Which bearing on the front pinion?

[Shawn M]

My D1 has a noticable 'bad bearing' sound coming from the front end when engine braking. I pulled the front prop shaft and the sound went away. Universal joints are fine.

I'm thinking one of the bearings on the pinion gear is bad. Based on deceleration causing the noise, would it be the inside bearing or the easily accessible outside bearing gone bad?

Thanks for any input.

Shawn

 

[marc olivares]

those types of noises can be a bad pinion bearing (typically due to play between the pinion and preload bearings) or to much backlash in the gear set. has the drop out recently had a locker installed? if so, perhaps the backlash wasn't set tight enough. if that is the case, i would start by correcting the backlash (.004"-.006") and go from there. new bearings will require a new diff setup etc...

pinion bearings are on the pinion gear
carrier bearings are on the ends of the carrier (part with the crown or ring gear)

also check transfer case output bearing, could also be the culprit.

 

[Shawn M]

Thanks for the reply Marc.

This is the original front end which has never been pulled since new. (119K miles on it).

I understand the drop out housing needs to be rebuilt if the inside pinion gear is replaced, but I'm wondering if I could get lucky and change only the outside bearing.

As the noise is only on deceleration, I assume (wrongly?) that only one bearing on the pinion gear is failing.

I had not considered the transfer case output bearing as I took the truck to LR and they had a tech drive it with me in the passenger seat to diagnose. He said to change the whole third member, and be done with it.

If I go with the "upgrade stuff as it breaks" line, can I swap my good rear set to the front and rebuild the front with a TT to put in the back? I believe they are swapable, but am not positive.

Thanks again for your suggestions!


Shawn

 

[Shawn M]

Anyone know how to tell if a bad bearing noise is the transfer case output bearing vs the front axle pinion bearings?

 

[Red90]

You should be able to wiggle the pinion flange and tell if it is a pinion bearing. The bearings are meant to have pre-load. If there is any movement, something is bad. It would be hard to change in place as the outer races are pressed in. Also check for movement on the t.case front output shaft and the front driveshaft u-joints.

Yes, you can swap the rear to the front.