W126 Steering Play?
 

Is this a normal/acceptable amount of play for the gear box to have while the car is parked running?

http://smg.photobucket.com/user/JamesDean59/media/WP_20140703_002_zps09d248c0.mp4.html

My 124 has zero play in it. I can't even remotely do this to it. I have two other w126 cars but both have aged/old/bad gearboxes so I don't have a great comparison.

U.S. DOT specifies a maximum of 2 inches of play for the steering wheel of a commercial motor vehicle. I don't know what the original play was in the 126 box, though from the nature of worm and sector steering, I suspect there was some. My 123 after 334,000 miles is getting loose but still has a bit of life left. There is an adjustment on the steering box (CCW is tighter), but after a certain point you only increase the steering effort without taking any more of the play out. Try an adjustment. If that doesn't get it to your liking, a replacement steering box will be your best option. I count six active 126s in your sig. Which one is this?

I had a problem with my 500 box leaking and desided to reseal it.
I found a site with great instructions that also included the adjustment.

How to reseal a MB steering gear

The instructions start with "remove the steering box" which I don't think you want to do just to adjust it but maybe you can get an idea of what needs to happen when you adjust it.
I followed all the procedures and every thing turned out great.
Sitting still, it feels like it has some play in it but I determined it was in the tires and very little in the box. The steering box has about 226K miles on it. It came out of an 89 420SEL back about 10 years ago.

Paul

I should have mentioned in the first post that all the steering parts on this car are new or less than 1 year old.

I rebuilt the front end of the car last summer. The tie rods and center drag link are lemforder brand.

I had a rebuilt gearbox procured and installed by my mechanic in August of last year.
The first one they sourced leaked after they installed it so it was replaced with another unit.

I had the car aligned locally and it kept having a leftward pull issue.
I took it up to MB in North Olmsted and they told me the gearbox is bad and has lots of slop in it.

I took it back to the shop and they agreed. They replaced the gearbox under warranty on Tuesday and what you see in the video is the result..

That's a new one?:eek: Ok, this will be hard to get on camera, but you should be able to discern it sticking you head out the window. How much do you have to move the steering wheel before the LF wheel moves?

Mine is not that bad, but close. I tried tried to adjust but some monkey REALLY cranked the adjustment nut and I have never been able to get it loose.

But when the car is running, there is no play at all. So never really bothered me.

James, it's kinda hard to quantify the amount of play with the engine running and the box pressurized, but this is what I found just now;
- with the engine turned OFF, there is 1/2 inch left and 1/2 inch right of pretty easy free play. Then it toughens up quite a bit, indicating the tires are resisting. This is considered normal in the service manual, and mine has been about that way since new.
- with the engine running, there is an immediate resistance to turning the wheel, no real freeplay at all. BUT... the resistance increases linearly through about that same 1/2 inch until it noticeably tightens up as it does with the engine off. You can visually see the wheels move when turning the wheel left and right 1/2 inch (1" total). When driving, there is zero sensation of any play at all.
So, it's probably the same sensation you describe on your other car - virtually no freeplay.

Mine is a '91 SE with 240k miles. I did tear the unit down about 8 years ago to repair a seal, and I adjusted the preload torque to factory specs while in there. Kinda fun, set up a little lever arm with a specific weight on the end to measure the release torque - I saw Ed on Wheeler Dealers do the exact same thing a few weeks ago.

So, in summary - you got a loose box.

DG

I suspect its a loose box as well.

What I fear--and what happened to the last box they put in--is that it'll be "fine" but in a few thousand miles (after I've paid for an alignment) it'll go to hell and I'll be back at the this spot.

http://i.imgur.com/h4kVRle.png

FSM specs with engine off and wheel centered...25mm is max..kinda thinking I'm wayyy past that but I'll double check.

Ok so I took a crude measurement of the slop.

Here is what I did

1) Blue Sharpie rubber banded to the top center of the steering wheel.
2) Piece of wood behind steering wheel, just ahead of instrument cluster with a piece of paper on it.
3) Forced sharpie into paper and moved wheel back and forth until I felt resistance.
4) Did this a few times to make for good measure. As you can see on one pass I went a bit hard to the right and took the marker further beyond the initial resistance, this was an error.

This created a nice curve on the paper...that I hope represents the slop in the box. The sharpie was held nice and tight so that it did not tilt left/right as it was dragged across the paper.

Some things:
1) I know that the caliper measurement is not exact because the wheel is curved, but should be good enough.
2) I know that there is a decent amount of error that could be in this as well.

Here is the result. Let me know what you think about this approach and the result..

http://i.imgur.com/tMQYCTRl.jpg

As far the interpreting the result:

Mercedes states that the maximum allowable slop is 25mm. This is to be measured with the wheel straight and the engine off. I measured 89mm linearly (3.531 inch = 89.70 mm.)

If I could flatten out that line it would be longer than 89mm.

So my conclusion is that the box has excessive slop and should be rejected.

I agree. I finally drove my car after several days of taking the bike everywhere. My steering slop is less than what your video shows, and mine is an apparent 334,000 mile original and feels a little worn out going down the road.

That must be reeealy worn out as the 420's have self compensating boxes too......that amount of play is about what my bro's old W123 had.....334k is probably time for a rebuilt box. We just put one in my dad's 300SD with 340k on it and it made a big difference.

Yeah, its kind of disgusting if you ask me. I mean its supposed to be "rebuild" but I'm pretty sure all the supplier did was reseal and sandblast/paint to make it look pretty.

Who was the supplier? I just installed one on my dad's '82 SD from C&M hydraulics in Nevada and they did a good job...very little if any play....it was over $400 though.

There is an adjustment screw in the box.

It's on the top of the box. You loosen the lock nut and with a hex turn the adjustment nut OUT. A little bit goes a long way.

One of the interesting things about adjusting the box is that you do not want to over turn the adjustment. This tightens up the box, hides slop, and prevents self centering.

When I adjust, I always make sure there is still some play in the wheel before I lock it down.

The new box,is it possible that someone sneaked a used with too much adjustment in it into your car? Or. you might try turning the adjustment IN a bit and see what happens.

Jim

I am not sure. Like I said, I had the shop procure it. I asked my dad to ask them and all he could get was "a guy in Florida".

I'm 100% okay with $400. I paid $700 (parts and labor) for the first box to be installed...

I am aware of this adjustment. I made it a few times on my one 300SD, it helped a bit but the box is still crap.

I believe that on the newly installed box (which was done last week) that I should not have any responsibility to adjust it at all. If it was old and out of warranty,etc sure I'd do it. but not with something like this.

Agreed, new box should come ready to go, especially if its one of the self compensating ones found on later cars. The box I installed last week needed no adjustments at all. I did install a bolt in the drain hole to keep it centered during install, but that's it.

James, There are several adjustments on the steering system and they have to be done in a specific order.

Steering shaft must be in the locked position.
Steering wheel must be straight
The shaft going into the steering box must have the correct preload on the bearing to prevent end play.
The adjustment screw must be adjusted so there is a slight tight spot at the exact center of travel.
The steering box must have a locking bolt installed to keep the box centered during instillation.
Last but not least, a good alignment AFTER all the above adjustments are made.

I am thinking that somewhere along the line something was not adjusted correctly and the boxes were just installed the way the old one came out. Then the alignment was done to make the steering wheel straight when the car was going down the road.

The first few things can be easily checked. Just remove the key and turn the steering wheel until it locks. Is the steering wheel straight? It should be.
Next unlock the steering and have someone turn the steering wheel back and forth through the play. You look very carefully at the shaft going into the steering box and see if you see any in/out motion. If you do, the box is not adjusted correctly.
The next step will be to remove the drain bolt from the steering box (you will lose some fluid) and with the steering wheel straight you should be able to see a hole up in the piston that moves back and forth in the box. This is where you insert a pointed bolt in the drain hole to hold the box in the centered position. At this point the front wheels should be straight.

The whole point of all this is that if the box is not centered when the car is moving straight, then there will be play in the steering.

I just did the reseal on my 500 that has a 420 steering box and went through all of these adjustments and found the steering shaft was not correct. It didn't lock with the steering wheel centered. I locked the steering shaft and changed the steering wheel so it was correct. I did all the adjustments to the box with it on the bench. Installed the centering bolt. Installed the box. Had my alignment man adjust the front end using the lock bolt in the box. It is a different car. One problem I had was in gusty winds, the car was hard to handle. Now you can't even feel them. It doesn't pull at all. Life is good.

Sorry for the long post. I am just trying to help. If the person installing the boxes isn't aware of all this, you will never get the problem fixed.


Paul

Hi Paul. Thank you for the lengthy post. I actually spoke with Christ @ C&M Hyrdraulics at length today. He is extremely knowledgeable in his craft and he brought up many of the same point as you. I will look more into this when the car is back. It is currently up at the mechanic's shop.

He did ask me where the box came from and the best answer I got from the shop was "a guy in Florida" and Chris new immediate who he was talking about---Atlantic Enterprises. Chris did not have many nice things to say about the quality of their work and I believe he said he would not be surprised if I got bad boxes from them. However he insisted that I check the same things as you mentioned and I will sometime next week.

The shop is going to get in touch with Atlantic and see what they have to say about all of this. I did recommend to them that they try out C&M, not sure if its what they will do or not but we'll see.

I know that in the future when I go to replace the gearbox on my 300SD (145K miles) I'll use a C&M box. The 300SD has been in the family since new and its gear box had a massive dead spot in the center. You can shake the wheel and look at input shaft move and see 0 movement in the pitman arm for a sizeable amount of wheel travel. I know when I changed out the fluid in the car a number of years ago it was horrible looking. I dont think it had ever been changed in the 30 years of ownership. The filter was horrid. Perhaps that lead to its death. Beyond that, I'm not sure what exactly the story is there but one day I'll get to it.

Chris also recommends that I use Dexron instead of modern Power Steering Fluid. Good deal to me.

Will report back when I heard/do more.

Right now, back to installing a/c on a Chevy R10 pickup.