Steering Box R&R DIY - Page 2 - PeachParts Mercedes-Benz Forum

Stretch · #16 01-21-2014, 01:49 AM

Quote:

Originally Posted by unkl300d

Excuse me if this question is out of place in your thread.

But are diesel W123 steering boxes all the same part number ?
i.e. 1978 to 1985 300D same as 240D ? All interchangeable?

Your thread is most welcome and informative !

Great service you are providing also !

There are several part numbers that identify different power steering boxes - but they are more or less the same units. The spares within, however are sometimes different so if you go fishing for second hand bits within the steering boxes you might come a cropper.

From a changing of one unit to another perspective the biggest differences - and there's a great big fuss made about this in the FSM - are in the Pitman arms <= Pay attention to this => and measure the relative height of the idler arm and fitted Pitman arm to make sure you don't have messed up steering geometry.

The only other difference that might be worth mentioning are power steering boxes and ones with no power assistance (very rare in the US of A though)

martureo · #17 01-21-2014, 09:14 AM

Quote:

Originally Posted by unkl300d

Excuse me if this question is out of place in your thread.

But are diesel W123 steering boxes all the same part number ?
i.e. 1978 to 1985 300D same as 240D ? All interchangeable?

Your thread is most welcome and informative !

Great service you are providing also !

Read Stretch's comments above first.

The answer is yes/no. All power steering boxes for w123s are the same-ish. The ball pitch and the internal stop are the only internal differences, and as Stretch mentioned the pitman arm is the main external difference.

Don't bother yourself with the ball pitch, I can't tell the difference in feel and I've rebuilt and driven with each box type. What you do need to know is that the early boxes had an external stop on the chassis which would stop the box from going too far to either side. The later boxes had this stop internal to the box and no stop tabs on the chassis. So you can put a later style box into any early car, but you can't put an early style box into a later car and be safe.

I can't remember the exact year or if there is one. I'd suggest that if you're looking at a car 1982 or younger look for the stopping tabs on the engine crossmember, and look for an "A" on the box (which means it has an internal stop. If you buy the box from me (or have yours rebuilt) I'll talk with you to make sure you get the right one.

It might be information overload but this link will show you the different power steering boxes and what they went in.
http://www.startekinfo.com/StarTek/outside/12265/disc_2/program/Chassis/46-010.pdf

martureo · #18 01-21-2014, 09:29 AM

Quote:

Originally Posted by Stretch

Sorry I missed this before - been busy

I get the feeling it is a little bit more complicated than backlash - backlash would put you back in the same place. To me it is a little bit more like Hysteresis - Wikipedia, the free encyclopedia but anyway...

...whatever it is a weird one

Sorry, when I thought through it again I think it might be a combination of the two, and I realized I didn't explain where I thought the backlash was.

When I said it had backlash I didn't mean in the adjustment screw threads themselves. I was thinking more in the fitment of the adjustment screw in the pitman shaft. I don't know if you experienced it, but the adjustment screws usually have plenty of play coaxial to the pitman/output shaft they are secured to.

So when you tighten a box the screw pulls the pitman shaft in to the box. But if you loosen the box by turning the screw in, the screw has a mm or two to go before it reaches a point where it makes contact with the pitman shaft to push it out.

So say there is 2mm worth of play coaxial to the adjustment screw and pitman shaft. If you wanted to tighten the box by pulling the pitman shaft in 3mm, but on accident went to 4mm, you'd have to turn the adjustment screw in 2mm to account for the play, 1mm to get back to where you want to be and maybe another 1-2mm to be safe. Then you'd have to back out the screw again 2mm to contact the pitman shaft to even begin adjusting/tightening it again.

But you're right, even thinking this through in my mind and trying it out on a box, there does seem to have a sort of "memory" in the box workings.

DeliveryValve · #19 01-21-2014, 09:42 AM

Quote:

Originally Posted by martureo

...
....I'd suggest that if you're looking at a car 1982 or younger look for the stopping tabs on the engine crossmember, and look for an "A" on the box (which means it has an internal stop. If you buy the box from me (or have yours rebuilt) I'll talk with you to make sure you get the right one.

....

Can you post a picture of the location of this "A"?

.

martureo · #20 01-21-2014, 10:05 AM

Quote:

Originally Posted by DeliveryValve

Can you post a picture of the location of this "A"?

.

After some searching through Stretch's and my threads I finally found a picture which had the location visible.

You can see the machined flat just to the right of the shiny locking tool.

This is a closeup of the tool, but you can see just to the right the markings on the flat. The first marking is the "A."

Sometimes you do have to clean that surface off. The box in the picture was completely stripped of grime and wasn't repainted before it was installed. I say this because the markings are shallow enough that paint can obscure them.

DeliveryValve · #21 01-21-2014, 10:58 AM

Just to get it straight, so it is the stamped letters/numbers - AK2243

The "A" in front of the "K" suggest an internal stop.

Thanks!

unkl300d · #22 01-21-2014, 03:09 PM

Thanks to all for the insights.

Mine is OK right now but I wanted to be informed about the subject.

NICKPAP · #23 02-04-2015, 07:29 PM

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Quote:

Originally Posted by martureo

Then thread the power*steering*lines back under the other lines and thread them into the*steering*pump housing.
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Reinstall the the tie rods and retaining nuts. Then remove the centering tool from the box and*install*the drain plug with new washer. If you removed the driver's wheel, reinstall now and don't forget to retorque the lug bolts again once the wheel is on the ground.

Go ahead and make sure all lines, bolts and most importantly, the drain plug are sufficiently torqued before filling the system with fluid.

Fill the pump reservoir with fluid, almost to the brim (if your engine has the shakes don't or it will spill). I use both Power Steering Fluid and Transmission fluid (Dex/Merc). I've used both in the past on number of vehicles, and while I use Transmission fluid on my on vehicles I don't see any problem with either.

This next part requires two people. You need someone to steer from opposite lock to opposite lock (all the way left to all the way right) at a medium, steady pace. Continue supply the pump with fluid until the bubbles stop, DO NOT LET IT RUN DRY. There is a “Fill To” line in the reservoir (you'll see it). Cap the reservoir and you're done.

Depending where you sourced your box you may need to make a finite adjustment to the steering after you've taken a test drive.

Steering Play Adjustment

This can be done with the box installed.

With a 17mm combination wrench, gently loosen the steering adjustment jam nut. Use a 6mm allen key to back out the adjustment screw a quarter of a turn at a time. Tighten the jam nut when at desired position. Repeat until desired "tightness" is attained.

CAUTION. Over tightening the box can result in a dangerous condition where the steering box might not be able to turn. DO NOT OVER ADJUST THE BOX.

mbz300cd · #24 03-09-2017, 07:25 PM

MARTUREO your mail box is full. I need your services please.

Stretch · #25 03-20-2017, 06:33 AM

Try an email instead

Dmitry at Pelican Parts · #26 04-06-2017, 07:28 PM

If anyone is looking for a full steering rebuild, please check out the link below:

Mercedes-Benz W123 Steering Rebuild | W123 (1977-1985) | Pelican Parts DIY Maintenance Article

-Dmitry

BillGrissom · #27 04-07-2017, 02:42 PM

I suspect one problem that can't be fixed by just seal replacement is wear of the metal parts. I have looked at several junkyard W123's over the last year and all had the sector shaft adjuster screw backed out to almost max adjustment. I found one that didn't and thought, "lucky" but reconsidered before under-taking removal. I found the steering shaft had much play (how did they drive like that?), unscrewed the adjuster to get rid of play, and found the same ~7 threads showing as all other boxes (and my cars).

A youtube by Ken of MS says he sees the same wear, though he suspects it is from using ATF fluid. I doubt all these cars used ATF. In sum, if you buy a reconditioned gearbox, but it has too many adjuster threads showing, it may not give much life. If I get desperate, I will get a worn spare to take apart and see if there is brass bushing or such which can be re-fabb'ed. Worm gear balls would be another fairly easy replacement. Gear teeth and pistons would be very expensive to fab.

pj67coll · #28 04-08-2017, 12:44 PM

Quote:

Originally Posted by BillGrissom

A youtube by Ken of MS says he sees the same wear, though he suspects it is from using ATF fluid. I doubt all these cars used ATF.

What should one be using in these besides AFT? I thought that was the recommended fluid.

- Peter.

cmac2012 · #29 04-08-2017, 01:01 PM

PERFECT thread revival. I'm thinking to go get a box at a boneyard and then move up to a rebuild in a year or two. Some great info in the OP and after.

Edmundito · #30 08-13-2017, 12:30 AM

Do I have to take off the ignition switch or remove the whole steering column to remove the gear box? I need to replace the gasket on the oil filter housing, and there's a bolt that holds the housing which is close to impossible to take it out if I do not remove the gearbox first. The gearbox gives me less than 5mm clearance to stick an allen wrench, but I need more than this clearance to take the bolt off to be able to remove the housing.
Do I have to really take off the gearbox to get the oil filter housing off?
and to change the oil cooler lines, do I have to lift the engine, according to my observations, is it all of this necessary??????, beacuse the steering pump pulley robbs against the upper oil cooler line and is about to cut through it. I am in a big mess, I cannot believe these dumb german engineers on how they put this car together!!!!!!!!!!!!!
Having to take off gearbox to remove the oil filter housing gasket....
any help would be gladly appreciated....