Do I adjust camber in the rear after lowering my Mini with the upper or lower control arm? I have a set of Hotchkis arms and am not sure which ones to replace.

 

Technically, it can be done in either location, but it is easier to replace the lowers and adjust camber via the lowers. Toe will be affected by both lowering and camber adjustment so that should be included in the alignment; toe adjustment will be needed up front as well.

 

We gain toe in the rear from lowering as well? Any idea how much?

I thought only the front toe was noticeably affected by lowering.

 

But what is the best one to change out as I am going to keep the other arms stock and don't want to break them.

 

I have either seen lower changed out or both. I have never seen someone switch out the upper control arms only.

 

If you're only get one set, you put them on the bottom so you can easily change camber. The top ones are generally regarded as the ones upgraded to change toe.

 

What year is your MINI? If it's +'05 there may be enough adjustment to dial out any excess camber.

 

If you adjust the uppers and lowers it will impact the distance between the wheels (track) and to a lesser extent toe. Toe should be adjusted at the trailing arm bracket only. If you try to adjust toe via the upper control arm (lowers must be adjusted also) it gets very complicated because camber affects toe and adjusting for toe (via control arm) impacts camber and track along with it.

 

What Kieth wrote is VERY important!!! I'll write it again, DO NOT ADJUST TOE VIA CONTROL ARMS. Camber and toe curves have a very important relationship and together these affect grip and stability.

Theoretically, my observations, if you correct for too much neg camber via the lower control arm the virtual swing arm is shortened a little and if adjusted via the upper arm it becomes a little longer.

The virtual swing arm is the lever arm or pivot each control arm moves thru connected via the instant center - think of two compasses connected to a single point whoes length is established by each control arm. I won't bore us with a description beyond this. Know this, a shorter virtual swing arm will quicken camber gain, like narrowing the track a little. Depending on alignment specs and damping rates this may be just fine. A longer virtual swing arm will reduce camber compensation because the arc circumference the wheel travels thru is larger.

Niether of these is really a problem under most conditions as the differences are pretty small. Either one can be offset by changing track width - in either direction. When I had my track setup with 38mm offset wheels and a 5mm spacer, I added about 1/4 deg static neg camber to help offset the loss of camber gain.

This is only true for the rear multi-link design - does not correlate directly to the Mac Strut design up front.

 

Replace the lower control arms.