Overly Tight Steering- W126 - PeachParts Mercedes-Benz Forum

GradyService · #1 04-23-2008, 10:04 PM

My 560SEL has always had really tight steering. It got a little better with a new left lower ball joint, but it still is the stiffest power-assisted steering vehicle I've ever driven. (Way tighter than my former 124 cars, or even my 107 SLC) What could cause this? I know that, usually, as cars get older the steering works loose, but this car seems to be doing the opposite. I understand there is an allen head bolt on the steering gearbox which can be adjusted to tighten or loosen the steering. Is it advisable to try and loosen that bolt?

Thanks, Dave

crashone · #2 04-23-2008, 10:57 PM

Someone may have tightened the steering box too far. You could try to loosen the allen bolt a 1/4 turn at a time to see how that does. Loosen it and drive it down the street turning left and right to check on behavior. Keep loosening and checking until it feels better. When it is tighted too much the car will have a problem coming back around to center on its own.

GradyService · #3 04-23-2008, 11:21 PM

Well, it comes back to center on its own fine. It's just that it has the stiffest steering I've encountered since I drove a 4000 Ford Tractor. Oh, what size allen head does it require to loosen the bolt?

Thanks, Dave

donbryce · #4 04-24-2008, 09:35 AM

Can you see the adjusting screw/locknut? I think it's a 6mm allen and a 3/4" nut, or metric equivalent. The problem is access.
The factory manual for my SL shows a wierd, twisted allen wrench and box end wrench that appears to be fitted to the adjuster and locknut from below.
I have verified that I can reach the allen socket from above with extensions and a flex-end, through the exhaust manifold between cylinders 7 and 8, and turn the locknut from below with a stubby end wrench (on th SL). You may be luckier with your 560SEL.
This is theory, though, as the car isn't yet on the road again after I did a steering gearbox overhaul. I'm praying I won't have to adjust it.

crashone · #5 04-24-2008, 09:55 PM

The adjustment is really easy on the w126 300SD, not much in the way

!!! You are going to have fun!! It is a 19mm wrench and a 6mm allen key as pointed out good luck.

t walgamuth · #6 04-24-2008, 11:38 PM

I would recommend shooting some grease into the ball joints with a needle on your grease gun. They are your steering pivot too.

Good luck

Tom W

pmckechnie · #7 04-25-2008, 07:50 AM

If you try to adjust the steering box, you would turn the allen clockwise to loosen it. Just backward from what you would think. But I doubt that is your problem if the steering returns to center as it should. I would check the power steering fluid and filter, belt, and steering shock. If the car squeaks when you bounce it up and down then check the upper and lower ball joints on both sides. My 84 500SEL is a little hard to steer at very low speeds or stoped but drives like a dream when at highway speeds, which is what these cars were designed for. My 91 300D steers easier, but it is 7 years younger.
How long have you had this car? Has it always been this way?
Paul

GradyService · #8 04-25-2008, 10:59 AM

I bought her in 2005, and she has always been very tight/stiff at any speed. With regards to the power steering pump, its full of fluid, but I've never changed the filter. The car does squeak a little when you bounce the front end, come to think of it. I'm going to try the allen nut, but if that doesn't take care of it, I suppose it's time to go see the front end shop.

Dave

Robert Squires · #9 04-25-2008, 11:26 AM

* Might be worth replacing the pressure relief valve in the pwr strg pump. If it's not closing all the way, i.e. leaking a little, you won't have as much assist as you should.
* To eliminate the suspension as a cause, jack the front end up in the air, disconnect the tie rods at the outer joint and move (steer) the wheel by hand. If there's any binding, you'll be able to feel it. You can check the tie rods and drag link too for a binding tie rod end (not very likely).

t walgamuth · #10 04-25-2008, 05:48 PM

Quote:

Originally Posted by GradyService

I bought her in 2005, and she has always been very tight/stiff at any speed. With regards to the power steering pump, its full of fluid, but I've never changed the filter. The car does squeak a little when you bounce the front end, come to think of it. I'm going to try the allen nut, but if that doesn't take care of it, I suppose it's time to go see the front end shop.

Dave

grease will stop often stop the squeaking too. Or you can spend hundreds and just replace everything.

Tom W