Differential problem, best approach?

[cascadia]

I lost my differential yesterday ('65 230SL 4 spd), the drive shaft is turning but the car has no movement.  What's the best approach here?  I do have a lift but limited knowledge in this area.
Bob in Portland

[waqas]

I had the same issue a few years ago. In my case the splined universal had sheared off. I had a long-running thread on the diagnosis and replacement of the differential entitled "Replacing my 230sl differential..."  located here:

http://sl113.org/forums/index.php?topic=1642

There is a post by Joe Alexander (I think 4th reply) showing the exploded parts diagram with the part in question.

[cascadia]

Great info, thanks.  One question, though, if the splined universal has indeed sheared off on mine, is it worth a try to just replace that part of the driveshaft?

[waqas]

It would not be as cost-effective as replacing the entire rear axle... which you can probably do yourself. Opening up the differential and replacing the universal (which are prohibitively expensive as a stand-alone part) is quite an involved job.

You can swap out the entire rear axle and then open up your old unit at your leisure, at which point you can always decide what to do with it. Make sure you keep your hand-brake assemblies (cable and aluminium housing units) as they are expensive to replace.

On the other hand, after all these years, my old axle is still awaiting my leisure time lying in the back of the garage...  

[cascadia]

Thanks Waqas, your first hand knowledge saves me a lot of guesswork!

[waqas]

Bob, you're most welcome.  I look forward to future installments of your "Barn Find" thread.

quote:Originally posted by cascadia

Thanks Waqas, your first hand knowledge saves me a lot of guesswork!

[benz87]

Theres a rear axlr on EBay Though I hope in your case it's not that serious, I had a similar problem a few months ago and it turned out only to be a broken universal joint inside the rear axle pivot. Good luck!

[cascadia]

Did they have to tear into the differential to get to it though?

[ja17]

Hello Bob,

Sometimes the attachment bolt for the splinned universal just comes loose. Other times as mentioned, the spline simply shears off. You can go in through the right axle tube to check for the loose bolt. Rmove the axle and take a look in with a flashlight. If if is still in place and tight, a diff. removal is in your future. Plenty of good used units around since many owners are swithching do different ratios these days. If you decide just to replace the universal let me know I have some good used ones laying around here.

[waqas]

In case you choose to inspect the splined universal as Joe suggests, here is Joe's excellent "Rear Wheel Bearing Tour" where axle removal (from each tube) is covered:

http://sl113.org/forums/index.php?topic=4487,tour

FYI-- Removal of the entire rear axle does not entail removing the individual axles. You simply remove the springs, disconnect the shocks and brakes, and then lower the entire differential/axle assembly. There is a specific procedure for this that has proven reliable for most people (see one of Joe's posts in my "Replacing..." thread linked below).

[cascadia]

Thanks for the advice everyone.  
Joe, if, after removing the right side axle, I see the UJ's attachment bolt is indeed loose, is it just a matter of then removing the axle tube to get at it?  Also, this is a limited slip rear, I forgot to mention that earlier, not sure how much of a difference that may make.

One other little detail I've noticed is that previous to the rear end failure, the car was sitting high in the rear with quite a bit of positive camber, which I thought was due to the weight difference from me having removed the soft top assembly and spare tire from the car.  Now the car is sitting level with zero camber.  Related?

[waqas]

quote:Originally posted by cascadia

Also, this is a limited slip rear, I forgot to mention that earlier, not sure how much of a difference that may make.

Wow, you got a great deal on that car! I would try to repair it, as these axles are very hard to come by.

quote:

One other little detail I've noticed is that previous to the rear end failure, the car was sitting high in the rear with quite a bit of positive camber, which I thought was due to the weight difference from me having removed the soft top assembly and spare tire from the car.  Now the car is sitting level with zero camber.  Related?

Not likely, unless you really did "lose the differential."  When these cars are raised and lowered from the rear axles, they tend to have very positive camber until the car is moved (allowing the rear suspension to fully settle).  Different levels of petrol in the tank?

[cascadia]

quote:
Not likely, unless you really did "lose the differential." When these cars are raised and lowered from the rear axles, they tend to have very positive camber until the car is moved (allowing the rear suspension to fully settle). Different levels of petrol in the tank?

Yes, normally these cars settle down into normal camber range within 500 feet of driving after being on a lift.  I thought it was strange that it still displayed this positive camber after several miles.

 

quote:Wow, you got a great deal on that car! I would try to repair it, as these axles are very hard to come by.

 I was surprised to discover the limited slip rear, it doesn't show up on the datacard, apparently this car's rear axle has been out before!

[ja17]

Hello Bob,

If the bolt is found to be loose, recover it with a magnet and clean it up, I believe it may have a lock washer also, but I always add some locktite before re-installing it. It can be re-installed with the axle together in the car just by using a long 1/2" extensions and a torque wrench. Get the right side axle housing as level as possible first. Some cars had a 17mm hex bolt and others used a 8mm head allen bolt.

[cascadia]

Well it's worth a try, I'll give it a shot.  I'll use the 'rear wheel bearing tour' as a guide, that's going to be a lot of help.   I'm about to head out of town so I won't be able to jump into it until the beginning of July.  I'll update the post once I have some new info.
Thanks!

[cascadia]

Ok, one more question here.  I had a chance to get the car up on the lift today and have some observations I want to run by the group.

With the car in the air, out of gear, turning the wheels will turn the driveshaft as well, and the wheels turn in the same direction.  Limited slip, right?
With the car in the air, in gear, turning the wheels will not turn the driveshaft as well, and the wheels turn in opposite directions.

With the car still in the air I started the motor, engaged first gear and observed the driveshaft turning the wheels.   Dropped the car to the ground and tried it again, now just the spinning driveshaft, no wheel movement.

Probably "rear axle 101" to most, but a mystery to me!  What does this suggest?

[ja17]

Hello,

Loose bolt may be allowing splinned shaft to slide in and out depending on the orientation of the axle halves?  You may get lucky and just have a loose bolt. Proceed with the plan.

[Benz Dr.]

How do you know it's a limited slip rear axel? There's nothing different as far as outward appearance to tell you that it is. The only clue is the two wheel marks you get if stuck in the mud or loose gravel if you spin the wheels. There is a small tag on the dif housing that says to use special oil printed in German. I have one of these units so I know they look just like a regular axel.
The forward bite coming out of a corner is something you have to exprience to apreaciate just how much difference they they really make. I've only seen 2 or 3 in the last 20 years.

[ja17]

Hello Dan,

Frank Cozza has one in his W113 also.

[cascadia]

I'm assuming it is based on the behavior of both wheels turning in the same direction when it's on the lift.  Of the 15 or so I've sold, I've only had one other with the lsd rear, and it exhibited the same wheel rotation characteristics while on a lift.  All the other ones had wheels that turned in opposing directions.

[jeffc280sl]

I hope some pics will help explain.

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Download Attachment: univspline.JPG
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Download Attachment: univallen.JPG
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[cascadia]

I found a little time to work on the car today to try to get that axle shaft out and have a look inside.  I have the brakes torn off and the backing plate loose.  The car is on a lift with the right side of the axle jacked up independently to make it more level.   I built my angle iron "puller" per the photos in Joe's rear wheel bearing tour.  I'm using a 3lb sledge hammer but the axle doesn't want to come out.  My question is how hard and how long am I supposed to be banging on this?  I'm at about a dozen blows from both sides and thought I'd stop and post the question to the group before I mess up anything.  

[DavidBrough]

Hi Bob,

The axle shafts are not usually that tight and should come out with a little positive persuasion. I must admit that I have always used a slide hammer and no more that half a dozen blows have been necessary, in fact the bearing usually starts to move after two or three good hits. Joe’s tool should be fine for the job but you may need to use two hammers to try and hit both sides at the same time. If that doesn’t work you may need to buy or borrow a slide hammer. When removing the right hand shaft don’t try to pull it out in one go, once loose just pull it gently until it hits the internal circlip then give it a good pull and it will come out.

Good luck



David Brough
1969 280SL Auto with A/C & 3.46 Axle

[cascadia]

Well, I gave it a few more tries today, it's not budging.  Then I started thinking maybe I didn't get the axle assembly level enough when I lifted the car and could that have anything to do with it?  I put the brakes and wheel back on the car, lowered it down and rolled it a bit to get the car to sit level again.  

The rear end wasn't settling down to level, it had the same excessive positive camber as before the failure.  On a hunch I started the car, put it in gear, and sure enough, now it moves.

So whatever is causing this positive camber is allowing for the car to move, and as I experienced before, when the rear did go level, no axle engagement.

Per Joe's previous post, it sounds like I still need to get in that right side axle tube to look for the loose U-joint bolt that could be causing this, but is it possible that this stuck camber condition is what is preventing the axle shaft from releasing?

Bob

[DavidBrough]

Hi Bob,

Under normal circumstances it’s the axle bearing just behind the brake back plate that needs to be released, the splines that fit into the UJ are normally just a hand push fit. However, given that you have a problem in there it is possible that something has damaged the joint between the axle shaft and the UJ. If that is the case I’m not sure how you’re going to release it with anything other than brute force or complete removal of the axle and cutting off the rubber boot to see if you can see anything wrong in there. The obvious seems to be the locating bolt fouling things up. A replacement axle may prove to be the easier approach.



David Brough
1969 280SL Auto with A/C & 3.46 Axle