I am getting accelerated tire wear on the inside tread of one of my rear tires. Just sticking my head under the car it looks like the inside pivot for the wishbone has an eccentric bolt. Are there any other adjustment points on the rear suspension?
What are the alignment specs for the rear on a '72 411 4dr?
Rear Wheel Alignment
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raygreenwood
- Posts: 11912
- Joined: Wed Jan 22, 2003 12:01 am
The adjustments are few and far between. The eccentric is to adjust toe-in. What you may be getting is excessive camber. The camber comes from a combination of two things. (1) some settling and sag in the steel of the rear beam and teh trailing arms. You cannot correct that, but you can adjust for it. Also, once it sags to a certain point...kind of its fatgue point....it does not increase. Generally once you adjust for the sag it has...it will stay the way it is. (2) the trailing wishbone rubber bushings will cause excessive camber when they are worn out.
Adjusting camber....is a lot of work. There are two ways to go about it. (1) Calculate how much it is off, take the wishbones to a frame shop and have them bent, This is trial and error...and I do not reccommend it at all.
(2) If you look at the mounting points for the trailing wishbone...both inner and outer....you will notice that they are in slots. This is so the centering of the rear wheels in relation to the track and the driveshafts can be adjusted. If you happen to remove one of tehse mounting points from teh beam....you will see a steel spacer inside of the beam that keeps the torque of the mounting nuts from crushing the beam.
What you need to do.....is remove the inner mounting point....the one with the eccentric. Then...with a die grinder.....enlarge the height of those slots...upward. You need to enlarge teh slots in the metal spacer as well. Then.....on the bottom of the beam...you need to drill a hole and thread in a bolt to push upward on that spacer. This way you can adjust the height of that spacer...and therfore the entire inner mount...before you torque down the mounting nuts.
To adjust...you lightly loosen the outer trailing arm mounting point nuts...and the inners that you have just modified.....and with the car on the alignment rack....tighten that new bolt you just installed until the camber is straightened. Then tighten the inner and outer mounting points...and readjust your toe-in.
It takes about an afternoon to do all of this. Ray
Adjusting camber....is a lot of work. There are two ways to go about it. (1) Calculate how much it is off, take the wishbones to a frame shop and have them bent, This is trial and error...and I do not reccommend it at all.
(2) If you look at the mounting points for the trailing wishbone...both inner and outer....you will notice that they are in slots. This is so the centering of the rear wheels in relation to the track and the driveshafts can be adjusted. If you happen to remove one of tehse mounting points from teh beam....you will see a steel spacer inside of the beam that keeps the torque of the mounting nuts from crushing the beam.
What you need to do.....is remove the inner mounting point....the one with the eccentric. Then...with a die grinder.....enlarge the height of those slots...upward. You need to enlarge teh slots in the metal spacer as well. Then.....on the bottom of the beam...you need to drill a hole and thread in a bolt to push upward on that spacer. This way you can adjust the height of that spacer...and therfore the entire inner mount...before you torque down the mounting nuts.
To adjust...you lightly loosen the outer trailing arm mounting point nuts...and the inners that you have just modified.....and with the car on the alignment rack....tighten that new bolt you just installed until the camber is straightened. Then tighten the inner and outer mounting points...and readjust your toe-in.
It takes about an afternoon to do all of this. Ray