The only readily adjustable alignment item on a W123 is toe-in. Why even bother to bring it to a shop? 1/16 to 1/8" toe-in is easy to measure with various methods by rolling the car forward with weight-on-wheels 180 degrees, no spreader bar necessary. I've done my own toe-in adjustments this way for years with excellent results.

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85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked

This is a 126 and fully adjustable. I took it in again today and the job is sufficiend judging by the way it handles. So.....on the rack immediately after the front end rebuild, another time after excessive tire wear and to be told that "you (meaning me) must have bent the tie rod", once more after tie rod replacement, again for a check only by the competitor from which I bought tires and finally again today to make the final adjustments = 5 times to (hopefully) get it right. It drives nice!!!

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.

Good luck with the Defenders, mine only lasted 33K. Lots of cracking on the sidewalls and lousy tread life. I can't swear by the shop that aligned the car, but it always drove straight, lots of new parts on the front suspension and I rotated the tires about every 5K.

I recently tried a new shop for an alignment and the car tends to veer left. Everything looked good on the print out, but I'll bring it back and see what they can do.

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'81 300SD

I'm hoping the Defenders are good. I bought because they are one of the few listed for the 14" Bundt. They're supposed to go much longer than 30,000 mi. It seems tires are becoming more expensive. These were $550 out the door including 10% TN tax.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.

charmalu,
Thanks for the link on the spreader bar. Neat idea and first I heard of one. The concept is that you want the front tires almost perfectly parallel while driving (0" toe-in). Since there is slight play in the steering and suspension, RWD cars spec slight toe-in so as the front wheels are pushed back in driving they become parallel. Since FWD car fronts pull, they spec slight toe-out. The factory doesn't know how worn parts are so give a spec range. My 60's Mopars spec 1/16" to 1/8" toe-in, the former if new and tight parts. It seems the spreader bar is intended to give just a slight force to take up the main play in the steering. The wheels must rotate a little more when actually driving since M-B specs a little toe-in even with the spreader bar.

I wouldn't worry about caster too much. That is the "shopping cart wheel" effect where you want a line thru both ball joints to hit the road in front of the "tire patch center". That is mostly designed into the car. You need to move the lower ball joint forward or the upper ball joint backwards to increase caster. 60's cars were designed for bias ply tires which deflect when driving, moving the tire patch aft. With today's radial tires, they don't have enough caster and you can't get there w/ the factory adjusters, so people use offset bushings and such to reach spec. My 80's 300D's were designed for radials (began ~70's), so caster shouldn't be a big concern, though you could adjust the guide rods or replace a worn guide mount. If you get camber (tire lean-in, using lower control arm cam bolts) and toe-in correct, I doubt you would notice anything. You can never stay perfect since all changes as parts wear and the suspension sags. In my experience, a pull to one side is more often from the tires themselves. Swap L & R and see if the pull follows the tires.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

I've had that happen many times. The more play there is in the suspension and steering the more a tire pull will affect it. On front wheel drive cars the pull sometimes gets worse when you're on the throttle and goes away when you coast.

The worst is when everything seems fine for a while, then you rotate the tires front-to-back and suddenly the car wants to veer to one side.

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1981 Mercedes 300TD, 1994 Honda Civic Del Sol
http://mefi.us/images/fuelly/smallsig-us/67195.pnghttp://mefi.us/images/fuelly/smallsig-us/103885.png

You have to be careful out there. Most modern alignment equipment will not produce the alignment program for your old Mercedes unless it senses the bar is hooked up. We have a guy with an older unit in town that will accept my car without the bar.

Do you know if they are setting another car in the computer for alignment guide and print out? Absolutly the other four computer alignment machines in town of various manufacture will not come up when they tried.

Simply requesting the operator to install and hook up the spreader bar first. Of course they have none. I have never seen one but assume by that they may apply a variable pre load.

I priced alignment for the Honda the other day around town after the garage changed out a tie rod end and messed it up. About a hundred with tax and the majority of cars today are pretty much limited to toe settings unless replacing parts.

In fact the alignment shop I usually use is cheaper and will do everything needed on my old Mercedes. Thats if I am standing there watching him. Setting toe in is not an alignment job on these old buggies. All axis are adjustable if needed and of course interact so this meant the user must apply more mental effort that they perhaps are used to doing now.

In a way many alignment shops seem little more than a scam today. Some larger brand name cars do not even have enough structural integrity to hold an alignment. I took at one time an almost new American sub compact car in for a neighbor. Forget the model name.

There was no way that car should have been sold to the public. Even my alignment guy who is friendly with me mentioned these cars where a total joke. Was the North American public ever being taken in by that member of the big three at the time.

The machines I've seen may ask for the bar but don't require or have any way to determine whether is is installed. Getting a tech that is competent and gives a care has been the challenge. I've heard "it's in specs" too many times to count and had the car pull to one side or another just like the print out said it would. At least with the lifetime from Firestone I get to try another store at only the cost of my time and fuel. It would be worse to loose fuel, time AND money.

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.