I read somewhere, that there is a difference between the left and right control arms. Can someone shed some light on the differences between to two? What would happen if they were installed on the wrong sides?

 

The upper arms are not perfect triangles in that the ball joint is offset (to the rear? Can't remember w/out looking at one...) on both sides. Therefore, each side has a unique arm. I had to deal with this after a vendor sent me two correct rebuilt lowers and two of the same uppers - of course, the car was apart before I figured it out... Luckily it was not needed for transportation and could stay on stands in the garage for the week it took me to get the correct upper arm and send back the duplicate... This is a good time to replace the front springs as well...

You also want to consider use of OFFSET upper arms like I had to do. My car could not be aligned to spec with the standard arms having a straight shaft. Luckily, the vendors are aware of this possibility and they sell upper arms that feature a shaft that has its ends offset from the middle. Typically, the problem is that the arms need to come in more than normally possible, so the offset shaft allows this to happen... Ask Van Steel!

 

Thanks for your quick response.

From the ball joint to where the mount, are they the same length?

On my car the right front tire seems to be about 1 inch more outboard than the left fron tire. They are not original, becuase the right side upper a-arm has been marked in paint with the letters "LT". I thought that maybe this signified Left Top and they were put on the wrong side at some point.

 

If you look at the upper arm, the ball joint should be tipped toward the rear of the car. I would guess the car would be undriveable if the arms were reversed because the suspension geometry would be so far off. There could be various reasons for the difference in wheel offset. The body might be off center on the frame - you can reach or measure between the frame and the rocker channel to see if the gaps are even. The frame could be bent - not good news. The wheels could have different offsets - easy enough to fix.

These cars were not put together with the attention to detail that we are used to seeing today so you have to be more flexible when it comes to "quality control", and there have been 30 years for Bubba to perform his miracles.



Rick B.

 

Thanks for your help. I am want to change the fron coils on it, but the weather is way too nice right now. As usual I will turn to this forum for guidance. You guys ROCK.

 

You'll have the steering knuckle separated from the A-arms (obviously) and you will have pulled out your existing springs as part of the process...so when you swap in the rebuilt arms, instead of putting back in some questionable old (maybe even original?) springs, it's a good chance to put in some new springs of known rate - such as 550-lb fronts...unless you know that you have newer (and good) springs. They cost maybe $50 or $60 apiece?

Look your car over and consider this little story: On my car, the right tire seemed to want to sit far back in the wheel opening compared to the left when viewed from each side - a sign of frame sway as I learned from posts on this forum. Also, the shop could not bring the alignment into full compliance with the specs - mechanically limited with a need to take all shims out on the right front upper bolt location - and still not enough! This is apparently common on the big-block cars with all that engine weight... Once I got the offset arms and a proper wheel alignment - where the offset arms now allow full compliance with alignment specs, having shims at each of the 4 (2 per side) upper bolt locations - it all looked good. I did have the shop inspect carefully to be sure that there was no hidden accident damage causing this and they said no evidence of such....so frame sway it is. The car is now in good shape.

 

I don't think the suspension could even be fully assembled with the top arms swapped left-right. The upper ball joints would be at an angle preventing reassembly.

Camera horizontal:



Top photo: correct A-arm.
Bottom photo: right-hand A-arm fitted to left-hand chassis mount.

When the wrong arm is installed, the ball joint is too far forward and tipped back too much.