W126 Steering Play? - PeachParts Mercedes-Benz Forum

JamesDean · #1 07-03-2014, 11:47 PM

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.

Skippy · #2 07-04-2014, 07:59 AM

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?

pmckechnie · #3 07-04-2014, 09:16 AM

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

JamesDean · #4 07-04-2014, 02:14 PM

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..

Skippy · #5 07-04-2014, 05:58 PM

That's a new one?

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?

LandYaghtLover · #6 07-05-2014, 02:19 PM

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.

S-Class Guru · #7 07-05-2014, 04:53 PM

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

JamesDean · #8 07-05-2014, 05:29 PM

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.

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

JamesDean · #9 07-08-2014, 11:33 PM

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..

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.

Skippy · #10 07-09-2014, 12:01 AM

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.

pawoSD · #11 07-09-2014, 11:09 AM

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.

JamesDean · #12 07-09-2014, 11:12 AM

Quote:

Originally Posted by pawoSD

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.....

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.

pawoSD · #13 07-10-2014, 03:05 PM

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.

JimFreeh · #14 07-10-2014, 03:45 PM

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

JamesDean · #15 07-10-2014, 04:03 PM

Quote:

Originally Posted by pawoSD

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.

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...