Install new flywheel and clutch - Should I balance?

[JayB]

Acquired a balanced, rebuilt, bolted flywheel from CA Corvair. Looks great! I have NOS GM clutch plate assembly and NOS GM clutch disc. CA Corvair recommends to balance Clutch plate assembly with flywheel. Is that really necessary since I'm using NOS?

Is such balancing normally done for a regular driver car? Any advice would be great help. Thank you!

[Scott V]

balanceing the parts is a good idea - nos/used or rebuilt.

-Scott V.

[66vairguy]

ALWAYS balance the pressure plate and flywheel as an assembly. The shop will also install a marks on the flywheel and PP so you can orientate them correctly when you take them apart and reassemble.

I have NEVER had a flywheel/PP assembly that was in balance. An no you don't install the clutch disk when balancing the flywheel/PP. Some do check the clutch disk balance separately, but the clutch disk spins separately and any high spots wear in fast. Usually a disk does not have a balance issue.

[bbodie52]

You mentioned an NOS pressure plate and a new bolted flywheel from California Corvairs. I wanted to point out that there are two clutch designs for the Corvair. The "Flat Finger" pressure plate MUST be matched with a flat surface flywheel as shown in the top picture below. This is the design for 1960-1963 Corvairs. In 1964 a "Bent Finger" design was implemented, and this was the design used in 1964-1969.



The Clark's catalog page above also mentions a recommendation for balancing the clutch disc and flywheel as a unit.



As shown above, either combination can be used on any model year Corvair, but the clutch components cannot be mixed. The correct pivot ball stud must also be matched with the bent finger or flat finger design combination. The correct throw out bearing must also be matched with the pressure plate and flywheel combination chosen.

[azdave]

I know that it's a better idea to balance them together but when I ask around town I've yet to find someone who actually did that. I've been doing Corvairs since I was 18 and I have yet to balance them as an assembly before I install.

Just last month I installed a CU bolted-flywheel into my 65 Corsa along with a rebuilt pressure plate from another source and a new clutch from a vendor at Palm Springs. If it's out of balance I sure can't tell and I've put a couple of hundred miles on it already. This is at least the 6th or 7th time I've changed out failing Corvair flywheels without any concern about balancing the two parts.

[JayB]

Thanks for all of the great insights and advice. I have been careful to use absolute NOS GM for the 1960 year, with the flat fingered PP and a flat Flywheel. The other parts are from Clark's and I know they are sticklers for accuracy. Since it is a low mi. original I hope to use NOS unless there is something improved to replace, like that balanced, bolted flywheel instead of the riveted original. Thanks again!!

Next is to take that engine package out

[JayB]

Seems like if it's genuine GM NOS pp assembly it is what would have gone into the original vehicles back then. When I look at it I see evidence of balancing like little flat pieced welded on and shallow holes drilled, like it was balanced in is manufacture.

[bbodie52]

...Next is to take that engine package out...

If you haven't done that before the attached guide booklet may help with the procedure. It is a good supplement to the guidelines contained in the factory Shop Manual...

[66vairguy]

I know that it's a better idea to balance them together but when I ask around town I've yet to find someone who actually did that. I've been doing Corvairs since I was 18 and I have yet to balance them as an assembly before I install.

That's odd since it's very difficult to center a pressure plate and balance it by itself. If the shop can mount the flywheel to a balance fixture then having the pressure plate attached to the flywheel should not be an issue. In fact I was told by my machine shop "We can't balance the pressure plate separately from the flywheel".

I is best to balance the flywheel by itself before adding the pressure plate assembly for the final balance, but not necessary for the average engine build.

[JayB]

Thanks everyone for great advice. I used a California Corvair balanced, bolted flywheel with GM NOS clutch pressure plate assembly and disc and new pilot bushing and release bearing. Since there is no shop in town I took a chance and did not balance flywheel with pp ass'y. The NOS pp ass'y was from factory NOS and looks like some balancing had been done when built with little welded on metal pieces. Anyway, it all went together fine and all the old clutch noises are gone. The balanced flywheel made the engine MUCH smoother and quieter with no vibrations as before.

Thank you for helping make this a successful "DIY" project.