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View Full Version : 123 Steering Box

11-27-2004, 10:29 PM
What is the best way to tighten my steering? I have replaced the tie rods, replaced the steering idler arm, replaced the steering shock...what else? Should the steering box be rebuilt? Thanks!

11-28-2004, 08:33 AM
what size tires are on your car ? and which model is it ?

the steering box rebuild is usually not needed to it has oil pouring out of it seals , or , 200,000 miles . And then yiou exchange it , not rebuild it . First adjust the box tension with the adjustment screw on the top of the box. Loosen the lock nut (it's REAL TIGHT !)and move the adjusting screw 1/2 turn and retry . Mark the original position of the adj. screw for reference. There is a lengthy correct proceedure of disconnecting the tie-rods from the steering box arm so you can isolate the steering box from the rest of steering parts. Remove the horn center emblem and with a long socket on the steering wheel nut , and a friction meter (like a very small torque meter)you measure the friction as you turn the wheel/box back and forth - 1 turn from left of center - past center to 1 turn to the right. The reading increases slightly as you pass thru the center position and that's the reading for correct box adjustment.
So without the elaborate tools - your left to trial and error on the ground with all the stuff attached.

11-28-2004, 08:45 AM
BUY this 123 manual on CD - it's all there.You can purchase from any M-B dealer of on-line like this link:

the reason I ask'd about your tire size is IT IS A CRITICAL ISSUE !
the popular fad if mounting fatter tires to 240D, 300D, 300DT , 300wagon is number one worst case of molestation to these cars.
The steering geometry is vastly different that every other car made.
Caster settings from 8.50 to 10.5 degrees and all the other STUFF involved -like scrub radius - keep the reccommended size on the car. That is where your 'dead' steering and loss of steering sharpness comes from.
a 123 240D should have 175x14 tires - not 185 , 195 or 205's!
a 123 300D Turbodiesel should have 195/70x14" tires - not 205, 215 225 or any other fat steering numbing size.

11-28-2004, 08:53 AM
here are the steering friction measuring tools
two different scales - but the same torque range
these are ingact Mercedes-Benz special tools from my days on the line
at a dealership from 1970 to 1990. The information with the picture is for my other addiction at the moment - BMW 2002's - but nearly the same as the M-B specs. You can even do the same measuring of your friction using a small scale Snap-On "dial & needle" torque wrench - one in pounds inch. . . . .

11-28-2004, 08:58 AM
my car at German Car Day Larz Anderson Museum of Transportation, Brookline, Mass.

before the Euro headlight conversion

Creighton Demarest

M-B Star Technician from 1970-1990
BMW Master Technician since 1990-present

11-28-2004, 09:07 AM
thank you for all the information. I am guilty!! I have two 240D's, a manual and an automatic and I have upgraded the tire size to 195 on both of them. I had no idea this would make a difference....but Michelin doesn't offer a size 175 anymore, at least not on TireRack. I have only wondered if the change in tire size would affect the speedometer reading? Thank you again for the comprehensive info!

11-28-2004, 09:55 AM
the only good thing about larger rolling dia. tires is it does lower the rpm for highway speeds - but you loose on accelaration, and it does change the speedo readings

back to alignment:

the Caster also needs to be adjusted to the max ie. 9*45' POS
the camber at zero - to -30'
and the toe-in to 4mm each side
alignment is very involved with this chassis and hugely important.
another area of looseness comes from the caster rod mounts being worn.
The mounts are on the lower firewall and involved to replace. Upper control arm that attach to the front anti-sway bar and the bar rubber mounts on the upper firewall all help to tighten up the handling. Replacing all these front suspension parts is needed after 25 + years and 150,000+ miles.

Darien, Connecticut.
your right - look at these - (

01-08-2005, 10:32 PM
CD--should those 175 tires be 65's, 70's, or 75's?? what's the difference? THANK YOU, toby

01-10-2005, 06:32 AM
seems 175x14 are not a 'common' size anymore

next size closest is 185/75x14
185/75x14 choices here (

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