GM 8.5 ten bolt crush sleeve

[Lou Jeffery]

The easiest way to understand the function of a crush sleeve or solid spacer is to compare it to front wheel bearings on a spindle.
Ever notice how little amount of torque it takes on the spindle nut to cause drag? Then we back it off slightly to give running clearance. That said our pinion bearings require NO running clearance they actually require preload that we measure in a torque to turn sequence. So we know that when we torque a nut pushing two tapered bearings together we cannot have much torque or the bearings go metal to metal and will not rotate.
Now we either install a collapsible steel sleeve called a crush sleeve or we install a solid shim spacer between the pinion bearings so we can achieve our torque to turn measurement and be able to have adequate pinion nut torque.
The crush sleeve although commonly misunderstood as being somehow inferior has one limit and that is the amount of torque it takes to yield and collapse. If it yields at 250 ft.lbs. that is the maximum torque able to be applied.
The solid spacer commonly used in Dana axles and now aftermarket applications has no limit because it is not compressible.
Either is suitable with the crush sleeve being Much less time consuming.
No matter what application, amount of load, RPM, pinion angle, brand etc. etc. The crush sleeve or solid spacer cannot be affected in any way until bearing failure.
One last thought " Inadequate preload causing gear deflection consumes more energy than proper preload drag"

[DIV3CR]

Is the 12 bolt solid spacer the same for the 10 bolt-8.5

[Mark Yacavone]

Originally Posted by DIV3CR

Is the 12 bolt solid spacer the same for the 10 bolt-8.5

No.
The 12 bolt goes from inner to outer inside bearing races.
The 8.5 (and the 7.5) seats against a shoulder on the pinion ,and loads the outer race only. The 8.8 Ford has a similar setup.

[MikeMoller]

Thanks for all the input guys.
The rear gears got installed today(thanks Doug Smith), elected to use the Ratech crush sleeve and it worked really well. Minimal effort to get the preload, if anything you need to be carful not to over tighten.

[henrys57wagon]

Originally Posted by Mark Yacavone

No.
The 12 bolt goes from inner to outer inside bearing races.
The 8.5 (and the 7.5) seats against a shoulder on the pinion ,and loads the outer race only. The 8.8 Ford has a similar setup.

Years ago I made solid spacers for 12 bolt's and when I was going to put an 8.5 in my HenryJ I looked at making a solid spacer but have it go from bearing to bearing. Went to a 12 bolt instead.