Originally Posted by hprt

Here is a post I made in the Tamiya Mini Cooper thread many moons ago (back when I was running the M06 in the Canadian WCICS series):

First off, I would like to say that I love RWD cars.

That being said, I abandoned the M06 because it was too hard for me to drive consistently over the weekend at WCICS events. Here's my thoughts:

The M06 can be set up to be smooth and easy to drive, but that is not always the fastest way around the track. In order to make the M06 fast, you need lots of front grip, which makes the car extremely twichy on corner entry, which then transitions to understeer on corner exit. For drivers with less than smooth throttle control, a setup like this is also prone to oversteer. As the traction comes up over a race weekend, the problem gets worse, and the car gets even harder to drive smoothly, which leads to more clipped apexes when driving the tight lines required in mini. Compared to the RWD, the FWD cars maintain the same driving feel but simply get faster as the grip comes up, so they are as easy to drive in Friday night practice as they are in the Sunday mains.

Now that I have explained why I no longer run the M06, here are my tips for making it fast. You can worry about the consistency issue yourself.

The key to RWD is to get as much rear grip as you can, then slowly work towards increasing front grip to get a balance you can drive consistently. For me, on a low grip track, like club races, start with new S-grips on the rear, and type A slicks on the front. No need to glue the sidewalls at first. Yellow rear springs, red front. no swaybars. 30 wt oil front and rear. This is a soft setup that works at both of our local tracks (KARZ and Carcar). If you are looking for more front grip, you can go to S-grips on the front, but I like to stiffen up the front end with blue springs at the same time to try to take away some of the weight transfer and the off-throttle steering the S-grips bring.

Once you get to be a master at driving around the twitchy steering, you will find that you actually need more rotation mid corner in order to keep the corner speeds up and to reduce the mid-corner understeer. This will drive you to adding rear sway bars or going to blue rear springs.

For really high-grip (as high as we get around there) I have used tamiya type-B slicks on the front with full sauce and no glue on the sidewalls. At a WCICS event, this sacrifices some of the ultimate corner speed, but results in a car that is drive-able on Saturday night qualifiers and Sunday mains.

Some people will tell you that if you glue the outer rib of tread using S-grips the car is fine- this is the same as using less grippy tires, as you are effectively making the tire narrower by adding CA glue to the tread. The problem I have with that is the glue wears off, and every time you re-apply the handling changes slightly. using glue also requires you to clean off the glue area before each race to ensure the same traction and driving feel.

as for the car itself, always run a fully open diff on RWD - otherwise you will be doing donuts.
The M06 shock lengths are different front to rear, use the OEM setup lengths - the extra rear droop helps with weight transfer off-throttle on corner entry when using the harder slick tires on the front.
front toe setting for me is typically 1° out, linkage setup to minimize bump steer
I run the pro kits, so the rear hubs are the 1.5° toe in each side, lower pivot hole
we have no min ride height requirement in mini at the WCICS - I run about 3.5mm, and use adjustable top links to compensate for camber gain with reduced ride height. Camber is set to about 2° front and rear
You can play with battery location to adjust weight distribution - I run with it forward.
I use full size square packs in the M06 - seems to work better for me with the 225 mm WB

after re-reading your post, I see you are limited to M and S grip tires. Use the M grips with the extra hard inserts on the front and glue the sidewall/tread edge. Use the S-grips on the rear with hard inserts.