Adjust Castor, Steering in 300 TDT pulls right

I have a 1982 300 TDT. The steering is pulling to the right. I took it to my favorite alignment guy and he adjusted the castor and the car was tracking properly. I must have hit a chuckhole or something,
because the car is pulling right again.
If the car is pulling right do I want to move the right wheel forward or backward to correct it? Does anybody know how many centimeters to move it as a first try to see what happens? I am thinking this will be trial and error and take a few tries before I get it right. I live way out in a remote part of the California desert and it would mean a 200 mile drive to take it back to my alignment guy so I want to give it a try myself.
Will adjusting the castor throw off the toe-in? My tires are wearing well right now with no uneven wear like smooth shoulders or anything.
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I suggest you check all your suspension parts. Our cars are getting old so the more we change in suspension, the more it drives like new. I am suspecting that it is possible either upper control arm bushings or the lower one is one the way out that with a bump, it shifted position... affecting the castor.
Also for your steering... if your tie rods are old... you should change them out. Lemforder or Moog only... don't go with cheaper brands as they don't last long at all... My Meyles are wearing out so rapidly.
Also check your tire pressure... one pound off is enough to make car pull to one side.
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Thanks Tiger. I have changed the control arm bushings, but with 480,000 miles on the car they may need replacement again. My alignment guy is a pretty good mechanic and he goes over it when he aligns it and says everything is in good shape, but what you are saying makes sense and I will check it out when I get the car in the air to set the castor. I have done the tie rod ends too. I think I need a steering damper, but that shouldn't make it pull I don't think.
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WOW... almost half a million miles!
Biggest change to suspension for most people are sway bar links... these are super neglected. Once you change all 4, the car feels so planted to the road.
Next big change is to change the springs... I feel they should be changed every 100,000 miles. Upgrading to Eibach or any reputable lowering spring kit is a huge improvement to all MB with spring suspension.
Shocks and struts are to be inspected before changing... You inspect it by taking it partially out and work the rod in and out to see if they are still strong or not. Forget about trying bounce test. Bilstein or the old Fitch (remember this brand) on the older MB are pretty much last forever...
Usual upper and lower control arms are usually changed when ball joints are worn... you can easily inspect the upper ball joint by grabbing with your fingers and bounce the car with your chest... if you feel movement, it is worn out. If it is really worn, you will hear clunk when you turn... another way to test it on your drive way... turn all the way to either side... give the car a little gas and slam on the brake... if you hear "THUCK" or "THUCK THUCK" your ball joint are worn out. Repeat for the other side.
Again, for these upper and lower control arm... it is best to change them at 100,000 miles too.
The least inspected parts are the subframe bushings... Even myself... I am not sure how to test them... but I'd suspect they are worn out by 200000 miles.
If you are handy, you can do all these stuff at very low cost. Consider the fact they only cost X amount of money... and have a lifespan of 100000 miles... I think they are damn cheap for outstanding ride quality.
It pays to use high quality parts such as Lemforder, Moog and BIlstein... they last a long time. Cheaper brands like Meyle ( I have used them) or others... they don't last long at all... as short as 12000 miles. Mileage varies depending on type of parts... but for suspension, cheap parts wear out super super fast.... waste your time and money.
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I have changed the springs, but it's been a while, probably more like 200,000 miles. I had the engine remanufactured at 430,000 miles.
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This is great info! I have the same car and I hear a kind of clunk in the front end when I turn the wheel either direction, not always but frequently. Sounds like ball joints maybe? I have replaced the tie rod ends not long ago. I've "only" got about 280,000 on mine. Still runs like a champ and rides like a dream.
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