Ax15 clutch chatter

[Colliedog3]

I have a bronco with a 351w, ax15, Dana 20 combo. Also has 4:11 gears, Detroit locker and 33s. It has a brand new center force clutch, new pilot bearing, new throw out bearing, new driveshaft, as well as a freshly resurfaced flywheel. This is the second time I’ve used this clutch and have had chatter both times when starting off in first gear. I went all over the truck re torquing motor mounts, trans mounts and u bolts. I also checked t case and rear end for play and had no noticeable play. Was wondering if anyone had ran into a similar thing and what the solution was. Clutch has 100 miles of easy driving and just started doing this.

 

[JB Fab]

Same exact combo (351w, Centerforce, ax15, Dana 20, 4:11, old school tight AF Detroit locker) except 35s
Same issue... I know, sounds weird.... If I was to post this on Pirates, I would get flamed... one rear tire had lower pressure than the other (decreasing the rolling radius).
Didn't discover it until I replaced the clutch for the second time in a week......
I've been told that's not possible, had to be something else.
Check to see f your tire pressures are different side to side. Don't be me, it sucks (to replace the clutch for no good reason).

 

[DirtDonk]

Also, just for giggles, verify your rear opinion, angle, and condition of the grease joints in your driveshaft. I know you said it was new, but if you didn’t verify that it was fully greased, now would be the time.
Reason I’m saying, check the angle, especially your opinion angle, is because during initial acceleration, you can get a vibration that can transmit itself through the transmission and make you think it’s the flywheel. When it’s actually the driveshaft.
Might not be your thing. But I would check it anyway.

 

[WILDHORSES]

To add to what's already been suggested I like to remove the rear driveshaft altogether and just use front drive to verify the issue. Real clutch chatter will still show up with the rear driveshaft removed.

Jim

 

[Colliedog3]

Sounds good! Thanks yall I will try all of these things tomorrow. Will update with results!

 

[Colliedog3]

Disengaged rear and engaged front and chatter is gone. Tire pressure is close to the same on rear but t case angle and rear end angle are about 8° off. Going to order 6° shims and see if that changes it. If not the problem I’ll investigate on the rear end internals. Thanks for the help yall!

 

[DirtDonk]

Didn’t happen to take a picture before you removed the driveshaft by any chance, did you?
Just curious what it looked like.

Did you mention whether you have a suspension lift or not?

 

[Colliedog3]

I did not take a picture. I do have a 2.5in lift with wild horses springs. No blocks.

 

[ntsqd]

When I had a Detroit that I drove on the street a lot I used one of those self-coiling air hoses with a tire chuck on both ends to equalize the tire pressure. At one point I added a 'T' on one end and put a tank valve in the branch. That way I could inflate both at the same time. I only used it that way when I was just a couple PSI off what I wanted the tire pressure to be because using it to air-up was really slow.......

 

[DirtDonk]

I did not take a picture. I do have a 2.5in lift with wild horses springs. No blocks.

No problem. It was just a curiosity.
But with the lift, it’s a good bet that your angles were off.
Crossing fingers even way out here just hoping that the shims take care of it.