NOW SOLVED! Rear axle bush stuck (the hard one)

[jameshoward]

I'm trying to disassemble a 3,46 rear axle so it can be sent off for powder coating and then eventually put onto my car to replace a 4,08. The latest problem is that I cannot get the bush off the pin - it just will not budge. I've attached a photo to show what I mean. Before I resort to cutting it (which could take a while...) I wondered if anyone else had any bright ideas?

Thanks,

James



 

[merrill]

James
not sure if this link will help

It is the exploded diagram of the rear axle parts.

http://www.sls-hh-shop.de/index.php/cat/c3_Mercedes-Benz-230SL-250SL-280SL-Pagoda--R113-W113-.html/XTCsid/f5cf1c3959c4fbe75850d2dc0fb99eba#cat_68

[jameshoward]

Hi Merrill,

Many thanks. I don't know how many times I've looked at that blow-up but clearly I haven't paid any attention to it as, viewing it again, I can clearly see that the slip collar thing is part of the bush!!

So that means that my bush is just stuck fast on the pin, as feared.

Still holding out for a top tip of how to remove the thing before resorting to violence and cutting discs.

JH

[graphic66]

Oxy acetylene torch, get it red hot, it will come off.

[George Des]

I'm having a tough time visualizing exactly what point you've got to here. I can tell you though when I did my rear axle a few months back, I had to drive the pin out of the axle and the pin came out with the rear bush intact. I then used a press to remove it from the pin. To replace with new bushes, I used dry ice on the pin to shrink it.. The bushes will slip right on this way. I left a post elsewhere in the forum on how to do this. You need to be careful when driving the pin in or out. It is very easy to "mushroom" the end making it impossible to remove or replace the bushes. Ask me how I know! Try the dry ice trick. It is amazing how much it will shrink that heavy pin!

Hope this helps

George Desiderio

[jameshoward]

Thanks for the replies.

I didn't think that oxy acetylene would work because I'd effectively be heating the collar of a metal that surrounds the rubber bush and so would act as an excellent insulator. It's the inner collar that is preventing the thing from moving. Perhaps if I cut off the outer collar, remove the rubber and then heat the inner collar it may come off? I only have a burner, not a torch.

George, Naj has mentioned using a drift of some sort to knock the pin out and I'll give it a go. I think that the problem is that the axle is in such a state that the corrosion is pretty advanced. That goes for the pin, too.

But I'm going to have another go at the weekend.

James

[DavidBrough]

Hi James,

Please be careful when you hit the pin because, as George says, it's very easy to damage. At first I left the bolt in but then damaged the threads so took the bolt out and then damaged the end. Thankfully I was able to have the threads re tapped and the end turned so it was OK but only just, try using a piece of hardwood. The best approach is to cut the bushing with a hacksaw or dremel to expose a bit of the pin then let it soak in penetrating oil as it's just a push fit. If you can cut it enough then that may well release it to come straight off.

Best of luck

[George Des]

Taking another look at this, I'm thinking now that the dremel tool with an abrasive wheel--the fiberglass reinforced one-may be the way to best approach to this. Just be careful. You may be able to split the bushing with a chisel after to you cut through it a way. The rubber bushing piece is not that expensive to replace and you may want to that do anyway as part of a full rebuild.  I replaced this part, the pin and both bushings as part of my rebuild and it wasn't outrageously expensive to do so. I do suggest the dry ice technique on the re-assembly. There is a way to put this all together in a sequence that allows the parts to literally slip in together with a minimium amount of driving on the pin and you'll need to fashion a "dummy" pin to hold all the shims and rubber rings properly while you insert the actual pin. I'll need to get back to you on exactly what that sequence is--Ifound it by trial and error and only after I ruined two pins by mushrooming the ends.

George Desiderio

[tel76]

Hello James,
Why not try removing the pin from the other end,IE remove the circlip and washer from the rear of the pin,remove the clevis pin and using hard wood brush handle(ground to the correct diameter) drive the pin forwards.once you have got the pin and bush out you can press of the rubber assy:
I have just been through this operation and i used the pin from my old axle as a mandrel to keep everything lined up as you remove/refit the assy:
PS to carry out the above you will have to remove the front pinion/oil seal cover, but i think you already have this removed.

[mbzse]

In addition to the tips already given, I'd like to add one more "general" suggestion here:
(Not just for you James, as you are past this point in your disassembly)

After the conical locking pin is carefully knocked out (removed),
you can ease the removal of the sleeve of the upright support off the rubber axle bush.

Do this by removing the two M8 bolts that clamp the sleeve around this rear axle bushing.
Insert two metal sheets (two fairly thick washers will do the trick) and then insert the M8 bolts
in the threaded part of the sleeve ("backwards" in their holes, if you will). By tightening the bolts,
you will now force open the gap in the sleeve, helping the release of the old axle bushing.
/Hans in Sweden

.

[ja17]

I agree with graphic66, I would try the heat approach. Most likely you would just need to warm it up. I would not get it  red hot so the temper of the metal is not altered. The outer sleeve will warm up first and allow its removal.

[al_lieffring]

Could this rubber bushing cause drive line chatter when the clutch is being engaged from a stop? I have always had clutch chatter, even after putting in a new clutch plate and throw out.

[Naj ✝︎]

Hi, Al,

I hope the bush is not just slightly worn as in the picture  :'(

[ja17]

Hello Al,

Interesting..............................I  have not experienced this to bea cause, but I agree with your concern that it could be.

[jameshoward]

Thanks everyone, for the tips. I'm going to have another go at this hopefully at the weekend. I'll try heat, and dremels, and drifts and brute force backed up with plenty of ignorance.

I have no idea where to get dry ice in the UK, though. Knowing our government it's probably banned because of some random terrorist links or something. I remember seeing it all over the place when I lived in the US. Never seen it here.

James

[George Des]

You should be able to find it--dry ice- at an ice cream wholesaler or any food distributor that mails out seafood. Here in the states you can get it at supermarkets like Harris Teeter where it is sold primarily for making carbonated drinks. Also might want to ask around at some engine repair shops since it is coomonly used to replace valve guides when doing a head reconditioning.

George Desiderio

[jameshoward]

In the unlikely event that anyone is on line right now and has any bright ideas, I can't get the damn conical locking/ tampered pin out that holds in the pin. Because of the angle and the fact that the other axle half is still attached, I'm having to hit a bar with a hammer using it as a level to knock the pin out. But it WILL NOT move.

Not sure what I'm missing, but I can't see how a paint brush handle would work. I've just broken an expensive half inch thick screw driver.

 

[280SE Guy]

Are you talking about number 267 in the attached diagram? Did you remove number 275 nut and 271 lock washer?

You might be better off in the long run if you order a new shaft, number 245 from your local MB dealer they are not that expensive.

[jameshoward]

Yes, that's the culprit. Got the bugger off now. I had left the dampener on to protect the oil seal lip where the boot goes from any unintentional knocks. Once I'd removed the whole assembly I was able to get a decent hit on the nut and bolt and it eventually came out after a bit of soaking. It was pretty well stuck in there though.

I now have the axle in two parts, almost ready for shot blasting and coating.

[mbzse]

Are you talking about number 267 in the attached diagram? Did you remove number 275 nut and 271 lock washer?

Another rear axle tip: If this conical pin is really stuck, one can relieve some of the restraining force on it by marking the end
with a chisel tip and then drill a hole of say 6mm dia into the end of the pin... this will weaken pin and allow it to be
knocked out more easily...

For those of you like "280SE guy" that in addition to a W113 Pagoda have a 280SE (W108 or even W109) equipped with a Boge
damper on the rear axle: be careful with it. If you remove it w/o a special tool that restrains its
movement (see in BBB section 32-7) it is likely to leak and become useless when re-mounted...

However, one good thing, the factory  (now ZF- Boge) actually refurbishes these devices!
Web is: http://www.zf.com
You can send a mail requesting info (in English if you wish) to Herr Dieter Narres; mailto: dieter.narres@zf.com
and they will send all info about shipping and costs etc.

/Hans in Sweden

.

[jameshoward]

Thanks, Hans. I'm not going to reuse the damper, as I want to use the spring, although I suppose I haven't really thought about why. I just assume that since the car was designed with a spring, a spring is probably all that's called for. I would imagine that the cost or refurbishing a damper is eye-wateringly expensive. A new spring is about 50 euros. I think I may need a new one.

I've decided on trusted advice to take the pumpkin apart and string the whole thing down to learn more about the condition and make it easier to powder coat. I'll tackle the bell housing tomorrow.

I have to say that's it's been a real experience to date. Still can't get the bush off, though. I'll take it to an engineering shop with a press.

JH

[mbzse]

I'm not going to reuse the damper .../... although I suppose I haven't really thought about why - I just assume that since the car was designed with a spring, a spring is probably all that's called for

This is interesting really. No (technical) reason why one can't fit a Boge damper to one's W113 Pagoda... Should prove interesting... But I never heard of
it as a factory option. There was a kit available in order to retro-fit a Boge damper to one's Fintail sedan in the sixties, from Mercedes.
The W111 coupees and cabriolets had them factory installed. This was also true for the sedan W108/109's, when those cars came off the production
line beginning middle of 1965.

I would imagine that the cost or refurbishing a [Boge] damper is eye-wateringly expensive

Well, all is relative... I did one for my 250SE a couple of years back, at ZF, it was less than 400 Euros freight included...
You need to enquire what they charge at present
I do really feel the difference (improvement) of having a Boge installed, compared to the spring I had as a stop-gap.

 

can't get the bush off, though. I'll take it to an engineering shop with a press

That sounds like a sensible approach James - the forces involved when parts are stuck are considerable, so...  please let us hear of your
continuing work with the rear axle!
/Hans in Sweden

.

[tel76]

Using a piece of hard wood was for removing pin #245 not cotter pin #267
Cotter pin#267 was removed by removing the retaining nut,remove the spring washer and refit the nut, screwing the nut on until the nut is flush with the end of the cotter pin threads(this stops damage to the cotter pin threads).
Use a length of flat metal, place on the cotter pin nut and hammer about two inches below,well out of way of the axle tube.

[jameshoward]

Ah. That would make sense. Tried the flat metal way - ie using a lever + heat (lots) and that didn't work either.

The easiest way to remove the cotter pin - after several hours of trying yesterday - is to remove the compensating spring or damper (if using a donor axle like me) which then gives enough movement between the two halves of the axle to flex it the other way to the position in which it would normally sit were it on the car. With the halves in that position, one is able to use a drift to simply knock out the pin (with the nut on to prevent mushrooming the threads). One should probably remove the boot first and check continually that the angle in which the halves are placed is not too extreme otherwise one risks breaking the lip on which the boot sits = game over.

[ja17]

Hello,

I try to avoid blasting any mechanical assemblies.  That grit just never seems to completely go away and will end up in the mechanism.