[aisr]

I was wondering if anyone here has any more good reasons why a solid spacer is better than a crush sleeve. All that comes to my mind is less wear/tear on the pinion nut, and possibly easier installation if one does not have the right tools.

My personal experience- I typically build between 50 and 75 rears a year, mostly Ford 8.8 and 9", and always use a new pinion nut, thread locker, and most of my builds use a crush sleeve. I've never had any problems i can remember caused by either, so i'm just trying to form an opinion. Hard to do without personally having any problems related to crush sleeves.

...What do you think- is a solid spacer being better a myth or is it something that actually adds some measure of performance potential and i just don't see it?

[big gear head]

I've built hundreds of rear ends myself and I've never had a bearing problem caused by a crush spacer. I haven't seen any benefits in using a solid spacer. I had a few Ratech crush spacers split in the seam when crushing them, but that was just a few for the Chevy car 12 bolt. I haven't seen that problem again in years.

[SUX 2BU]

I have no idea if this is relative to a crush sleeve or spacer discussion but since you guys have had a lot of experience building diffs, maybe this makes some kind of sense to you as I have thought my problem was related to crush sleeve movement:

I had a 3.40 ratio truck 12 bolt in my Chevy ½ ton. It was a junkyard replacement for the 2.76 I used to have, but put it in and no noise whatsoever. Worked fine except for the Gov-lok that didn’t work. I took it to a very well known, diff-specialization shop to have a rebuilt Eaton Positrac installed. They had to torch out the old, non-working Gov-lok in order to install the Eaton. That is where I think the problems might have started. They reinstalled the old 3.40 gears again and the new Eaton along with new bearings at their suggestion. Well, 5 days later I started to get gear noise but only after doing WOT runs. My trucks shifts rather hard on the 1-2 change. It has a 325-350 HP 350 and a TH350 with a shift kit. Anyway, doing 5 more WOT 1-2 shifts toasted the rear gears. Lots of growl and ugly noises. Took it back to the shop. They said well sometimes reinstalling R&P can destroy them as the original wear pattern doesn’t match exactly the same when reinstalled. Fair enough. They covered install, I covered parts for new Yukon 3.73 gears. Followed break-in procedure to the T, then at the first WOT run with a 1-2 shift I got a little noise. Another shift, more noise. 3 more WOT 1-2 shifts and I’m back to square one: toasted R&P. I’m mad, they are mad and blame it on my ‘race’ truck. Long story short, they replaced the 3.73 Yukons with the same. Break-in procedure again followed to a T. First WOT 1-2 shift and here comes the noise. I do 2 more of those and I know where things are headed. I phone them back, we are all mad again and they have no explanation for me. I ask if the crush sleeve is moving on the 1-2 shift, causing the bearing preload to be lost, letting the ring touch the pinion. They just maybe. I said maybe it was when you torched out my old Gov-lok that you tweaked my housing. They said maybe, but find us another housing at your cost and we’ll replace everything again. I said do you know for sure if I’ll have the same problem? They said nope. After a BBB complaint I said I want my money back, every dime I spent. They said okay, just give us back the Posi. I said fine, gutted my diff and gave it back.

So, after all that, any idea on what it was? I ended up finding another 3.40 Gov-lok and put it in. The previous housing is sitting in my garage. At least I have a spare set of axles!

[big gear head]

My guess would be that the bearing preload wasn't set correctly when the rear end was assembled. I've built many 12 bolt, 8.2 and 8.5 10 bolts and 8.8 Fords that were abused much more than that with no problems. They all had crush spacers in them. I built a 8.2 10 bolt that went into a '69 Camaro with a 383 and 4 speed that was lifting the front tires with slicks and it didn't give any trouble. It also had a crush spacer in it.

[prostreet6t9]

Originally Posted by SUX 2BU

I have no idea if this is relative to a crush sleeve or spacer discussion but since you guys have had a lot of experience building diffs, maybe this makes some kind of sense to you as I have thought my problem was related to crush sleeve movement:

I had a 3.40 ratio truck 12 bolt in my Chevy ½ ton. It was a junkyard replacement for the 2.76 I used to have, but put it in and no noise whatsoever. Worked fine except for the Gov-lok that didn’t work. I took it to a very well known, diff-specialization shop to have a rebuilt Eaton Positrac installed. They had to torch out the old, non-working Gov-lok in order to install the Eaton. That is where I think the problems might have started. They reinstalled the old 3.40 gears again and the new Eaton along with new bearings at their suggestion. Well, 5 days later I started to get gear noise but only after doing WOT runs. My trucks shifts rather hard on the 1-2 change. It has a 325-350 HP 350 and a TH350 with a shift kit. Anyway, doing 5 more WOT 1-2 shifts toasted the rear gears. Lots of growl and ugly noises. Took it back to the shop. They said well sometimes reinstalling R&P can destroy them as the original wear pattern doesn’t match exactly the same when reinstalled. Fair enough. They covered install, I covered parts for new Yukon 3.73 gears. Followed break-in procedure to the T, then at the first WOT run with a 1-2 shift I got a little noise. Another shift, more noise. 3 more WOT 1-2 shifts and I’m back to square one: toasted R&P. I’m mad, they are mad and blame it on my ‘race’ truck. Long story short, they replaced the 3.73 Yukons with the same. Break-in procedure again followed to a T. First WOT 1-2 shift and here comes the noise. I do 2 more of those and I know where things are headed. I phone them back, we are all mad again and they have no explanation for me. I ask if the crush sleeve is moving on the 1-2 shift, causing the bearing preload to be lost, letting the ring touch the pinion. They just maybe. I said maybe it was when you torched out my old Gov-lok that you tweaked my housing. They said maybe, but find us another housing at your cost and we’ll replace everything again. I said do you know for sure if I’ll have the same problem? They said nope. After a BBB complaint I said I want my money back, every dime I spent. They said okay, just give us back the Posi. I said fine, gutted my diff and gave it back.

So, after all that, any idea on what it was? I ended up finding another 3.40 Gov-lok and put it in. The previous housing is sitting in my garage. At least I have a spare set of axles!

Not sure what the problem is there but I really doubt a hard shift would move the crush sleeve. I would lean towards incorrect pinion preload causing a pinion Brg failure unless the races are loose in the housing.

A lot can be told when disassembling the differential. Where the pinion Brgs burnt up? Are the Pinion Brg races tight in the housing? If either of the races are spinning in the housing the Brgs will fail prematurely even with the correct preload.

[302 Z28]

Long time ago when I attended Ford Motor Co school on rear axles the one thing they continually drove home is do not use an air impact wrench to crush the sleeve and pre-load the pinion bearings. I have seen this done more times than not, even on some highly touted hot rod TV shows. Yes I have seen rear axles go 100K+ that had the sleeve crushed with an impact.

Think about what is happening to those new bearings as that impact is hammering away. I prefer not to take the chance and use a breaker bar with cheater pipe to establish pinion preload.

Vince

[prostreet6t9]

Originally Posted by aisr

I was wondering if anyone here has any more good reasons why a solid spacer is better than a crush sleeve. All that comes to my mind is less wear/tear on the pinion nut, and possibly easier installation if one does not have the right tools.

My personal experience- I typically build between 50 and 75 rears a year, mostly Ford 8.8 and 9", and always use a new pinion nut, thread locker, and most of my builds use a crush sleeve. I've never had any problems i can remember caused by either, so i'm just trying to form an opinion. Hard to do without personally having any problems related to crush sleeves.

...What do you think- is a solid spacer being better a myth or is it something that actually adds some measure of performance potential and i just don't see it?

I have to agree with you on this one. I do large a large volume of differentials in all makes & models using crush sleeves and I've never had a "crush sleeve" related failure.

I do think the solid spacer is a little easier for the little less experienced guy to use.

[lmsport]

I consider solid spacers to be for race-only apps, when minimal preload is desired for frictional loss minimization, and/or when loads are extreme.

[aisr]

Originally Posted by lmsport

I consider solid spacers to be for race-only apps, when minimal preload is desired for frictional loss minimization, and/or when loads are extreme.

In your opinion, how is the solid spacer doing a better job in those cases? I'm just trying to find the reasoning behind your consideration.

[lmsport]

Originally Posted by aisr

In your opinion, how is the solid spacer doing a better job in those cases? I'm just trying to find the reasoning behind your consideration.

In max effort drag, an app that should probably use a ball bearing support if an F9, when the car launches, and the resultant force on the pinion is forcing the pinion back into the driveshaft, the front bearing can unload letting the pinion move off axis causing damage to the gears and bearings, and often breaking the housing at the pinion nose bearing journal. A tapered bearing has to have enough preload such that under max laod the bearings are still forced to run on axis.

The stock car guys all want to minimize friction meaning they run with almost no
preload, on a unit that has been dynoed or pre-run. The preload is set to a minimum,ie zero, and the unit will run that way.

[aisr]

Originally Posted by lmsport

In max effort drag, an app that should probably use a ball bearing support if an F9, when the car launches, and the resultant force on the pinion is forcing the pinion back into the driveshaft, the front bearing can unload letting the pinion move off axis causing damage to the gears and bearings, and often breaking the housing at the pinion nose bearing journal. A tapered bearing has to have enough preload such that under max laod the bearings are still forced to run on axis.

The stock car guys all want to minimize friction meaning they run with almost no
preload, on a unit that has been dynoed or pre-run. The preload is set to a minimum,ie zero, and the unit will run that way.

So what keeps you from achieving the same things with a crush sleeve?

[302 Z28]

AS far as I am aware, there is no advantage performance or race wise to using either. The spacer and shims make setup easier than repeatedly crushing a sleeve to check patten.

Vince

[big gear head]

You don't use a crush spacer or solid spacer when checking the pattern. That is left for the final assembly.