2014 RCSB.

I had the new Belltech 988 kit installed for a 3/6 drop. It's the new model spindles & coils up front and a flip kit in back. I left the factory shocks on.

I started to notice a shudder from about 20mph to 35mph; peaking in intensity about 30mph.

It's not severe or shaking, more felt in the seat of the pants. Above 35mph I don't notice anything. I've had it up to 80mph with no drivability issues.

Any ideas on what I need to be looking at?

 

The pinion angle of the rear end must have changed. Find the angle of the output shaft and then measure the pinion. They must match exactly.

 

Thanks for the suggestion. Off to check it now.

One of the selling points of this kit was that the pinion angle would remain true.

 

Couldn't get any lift time today. I'll check later in the week when my shocks come. I'll go ahead and order a shim kit just in case.

 

Sounds like it's only a very small amount. If you're lucky the pinion will be slightly too close to level in which case the simplest method will be to shim the transfer mount. Loosen the collectors on the manifolds before doing that, then retighten after.

 

You need to measure the truck on the ground. Angles will change when the suspension droops on the lift.

 

Don't mean to high jack thread but does the same apply for a 2-piece driveshaft? (james B)

 

4 post lift.

 

Finally able to get on a 4-post lift and measure.

Trans: 4* down
Driveshaft: 4* down
Pinion: 0*

So it looks like I have a problem. The kit came with a trans mount space that's about an inch thick. Wonder if I remove that it will be kosher?

I'll be following up with Belltech & the installer.

 

I removed the trans space and it seemed to help ever so slightly, but the shudder remains.

Put the spacer back in.

I guess I need a 4* shim for the axle, right?