A few years ago when I had a shop called "The Rear End Shop"upgrade my differential with new parts he explained why a solid pinion spacer was not necessary with my build. Since then I have looked for that information and finialy found it.These articles do not deal with Thirdgens specifically but should give us a general idea as to how they work. Opinions welcome
It says =
Sorry, but this is an absolute myth. There Is no way that the crush sleeve can crush further under heavy load. Any Additional heavy load would be absorbed by the bearings, the bearing races, and the bearing retainer. The crush sleeve is not involved. The pinion is held rigidly in place by two tapered bearings, all the crush sleeve is doing ensuring the right amount of preload between the two tapered bearings. You can even leave the crush sleeve out completely as long as you have the right amount of preload between the two bearings.

True statement, I used to preach the crush tube deal, but it just isn't possible
To compress the crush tube, you'd have to push the pinion forward AND hold the front bearing from moving.
Theoretically, with some bearing wear, you could move the pinion forward a few thou under heavy shock loads, but there is no resistance on the other side (yoke side) that would compress the crush tube. The pinion would take up whatever slack there was and drive shaft would just slide into the tyranny a bit
I still prefer a spacer for two reasons:
First, I set it up on the bench without a seal and without a lock nut and can feel exactly what its doing, then I slap the seal in and a fresh lock.
Second, if I have to change a yoke or pinion seal, I can do so without pulling the pinion housing to check for bearing preload.
However, even with a spacer, its just a few 3/8 bolts to pull the housing and reset it on the bench, so its not a HUGE benefit, but it does save a little time.

Pros to solid spacer ? =

http://www.weirperformance.com/solidpinionspacerkits.html

Solid Pinion Spacer Kits
Our solid pinion spacer kits are over 3X stronger than the typical o.e.m. crush sleeves. What does all this mean? What these parts do when correctly installed is set the distance between the inner and outer pinion bearings (bearing preload). At the same time, these parts also locate the pinion gear relative to the ring gear within the casing. So, why does the crush sleeve fail? It fails because it is too weak to resist deflection when high pinion loads are applied. This is why we often hear people say, “my ring and pinion finally blew up”. The failure is not instantaneous as it would be if the gears were over-powered. The failure happens over time, due to repeated hard driving. High pinion loads deflect the pinion gear over and over until the o.e.m. crush sleeve becomes “loose” and cannot properly maintain the bearing preload. This also allows the position of the pinion gear within the casing to move causing misalignment of the ring and pinion gears. Over time, this leads to “howling” gears followed by “ground up” gear teeth and eventually destroys the gears.

 

I use a solid sleeve spacer. With shims, it's easy to adjust. It's reusable and nothing special needs to be done for installation. Adjust the right amount of shims for the preload and tighten up the pinion nut.

Under hard acceleration, the ring gear is trying to exit out the back of the diff and the pinion is trying to exit out the front of the diff. With a crush sleeve, it's always possible to produce enough force to crush it slightly more which will result in loose pinion bearings. For the majority of street cars, a crush sleeve is just fine however if you screw up the installation, you'll have to buy another to try again.

 

I really liked what they said above about the crush sleeve/solid spacer being a myth because of my situation. The main reason I started this thread is to finally find out all things considered did I get the proper advice for my application .I spent quite a bit of money for the build including the best parts necessary for the installation. The last thing I would have done is skimp out on something as simple as a solid pinion spacer.I basically took suggestions/advice from "Dan" the owner and his Mechanic (both with over 20 years experience with differentials.)As I look back on it compared to the massive trucks in his bays mine probably looked like small potatoes . He even took a look at the axle tubes because I mentioned welding them and he said the way a torque arm in the Thirdgen works it also was not necessary. I was new here and new to this kind of work so I did what he said including the parts I used( Eaton posi,28 spline axles,ring and pinion ratio, the support cover, etc) . The HP I mentioned (around 350 hp )with the engine swap I am planing when this one quits played a roll in his suggestions including the cars automatic trans. and he mentioned he would give me a 3 year warranty on parts and labor if I don't run slicks at the track ..The car is my DD and really only sees any hard driving off the line once and a while.
With what I know now and the fact I have done mods that were not "absolutely necessary" I most likely would install the solid spacer and weld the tubes. As it is now with the L.P.W. Support Cover I have I could install the axle braces that are offered from L.P.W. and call that done. = http://www.lpwracing.com/Axle_Tube_B...ing_brace.html

 

Think about front wheel bearings:

You tighten the nut by hand, then add a bit of preload, then put a cotter pin in place to hold the nut.

Well, pinion nuts used to be EXACLY like that; except, a cotter pin is nowhere near stout enough to deal with as much spinning force and speed as there is on the pinion, in a car with something better than a Sufferin Six that can go above 60 mph with gears w a higher # than 3.08. (on a front brg, the spindle is sitting still) So some better method of keeping the nut from backing off came to be needed.

That's all the crush sleeve is; something to tighten the nut against. You tighten the nut until you get enough preload on the bearings, just like a front wheel; and the force of crushing the sleeve, helps retain the nut.

Problem is, in most of these rears, you don't get much over 100 ft-lbs on the nut before you reach the desired preload; and it STILL tends to back off.

That's the benefit of a spacers w shims; you can tighten the nut until it screams for mercy. I use about a 4' breaker bar and yoke holding tool; I'd be surprised if there's any less than 200 ft-lbs on he nut that way. Maybe more, maybe ALOT more. I REALLY REALLY REALLY like to tighten them.

HP by itself isn't so much of an issue, it's more just a matter of reliability.

The tubes should always be welded IMO. When the car is accelerating, the wheels are pushing forward, trying to break out of the housing. Granted t's not as bad as in some other types of rear suspension where they're trying to TWIST out besides; (leaf springs) but still. Plus, there's the matter of leaks; those plug welds ALWAYS leak. If you're fixing that, might as well beef up the other at the same time, since you're already 95% of the way there.

 

Thanks for that information. That clears up a lot for me . If I had known how important they could be I may have had them done.. I think I will do the axle tube braces, that should help. I'm not going to tear into my differential until I have to.I don't know how much difference staking the nut and using Red loctite makes but I can see the Loctite on the load bolts for the caps in the support cover, I would think it was also used on the pinion nut.. From what I have read already ( about what feels like a hundred articles and posts on the subject) I'm not concerned. I will listen for any problems and deal with it if it starts to give me any trouble. You try and try and try but there's always something isn't there. I tried to build as strong of a 10 bolt as I could and now I have to worry about a crush sleeve. With my driving habits and how hard I'm going to push the car , I don't think so.
Heres a link to the build = https://www.thirdgen.org/forums/tran...de-photos.html

 

I've used the crush spacer in many hundreds of rear ends that went in cars that had much more power than the average street hot rod and none of them have ever failed. If there is a problem with the crush spacer it will not result in a loose pinion. It will be just the opposite. If the spacer crushes more after the assembly is done then the bearings will get tighter, not loose. The average crush spacer requires about 300 foot pounds of torque on the nut to set the bearing preload, which is MORE than the average solid spacer. The solid spacer than Ratech sells comes with a paper that says to torque the pinion nut to about 125 foot pounds. I usually go to about 200 foot pounds because that is what was used in the old 9 inch Ford rear ends with the Daytona pinion housings. And no matter what the average person says about the solid spacer, you can change the bearing preload with a solid spacer by increasing the torque on the pinion nut. It will not be a big change, but it will change slightly. The only problem that I have ever had with a crush spacer was when I got some cheap ones in some of the installation kits that I was using and the weld seam busted when I crushed them. I had to disassemble a 12 bolt and replace the spacer when this happened and replace it. And as always, when I contacted the manufacturer and told them what happened I got the standard replay "we have never had that problem before and no one else has said anything about it. You are the only one who has had that problem". Makes me want to choke them.

As for the axle tubes, if you don't weld them correctly then you are wasting your time. I've heard of many people who use a MIG welder with steel wire to weld the axle tubes in a rear end. This is totally useless. You can not weld cast iron and mild steel together with a MIG wleder and steel wire. It will look great and you will think that you did a good job, but if it is ever stressed it will break. Steel will not blend with cast iron. It will just stick to the surface and then break off when it is stressed. You must used nickel to weld steel and cast iron together. And welding the axle tubes will not stop the leaks at the plug welds because the plug welds are on the inner side of where you would weld the tubes, so oil is going to get to the plug welds before it gets to the place where you welded the tubes. As for welding the tubes in a 3rd gen, I don't think it's needed because the torque arm is taking most of the torque and not transfering it to the axle tubes. In the 1st and 2nd gen all of the torque is being transfered into the axle tubes and the plug welds will sometimes break and allow the tubes to spin in the center casting. This is rare in street cars and not real comon in drag cars. The 8.5 rear ends were much worse than the 12 bolt rear ends because the quality of the plug welds went way down with the 8.5 rear ends. Most of the time the 3rd gen will break a gear or axle long before the axle tubes see enough torque to cause any problems at all.

 

Thank you

 

If the crush spacer somehow gets additionally crushed after assembly, it will result in the thing that the nut is tightened against, moving out of the way; and the nut being released and more freely able to back off.

My experience with 10-bolts is different... I have NEVER gotten significantly more torque on one if them than a bit more than a head bolt takes before I reached my desired preload (which I will add, I prefer to set mine up to the tight side of specs anyway, which you'd think would require tightening the nut somewhat extra...). The crush sleeve in them just doesn't seem to have very much "crush" to it. Additionally I have come across loosened nuts NUMEROUS times, both in factory-built ones, and in ones that had been worked on in the field.

I agree 100% with the comment about "weld them correctly"... it should go without saying that if you're going to do something, or have it done, "correctly" should be a given.

Part of "correctly" doing that repair, in addition to using the right materials, is making sure the tubes are in the housing in a straight line. Kinda sux to permanently weld your rear into some oddball random caster or camber on one side, without even realizing it. Not hard to fix with some threaded rod, nuts, and some cones like the ones that are used with tire balancing machines.

Both the rear that came out of my 83, and the 91 or 92 ish one I put in (when I got it), had the plug welds already so broken and weakened, that the tubes could be moved in the pumpkin by hand. I also have an old full-size with the 8½" that had the same problem. I don't see a lot of point in "beefing up" a rear when the parts that are supposed to hold everything still, are flopping around out there in the breeze.

 

One of the things I have confidence in would be that the shop I took mine to would have noticed a problem with my tubes so if I spend more money on this rear it will be strictly as a upgrade to prevent damage in the future.That includes the solid spacer. As I see it so far I have two choices. One jump the gun and dump more money to have basically a total rebuild done using the parts I have now in order to have a solid pinion spacer installed along with having the tubes welded.I figure around $300.00 for the solid spacer installation and another $100.00 to weld the tubes.( I have found out it would cost much more because of the procedure involved)

The other is run what I have now and don't sweat it. And if a problem arises fix it, adding the spacer at that time and only welding the tubes if its necessary for the repair.I believe I'm going with option #2 for now.

sofakingdom,
I love the way you put words to paper.You just have a killer way of saying it. "Flopping in the wind" that's good and to the point. A little over kill but I get it. You have to remember that its different for those of you that can do this kind of work in your sleep.If you don't like something ,no problem just tear it down and do it again. Easy . I have to pay someone to do it. I don't mine saving and buying the best to modify the car but I think I have sunk enough money in to it for now . Although I am still looking for a nice set of front seat.

 

Having the tubes welded correcly will be more expnsive than that. The last time I bought nickel wire it was $99 a pound. I TIG weld them, but they can be stick welded with nicke rods. The housng needs to be preheated, so it will require a complete disassembly. The area to be welded will need to be ground to remove the surface layer from the cast iron. The space between the axle tube an casting will probably have some oil in it that will be hard to get out. Heating and flushing seveal times usually gets it clean enough to weld.

Do you drag race this car a lot? If it's a steet car then I just don't see the point of doing this. I've never seen or heard of a 3rd gen having axle tube problems.

 

Thanks Ron...

Frankly, if it's together and working and causing no trouble, I'd leave it alone. Mark whatever other improvements you'd like to make, on your to-do list for "next time".

BGH is right about the welding technique; it's a bit more skilled/specialized than a do-it-at-home kind of thing. It's not cheap, and requres significant prep. But also consider that at the same time, if you're installing LCARBs, having it powder-coated, etc., you already have it most of the way to the correct state, and can combine some of the steps.

For cleaning, if you can get it to somebody that has a big enough oven to do a rear the same way they do blocks these days, that pretty much clears up the leftover fluids and whatnot. Again though, probably not cheep. Not something you want to spend money on doing to anything less than the absolutely ideal core.

 

http://www.nastyz28.com/forum/showth...ing+axle+tubes
Just wanted to add this. Post 37 and 38 are interesting.

 

WOW!!!!


Big Gear Head, thank you!

Chuck