Driveshaft movement

[mikebGMC70]

I have a 70 c20 with a manual 4 speed. Having my 2 pieces drive shaft balanced and mentioned to my driveline shop I’m bagging the truck and they mentioned the driveshafts might push in on the transmission or rear end to hard when going up or down with the bags. Any thoughts on this? Thanks

[Overdriven]

When you lower a trailing arm truck the rear axle moves forward pushing the driveshaft forward. The slip yoke going into the transmission has some wiggle room there and the stock carrier bearing is rubber mounted to account for some of this movement when the suspension is compressed at stock ride height. Lowering with airbags obviously moves the driveshaft more than hitting bumps in the road at stock ride height. What is the limit? I don’t know.

For those who want to never worry about this, the fix is a billet carrier bearing and adding a slip yoke (telescoping shaft) to the driveshaft after the carrier bearing. The billet carrier bearing has no rubber mount to degrade and as such doesn’t move. To account for the movement a slip yoke is added between the carrier bearing and rear axle.

[mikebGMC70]

My carrier bearing has a slip yoke style. Would this work with the airbag setup?

[mongocanfly]

You need to get the truck at ride height...then determine what the driveshaft needs....be mindful of changing pinion angles when lowering...trailing arms tend to roll the diff yoke down as the truck drops..

[EVRLET]

This is what a bagged truck 2 piece driveshaft looks like.