Upper Control Arm LH vs. RH Differences

mattster03 · Mar 5, 2015

I have a 2004 FX4 Level II that I was working on changing out the upper and lower ball joints this weekend and I ran into an issue. My new LH (driver's side) upper control arm was a different shape that the one I pulled out... the different shape seemed to locate the upper ball joint in a noticeably different location than the one I pulled out. What made things even more strange was that the LH upper control arm that I pulled seemed to match the new RH control arm that I purchased.

Can anyone confirm that the LH control arm on this generation of ranger is in fact a different shape than the RH? I do believe that my truck had a front left fender bender in the past and I am wondering if maybe someone who didn't know what they were doing put a RH upper control arm on the LH side when replacing it. Any help would be great!

The part numbers I have are:

LH: MK8708T
RH: MK80068

ianyboy · Mar 5, 2015

Indeed, I confirm, both Upper Arm are different.

gw33gp · Mar 5, 2015

I just replaced the upper control arms and ball joints on my 02 FX4 a couple months ago. I can tell you for sure, the L and R are different. My original right control arm was the two piece style. The new one was a one piece style but still different than the left side.

mattster03 · Mar 5, 2015

Thank you for the responses! It seems very strange that my LH looks exactly like the replacement for the RH side. I will take some pictures tonight to be sure.

adsm08 · Mar 5, 2015

They are a different shape. They do look very similar, but they are not the same. If you turn them around and use them on the wrong side you can't ever get the caster correct because the location of the ball joint relative to the ends of the arms is not the same.

The reason is that you don't actually want caster to be equal side to side. You want it to be a little higher on the left so the vehicle doesn't just run off to the right with the crown of the road.

mattster03 · Mar 5, 2015

I went to the shop and took a few pictures. As you can see, the overall "look" of the LH control arm just seems different to me. Different sized ball joint, some extra bends "up" and a noticeably different location for the centerline of the ball joint. Also, the outside to outside dimension is different:

LH: 15-1/4"
RH: 15-1/16"

Is this normal? Just doesn't seem "correct"

adsm08 · Mar 5, 2015

It's correct, it's normal, it's design intent. I already explained how the desired alignment geometry means different shapes, and ball joint center lines, between the two sides.

mattster03 · Mar 5, 2015

adsm08 said:
It's correct, it's normal, it's design intent. I already explained how the desired alignment geometry means different shapes, and ball joint center lines, between the two sides.

Thanks... that's really helpful. The problem is that the LH upper control arm that is on my truck (check and it is in fact stamped "LH" on the bottom) which I pulled does not match the new LH upper control arm that I received. I understand now that the LH and RH are different, but why is the one on my truck different than the new one?

Upper Control Arm LH vs. RH Differences

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