if you wanna take that risk.

3v0

guys, you are great! in the first pix up there i had it cleaned with WD40 and did not even think of the possibility that those "cracks" could actually be some kind of thread locking adhesive. now i gave it a good rub with something more aggressive:





one last thing .. should i be worried about the machined circle around the bolt holes? why is that?

OldCobraGuy

iTrader: (2)

Somebody didn't use the proper flywheel bolts/washers when mounting that thing. It's aluminum...you must use the proper washer arrangement. Just like a head bolt on an aluminum head.

SPEC-01

iTrader: (2)

You will always have marks on the flywheel from the bolts heads. This does not evidence an issue.

OldCobraGuy

iTrader: (2)

Not like that you shouldn't. I'm surprised you would say that in this case.