Help! Steering box input shaft clunking - PeachParts Mercedes-Benz Forum

JHZR2 · #1 02-27-2004, 01:49 PM

Hi,

First some background: I had the guide rod mounts, balljoints and one tie rod assembly replaced. Got it back last night and it didnt clunk or anything.
Took it to the dealer this morning to get it aligned.
After I got it back, I was playing with the steering, and I noticed what seemed to be a louder than noprmal clunk when I lightly jerk the centered wheel slightly right and back, in a rapid, repeated fashion. Total arc of swing of the wheel is maybe 1-2 inches, max.

So I get a clunk noise. Only really when the car is sitting still. When rolling it is MUCH harder if not impossible to get this to happen.

My problem #1 is I dont know if I can blame anyone. I checked by steering hard back and forth while rolling, after getting my car back from the indy to make sure there was no popping of the suspension (there was none) But I didnt check for play in the steering. I doubt it was my indy who did it, becuase as Ill explain, it is the input shaft of the steering box, which he surely didnt mess with then changing balljoints.

My problem #2 is that I dont know if it was like this before I did anything to the car. I dont routimely swing the centered wheel side to side to see what kind of a clunk I can get, and if I ever do (to check for play), the car is usually rolling and I wouldnt get the clunk then anyway. Plus whjen I shake it for paly,m i dont do it this fast/violently. I just did after the alignment to see what the car could do...

I traced the clunk and it is almost 100% definitely coming from the input shaft of the steering box. The steering wheel/column shafts all the way to the input of the box are fine, no problems, no looseness, etc. And there is no play in the suspension (the amount of steering movement requred to ge tthe clunk barely moves the tires at all, more like a little jolt to the tire that doesnt change its position) nor does the pitman arm even move when I jerk the wheel to get this to occur.

So it has something to do with the input of the steering box. The sound ewven seems to come from the top of the box (where the input shaft comes in). The car drives really well otherwise, steering is firm and just right. Control is fine, no shaking, wobbling or swaying on the roads at any speed.

Its just that stupid clunking sound. Is the input shaft a splined shaft, that perhaps has a little bit of a loose fit between the splines? Is there some way to tighten that up? Ive tried the allen screw ont he box, up to 1 full rotation either way. Doesnt change the clunk.

Any help/suggestions would be great. I would just assume live with it, as I dont think its noticable unless I attempt to induce it. But Id hate to have a steering failure with all the high speed driving I do.

Any help would be great.

Thanks,

JMH

psfred · #2 02-27-2004, 02:13 PM

Steering coupler bushings are gone, replace steering coupler.

Peter

JHZR2 · #3 02-27-2004, 02:31 PM

Thanks!

Unfortunately doing a search on the steering coupler didnt provide me with much useful info. Could you tell me more about it, where it is, what it does and how to replace it?

Thanks again,

JMH

JHZR2 · #4 02-27-2004, 02:33 PM

I realized that there is a picture of this part in fastlane...

I know i have two of these, one under the kickpanel, and one just through the firewall in the engine compartment. Both are fine and fully tight.

I actually turned the steering shaft by the coupling closer to the steering box, and the noise persisted. Definitely wasnt coming from the coupling, but rather further down the line at the steering box itself.

Thanks

JMH

whunter · #5 02-27-2004, 05:37 PM

Hello JHZR2
If you are correct.
This could indicate that the worm gear bearings are gone.
That would be lethal to drive.
Time for a rebuilt or used steering gear box.
Have a great day.

psfred · #6 02-27-2004, 08:24 PM

Only way to check is to watch the coupling and box shaft -- if the coupling can rotate slightly before the shaft moves (or you can see the pins moving in relation to the rest of the coupling), it's bad.

If the slop is internal, sway the steering box.

Peter

wolf_walker · #7 02-28-2004, 12:16 AM

Anyone ever pulled one of these boxes apart and seen what wears? There not cheap rebuilt or new, and if it's just bearings, there pretty cheap. I suppose I should search and look at my manual...

BoostnBenz · #8 02-28-2004, 02:46 AM

I've never opened one up but would like to once I find the replacement for my current one. I have over an inch of play in the steering wheel that I'd like to rid of, but it won't adjust out. The input shaft moves but the output shaft doesn't....

leathermang · #9 02-28-2004, 07:45 AM

There is a huge section in the 123 chassis manual on rebuilding the steering box.... ( if that is what is needed )
I suggest listening to WHunter and hope he is correct.. nothing inside the steering box is easy.

JHZR2 · #10 02-28-2004, 07:53 AM

The thing is, getting that clunk to occur is actually a hard task. The way that I have to spin the wheel side to side hard and fast (over that 1-2" range) is not something that I would ever do or be able to do in everyday driving. And the box is nice and tight the rest of the time.

I think maybe it has been like this for some time, and just has something to do with the internals of the box, which is inherent to its design.

If it would make this noise easily or all the time, maybe Id be more worried. But sitting still rocking the wheel hard through the centerpoint isnt very normal.

Do the worm gears have some end point, perhaps where they physically have to catch on something else at some degree past the centerpoint, to turn the stuff right or left? The way I see it, there would need to be two sets of gears, that engage and spin in opposite directions depending upon which way the steering wheel is turned.

But that said, Im going to start shopping for a steering box. Any ideas how much they are new/rebuilt?

Thanks,

JMH

leathermang · #11 02-28-2004, 07:59 AM

Have you done a search on adjusting the steering box ?
I think they were supposed to lock it during the centering process when they did the tie rod deal... and that is pretty unusual to only replace one side on suspension components... usually done 'per axle' .....

JHZR2 · #12 02-28-2004, 08:03 AM

Yes, ive tried the adjustment... But the adjustment screw is siezed up pretty bad. I got it to move ccw about 1/8 turn, and it didnt change a thing. For a test, i moved the whole thing, adjustment aqnd locknut about 1 turn CCW, and it didnt make any difference either.

I need to reiterate that the car drives, handles and steers really well. I just get scared when I manage to find new sounds, or uncover old ones.

I dont know if it was 'locked' in place, but they definitely measured everything to get the lengths right. Even before aligning the car, it drove like before I had the tie rod assy changed. And looking at the before and after printout from the dealer's alignment computer, nothing was significantly off at all. Only a few degrees, which was an amount similar to the amoutn off on the side where the tie rod wasnt changed.

I only did one side because the one on the other side was new looking (dealer changed that one about 40k ago when I took it for an alignment, because they said it was siezed up). Only reason why I had to change one this time was becuase there was play in it.

Thanks,

JMH

whunter · #13 02-28-2004, 08:45 AM

Hello Everyone
The steering gear box can get someone killed.
That is the reason MB no longer recomends field rebuild.
It is easy to screw up!!!!!!!!

TwitchKitty · #14 06-23-2004, 12:24 PM

Quote:

That is the reason MB no longer recomends field rebuild.

You know how the world works today, these boxes are probably rebuilt by illiterates in some third world country. If not now, in the near future. I understand the risks and think I am up to the task. The costs of parts and tooling would be the downside to me.
What are the costs of parts and special tooling?

My steering box is ok but could be better. It is not worth it to me to buy a rebuild for the difference. If I could rebuild it for $50 or $80, I would consider.

whunter · #15 06-23-2004, 04:48 PM

Quote:

Originally posted by TwitchKitty
You know how the world works today; these boxes are probably rebuilt by illiterates in some third world country.
If not now, in the near future.
I understand the risks and think I am up to the task.
The costs of parts and tooling would be the downside to me.
What are the costs of parts and special tooling?

My steering box is ok but could be better. It is not worth it to me to buy a rebuild for the difference. If I could rebuild it for $50 or $80, I would consider.

I checked with a local steering gearbox rebuilder, he says $750.00 in tools, parts and jigs.
Note:
That is if you only do one type of MB steering gearbox.

He also stated that a Master Tool Maker could do it himself; but it would take a lot of time.

In a month or two I will swap the one in my 1985 300SD.
I will try to rebuild it before winter, and take lots of pictures.