Engine/Transmission (1998.5 - 2002) Flywheel minimum thickness?

[Texas Diesel]

Anyone know the minmimum thickness for flywheel for a 2001 HO 6 speed?



Need to know ASAP.



Thanks!

 

[Joseph Donnelly]

Back in 12 valve days, Dodge and Cummins recommended not removing "heavy stock" meaning I guess that a few thousandths is all you should take off. Stock the flywheels are 1. 505-1. 509" thick and I try not to go under 1. 490". The blanchard stone surfacers will take off only a thousandth or two if it is already flat, as it usually is.

 

[Texas Diesel]

Thanks Joe! What do you think of flywheel shims if it is a tad thinner than 1. 490"?



I hate to buy a flywheel if I dont need one.

 

[Joseph Donnelly]

absolutely not. The flywheel won't clamp to the crank tightly enough if you have added torque. I'd sooner use a thin flywheel. As long as the hydraulic clutch linkage releases the clutch well, it is OK.

 

[Texas Diesel]

Thanks again Joe. Thats what I was thinking too, I'll get the final thickness and post here.

 

[GCroyle]

Minimum F/W Thickness

Texas Diesel,



We have measured the 6 speed thickness at 1. 477". The measurement is based on the dimension from the contact surface of the F/W to the crank and then up to the friction surface.

 

[Joseph Donnelly]

I just use a 1-2" mike several places around the outside, about 1/2" in from the perimeter. I based my post above on the wheels I have measured that way.

 

[jelag]

We not only grind flywheels but build grinders for production... . Clutch Rebuilding...



I'm not aware of a standard for truck flywheels other than the following.....



We see a lot of flywheels with over 1/4" removed (15 1/2" clutch) to the point that the springs in the flyweel disc hit the flywheel mounting bolts... where we see the problem is the heat build up from a bad driver slipping the ceramic clutch..... On these truck flywheels and ceramic discs its not uncommon to grind off . 060" when they are worn... .



And I can't see where you'd take off less than . 015" when you grind a flywheel with an organic disc..... Like joe mentioned... . I'd never use a shim... to back space the flyweel as you also now spacing the ring gear / starter drive...



On a diaphram type clutch all you've done is move the cover that much closer to the engine... . which if you have to... you can deal with using a longer push rod for the linkage... .



If there is a published specification... . we've never found one... . Also, we've found that often the same flywheel from year to year of the production might have a different thickness... . we don't have a clue why that is... .



What you MUST do is make sure who ever grinds the flywheel for you (never machine) makes sure that the crankshaft mounting flange is where they register the flywheel to on the table..... this assures a flat and parallel surface.....



I've personally never seen a lathe that would allow you to dial in the back of the flywheel (crank mount surface) to make the clutch mating surface parallel... ...



I know this is not an answer but its the input and information we give to those who we teach how to grind flywheels... .



One last comment..... we teach installers to first put the disc, and cover on the flywheel on a bench, push the alignment tool into the disc... . and make sure that all looks normal before they install the flywheels and clutch to the engine...



Hope this helps..... I can talk about this and the problems related to it for hours... . hope this isn't too long... .

 

[Texas Diesel]

Thanks for all the thoughtful replies.



this is the second time we have resurfaced this flywheel and it measured 1. 508". Not sure how he measured it but that is the number he came up with.



The Con-O is doing nicely so far. I'll let it seat few hundred miles before a WOT run. I dont expect any slippage with only 275's and a VanAaken CPCR box.

 

[GCroyle]

Pass the salt and pepper.

I just checked a 5018 079AC, casting #3968059 on our coordinate measuring machine and the crank to friction dimension is 1. 506" on this sample.



Jim had lots of good points on resurfacing and inspection, deep hot spots can be an issue on these flywheels too.