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1981 240D
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185 Posts
Discussion Starter · #1 ·
I recently did a complete overhaul of my front suspension/steering. Some of you read my thread on "240D Swaying Down the Highway". As I mentioned in that thread, I replaced the rear shocks. I also had an alignment performed. The reason I am starting this thread is because there is a new issue, apart from the swaying during my first post-overhaul test drive.

The mechanic who performed the alignment told me the closest he could get the front-passenger camber to specification is positive 5/8. Technically, it is within specs, but he wanted to get it to zero. I am not concerned about this so much, but I am concerned that the steering is loose. The play in the steering wheel is about 6 fingers width. The car goes straight down the road, but uneven surfaces of the road cause the steering wheel to move if I remove my hands from the wheel.

I know I will likely never get the steering as tight as it was new, but I would like to tighten it up as much as possible. My questions for the collective group are:

1. What should I check before replacing the steering gear box?
2. How difficult is it to rebuild a gear box?
3. What pitfalls should I avoid, based on your experiences with this problem?

If you have read my thread on "240D Swaying Down the Highway" you know I already replaced the steering damper, tie rods, LCA bushings, UCA assemblies, lower ball joints, shocks, idler arm repair kit, guide rod mounts, guide rod bushings, sway bar bushings, brake rotors, calipers, hoses, wheel bearings, tires. I thought this would do the trick, but the steering is still loose.
 

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2001 Volvo V40
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2,955 Posts
There is an adjusting screw on top of the steering box, that tightens up the steering.

The procedure is described on the FSM:
46 Steering
46-480

but most people follow a simpler procedure, by turning the adjustment nut half a turn and testing whether the steering is good and does not lock.
 

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430 Posts
yes, it is very common for w123's to be out of adj in the gear box. it takes only minutes to do. 3 out of my 5 old benzes needed this.
 

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1984 300D
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5,513 Posts
The Adjustment is on the top of the steering Box.
Spray some penatrating Oil on the Nut and let it soak as they can be really tight and rusted inplace.
 

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1981 240D
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185 Posts
Great info. I really appreciate all the help! If I make adjustments to the steering gear box, will it affect my alignment? That is to say, will I need to have another alignment performed after I make an adjustment to the gear box?

Okay, disregard my last post. I read through the full job sheet in the manual and went to look at said nut. I put a few drops of liquid wrench in there, like 300Dman suggested and used a 19mm box-end wrench to loosen the lock nut. I used a 6mm allen wrench and tightened the adjustment screw, while I had my wife rock the steering wheel back and forth. I tightened it until I reached the point where the slightest turn of the steering wheel turned the front tires and there was no longer a clunking noise from slack being taken out of the steering. I then started the car and turned the wheel lock-to-lock to make sure it did not bind. I took my car for a short test drive and it is 10 times better. It is now tighter than my Honda Civic! One thing I noticed though: The steering wheel doesn't "slip through my hands" when I complete a turn. The car straightens itself about 85% and I have to manually correct the other 15%. I can live with that considering there is absolutely no play in the steering wheel.

Oh, one more thing..... I had to turn the adjustment screw approximately 1.5 turns. Does that seem excessive?
 

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1985 300CD Turbo coupe, 2006 E320 CDI sedan
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573 Posts
I think you over-tightened. Back it off till you have ~1" total play in the wheel. That's about factory spec. Less than that, you're going to have trouble with the steering wheel lock

//greg//
 

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1985 California 300 D Turbo Diesel and '85 Federal 300D Turbo Diesel. '84 Cali 300D - SOLD
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360 Posts
^^^yep, you are too tight now^^^
 

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282 Posts
I would like to adjust the steering box in my coupe.. but I don't understand the term "binding". What exactly does it mean to adjust it so much it binds???

thanks
 

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1977 230, 1990 300E 2.6
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243 Posts
If your power steering system still has ATF as the fluid, flush it and replace with current Power Steering fluid. ATF was recommended by many auto manufacturers years ago until they noticed premature wear on steering box components caused by the friction enhancer additive in ATF. Mercedes recommended ATF for the W123 and this series experiences abnormally high rates of box wear. Power steering fluid is recommended for the W124 and the failure rate of these boxes is dramatically lower - ask any rebuilder and they will concur. The box on my '77 was worn to the point of not being able to adjust properly in just 80K miles. The car was bought new by my best friend and only driven on trips. He is a fanatic about cars. I say this to explain that the car was not abused or beat up during those miles but driven gently. Another box was installed at 80K. Just a couple months ago I had the original box rebuilt at 155K miles because the second box was worn out. I flushed the system and replaced the fluid with power steering fluid. The rest of the steering components show no wear and are very tight.

About 3 decades ago GM realized the same thing was happening with their power steering boxes when using ATF. They released a bulletin recommending changing out ATF for power steering fluid.
 

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2001 Volvo V40
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2,955 Posts
I would like to adjust the steering box in my coupe.. but I don't understand the term "binding". What exactly does it mean to adjust it so much it binds???

thanks

Binding means that the steering wheel locks, i.e. that you cannot turn it back. Not very handy or safe.
 

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1959 220S cabriolet, 1983 240D original owner, 1999 E300 turbo diesel, 1988 560SL, 2003 SLK320
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3,513 Posts
Just a note on ATF in the steering box. I have had my car since new and have had ATF in the steering box since new. The box is original and has never had to be adjusted and is well within spec. I think that more damage is done trying to adjust the boxes than problems solved. The box should be the last thing touched not the first like lots of people do. Every component in the front end needs to be tight and the steering column rubber donut needs to be good before touching the box.
 

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1981 240D
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185 Posts
Discussion Starter · #12 ·
Okay, when I get home I will back it off a half turn or so. I drove the car to work today and it seemed fine. It drives a lot better than it did before.
 

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1985 California 300 D Turbo Diesel and '85 Federal 300D Turbo Diesel. '84 Cali 300D - SOLD
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360 Posts
^^^Just noticed you're in Yuma. My youngest son is stationed there and works on Harriers. :wave: ^^^
 

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1981 240D
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185 Posts
Discussion Starter · #14 ·
^^^Just noticed you're in Yuma. My youngest son is stationed there and works on Harriers. :wave: ^^^
Awesome. I was also a Marine. That is how I ended up here. Encourage your son to take advantage of everything they offer. They paid for my Bachelors and my Masters. They will get everything they can out of him, so he has earned it.
 

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i got a rebuilt steering gearbox for my 300D, but it was also leaking, was 300 dollars and i got my friend who owes me to do it for free. so definitely worth it. also if its leaking, dont waste your time with seals,
 

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1983 3.0L 300TD
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57 Posts
So lemme get this straight you turn the allen key to the right after you loosened the nut around it to tighten... well I did and it was all ready tightened all the way even with the nut loose around it. My steering is very very loose...
 

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2013 MINI Copper S Clubman, '84 300CD-weekend car
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10,152 Posts
Turn the allen CCW to tighten the steering, at least on 123's and Gen I 126's.
 
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