'01 QX4 | Rear Upper Control Arm Replacement

[tabrown11]

Hey All,

I am currently having an issue with my rear suspension: when I come to a full stop or start from a full stop there is a thud heard from the rear of the car. I took the car to a mechanic to take care of something else for me [calibrating the TPS] and he noticed the thud when test-driving it. His suggestion was to replace the Rear Upper Control Arms. I visibly inspected the control arms and there is nothings visibly wrong, but honestly there is not a lot of visibility.

So, I have two questions:
- With what I am experiencing [when I come to a full stop or start from a full stop there is a thud heard from the rear of the car], does it make sense that replacing the rear control arms could fix this?
- If so, how do I need to jack up the car to replace the rear control arms?

Thanks for the help!

[atraudes]

I could see the thud being caused by the upper arms if they were loose enough to allow the top of the axle to move back and forth, causing the thudding. In that case the lower arms would be the pivot point. Whether that's the cause of your noise, it's hard to say.

Here's a diagram of the rear axle, to give you a clearer idea of how things are set up, in case it helps. They refer to the arms as links.



If you decide to tackle it, check out my writeup on how to do it. If the upper arms are in need of replacing, I'd replace the lower ones as well. The good news is by doing this, you won't have to worry about the infamous death sway

[fueler]

Check driveshaft, u-joints. Theres an entire section on it in FSM

[rgk]

I second what fueler said. Bad control arms are more likely to cause a sway.

[Silverhorn]

I'm currently upgrading my rear suspension (2" lift) and I'm wondering what other pieces I should check/replace. Is this a good thing? If so what am I looking for to tell that its good, or needing replacing?

I've got new shocks and springs for front and back, and that's it suspension for suspension parts.

Can you guys suggest other things on the suspension that I should look into?

[atraudes]

Replacing the rear control arms is recommended for every owner if it hasn't been done already since it's such a common issue on our vehicles.

I'm sure each component has its own tolerances as far as play and such that you can test, but all the mechanics I've seen just wiggle things. They use that in conjunction to what they feel in the test drive to determine what's gone bad.

I replaced all of the rear suspension components this summer wholesale because I wasn't exactly sure what to look for, and I'd rather know everything is rock solid (and I won't have to think about it again for some time). Check out my post here for a list of other suspension components to consider replacing (and the make/model that I bought) in addition to the control arms. I recommend Proforged wherever possible because they manufacture high quality, zero maintenance products.

[Silverhorn]

Thanks atraudes!