I have a 1985 300DT (W123 chassis) that has had the center link replaced. Now it needs a front-end alignment.

I am being told (from a national major-brand tire/alignment/repair chain) that a special tool is required for this job that they don't have. Something about applying pressure to both front tires evenly and simultaneously.

Is this true? Can I fabricate this tool? What are the specs of the tool? Are there alternatives?

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Mike Frederick
1986 300SDL, 240K+ miles
1985 300D KaliKar, 270K+ miles

There is a tool, I don't have the specs at hand, you can fabricate a tool that will perform the function using a long section of AllThread rod, a nut for adjustment on each side, and a shorter section of EMT that fits over the all thread at both ends. You then get the "tool" in position, adjust the nuts so as to extend the overall length of the tool by forcing the sections of EMT outwards against the front rims. You can modify the outside ends of the EMT with a groove to fit onto the tire rim's edge, then you can measure from the inside dimension of that groove four or five inches and make a register mark on both ends. That way you can take those known end piece dimensions and adjust the length of the center section made up by the AllThread rod and the thickness of the nuts to create the exact length you need.

There is such a tool. It's called a spreader bar and, I think, it is supposed to be used to simulate the dynamic pressure of driving at speed while the car is actually at rest on the alignment stand. There's a range of opinions as to its utility or necessity. It may be "old technology" that has been supplanted by modern laser alignment tools, or it may be useful.

The quality of your alignment is probably more a factor of the condition of your suspension and steering components and the skill of the technician than a single specialty tool.

Here's a link:

83 300D camber problem

Why not just take it to a Mercedes dealer?

You'll likely need parts if your car truly requires alignment, and that's where they come from.

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Kent Christensen
Albuquerque
'07 GL320CDI, '10 CL550. '01 Porsche Boxster
Two BMW motorcycles

There is loads of information on this:-

Take a look at the following search results

http://www.peachparts.com/shopforum/search.php?searchid=5178767

Sorry I forgot to mention it is called a spreader bar - I've used a DIY clamp (that converts to a spreader) as an alternative when I recently did my own alignment.

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

I'm impressed they didn't just take your money and get it wrong!


M

Ho much would the error factor be without a spreader bar in place, i assume it effects the toe- in tracking only.
mak

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mark

I think that is difficult to say - on slip plates with a spreader bar fitted I got the impression that the tyres on my W123 moved about 3cm apart. I didn't measure this though.

I tell what I'll do when I get to checking everything out again (when my engine is in etc etc etc) I'll measure the movement induced by the spreader bar. I've now got a way of measuring and applying the force applied.

I'll post my results in this thread:-

How I adjusted the toe in / out, camber and caster on my W123 300D

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!