Do I have to machine the flywheel before I install the new clutch, or can I get away with not doing it? My truck is apart and nobody is open to machine it

 

If you can handle the wait, you're better off.

Don't let anyone try to tell you that a lathe cut is fine.

Ask to have it Blanchard ground.

 

I'm going to stick my neck out a bit 'cause I'm not that familiar with Cummins: in general you don't need to machine the flywheel at a clutch change unless you were experiencing clutch chatter before the clutch job. Even then it's rarely caused by the flywheel, especially with the sheer mass of the Cummins piece. It would take a lot to warp one. You can straight-edge it to get a better idea. I wouldn't worry too much about it....

JimmieD

 

Ask yourself, do you want to take it apart again in a short period of time because you didn't surface it? If you don't mind pulling your tranny and the flywheel is flat and doesn't have any cracks or heat marks put it back together, otherwise have it ground.

 

whatever you do not not resurface the flywheel!!!!!!!!!!!!!! if it needs resurfacing you need to replace it. i have done several clutch jobs on 2500 models with people who tow 5th wheels and it will chatter win going in reverse. it also says this in the manual do not resurface flywheel!!!

 

That would depend entirely on the clutch material and manufacturer.

Also, if you experienced chatter after having your flywheel resurfaced there are a number of reasons why.

One possibility is that is was cut instead of ground. Surface finish has a lot to do with break-in and holding power.
More likely is that they did/did not taper the surface. Some manufacturers even actually prefer a convex surface.
Once again, it depends on the application.

In almost every instance, if you install a clutch without resurfacing the flywheel .... the manufacturer will NOT guarantee the clutch.

If you would prefer to replace the flywheel instead of resurfacing, then do so. But you need to realize that the only difference between the new one and the resurfaced one is the quality of the machining. If you have clutch problems, it's time to find a new machine shop.

 

It Was Sent To A Machine Shop With A Flwheel Grinding Machine. By The Time You Machine It To Get It Smooth It Is To Thin To Handle All The Torque. No Other Problems Resurfacing Any Other Flywheels Except On A Cummins. I have read in alldata that flywheel run out shhould not exceed .08MM. measure run out at the outer edge of the flywheel face with a dial indicator. mount the indicatoron on a stud installed on the clutch housing bolts. the flywheel clutch surface is machined to a unique contour and machining will negate this feature. however minor flywheel scoring can be ceaned up by hand with 180 grit. this applies to factory stock unit and an aftermarket clutch or complete set up may be diffrent i can not say. not trying to start an argument just trying to give some advice i wish i had on this situation for issues with the flywheel.

 

Wow. I can't believe that they're warping flywheels. That only happens when you have excessive slippage resulting in excessive heat.

That can only happen if the clutch was abused ( sledpull, burnouts , etc.. )
or the if clutch was slipping under a load. If they're towing heavy and having clutch problems, they need to upgrade the whole assembly.

When a clutch is rated for a particular h.p. rating/torque rating, it's at a specific vehicle/towing weight.
You don't have to exceed the h.p. rating to burn up the clutch. All you need to do is add weight. A trailer is the easiest way to fry one. You may not even know it's slipping.

And for the guys running a turbo that comes on like a freight train .... it's very easy to abuse the clutch and not realize it. The clutch will be fine 99% of the time. But during that transition from mild to wild boost, the clutch can slip. Do that enough times and the clutch will gradually lose holding power.

I hope that you guys have some better luck in the future.