The Stovebolt Site Forums The Shop Area Engine Shop 37 flywheel

I posted a message a few days ago about my transmission that would not shift (grinding). In getting into the mechanics of the truck, I have found that my newly acquired "restored" truck needs most of the transmission gears replaced as well as the case. In addition the clutch facing, pressure and linkages need work. This work will be completed in the next few days. My question concerns the flywheel which from the looks of it was not turned during the "restoration". It is a 1962 engine. My mechanic thinks the flywheel can not be turned down more than 60 thousands without causing problems. Does this sound right? We of course don't know the history of this flywheel or how much material may have been removed over the years. Anyone know how thick this thing was to begin with? Anyone know where there might be a new one? Thanks

In the post I just made, the subject is 37 flywheel but in fact I don't know that. The engine is a 62. Would they have likely used the 62 flywheel? How do you tell the year of the flywheel? Thanks.

The best way to tell the age of a flywheel is to cut it in half and count the rings.

Just kidding.. I have no idea how you'd tell the age of a flywheel unless there were a part number on it.. but my guess would be that the flywheel is probably the same year as either the tranny or the engine.

When it comes to flywheel thickness, i'd say it's probably pretty important since the amount of "grab" you have is based on how tight the pressure plate pushes the clutch plate against the flywheel.

If the flywheel were significantly "thinned" then it seems like the pressure plate would have to press further in order to provide the same amount of "grab".

Now this is all just a guess based on my limited experience working with a clutch and flywheel in my '46.. and I know that plenty of folks have their flywheels ground down a bit when they have lots of rust on them, or when they let the clutch plate wear down to the rivits and it starts to groove the pressure plate and flywheel.

I'm sure there is a minimum amount of thickness the flywheel needs to be in order to work.. that thickness would depend largely not on the engine year, but on the kind of tranny you have behind it, i'd guess.

Thanks for the reply. I think the number of teeth are different between early and late chevy 6s. Just trying to determine if I had the 37 or 62 flywheel.

Ken, you are right. The early flywheel has less teeth than the later flywheel.

If you could count the teeth, that would tell you which flywheel you have. The other way is to determine if your starter is a 6 volt or a 12 volt. The 6 volt starter would indicate the older flywheel and the 12 volt starter would indicate the newer flywheel. However, you could have a 6 volt starter operating on 12 volts.

If you can count the teeth, the early flywheel has 139 teeth and the later flywheel has 168 teeth.

1937-38-39 Chevrolet flywheels only had 4 bolts attaching them to the crankshaft. GMC shared this 4-bolt flywheel from 1939-53. A 1937 flywheel won't fit anything beyond 1939. 1942-1962 flywheels were all held on with 6 bolts

You can take a lot of metal off of an old flywheel before it's ready for scrap. People "lighten" flywheels all of the time. I would turn it until it comes clean, unless it's cracked, and then run it,
Scott

The only thing to worry about in turning a flywheel to much, is the disc damping springs will hit the flywheel bolts if turned to much.

Thanks everyone. Flywheel now out of truck and at the machine shop for turning. Will let you know how it turns out.