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crush sleeve purpose - lock washer for pinion nut or ... ??

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crush sleeve purpose - lock washer for pinion nut or ... ??

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Old 12-28-2016, 12:19 AM
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Default crush sleeve purpose - lock washer for pinion nut or ... ??

I've attached a pic to help illustrate.

for the axle pinion the two tapered roller bearings face each other,
the larger inner bearing is pressed on against the pinion gear head,
the smaller outer pinion bearing can slide down the pinion shaft and would go up against a crush sleeve,
but the races for these two bearing are pressed into the axle housing, which cannot move so ultimately that's what you are tightening everything against to reach a whatever lb-inch preload.

Furthermore, the crush sleeve as you crush it is providing a force in the opposite direction which would push the bearings away from their races.

It is the pinion nut which pushes the pinion yoke down against the smaller outer pinion bearing which then locks this assembly up into the axle housing ultimately against the two races that are pressed in to the housing.

a) Tell me why do we need a crush sleeve between the two bearings?
People say "it sets the preload on the bearings". No it doesn't, the resulting force from it would unload the bearings from their races would it not? The preload is determined by how far you tightening down the pinion nut, and i can do so and get 10-15 lb-inch preload without using a crush sleeve.

b) How is the geometry of the pinion installation with two tapered roller bearings requiring preload any different than a wheel hub on a trailer or the rear wheel hubs on my truck which do not use any kind of crush sleeve?

c) One thing i can think of is it provides a force against the pinion nut which would act as a locking function...
but isn't that the purpose of thread lock on the pinion nut?

d) are there any axles having a ring & pinion of this nature that do not use a crush sleeve or spacer between the two bearings? Was there ever a time rear axles were built without using a crush sleeve between the two pinion bearings? Is it just a GM 10-bolt thing?

e) i have one other thought which i have never read or heard about it as a reason...

edit: this guy says "when I worked at Dana corp. the axle group told me the crush sleeve is more for a production set-up. they have machines that tighten the pinion nut and rotate the pinion at the same time while measuring the rotating force of the bearings,that way they can "sneak-up" on the bearing preload."
http://www.stevesnovasite.com/forums...p/t-78003.html

Ok so if there's a million dollar machine with sensors to do this automated, i'll give it the benefit of the doubt crush sleeve for the win. But in my garage doing a gear install by hand, is the crush sleeve really needed?
Attached Thumbnails crush sleeve purpose - lock washer for pinion nut or ... ??-rongear.png  

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Old 12-28-2016, 06:47 AM
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"it sets the preload on the bearings" is the term 'they' use due to lack of understanding. It should be 'the crushing of the crush sleeve allows the pinion bearings preloads to be set'.
Why need a crush sleeve ? The two races are pressed in the housing and can't rotate,the inner large pinion bearing is pressed onto the pinion and can't rotate rotate,the outer small pinion bearing CAN rotate on the pinion. Because it's dimensioned as a very slight/perfect slip fit,the crush sleeve bears against it and causes it to act as though is pressed onto the pinion. That simulated press fit doesn't last long though,as almost every pinion I've removed,the pinion was highly polished under the small outer bearing meaning the race was spinning on the pinion. To set a 'true' preload,the bearing should be functioning as tapered roller bearings were designed with the rollers spinning between the two races versus the rollers not rotating between the two races and the race spinning on the pinion.
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Old 12-28-2016, 10:41 AM
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Either use the crush collar OR use shims to lock the inner race of the small pinion bearing. Also another reason crush collars are used is as the bearings wear you can easily retighten the pinion nut to adjust the bearing preload. Using shims you will need to disassemble to adjust bearing preload. DON"T put it together without the crush collar, It will work if the use loctite on the pinion nut but the inner race is going to fail.

What I like to do is reuse the old crush collar, I simply put it in a vice and lightly hammer on the bulged area in the center all around. This action expands the collar a bit so it can be reused. NEVER had a failure yet. Its just enough pressure on the inner race to keep it from spinning. I've also seen the factory use Loctite on the inner race but they still use the crush collar. Makes it a real PITA to remove or readjust the bearing preload later on. So I wouldn't do it.

I always use Loctite on the pinion nut, new or used. AND don't forget to seal the yoke to pinion splines with silicone sealant. Good Luck

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Old 12-28-2016, 11:16 AM
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I see the OP posted this at midnight. We shall offer him forgiveness as he was clearly drunk when he developed his irrational hatred for the crush sleeve. Try as you may, they are there for a reason, some listed above by the sober posters in this thread. Please read those responses now that you yourself have sobered up, hopefully.
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Old 12-28-2016, 11:25 AM
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As in post #3,I re-use crush sleeves. Measure it prior to 'rework'. I have a heavy walled plumbing pipe that just slips into the crush sleeve. On the concrete floor,hammer the bulged area until I get the longer dimension that I wanted.
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Old 12-28-2016, 10:17 PM
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not drunk, sick and nothing on tv. I can only take so much mythbusters and they never did an episode on the crush sleeve.

my other thought was, is the pinion no different than a large bolt?
Normally when you tighten a bolt/nut you torque it up to it's yield point to provide maximum clamping force, but which also prevents deformation.

with the pinion you can't have that max clamp force on the pinion bearings,
but with using a crush sleeve that takes 200+ lb/ft of torque to crush, is that force to compress the crush sleeve then causing the pinion shaft to stretch?

my understanding with differential carrier bearing preload [not pinion bearing preload for a moment] you fit shims in which is actually forcing the axle housing outwards thus preloading the axle housing, preventing deformation when power is transmitted through everything.
https://www.ringpinion.com/Technical....aspx?tipid=11

so using this theory of preload to prevent deformation or deflection, is using a crush sleeve also serving the purpose to stretch the pinion shaft?
But i thought under driving forward the pinion head is thrust forward be the ring gear?

I would like to get an answer to d above in first post.

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Old 12-28-2016, 10:39 PM
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Originally Posted by FirstYrLS1Z View Post
the outer small pinion bearing CAN rotate on the pinion. Because it's dimension is a very slight/perfect slip fit,the crush sleeve bears against it and causes it to act as though is pressed onto the pinion [so the inner race doesn't spin on the pinion shaft].

That simulated press fit doesn't last long though,as almost every pinion I've removed,the pinion was highly polished under the small outer bearing meaning the race was spinning on the pinion. To set a 'true' preload the bearing should be functioning as tapered roller bearings were designed with the rollers spinning between the two races versus the rollers not rotating between the two races and the race spinning on the pinion.
I think i get what you are saying and agree, but...

during setup if you were NOT to use a crush sleeve, i find it hard to believe that rotating by hand at just 1 revolution per second with an inch pound torque wrench that those pinion bearings are not acting as they were designed. That the inner race of the smaller pinion bearing at the tail end of the pinion closest to the nut would spin on the pinion shaft with just ~20 lb-inch of preload ?

I can watch the outer bearing on the axle shaft of a boat/utility trailer NOT have it's inner race spin on the axle shaft when i grossly over-tighten that outer nut setting gobs of preload to where you can barely spin the wheel hub by hand, and these bearing slip on and off the axle shaft by hand. So i'm not convinced this would be the purpose of the crush sleeve in the rear axle ring & pinion... maybe a side benefit?

edit: i just checked my pinion removed from oem 10-bolt having ~70k miles. That outer tail bearing does not slide off or on by hand for me it is a very snug fit. In fact i had to hammer the pinion out of the housing because this outer bearing was so snug on the pinion shaft. With it on the bench now, i cannot push this bearing on by hand i have to hammer it. And i also have the broken pinion from my 1999 ss which is now a paperweight, and I know that outer tail bearing as well does not slide on or off that pinion shaft by hand; it's a very snug press fit.

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Old 01-01-2017, 07:33 PM
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so far it seems the only purpose of the crush sleeve is to stretch the pinion shaft.

Under forward drive load the pinion is thrust forward (toward front of car) because of the gears being a spiral bevel and the orientation they're in. So for the gear pattern to change the axle housing would have to deflect allowing the pinion head to move forward. The crush sleeve is forward of the pinion head bearing race so the crush sleeve has no affect under the forward drive load condition.
I am only focusing on the pinion, and disregarding the carrier deflecting rearward (which would also mean axle housing deflection).

But under reverse load or deceleration (engine braking) the pinion would then be pulled rearward and under enough load the pinion shaft would stretch, and then the pinion gear would move closer toward the ring gear center line along with the pressed on head bearing. This is bad because not only does the gear pattern change, the pinion gear itself would wobble because the head bearing would no longer be contacting its race as it has also moved rearward.

The weakest point of the pinion gear would be shaft of it having the smallest diameter, which is where the 7/8-14 inch threads for the pinion nut are then the ~30mm diameter of the shaft where the crush sleeve would slide over.


So the real purpose of the crush sleeve it seems is not for bearing preload but to stretch the pinion shaft enough to prevent any further stretch under certain driving conditions specifically reverse and engine braking/deceleration.

ballpark numbers to illustrate:
http://www.almabolt.com/pages/catalo...oadtensile.htm

7/8-14 grade 8 has minimum tensile strength of 76,000 lbs.
So we can put the pinion shaft under 76k lbs of stretching force before it breaks, however there is going to be some amount of stretch happening.
If we do not account for any of this stretch under driving conditions where the rearward force on the pinion is enough to stretch the pinion shaft, then the pinion gear & bearing moves closer to ring gear center line and the gear pattern has changed - and yes technically preload on the pinion bearings has also changed but really means the pinion will not be secured in the axle housing and the pinion will wobble as it turns chewing up itself and the ring gear. It is not simply bearing preload.

Enter the crush sleeve (and solid pinion spacer if used properly) to put a tension preload on the pinion shaft, and not on the bearings!
If we put X amount of lbs tension on the pinion shaft as preload using a crush sleeve, then it will take greater than X amount of pounds to then cause any further stretch. You can then floor it and put max power through your rear axle in reverse and not fear of chewing up the gears.

Under forward drive I put forth the crush sleeve has no significance
and is why many people report not using it and have no problems.
But If you have a 7.625" 10-bolt in a pickup and heavily load the rear axle in reverse then expect a problem, however the duration in reverse is never very long or at high speed,
or if there is any kind of true engine braking and the ring & pinion is loaded significantly on the reverse/coast side of the gears.

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Old 01-01-2017, 07:51 PM
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Failure Mode - why so many problems on 10-bolt oem axles

when everything working as it should where the crush sleeve is stretching the pinion shaft by some thousands of pounds, there is only 20-30 lb-inch of preload on the pinion bearings which is caused by the pinion nut.

This will only stay that way if the crush sleeve does not compress any more,
and the crush sleeve keeps providing the tensile force stretching the pinion shaft.

I suspect over time and heat the crush sleeve loses its compressive strength,
which means the steel pinion shaft tries to rubber band back to it's original length,
increasing preload on the pinion bearings.

That 200 or more lb-ft of torque it took to collapse the crush sleeve and stretch the pinion shaft now starts to becomes the force being applied on the pinion bearings above the targeted 20-30 lb-inch of preload. The pinion bearing preload goes up, those bearings heat up and wear and cause noise.
But the gear pattern should not change.


There's a smart sleeve replacement for the oem crush sleeve, which advertises it only needs half the torque needed to crush around 150 lb-ft. And same goes for solid pinion spacers - to torque pinion nut to 150 lb-ft while obtaining the 20-30 lb-inch preload on pinion bearings.
How did they come up with that torque value?
How did they determine only half the amount of stretch is required on the pinion shaft?
It would seem the smart sleeve & solid pinion spacer provide half the capability a non-failed oem crush sleeve would !

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Old 01-01-2017, 09:30 PM
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I think you are over thinking this, personally I would put it together like it was designed and forget about it. Most differential failures are lubrication or overloading related. The 10 bolt in the fbody is well designed and if properly setup and lubricated will last a very long time. The biggest pain in azz with these was pinion seal leakage because the pinion races-bearings are water damaged, this causes the pinion to slightly wobble and no matter how many pinion seals you throw at it they will leak until the bearings and races are replaced.
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Old 01-06-2017, 02:27 AM
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To your question d in the first post is GM and some other companies use the crush sleeves for a reason. Yes you can get the proper pre load with out the sleeve and the pre load will change over time and miles because you don't have any thing that keeps the pre load against the bearings all of the time. That is my answer and you can take it or not. It your car and money. Yes they do make a sleeve that you can use instead of the crush sleeve but you have to get the right size or use shims to get your bearings properly set preload. That is why they use it because it's goes down a line to a machine that sets it automatically.
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Old 01-07-2017, 11:37 PM
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Originally Posted by 1 FMF View Post
Failure Mode - why so many problems on 10-bolt oem axles

when everything working as it should where the crush sleeve is stretching the pinion shaft by some thousands of pounds, there is only 20-30 lb-inch of preload on the pinion bearings which is caused by the pinion nut.

This will only stay that way if the crush sleeve does not compress any more,
and the crush sleeve keeps providing the tensile force stretching the pinion shaft.

I suspect over time and heat the crush sleeve loses its compressive strength,
which means the steel pinion shaft tries to rubber band back to it's original length,
increasing preload on the pinion bearings.

That 200 or more lb-ft of torque it took to collapse the crush sleeve and stretch the pinion shaft now starts to becomes the force being applied on the pinion bearings above the targeted 20-30 lb-inch of preload. The pinion bearing preload goes up, those bearings heat up and wear and cause noise.
But the gear pattern should not change.


There's a smart sleeve replacement for the oem crush sleeve, which advertises it only needs half the torque needed to crush around 150 lb-ft. And same goes for solid pinion spacers - to torque pinion nut to 150 lb-ft while obtaining the 20-30 lb-inch preload on pinion bearings.
How did they come up with that torque value?
How did they determine only half the amount of stretch is required on the pinion shaft?
It would seem the smart sleeve & solid pinion spacer provide half the capability a non-failed oem crush sleeve would !
I've repaired many 10 bolt rears, that said the usual failure cause is because of low lubricant because the pinion seal leaks AND lack of proper maintenance.

The majority of pinion seal leaks in 10 bolt is cause by damaged races- bearing. The car-differential sits with a open vent and collects condensate water. Being low in the rear the pinion races and bearings PIT and become slightly damaged. The pinion no longer spins true and the pinion seals weeps oil. If the lubricant is not kept up to level the 1st thing to take SHEEET are the axle bearings and so on.

Above is by far the most trouble in the 10 bolt. The rest is from ABUSE........................

I personally have ran the **** out of many a Camaro and Trans Ams from dam near every year they were made over the past 45 years and ya know its funny I NEVER HAD ONE FAIL except for prior owner LACK OF MAINTENACE!

They were not made for drag racing but fir street use they last a very long time unless you abuse them.

ps If you think you are stretching the pinion shaft with the crush collar you really need to re read the service manual.
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