View Full Version : Check out the 60's flywheel

03-22-2011, 08:52 PM
I should have taken a picture before getting it machined...

but I didn't. It honestly didn't look TOO bad... but in two spots the metal looked "smeared"

Anyways, when i picked it up from NAPA after machining I noticed two heat affected zones... is this something to worry about? I don't have a whole lot of experience with flywheels, but I know that the metal properties in rotors can change if they get too hot in spots... even after machining I have noticed that sometimes they are prone to pulsing or juttering because the metal is different in the heat affected spots. I am slightly worried that my clutch might do the same....

Top view is the whole flywheel, and the subsequent shots are the heat affected zones. the two spots are directly opposite one another. I am also confused as to why it got so hot just in the two spots opposite one another.

03-22-2011, 09:06 PM
From the pix it looks more like corrosion than heat discoloration - but the pix are a bit blurry. I would expect the outer portion (friction surface) to be the hottest part of the disc rather than where its bolted to the crank.

03-22-2011, 09:08 PM
I don't know much about flywheels but I know a bit about steel. It would take some pretty high temperatures to mess with the heat treat. Especially on something that large. At least 300+ degrees.

03-22-2011, 09:16 PM
it is heat discoloration, i'll try and go snap another picture...

also, the friction disk goes all the way to the middle of the flywheel where it has that edge.

03-22-2011, 09:28 PM
A few more pictures.. hopefully a bit clearer.

The friction disk was pretty chewed up in the center. The Pressure plate is a centerforce one, the weights ran off center long enough to wear grooves in the fingers. I am HOPING that that is the source of some of my vibes.

I got a OEM style clutch to replace it with.

none of it looks as bad as some of the really bad clutches i've seen from JDM motors (honda) we've bought used and put in cars. Usually they have 3 puck clutches that are missing huge chunks of friction material. I'd say this one looked OK. not good, but OK. It's just where it got hot that baffles me. I think about twice in it's 60k mile life i got it hot enough it just sat there an slipped. I had to wait to let it cool before it'd grab. Other than that it worked well up untill last week when I pulled it. BTW, thanks Matt fo rthe help pulling the tranny, and thanks Bruce L. for the jack.

Air Randy
03-23-2011, 05:51 PM
As long as the fly wheel machined out nice, and there was not enough heat stress on it to cause cracks, I wouldn't hesitate to run it. It doesn't really take that much heat to cause a little discoloration.

03-24-2011, 11:42 AM
Probably happened when I let Sam drive your truck. ;)

Are the heat spots symmetrical in any way? Like at opposite ends of the circle?

03-24-2011, 11:56 AM
yeah, they are opposite each other.

I am gonna run it, i'm not too worried, just thought i'd post up. I have the new clutch ready and have the tranny most of the way apart

03-28-2011, 12:07 PM
I've used flywheels that look like that with no issues at all. As long as it is really, really flat when they're done turning it, that's the important thing.

This is a chebbie clutch and flywheel, right?

03-28-2011, 12:52 PM
This is a chebbie clutch and flywheel, right?