Norwood

[Sieg]

Roy Differential's called today about noon, I saw the caller ID and though oh sh*t something is not good. Wrong, rear end was ready to go. So off to the shop to pick it up I went and stopped by Coyote Steel and picked up some scrap aluminum to fab new lowering blocks with a 5* pinion correction.











All that's left is to connect the brake line and u-joint, bleed the system, mount the wheels and break it in.

[Sieg]

Buttoned it all up today and did some easy breakin laps around the neighborhood and backroads. Everythings sounds and feels good........hit the open road and at 50-52 mph the vibration begins and at 65 it ain't good.

The lowering block/pinion shim I built was 5* to replace the original 4* shim which had a slight driveline vibration at 65* in 5th and 6th. By slight I mean definitely driveable long distance and nowhere near what I'm experiencing now.

So.......I loosened everything up and cut a 2* wafer shim installed opposing the other to get to 3* total wedge.....test drove, no change in the level of vibration.

So......I loosened everything up and reinstalled the original lowering block and 4* wedge.....test drove, no change in the level of vibration.

60 mph in 4th 5th or 6th doesn't seem to have an effect on the level of vibration. It comes in just above 50 and increases.

Is it driveline/pinion angle, a bad set of gears, or ?????

Help!

[Track Junky]

U-joint or driveshaft balance?

[4mul8ion]

Does it vibrate when you're accelerating or decelerating in that speed range? Does it come in and go out when you tip in and out of the throttle? Or is it just there at 50+ regardless of accelerating / deceleration?

[Sieg]

Originally Posted by Track Junky

U-joint or driveshaft balance?

The u-joints and driveshaft have about 3K miles on them. They were fine on Thursday.

Originally Posted by 4mul8ion

Does it vibrate when you're accelerating or decelerating in that speed range? Does it come in and go out when you tip in and out of the throttle? Or is it just there at 50+ regardless of accelerating / deceleration?

When breaking it in I was running 1800 to 2500-3000 rpm easy accel decel and could feel or hear anything.

In and out of throttle doesn't seem to invoke anything.

Rolling up and through 50-52 mph it's there. The frequency feels higher than say a tire/wheel balance issue

[GregWeld]

But you did more than just the rear end -- you also added wheel studs... have you looked at that at all?

[intocarss]

Is the DS seated properly in the yoke?

[GregWeld]

Pinion nose is DOWN right??

[4mul8ion]

Any possibility of the U joint not seating correctly in the axle flange or the pinion flange not seating correctly on the new gearset?

One check to consider is to measure how much runout is on the driveshaft near the rear axle pinion flange, the center and near the front slip yoke end.

[glassman]

I know this is random, and u probably know this, but air pressure in the tires?