Steering Failure - saved by providence

[Styria]

Hi guys - you just have to be lucky sometimes ! Yesterday morning, as I was about to leave the petrol station, I turned the steering wheel, moved forward about five metres, and then nothing ! No steering response from the front wheels and you could spin the steering wheel itself any which way ! Clearly, there was a problem, either a broken coupling, or broken input shaft or whatever.

I finished up having to get towed to homebase, and this is the first time that 'Gleaming Beauty' has graced the top of a tilt tray. Upon closer examination, and after jacking up the front, it turned out that the coupling had come adrift from the input shaft to the steering box. This was sheer luck on my side - I would hate to think of the consequences if I had been travelling at speed, in traffic and no steering - wow, anything could have happened. Telegraph poles, head ons, mounting the gutters....some very, very nasty options !

So, how could all this happen ? The clamping bolts were reasonably tight - well, tight enough to stop the coupling from moving, yet move it did. Therefore, clearly there was an installation problem when the box and coupling were replaced about eighteen months ago, with the coupling not being fitted properly to the steering box spline.

If you're going to ask me who done the job, I can tell you that it wasn't me. I farmed out the job at the time to a trusty mechanic. Honest ! Regards Styria (still alive).

 

[Michel]

Talk about LUCKY !!!!

Did you go and buy a lottery ticket

My Godfather !!!

Lucky to be alive and the GB in one piece....

 

[s class]

Gee that's nightmare stuff. When I refit those couplings, I make VERY sure they are properly seated both ends - then inspect again with a torch - then poke a feeler wire in to make sure the two shafts extend properly into the coupling.

Failure in that regard is unthinkable.

Have you seen the difference between the W116 couplings and those fitted to many W123's?

The 116 item as we know has two metal ends linked by 'rivets' for want of a better term. The 'rivets' are encased by rubber - which is what eventually fails. But even if this rubber lets go, you still have a mechanincal connection - even if there is play.

The 123 item on the other hand, has the two metal ends not directly linked to eachother by metal components. There is only a mini-rubber flex disk connecting the two ends. As such they are not 'fail-safe' like the 116 couplings. Not nice.

 

[WGB]

Lucky, Lucky, Lucky.

I have replced one myself on my 450 and took great care that it was secure.

This rubber filled knuckle type is a later fitment -and probably is the only type fitted to 6.9's - whereas the earlier 123 type that S class describes was used on earlier 116's.

I will be interested to hear what the poblem was and hope it is only a loose clamp bolt But I would be removing it and checking the state of the splines.

When I changed mine I found it easier to remove the whole steering box as it made access much easier and also allowed me to adjust the free play in the box itself.

Bill

 

[6.9forever]

Very relieved to hear you're in one piece Styria -

(My priority list which you know about has changed overnight: now has steering at No.1) !

 

[BenzBoy]

Clearly the Guardian Angel of The Gleaming Beauty was on call!!!! Or maybe it was a Djin? phew!!!!!! imagine what it would be like here without TGF!!!!
I have to say my camel has suffered no such problems here in the Lost Quarter - but unfortunately I am about to board a flying carpet for somewhere in Germany....... now that will be a challenge!!!
Regards,
BenzBoy

 

[Styria]

S-Class, I had been aware that there are two types of couplings one can purchase-the W123 that you refer to which is quite a bit cheaper, and the original 116 type. I must admit to not really knowing the difference between the two, but have been told that the 123 unit is not particularly durable. So far, I have only ever bought the original 116 type. The one on Gleaming Beauty is the 116 type and only about eighteen months old.

Bill, I am hoping that both you and your wife are enjoying your holiday. The failure that occurred is one of workmanship rather than a components failure. The worrying aspect itself relates to the mechanic - a very experienced and very capable man that knows his Benzes backwards, yet in this instance commits a cardinal sin. I just don't get it. Before I re-positioned the coupling on Gleaming Beauty, I did a trial fit on another Steering Box and coupling on the bench just to make sure I'd know how far, in fact, the coupling fits onto the splined shaft - it is quite some distance, probably 20 mms. That's approximately how far the coupling was short of.

Idiot that I can sometimes be, I did not take the opportunity to centralize the steering box by removal of the bolt. I suspect that if I had removed it to check the central position, I would have had a major oil leakage. I just didn't have the time to attend to matters properly.

BenzBoy-I would have liked a pic of you and Stevie on the flying carpet - smoking away at a peace pipe and turban on heads !

Regards to everyone, inc. 6.9 forever - I am still about and annoying everybody. Styria

 

[TJ 450]

That's a bit of a worry, as it could have been disasterous. I just replaced mine a few weeks back. Was it not seated fully on the spline?

Tim

 

[Styria]

Yes Tim, that was the crux of the problem - nothing more, nothing less. I can guarantee that this time there is no way it is going to be loose again. Regards Styria

 

[Styria]

Well, I am not so sure what is, in fact, going on with this coupling, steering box etc.

Presently, with the heads removed from Gleaming Beauty's engine, one gets a much better look at the manufacturing process employed when putting these cars together. First of all, it involves separate sections that appear to be spot welded in, and there is nothing I would like to see better than fully welded sections. Parks reckons it's difficult to get a proper weld as there is some surface rust in certain sections and those do not lend themselves particularly well to MIG welding.

You see, there are small sections in the left inner guard that showed some cracks, and some rust. Now, these have been repaired, a new piece welded in and, for the time being, that's all I'll do. However, when by chance I looked at the other side, I saw no cracks but a coupling that had again shifted by about 5 millimeters away from the Steering Box spline ! On checking the star head shaped bolts, they were NOT loose, but only about 30 lbs.sq.in. tight. Now, under normal circumstances, one could assume that these bolts should have been tight enough at that pressure. Obviously not !

But are the circumstances normal ? Steering wise, I really have not been able to pick any faults. The car corners quite well both to the left and right, it tracks reasonably straight although far from perfect, and there just has to be tremendous stress and SOME form of MOVEMENT to cause the coupling to move.

Other than fitting the stiffening plate I have, I see no solution to what could be a problem of some kind. Perhaps others on the discussion board may have some pertinent suggestions. Regards Styria

 

[Styria]

I will need to have another look at this today - to be on the safe side. Also, I purposely have "bumped" this post, just to see if there could be any input from other posties that may have some idea of what is going on. Regards Styria

 

[SELfor50]

I will need to have another look at this today - to be on the safe side. Also, I purposely have "bumped" this post, just to see if there could be any input from other posties that may have some idea of what is going on. Regards Styria

Sh!t dude, I never saw this before... you were f*kn lucky! Steering failure scares the shyte out of me!!

I don't really have any solutions for your problem, I have never had the chance to pull one of these units out and inspect - though I would imagine the box itself is pretty f*kn sturdy yeah? Is there any past history of steering box trauma? (Acco's, gutters etc)

 

[oscar]

What he said! I can't believe that happened styria.

As to why, considering the steering box side has a depression in the spline to accomodate the bolt, you'd think even moderately tightened there's no way the clamping bolt would allow the coupling to move off the spline, even if your chassis was severly rusted and 6.9 torque at full throttle twisted the egnine bay inside out. There's no way it should let go. Something would snap before hand IMO.

All I can think of is that the clamping bolt wasn't seated in the spline's groove and was behind it/after it. Or the incorrect bolt was used whereby the shaft may be smaller in diameter compared to its thread. IIRC, the bolt's shaft should be the same diameter as its thread.

 

[s class]

Are you sure the coupling was pushed properly onto the splines? There is a 'neck' in the splined shaft to accomodate the allen head fastening bolt. It seems to me that even if this bolt is not tight, the 'neck' of the shaft would prevent the coupling pulling off.

 

[s class]

Sorry - I've just seen oscar's post now after I replied - basically the same thing I'm saying

 

[koan]

Nasty one, the coupling must have had the barest grip on the spline, very fortunate it happened where it did.

The steering coupling should be slipped all the way onto the splined shaft and inched up until the bolt will slip through without force.

No part of the steering box spline is visible when correctly installed, the coupling extends down past the spline.

I'm nervous, will have to look and make sure mine is OK.

koan

 

[Styria]

Hi Koan, thanks for that tip as far as the spline is concerned - I really had not been sure as to how far onto the sline the coupling was to go.

There is, of course, the 'indentation' that should prevent the coupling from sliding. This is an aspect I will pay closer attention to sometime today.

I still ask myself "WHY" though - where is the flex (if any), why should separation take place ? As you said, it's a bit of a worry and should be sorted out pronto. Regards Styria

 

[Styria]

Well, I can let all of you know that......it has happened again ! Last Saturday morning, to be precise. I took Gleaming Beauty for a short 'shake me up" drive and about 200 meters from home, trying to straighten up whilst negotiating a corner, again nothing..yes, as on the previous occasion.

Some of you may also recall that during the recent valve grind and de-coke job, I had noticed again some movement, and I should have ascertained its cause there and then as access would have been so much easier - anyway, that's another lesson learned.

So luckily this time, I wasn't too far from home, and after getting my "Danish" trolley jack (anyone know why it is called a 'Danish trolley jack') and some tools that I happened to have on hand, I crawled under the car and, sure enough, this time the coupling had pulled clear of the inner steering column shaft, so no steering. But what was to cause this ?

Well, the answer had to be simple, and it was but like some simple things, can be the most difficult to trace. As it is, I have never had the steering column and the shaft with the SQUARE END apart, but a friend of mine had one sitting on his bench, so I was able to examine the set up properly. The shaft comes in two halves which can be separated by sliding motion. It's an operation that requires some judicious blows with a hammer normally. However, in the case of Gleaming Beauty, it was easy to slide the inner shaft in both directions. So, it came to pass that when fitting the coupling to the square shaft, it actually would slide upwards and 'away' from the coupling giving the false impression of being located on the shaft. So, that's this puzzle solved.

Very easy to get trapped into committing a mistake, as really you don't have much of a chance of actually seeing what is going on. This time, however, the coupling WILL NOT MOVE from either location. Hopefully, not the famous last words. Regards Styria

 

[Michel]

This time, however, the coupling WILL NOT MOVE from either location. Hopefully, not the famous last words. Regards Styria

A bit of welding?

 

[Styria]

Hi Michel, no, there's nothing to weld - I would imagine that there needs to be some movement, but I would also hazard an 'educated' guess that the sliding feature of the two shafts is the be all and all as far as collapsible steering safety is concerned.

In any case, as long as the coupling is fitted 'properly'. the problem as I have experienced should never occur.Hate to say it, and there ought to be some excuse, it is the fault of both operators, viz. the previous mechanic initially, and now myself. Regards Styria