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  #1  
Old 01-16-2021, 12:12 PM
DLK DLK is offline
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W123 Steering Gear - Torque Tuning Question

Hi everyone,

I'm restoring the steering gear for my 1984 MB300TD W123. This 10 years old thread provided big help during the process.
What a feeling it will be! A properly adjusted W123 / W116 / W126 power steering box

I replaced all seals and gaskets and re-assembled the gear. All went relatively smooth. The problem came when I started tuning the torque by turning the adjustment screw. The torque value does not increase in the center (or middle rotation point). In fact, when I tighten the adjustment bolt in the middle so the geat just starts to feel tight, and then turn the input shaft CW or CCW, it starts "binding" closer to the end rotation points. So it looks like it's the opposite of what it should be. I re-adjusted the bolt several times with the same result.

The gear I'm restoring seemed to have no excessive wear inside. The torque value measured with the input shaft out of the gear was ~15 Ncm.

- Question #1: What did I do wrong causing having more friction at the ends than in the center? ... or maybe it's just totally dead gear, which would be really sad.

- Question #2: Is it worth installing this steering gear on the car at all?

Anyone more knowledgeable, - please help.

Thanks!

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  #2  
Old 01-19-2021, 11:05 AM
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Quote:
Originally Posted by DLK View Post
Hi everyone,

The gear I'm restoring seemed to have no excessive wear inside. The torque value measured with the input shaft out of the gear was ~15 Ncm.

- Question #1: What did I do wrong causing having more friction at the ends than in the center? ... or maybe it's just totally dead gear, which would be really sad.

- Question #2: Is it worth installing this steering gear on the car at all?

Anyone more knowledgeable, - please help.

Thanks!
Surprised you haven't had any responses. I am not knowledgeable but am interested because I may do similar job in Spring.

I do recall reading that a well used gear may have lower torque in center. It warned not to over-adjust to increase that because it could result in binding near full lock turns. Equal torque across full range may be OK?

Hopefully someone with more knowledge will help you.
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85 300D,72 350SL, 98 E320, Outback 2.5
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  #3  
Old 01-19-2021, 11:16 AM
A guy who likes to Benz
 
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Quote:
Originally Posted by DLK View Post
Hi everyone,

I'm restoring the steering gear for my 1984 MB300TD W123. This 10 years old thread provided big help during the process.
What a feeling it will be! A properly adjusted W123 / W116 / W126 power steering box

I replaced all seals and gaskets and re-assembled the gear. All went relatively smooth. The problem came when I started tuning the torque by turning the adjustment screw. The torque value does not increase in the center (or middle rotation point). In fact, when I tighten the adjustment bolt in the middle so the geat just starts to feel tight, and then turn the input shaft CW or CCW, it starts "binding" closer to the end rotation points. So it looks like it's the opposite of what it should be. I re-adjusted the bolt several times with the same result.

The gear I'm restoring seemed to have no excessive wear inside. The torque value measured with the input shaft out of the gear was ~15 Ncm.

- Question #1: What did I do wrong causing having more friction at the ends than in the center? ... or maybe it's just totally dead gear, which would be really sad.

- Question #2: Is it worth installing this steering gear on the car at all?

Anyone more knowledgeable, - please help.

Thanks!
Did you adjust the working piston nut? Or just replace all the seals/gaskets?
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Huius auctoritatis est, quod latine dolor facit me respice.

I recondition w123/w126/w124/w140/r107/r129/ steering boxes!


1984 300D "Elsa" odo reset 6/2011 111k
1983 300TD "Mitzi" ~268k OM603 powered
1995 E300 "Adelheid" 262k [Sold]
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  #4  
Old 01-19-2021, 02:54 PM
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Good that you are turning it thru the center as you adjust, since the tightest point should be in the center. You do know that you back out the sector adjustment nut to tighten it? I am still looking for a junkyard box which isn't showing the max 7 threads on the adjuster. Seems all are worn now. I expect that you should first tighten the input shaft. That is true on 1960's Chrysler gearboxes I have refreshed. They have a big axial nut you tighten with a special wrench (or hammer and chisel) to take most play out of the input shaft. Only then do you adjust the sector shaft. I haven't played much with my M-B gearboxes.
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  #5  
Old 01-19-2021, 05:14 PM
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I seem to remember hearing somewhere that since most of the wear happens in the center, you need to adjust so that it doesn't bind at either end and accept that it will be less than ideal in the center.

Michael
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  #6  
Old 01-20-2021, 09:52 PM
DLK DLK is offline
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Originally Posted by martureo View Post
Did you adjust the working piston nut? Or just replace all the seals/gaskets?
Yes. I did adjust the working piston nut and the seals. Out of the box, and after the adjustment, the torque was around 20Ncm.
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  #7  
Old 01-20-2021, 10:07 PM
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Originally Posted by BillGrissom View Post
Good that you are turning it thru the center as you adjust, since the tightest point should be in the center. You do know that you back out the sector adjustment nut to tighten it? I am still looking for a junkyard box which isn't showing the max 7 threads on the adjuster. Seems all are worn now. I expect that you should first tighten the input shaft. That is true on 1960's Chrysler gearboxes I have refreshed. They have a big axial nut you tighten with a special wrench (or hammer and chisel) to take most play out of the input shaft. Only then do you adjust the sector shaft. I haven't played much with my M-B gearboxes.
The input shaft torque after the adjustment was about 20 Ncm, which is within the spec (5...50 Ncm). Honestly, I don't really see how the torque value of the input nut can influence the dynamics of the output shaft. After giving it another thought and talking to a couple of people, I tend to conclude that the gears (mesh) are more worn in the middle than at the ends. I.e. the gear is at the end of its life.

The strange thing is that reportedly, this box came from the car with a mileage of about 170K, which should be no issue for these cars.

I'm still debating if I should through it in the garbage or try and use it despite the condition. As I said, there is no obvious play. It's just that the torque diagram is kind-of upside down. I.e. If I make the center up to spec, it binds at sides. If I set it to the same spec at the sides, the torque is lower in the center.
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  #8  
Old 01-20-2021, 10:23 PM
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Originally Posted by DLK View Post
...The strange thing is that reportedly, this box came from the car with a mileage of about 170K, which should be no issue for these cars...
It actually is.

The steering boxes in 123s are notorious for having play even lower mile examples.
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  #9  
Old 01-20-2021, 10:23 PM
DLK DLK is offline
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Originally Posted by 250 Coupe View Post
I seem to remember hearing somewhere that since most of the wear happens in the center, you need to adjust so that it doesn't bind at either end and accept that it will be less than ideal in the center.
Michael
It would be very good if someone could confirm what this approach results in. I.e. driving experience. I'd hate to throw a re-built and nice-looking box into the garbage. See the images...
Attached Thumbnails
W123 Steering Gear - Torque Tuning Question-dscf2680.jpg   W123 Steering Gear - Torque Tuning Question-dscf2679.jpg   W123 Steering Gear - Torque Tuning Question-dscf2678.jpg  
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  #10  
Old 01-20-2021, 10:24 PM
DLK DLK is offline
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Originally Posted by christuna View Post
It actually is.
The steering boxes in 123s are notorious for having play even lower mile examples.
Ok. Thanks. I will now know
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  #11  
Old 01-20-2021, 10:32 PM
DLK DLK is offline
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Thanks everyone for your thoughts and suggestions.

A related questions:
Does anyone have experience buying these steering boxes "refurbished"? I saw a couple of companies selling them for ~$400...800 and claiming that everything was rebuilt to specs.

Here is one example: https://www.buyautoparts.com/buynow/1984/Mercedes-Benz/300D/Power_Steering_Gear_Box/82-00116_R

I can hardly imagine how they could restore the worn mesh without putting in new parts.
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  #12  
Old 01-21-2021, 09:28 AM
A guy who likes to Benz
 
Join Date: May 2010
Location: DC Metro/Maryland
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Quote:
Originally Posted by DLK View Post
Thanks everyone for your thoughts and suggestions.

A related questions:
Does anyone have experience buying these steering boxes "refurbished"? I saw a couple of companies selling them for ~$400...800 and claiming that everything was rebuilt to specs.

Here is one example: https://www.buyautoparts.com/buynow/1984/Mercedes-Benz/300D/Power_Steering_Gear_Box/82-00116_R

I can hardly imagine how they could restore the worn mesh without putting in new parts.
Most of the boxes you'll get from the big box stores have been reconditioned by C&M Hydraulics out of Las Vegas. They've been doing these for 30+ years.

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Huius auctoritatis est, quod latine dolor facit me respice.

I recondition w123/w126/w124/w140/r107/r129/ steering boxes!


1984 300D "Elsa" odo reset 6/2011 111k
1983 300TD "Mitzi" ~268k OM603 powered
1995 E300 "Adelheid" 262k [Sold]
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