Slip fit rear axle .....

mrvette

mrvette

Phantom of the Opera
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What is so critical that a C2-3 rear axle which is press fit from GM and is most always rebuilt that a way.....from being redone in the slip fit mode, with cross drilled threaded end and a castle nut and cotter pin used??? just like the front ends of all cars????

for that matter, why is there some stupid high torque on a C4 output ahaft in the rear....I redid some bearings on one once, and stuck some locktight on it, and tapped them home with a 1/2 impact, never failed in the ensuing 5 years I know of, heavy driving too...really heavy....

same with FWD why bother, it's a 1/2 shaft onto a premade hub, not going anywhere at all.....I just tap them home same impact case closed....they NEVER hold a damn thing on the alignment at any time...

which I could MAYBE see the torque on the C3 design as being a requirement....since the 1/2 shaft is the upper strut...maybe...

:bonkers:


As I recall TVette, Jim, does slip fit his rear axle setups.....
 
The press fit is not because it's crucial, it's easier and cheaper to manufacture. Slip fit requires much tighter tolerances.

That's the main argument you see on not doing slip fitting, if the spindle breaks you loose the wheel (which I feel is debatable as the caliper is still in place, sure the rear caliper brackets are not very strong, they crack easily but only when not bolted down tightly by the 4 studs through the bearing carrier)...hell if the spindle or the halfshafts break, even if the wheel stays on you're not going anywhere and you will have a big problem..with wheel or no wheel.

I have slip fitted them, I've also done them press fit. I have a 40 ton press so it's not a big deal but the slip fit sure makes life a lot easier.
 
When you do this at home you have these options:

1) slip fit by machining either the spindle or the bearing. You need a lathe to do this. You will most likely have to pay a shop to do this. You'll likely pay more for slip fitting than for pressing the spindle into the carrier....If you have your own shop with a lathe you probably have a press also...

2) press fit - either pay a shop to do this or buy a $100 press, use it once and sell it on the local Craigslist if you don't want it to take up space in your garage....

I do not really see a technical problem with slip fitting but I also don't see the need for it.

One could say that if slip fitted you can replace the bearings and spindle with the arm installed. Most times if not everytime the wheel bearings need to be replaced it's about time to replace the front trailing arm bushing also so the arms should be removed anyways...

Gene got 150000 miles out of these bearings and they're still good..... if rebuilt correctly these should last somewhere between 150K-200K miles. It's not that you have to rebuild these every 2 years....
 
i really don't think you need a lathe. some sandpaper by hand will work fine on the spindle or a dremel with a sandpaper bit to work the inside of the bearing.

Press fitting is a lot of work. Even Gary as many as he has done gets flustrated between dry fit and greased fit breaking them down mutiple times. Thats a bunch of work.

The spacer being out of parallel is a HUGE issue. If you don't have the equipment to fix it you have to take that to a machinist. This may be a reason for a lot of failures. With 125ft-pounds torque on the nut the bearings are forced up against that spacer with a huge amount of force. Tons of force. If the spacer is not parallel, the bearings will warp. After so many heat cycles the inner race will crack and break apart as it has a twisting force placed on it. I've seen that on mine back when i did the press fit and spacer. Open it up and it looks like the inner race just grenaded.

Anyone who drives more than 100 miles from the house might want to think about a slip fit setup. Nobody knows how to work on these things so you will be screwed if the bearings go on a long trip. Or just carry a spare bearing housing with spindle already setup with you.
 
BBShark said:
Twin_Turbo said:
The press fit is not because it's crucial, it's easier and cheaper to manufacture. Slip fit requires much tighter tolerances.
Click to expand...

Why is a press fit cheaper to manufacture?
Click to expand...

I figured it would be, guess I'm wrong. So it's only press fit for the radial retention? Then I don't get it, why do it at the rear but not on the front.

I remember reading somewhere once that in a bearing setup it was adequate to have a tight slip fit or tap fit on the stationary part and a press fit on the rotating part. Now, the rotating part, hub has pressed in races since it's a 2 pt. bearing that is used on these cars. If it were a one piece system it would have to be set up that way to be able to assemble/disassemble the whole deal.

Is the bearing surface on the rear spindles hardened? That may be a reason why it's a press fit. The front spindle is hardened where the bearings go on right? If the rear one is only hardened on the splines and the end where it runs against the center pin, if the slip fit was too loose it would ruin the spindle.
 
Here's a photo of the spindle flange that I removed from one of the trailing arms I rebuilt - it was the one that was slip fitted. I measured the overall thickness and compared it to the other (undamaged) flange as well as the flange that I received from Mike (69427, thanks) - there's roughly .120" missing from the mating surface to the inner bearing race.

I cannot explain how this is caused by the slip fit but I also don't believe it's a coincidence that this flange came off a slip fitted bearing assembly.

Maybe the castle nut was loose at one time ... dunno....

2149352423039b8.jpg
 
Twin_Turbo said:
I remember reading somewhere once that in a bearing setup it was adequate to have a tight slip fit or tap fit on the stationary part and a press fit on the rotating part. Now, the rotating part, hub has pressed in races since it's a 2 pt. bearing that is used on these cars. If it were a one piece system it would have to be set up that way to be able to assemble/disassemble the whole deal..
Click to expand...

All motion is relative. Einstein said so. If i'm a roller bearing in free space how do i know whether the inner race or outer race is moving.??

Twin_Turbo said:
Is the bearing surface on the rear spindles hardened? That may be a reason why it's a press fit. The front spindle is hardened where the bearings go on right? If the rear one is only hardened on the splines and the end where it runs against the center pin, if the slip fit was too loose it would ruin the spindle.
Click to expand...

That spindle has to be hardened. I guess i need to take mine apart to see if there are any problems and if not to prove that it works. There is still no detectable bearing play when i push in on the top of the tire.
 
I believe the 1963 cars had slip fit rear spindles, maybe the lawyers and the engineers decided if a spindle broke and a wheel somehow got loose it would be bad for business...add in a lack of maintenance and they might have had a recipe for disaster...and just a few law suits...that said mine have always been slip fit.
 
Gene,
just fyi...... after I swap my trailing arms with those that I just rebuilt I'll rebuild the ones that come off my '79.
I'll rebuild them just like the ones that I just did except stock or poly bushings instead of the JohnnyJoints.
They should be done some time spring/summer if you're interested....
 
Most important thing to consider is to take the time to have bearing clearance within tolerance and with all needed spacers and shims in place.

Slip fit or press in the rears can be safe if following the design difference from the fronts due to the straight shaft in rear (needing the spacers and shims to make up the difference) vs the front spindle having a step design.

I would bottom line this repair as one not be left up to 'BUBBA' to do.
 
I guess I need to change my name to "Bubba". I did the rears last winter. Had the T/A's off, took the nuts off turned them around backwards and smacked the end with a big bronze hammer. Spindles came right out. had a guy press the outer bearings off. I got new seals and repacked the bearings. Put the outer bearings in the housing with seals, put the spindle back in and used the same hammer to put them back in the bearings. Same shims too. Inner bearing back in, seated it with a drift, put the yoke and nut back on, torqued and checked the end play. I don't recall what it was, but it must have been real close to or right on what it should be or I would have taken it apart again. :search: No problem so far.

I now have a 20 ton press, so no more paying someone to press stuff on/off. :pprrtt:
 
You lucked out then, I have a 50 ton press because a wimpy 20 ton wouldn't get mine apart. They were never worked on originals with the funny seals on the inside (the 2 pieces of steel w rubber in between and those folded metal "ears") anyway, being a 38K mile car, there was nothing wrong with the bearings but it was a bitch to get apart (had to do something about that rust and swapping to synthetic grease)

I finally broke the 20 ton when doing bearings on my daily driver, couldn't get the oomph I needed so I resorted to a long breaker bar on the handle, it didn't like that a lot LOL
 
turtlevette said:
Twin_Turbo said:
I finally broke the 20 ton when doing bearings on my daily driver, couldn't get the oomph I needed so I resorted to a long breaker bar on the handle, it didn't like that a lot LOL
Click to expand...

I wonder how many people have been mamed trying to get these things apart?
Click to expand...

OH, GOD, I remember decades ago, having a axle with the retainers in the brake drum area....NO C clip, and taking that axle/bearing to the shop to get pressed off....the guy said watch out, and stuck a bunch of heavy steel plates around the thing, and sure enough the outer race exploded, so he went to get the rest off, I forget how....

then I got smart...take a dremel and cut the inner race nearly though much as I can, take a cold steel chisel and hand sledge....break that inner race clean off there, then tap the new bearing on.....amazing how the tension on a inner race will snap that sucker after a dremel slot is cut into the surface and then encouraged with a hammer....

:clobbered::bump:
 
Everything on Ol' Red I've worked on has been that easy. Even the bolts in the T/A's came out. Put a drift on the end of the bolt and tapped them both right out.

When I got the car the odometer had 7600 miles showing- that's on the S-W speedo- the original odometer showed 23k-something when the PO changed it to all S-W gauges. I was there when he did it in 1974. And it hadn't been out in the rain since then.
 
There is a noise that sounds almost like tire or road noise, I'm worried I might have to check the bearings. How tight are these spindles after slip fitting ? I think I'll notice if mine are slip or press fit. If I can hammer them out they are slip fitted ?
 
Hi

I rebuild a rear axle for a friend who sheared the spindle right where the engagement slots end due to miss-shifting of his automatic 78.
So the nut with it's retention torque is gone !

The only thing beside the brake caliper holding the wheel in situe is the press fitted bearings now and they well did.

I rebuild my 68th rears using the original press fit method after this.

The sheared spindle was on a stock 78, so here the weakest link of the drive train was the spindle.

Front spindles do not have this drive torque and I suspect that's why they have the ordinary slip fit .

Rgds. Günther
 
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