Take it to a professional with the proper equipment and ask them to set your rear toe to zero. If they try and set it with the control arms go somewhere else... 2cents
IMHO, you should not attempt to set the rear toe yourself. If I remember correctly, the R53 is done with a couple bolts (on each side) that attach the subframe. You absolutely need to have a professional do this for you. Mine is at 0-toe and 1.5-camber. The car is great at this setting as it goes to 1.8 loaded. Extra tire wear is noted but unimportant as I do like the effect of the settings. Good luck! :beer
The rear toe is adjusted by sliding the Trailing Arm in sloted holes. There are three bolts that are loosened, the arm moved, and the bolts tightened. There is a special BMW tool for doing the adjustment but it can be done by trial and error without the tool. Measure, loosen, adjust, tighten, measure, and repeat. Many alignment shops will not adjust the rear toe because they say it requires a special tool. The alignment shop that I go to does it without the tool but said it was a pain in the butt the first time the tech did the rear toe adjustment (took him about an hour but I have a GP which makes it harder to access the bolts). When the bolts are tightened the toe tends to change a little making it a little guess at where to adjust before tightening. After doing the rear toe a few time, the tech is much faster. If you install aftermarket adjustable rear control arms, the toe can be adjusted using the control arms instead of the trailing arm bolts.
Even if one does have adjustable control arms, I feel that adjusting with the slotted holes on the trailing arm bracket is still the right way to do it, as opposed to changing the length of the control arms. I find that it helps to trace the outline of the bracket onto the body with a paint marker before making an adjustment; then you can see how far you have moved the bracket, and it makes it easy to find your original setting just in case things get really screwed up. Jason
Zero toe has zero benefit; why do you want something like that? If the rear control arms are used to adjust toe, they must be lengthened or shortened top & bottom together, and that affects the distance between tires. The range of motion for the trailing arm within its bushing will be reduced if track is altered drastically; the early model bushing/arm is slightly more forgiving than the later model, BTW. For this reason I recommend setting the upper arm to stock length if it is aftermarket adjustable, and don't mess with it. Either the top or bottom control arm can be used to adjust camber, they are not designated top for toe, bottom for camber; the lower arm is just easier to access. Only move the trailing arm bushing bracket to adjust toe.
I can't speak for Dawgscj7, but for me zero toe seems to be a great benefit over the massive rear toe in that most MINI's get from the factory. It frees up the rear end and dramatically improves tire wear. Zero rear toe is usually my compromise autox/daily street setup. Jason
Me and some others like a *little* toe in on the rear - like 1/8" total. Helps settle the rear a bit. But to each his/her own. When I got my last alignment, The toe adjustment was maxed out to get to 1/8" with -1.5 deg of camber. I wanted less camber, but couldn't get it without screwing up toe (even with adjustable lower arms). Not sure why, because I've been able to get it before with the rear even a bit lower than it is now. I'm gonna swap to adjustable plates up front so I can add more camber there, so -1.5 will be fine in the rear... but a bit perplexing. Hmmmmm.
and a little toe goes a long way - I once asked mine to be set at 1/8" total, but the mechanic set it to 1/8" per side for 1/4" total (rear toe in). It totally killed the car. Felt really stiff and not fun to drive. Sure went straight on the highway though. Anyway, backed it off to 1/8" and all was good. I've been curious to try less toe, but afraid it will be too nervous on the highway and it's not cheap or convenient enough to experiment with..
I've run mine at both - zero all around, and 1/8"in on the rear. Both feel good, not a crazy amount of difference. But with a lot of highway driving the 1/8" in is a good balance for me, and doesn't slow me down in the twisties.
0.00 Rear Toe, which is something I like, is rather twitchy, then again. I like that. Mr Chad was able to get me real close. -0.02 Left - +0.01 Right. Coupled with a -2.00 Camber on each side in the rear and some stickish summer tires. It's as if it's on rails. But twitchy...Just like "I" like the setup. Please Note that I don't use the car for a daily driver.
More rear toe will decrease oversteer. If you run a big rear sway bar (22mm) and a little toe in, you'll get a neutral rear end and a flatter car. It's a good combo for aftermarket springs that aren't as stiff as coilovers. I like to run a medium rear bar and zero rear toe, but the car was lacking roll stiffness till I installed stiffer coilover springs. BTW, any shop that knows how to align a BMW can align a MINI. Same semi-trailing arm mount setup as most of the 3-series cars.