Author Topic: Steering rack adjustment  (Read 195 times)

ptashek

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Steering rack adjustment
« on: 25 October 2020, 06:50 PM »
I need some advice and guidance from the collective experience here :)

The steering box on goldie has no leaks or other issues, but the slack is just too much and it irks me every time I swap from the W124. I haven't measured it precisely, but there's a decent amount of travel in the steering wheel before the wheels react. Everything else in the setup is barely 15k+ miles old, but other than resealing and re-painting, the steering box wasn't touched during the resto and it's always been this loose. Total oversight on my part while the car was with people who should have known better.

On RHD cars (V8), is there some trick to adjusting play in-situ, or is it a bench job? From what I see on my car, the exhaust manifold is in the way and I have a couple joints too few in my hands...
 
Is there a WIS job somewhere that describes how to do the adjustment correctly?
All I know is it's done by loosening the outer 14mm (?) hex up-top, then adjusting play with the inner 5mm allen.
Do I need any special tools to figure out the sweet spot?

I've played around with a spare box I have lying around, to see how the box behaves as it gets looser or tighter.
Frankly, I can't feel much of a difference. Maybe it's just worn?

If that should be the case with the box on the car, can those be rebuilt?
I'm suspecting it's the sector shaft that wears out?
1993 "Pearl Blue" W124 280TE
1988 "Arctic White" W124 200T
1979 "Icon Gold" W116 450SE (history, resto)

daantjie

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Re: Steering rack adjustment
« Reply #1 on: 25 October 2020, 07:02 PM »
Be glad you don't have a 6.9 ;D  there is no space to get any tools in there for the adjustment.
Not sure on the RHD setup but I'm sure you know to turn the inner bolt out to tighten up the box, right?
Usually if the box still has life in it a quarter turn out at a time can improve things. Careful not to go out too far as it'll then bind up on the outer end of the range.
Might be best to remove it and reseal it at the same time.  Not a huge job just a bit finicky.
Some good posts online, luckily the logic is the same on multiple models of the same era.

Here is a very good writeup:

http://www.davidpetryk.net/Mercedes/Steering.htm
« Last Edit: 25 October 2020, 07:10 PM by daantjie »
Daniel
1977 450 SEL 6.9 - Astralsilber

ptashek

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Re: Steering rack adjustment
« Reply #2 on: 25 October 2020, 08:32 PM »
Might be best to remove it and reseal it at the same time.  Not a huge job just a bit finicky.
Some good posts online, luckily the logic is the same on multiple models of the same era.

Re-sealing was done during the resto, and the box is perfectly dry. It's just the play that needs fixing.

Quote
Not sure on the RHD setup but I'm sure you know to turn the inner bolt out to tighten up the box, right?
Usually if the box still has life in it a quarter turn out at a time can improve things. Careful not to go out too far as it'll then bind up on the outer end of the range.

That's as much as I've figured playing around with the spare box I have. I guess the real question is how do I know I've gone too far with the adjustment?
How does the "binding up" manifest, is it just more friction or it literally binds / locks up?

EDIT: Right, there some detail a the very bottom of the write up.
« Last Edit: 25 October 2020, 08:42 PM by ptashek »
1993 "Pearl Blue" W124 280TE
1988 "Arctic White" W124 200T
1979 "Icon Gold" W116 450SE (history, resto)

daantjie

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Re: Steering rack adjustment
« Reply #3 on: 25 October 2020, 09:03 PM »
As far as I know the "classic" tell of an overadjustment is if the steering does not readily and smoothly return back to center after you execute a turn.  Not sure really how to replicate this on the bench easily.  The service manual shows a lot of special tools and very specific torque ranges to set it up on the bench.  Looks tricky to be honest.
I guess one can try and do it by feel on the bench.
Perhaps best to try the adjustment with the box in situ and see how she goes :-\?
Daniel
1977 450 SEL 6.9 - Astralsilber

BCK1963

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Re: Steering rack adjustment
« Reply #4 on: 25 October 2020, 11:58 PM »
I can confirm Daniel's statement: a quarter of a turn out of the central allen nut, counter clockWise, made a notable difference on my car.
It will probably be difficult to properly adjust the box just by that method whithout knowing the condition of the central shaft. Depending upon the mileage the steering has on it I'd consider opening it an check as the  boxes were known as weak points on these cars.

ptashek

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Re: Steering rack adjustment
« Reply #5 on: 26 October 2020, 04:59 AM »
Mine would have under 90k miles from new. Looking at pics of it the only time when it was off of the car under my ownership, I'd say it was never adjusted before either.

If doing the adjustment on the car, I'm guessing checks should be done with the engine running?
Seems obvious, but the tech doc isn't specific in that regard.

1993 "Pearl Blue" W124 280TE
1988 "Arctic White" W124 200T
1979 "Icon Gold" W116 450SE (history, resto)

BCK1963

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Re: Steering rack adjustment
« Reply #6 on: 26 October 2020, 07:32 AM »
Not only with the engine running but also with the car moving. You have to feel the difference during regular driving if you cannot adjust to friction data.

daantjie

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Re: Steering rack adjustment
« Reply #7 on: 26 October 2020, 10:05 AM »
Indeed with adjustment with the box in situ it is very much a trial and error process.  The key is small adjustments at a time, test drive, then readjust if needed, and so on until you find the sweet spot ;)  if however the box is worn beyond what the adjustment can do then you have to go a different route of course.  But as you say if the box has indeed never been adjusted it bodes well for getting the feel better with said adjustment.  There is an outfit in the US, C&M Hydraulics who come highly recommended, but I'm not sure now with Covid and all how long you will wait, likely months :'(
Daniel
1977 450 SEL 6.9 - Astralsilber