How to check a flywheel?

Joined
Jan 23, 2014
Messages
542
Location
Australia
Hi guys,

I am about to purchase a second hand flywheel (single mass).

Just wondering what I should be looking out for? Is it like brake rotors where there should be a minimum thickness?
 
Joined
Feb 8, 2019
Messages
1,030
Location
WA
the surface, for gouges from running a disc too long. crazing, which is fissures/small cracks. < a machine shop may be able to mill small flaws off.
checking is hard/dark spots & can be milled/sanded off back to decent metal. And teeth, don't want a chipped tooth or shaved down teeth from many years use.
Some flywheels, like VW air cooled also feature the surface the main seal rides on. Another inspection surface.
 
Joined
Oct 9, 2004
Messages
13,085
Location
Cincinnati, OH, USA
A big piece of glass can show warping, otherwise it's pretty much all visual-cracks, deep grooves, burn marks, etc. I pray for the DMF in my F-450 every time I use it!
 
Joined
Jul 3, 2005
Messages
37,746
Location
NY
Visual inspection, mic it up for thickness and compare it to OE thickness. How many times it was cut? IMO I'd probably pass and buy new. Replacing a clutch and flywheel is no longer a fun job for me.
 
Joined
Sep 29, 2009
Messages
3,003
Location
Deep in the heart of Jersey
I'll never forget back in my younger days, I did a clutch job on a van I owned. I just thru a new disc and pressure plate on it and bolted it back to gether. When I started it, the clutch would start to grab a 1/2 inch off the floor, with no adjustment to it. When it heated up, that 1/2 inch went to about 1/4 inch. I took it all back apart, and had the flywheel cut. Night and day difference. I swore to myself I would never go all thru that again if I had to do a clutch on anything. Live and learn.,,,
 
Joined
Aug 12, 2019
Messages
453
Location
Sun and snow
If it has grooves and or small “bluish” colored heat crack you need a new one. Also check for a “ware ring” on the back where the rear main seal is. .
 
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