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D30 Bearing cap torque specs

Link in sig. "Tech Archives."

You might have trouble afterwards tho - reinstalling a carrier on used gears is more a matter of preload than of actual installation torque. You'll want to use a dial or a pointer-type torque wrench to turn the pinion before you take everything apart, and then check it when you get it back together. Torque to spec, check preload, and tighten incrementally until the bearing preload is back where it should be (I'll just about guarantee that you're going to have to tighten the caps more than you thought...)
 
5-90 said:
(I'll just about guarantee that you're going to have to tighten the caps more than you thought...)
Click to expand...

Tightening the bearing caps is not how you adjust preload. preload is adjusted by how you shim the carrier or the pinion gear, depending on which bearings you are preloading. Always torque the bearing caps to the manufacturer's spec, no more!
 
jeeperjohn said:
Tightening the bearing caps is not how you adjust preload. preload is adjusted by how you shim the carrier or the pinion gear, depending on which bearings you are preloading. Always torque the bearing caps to the manufacturer's spec, no more!
Click to expand...

I'd have to check, then, but that seems more to me like "setting backlash" and getting a mating pattern than anything else.

"Bearing preload" is usually determined by "crush" - which you get by tightening the caps a specified amount. It's like connecting rods and mains - those Babbitt bearings require a certain amount of "crush" to reach their operating size, and if you try to measure them loose, the mesurements won't be accurate. Torquing the bearing caps (for whatever sort,) "crushes" the bearing slightly, reducing operating clearances to a specified level. Since this cannot be measured directly, you measure it indirectly by measuring the force needed to turn the shaft/bearing/whatever.

And, since there is a conflict, I'm fairly sure we're both going to end up checking out our FSMs to see what's going on. Take me a bit tho - I've got some paperwork to get done first...
 
FWIW..I incorrectly stated my rear as a D30..I meant to type D35.I will be attempting to pull the carrier tommorow. I purchased a pinion bearing also just incase that is shot too.
 
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I believe the spec is around 50 ft/lbs. 5-90, I have never used any sort of carrier bearing procedure like you're talking about, it doesn't apply to diffs and sounds like a quick way to snap some bolts. Just go w/ the spec...
 
JJacobs said:
I believe the spec is around 50 ft/lbs. 5-90, I have never used any sort of carrier bearing procedure like you're talking about, it doesn't apply to diffs and sounds like a quick way to snap some bolts. Just go w/ the spec...
Click to expand...

As I'd said - I may have my wires crossed. Hell, I could be thinking pinion preload, and I'll look it all up in a bit to make sure... Just got to finish a couple of other things first.
 
Yep - thought I'd had.

The preload that you'd be measuring is on the pinion bearings, should you disturb the pinion nut, bearings, and/or seals.

Elsewise, they're correct - you don't need to have any adjustments with the carrier bearing caps. However, if you find the need to remove the pinion nut, you'll have work to do.
 
5-90 said:
Yep - thought I'd had.

The preload that you'd be measuring is on the pinion bearings, should you disturb the pinion nut, bearings, and/or seals.

Elsewise, they're correct - you don't need to have any adjustments with the carrier bearing caps. However, if you find the need to remove the pinion nut, you'll have work to do.
Click to expand...

Thanks..I'm hoping once I get the carrier out that the pinion will spin nice and free with no excessive play.
 
5-90 said:
I'd have to check, then, but that seems more to me like "setting backlash" and getting a mating pattern than anything else.

"Bearing preload" is usually determined by "crush" - which you get by tightening the caps a specified amount. It's like connecting rods and mains - those Babbitt bearings require a certain amount of "crush" to reach their operating size, and if you try to measure them loose, the mesurements won't be accurate. Torquing the bearing caps (for whatever sort,) "crushes" the bearing slightly, reducing operating clearances to a specified level. Since this cannot be measured directly, you measure it indirectly by measuring the force needed to turn the shaft/bearing/whatever.

And, since there is a conflict, I'm fairly sure we're both going to end up checking out our FSMs to see what's going on. Take me a bit tho - I've got some paperwork to get done first...
Click to expand...

The preload of the carrier is established by how many shims are installed at the ends of the main bearings. Take a measurement with no shims and that dimension is how much total shim you use as a starting point. If you put more shim in than that measurement it increases bearing preload, if you put less shim in it decreases preload. Torquing the bearing caps more than recommended specs will make the bearing race slightly out of round and will result in premature failure of the bearing. The bearing race is made of highly hardened steel and will not "crush" to any tolerance. Excessive torque will only deform the bearing race. On a pinion it is either achieved by placing shims between the bearing and the shoulder of the pinion or by using a crush sleeve that gets crushed to a certain amount to apply the preload to the bearing. Not trying to make anyone look bad or anything but the setup of ring and pinion is critical to the longevity of the unit.
 
Well..I pulled the carrier today and discovered what I had hoped NOT to see..a pinion gear that is very tight to turn by hand. At that moment I reflected back to the moment of stupidity that led up to this apparent pinion bearing failure. I had recently replaced a broken pinion yoke and apparently over-torqued the pinion nut resulting causing the bearing(s) failure.

This sucks.
 
89XJPIG said:
Well..I pulled the carrier today and discovered what I had hoped NOT to see..a pinion gear that is very tight to turn by hand. At that moment I reflected back to the moment of stupidity that led up to this apparent pinion bearing failure. I had recently replaced a broken pinion yoke and apparently over-torqued the pinion nut causing the bearing(s) failure.

This sucks.
Click to expand...
 
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