A stiffer rear bar reduces weight transfer at the front in a given turn, which means more evenly loaded front tires and thus more front grip. It increases weight transfer at the rear since total weight transfer in a given turn is the same unless you change COG, track width, etc. So less grip in the rear, but the rear generally has a lot of grip anyway and the net result is more overall grip. Generally. Just don't go too big. There are other effects of course from reducing rear roll (through stiffer rear bars or stiffer rear springs) but I think that's the main one we're looking at right now. - Andrew
I think we are all saying about the same thing. I could get in a semantics argument that the weight transfer in cornering is the weight transfer, and the wheel rate just determines how the resistance to roll is proportioned. These types of arguments are similar to the people who only want to use the terms understeer or oversteer, and look down on the terms push and loose. I do not totally agree that a stiffer rear bar will add grip. A rear bar loads both rear tires. Because you are adding load to the rear you are unloading the front. FWD cars are generally overloaded on the front, so unloading the front should reduce the slip angle, and at the limit of adhesion give the front more grip. The problem is that just like the NASCAR crew man twist wedge bolts during pit stops, the unloaded rear wheel is extending its travel because we use bars that are stiff to the point that we pick up that corner of the car. How many FWD cars have you seen autocrossing with the inside rear wheel off the ground? The extended unloaded rear transfers weight to the loaded front wheel. You added wedge in NASCAR lexicon. This would tend to reduce the grip at the front.
I agree, and I do see people going way too big with their rear swaybar (not just on the Mini). Meanwhile they're only running -0.2 degrees of camber up front when they could bump that up and have a much better handling car with the balance they want, without the negatives of a massive rear sway. - Andrew
Balance..... You can go too far with any adjustment. Like lowering the center of gravity to much at the expense of suspension travel and compliance ....
Most MINI's I know run the H-Sport 25mm adj. Competion bar. The 19mm street ,25mm comp. ,25mm race bars adjustment ranges over lap. (i.e.- 25mm race bar 'low' setting is lighter than the 25mm comp. 'high' setting) Talk to Hotchkiss if you want actual % over stock. I have the competion bar on my 05'S and switch between low & mid settings depending on tires an alignment. Wich ever bar you choose , next on your list should be adj. endlinks to remove any preload on the bar. I recomend THK-Powergrid. There is alot of good information on this thread. Just remember everyting works together, including your driving area , conditions and style. The only real way to find out is to try one and go from there. keep the shine side up, Scott B.