GM 8.5 ten bolt crush sleeve

[SSDiv6]

Originally Posted by Rory McNeil

I was always under the impression that under load, the pinion is trying to push itself foreward, away from the ring gear. If this is true, the main load is directed to the much larger rear pinion bearing, which is pressed onto the pinion gear against a solid step or stop, which prevents the bearing from moving. If so, I really don`t see how the crush sleeve is under any extra load during launch, as the force is trying to push the pinion gear foreward, not to the rear, which would be putting force on the crush sleeve. I have seen several 9" Fords that had pushed the pinion support right out the front of the case, or broken the pinion support. I have never seen one that the pinion was pushed back inside the case. I have even heard of guys using NO crush sleeve or solid spacer between the pinion bearings. They said that as long as you had enough bearing preload on the pinion bearings, and the pinion nut was loctited or staked, the spacer was redundant. I`ve never tried it myself, but it does kinda make you wonder.

Rory,
You are correct on the physics on what takes places during acceleration.
However, the bearing cone will deform under load due to plasticity and move.

Got to remember the crush sleeve was designed for OEM applications and not for constant high RPM and/or high torque acceleration and deceleration with steep gears.
Also, the weight of the car and pinion angle have an effect too.

Also, most of the crush sleeves you buy, most of them are made overseas and you may question the materials used for their manufacturing.

One heavy stock eliminator that I am familiar with, it enhanced its gear life from once a year to five years just by switching to a solid spacer on a 8.5 GM rear end.

Like shared in an earlier post, I have seen crush sleeves collapse easily and seen others so strong that either cracks the sleeve or damages the pinion threads.