Side shafts

[Jasper]

Hello all. Greetings from Copenhagen. My name is Jasper and I tinker with my fathers '73 Polaris 3.0 CS.

Does anyone know the differences between the 2500/2800 and the 3.0 side shafts? I know they're not interchangeable but would like to know why. I have a bad feeling about work done by a previous owner. The left hand shaft has no hole or broken of bolt for fixing the brake disc. Either side of the hub. And when mounted, the centerline of the disc is offset about 3mm outwards with no room for the caliper.
To overcome this problem an angle grinder has carved a mm or two off the caliper. :O

/Jasper

 

[Honolulu]

Not to worry, the wheel bolts will keep things together.If I understand correctly, the 5mm bolt pinning the disc to the hub is missing...?

But this doesn't explain why the previous owner trimmed the caliper. Are the threaded holes for the caliper "missing"?

A picture or two might clear up the problem, better than words can describe.

 

[Jasper]

This is what happened:

The car made a whining noise from the drivers side rear end.
I dismantled the rear brakes and saw that the left calipers inner piston had seized.
Then picked up the rebuilt set from dads old E3 (with ventilated rear discs, go figure) and tried to fit the left side. But to no avail. It only fits if the disc is slanted. The outer side of the disc hits the inside of the caliper.

-The stuck caliper fits with a sheet of paper thin gap on the outside and 2-3mm on the inside, and someone in the past has shaved the inside of the caliper. The right hand side looks similar.
The bolt holes for the caliper looks and feels fine and the caliper is in line (edit: parallel) with the hub when mounted without a disc.

So now I'm searching for possible explanations. The hub/side shaft was one of them since they look new-ish and only the drum ones are available. Either way I'm gonna have to pull them to see if anything is awry in the shaft assembly.

/Jasper

 

[Jasper]

Well. A lot of other parts have been taken apart and reassembled since last. But now I’m back to the misaligned rear brake discs since the car just arrived at my work. A recap: rear brake calipers won’t fit because the discs sit too far outboards.
Disc (ventilated) dimensions check out. As do rebuilt callipers.
I see two possibilities:

- wrong stub axles. Wallot does not have the 3.0 one. Maybe PO couldn’t be bothered or didn’t notice.
- Wrong or wrongly seated outer bearings.

I’d like to know the differences between 3.0 and 2800/2.5 axles and the dimensions of the outer bearing.

Thank you in advance.

/Jasper

 

[Dick Steinkamp]

Then picked up the rebuilt set from dads old E3 (with ventilated rear discs, go figure)

I could certainly be wrong (it's happened once before ), but I have not heard of stock ventilated rear discs on an E3.

 

[HB Chris]

Europe got the 3.3Li which had ventilated discs and the 3.0Si may be the same but never in the US.

 

[HB Chris]

3.0CS stub axles are shared with the e3, e12 and early e24 but not 2800CS is they have rear drums.

 

[eriknetherlands]

Could there not be a difference in the length of the half shafts? I recall, but I am not sure, that different lengths of these things exist.
(edit: sorry; in second thought - this can't be the issue: if the half shafts are too short, there would be a gap between them and the inside of the trailing arm. If the half shaft would be too lon, it wouldn't fit between the trailing arm an differential.)

 

[eriknetherlands]

Just a few pics that may help you out: here's the rear wheel setup of my 3.0 CSA with disc brakes. in order for the stub axle to be 3 mm to far outboard, I can think of a few reasons.

- wrong stub axle (don't know if there exist any versions with different length)
- Incorrect seating of the 2 bearings
- ommision of the spacer ring between the bearings (about 4 mm!)

Here's a pic to see where the bearings are (left rear wheel, in process of knocking out the old bearings):

Here the picture of the left wheel bearing and spacer set, with Diff side to the left. the thin ring is about 3 mm, and that is the element "C" in the drawing below.

The Stub axle sits against the large bearing: if that large bearing is not set deep enough I the the effect is what you would see: the stub axle would stick out.
Here's a picture with a fresh bearing pulled in: Taking a guess, the bearing is in by about 10 mm from the outside flange.

If element C is forgotten, then the small bearing could be set tto deep, resulting in the outer bearing being to far outward byt the the thickness of ring "C". Could Ring C be missing in your car?
Left is wheel side, big bearing is resting on a flange, it should be a few mm inside, unfortunately no dimension is given about how deep it is set.

One check would be to see if the sealing ring is flush to the wheel side flange of the trailing arm: the sealing ring should be flat with it, if in your car it sticks out by 3mm, then you know something is wrong behind it.

the stub axle also has it's own spacer:
As you indicate that your wheel flange is about 3 mm to the outside, possibly this spacer has been replaced in a wrong position, or with a too thick spacer. I think the dimension of this spacer is in the parts books.

another check to see where the problem lies is the following: the inside of the stub axle is held tight by a big nut; the one in this picture in the tech books: the thread of the sub axle sticks out by ~2 mm. It was exactly thesame in my car on both sides.
If in your car the stub axle sits 3 mm to far outboard, it would show as the end of the thread would be 1 mm below the surface of the nut, instead of 2 mm outside of the nut.

 

[teahead]

3.0CS stub axles are shared with the e3, e12 and early e24 but not 2800CS is they have rear drums.

Oh man, figures that I'd give my E12 to the junkyard and yet ANOTHER part that I need went with it.

Guess I'm on the hunt for some rear axles.

 

[tochi]

3.0CS stub axles are shared with the e3, e12 and early e24 but not 2800CS is they have rear drums.

For clarity - stub axles are separate and distinct from half shafts.

As HB Chris notes, "stub axles" have limited interchangability with the other models he mentioned. However, E9 "half shafts" may not be interchangable with E3, E12 or E24. I vaguely recall comparing E3 and E9 half shafts and found they were different lengths. REALOEM seems to support this notion as there are different part numbers for the two applications and no (apparent) cross reference between the two applications. E3 half shafts (3321105428) versus E9 half shafts (3321105423 -old; 3321105423-new). Obviously there may be exceptions and dubious work-arounds, e.g., use of spacers and mixing of different width CV joints. This is analogous with the fitting of a narrower differential from an E21 into a 2002.

 

[teahead]

Ah right, #13 here:

I gotta look in my stash to see if I have those from a 3.0

33411110355

 

[wkohler]

I have a pair on my workbench from an E24. They’re available if someone needs them. They don’t take studs but use the bolts. The E12 stub axles are a different length because E12s didn’t have vented rear discs. Top photo is the E24 and bottom are the E12. You can see the radius on the back of the E24 stub axle versus the flat back of the e12. Bearing locations are the same (the arms are identical) but the E24 has the hub flange 10mm outboard and consequently a wider rear track. I guess you could convert a coupe to use wheel bolts with these and a pair of front E12 or E24 front hubs.

 

[Jasper]

Hello all. Thank you for all your very useful replies. From the hivemind I gather the following:

- The difference between disc and drum shafts is length. And 10mm (not 3-ish) from the outer bearing to the hub.
- My problem is most likely an assembly problem.

That's what I like to hear. Lots'a ways to assemble incorrectly. If not, those shafts have a date with my lathe. I'll post again once they're taken apart.

/Jasper

 

[Jasper]

Arms removed and disassembled. The ~5mm shims were missing and the bearings were in-between their seats held together by the tube-spacer-thingamabob and the axle and flange. The outer bearing was 2,6mm off its seat. Nice work.

 

[eriknetherlands]

Nice detective work! Any pictures made during the operation?

 

[Jasper]

Not any worth uploading. But the right hand side arm still needs disassembly. I'll get a couple of shots tomorrow.

 

[bavbob]

Too be politically correct, please use "thingamajig" as "thingamabob" can be hurtful.

and..................yes I am kidding.

 

[Jasper]

I think the trained eye can see the rusted seats. Now to invent a magic and effortless rustoleum/por15-removal procedure, so the rusty parts of the trailing arms can be cleaned up.

/Jasper

 

[eriknetherlands]

It is advised in the bmw tech repair manual to not let the half shaft hang like this. The metal "funnel" to which the rubber boot is attached deforms when the axle hangs like this.
I believe there is a max 18 degrees angle they can take, beyond that the funnel deforms, compromising the seal making it more difficult to keep the cv joints' grease inside.