Normally, our customer projects start with a bare or base model, and the customer wants to take it to another level. But, in this case, the same objective existed, to take it to another level, but instead of starting with a base model, we started at the top of the food chain for MINI’s….the GP (specifically, a 2006 MINI Cooper S JCW GP). In MINI’s view…this was it, this is the best MINI of that generation there was….what more could be done, what more should be done?
Ah, we have our ways. This car will be a dual personality car, being used for daily driving, but also used for Autocross and track day events. Therefore, that defines the canvas and the needs…we need to improve the engine, the suspension, brakes, and tires. The GP is mainly distinguished from the other MINI’s or even the JCS (John Cooper Works) versions with body and trim upgrades. The engine, brakes, exhaust and suspension are the same as the JCW versions. The trim upgrades are the hood inlet duct (carbon fiber), the mirror caps, the interior trim (carbon fiber), the wheels / tires, the rear wing above the rear hatch, the rear trunk lid handle (carbon fiber), and the rear lower diffuser.
The JCW / GP already has many upgraded parts, and many that we would install on a base Cooper or a Cooper S. Example, we believe the “cold air intake” on the JCW to be the best solution on the market…better than any aftermarket “cold air intakes”. The JCW has the upgraded exhaust manifold…the JCW has the colder spark plugs, the JCW has the upgraded SC reduction pulley. So, what’s needed?
The crankdamper offers an opportunity …for two reasons. It is available in a reduction size…further reducing the parasitic drag on the engine, and freeing up Horsepower, but also, it comes in a design that addresses a fundamental shortcoming as delivered by MINI. Even if we weren’t looking for HP, we would recommend the upgrade to the aftermarket crank pulley. The stock unit, which acts as the damper, has a rubber center core. This is located right beneath the passenger side valve cover. If the engine develops an oil leak at the valve cover……yes, it will happen, it’s only a matter of time, then the oil can drop right on the damper, and the rubber in the center core. If it does, or if the rubber just ages out, then at some point the crank pulley will just shear, and the MINI will be stranded. The engine will run, but everything else dies, including the power steering and the cooling system. NOT a good thing.
In our view, the best aftermarket crankshaft damper is the one from ATI. And, to beat that, it comes in either stock size or a 2% reduction. We will take the 2% reduction please.
This would be the big area of change….mainly because the other features that distinguish a GP model are not suspension related, so this is indeed an area that could use some attention. As we have written about before on the R53 MINI Cooper, the suspension is rough, has limited suspension travel….but of all the various generations of MINI’s, the R53 has the lowest center of gravity. If the car is going to be used for autocross and track use, then even though the MINI sits relatively low, it is not set up well. We need still lower ride height without compromising the ride, we need more camber, we some of the suspension bushings to be upgraded to provide more crisp response, we need different and adjustable sway bars to allow for better initial turn in or corner rotation, and some of the control arms need to be upgraded in terms of strength, and we need more camber adjustment front and rear. Simple, right? In reality, yes it is, but quite a few parts need to be changed.
CAMBER (Front and rear)
Almost all cars, when they are going to be used for autocross and track, can use a much higher setting on camber front and rear. Depending on the customers use, we have defined six different alignment setups to accomplish the customers goals. Whatever level the customer wants, on a MINI Cooper, there are no stock adjustments available for changing the front camber. Therefore, we need to change that. The most straightforward way is to add a set of adjustable front camber plates. In our view, and all of our testing, the BEST set of adjustable camber plates is made by Vorshlag. Strong, better bearings than all others, thin (reduces the stack height), and easily adjustable, this is just what this car needed.
At the rear, the stock MINI (all of them), has some rear camber adjustment built into the rear lower control arm. However, depending on how much camber you want, this may not be sufficient (and also remember, we will be lowering this car, so we will gain some natural negative camber from the geometry of the suspension, but we will still need more). That’s need part A on the rear….the other need on the rear lower control arms is strength. We have seen MINI’s, where the strain on the rear suspension, has caused the rear lower control arm to buckle or break. The stock rear lower control arm on the MINI is very soft, very thin, you can even grab it with your hand, and both twist it and distort it. Yet this is the arm that bears most of the force under cornering. So, another benefit of introducing an adjustable lower control arm is strength.
The MINI….all of them, much like many BMWs, comes with a slightly amount of understeer when driven hard. However, for autocross or track use, this is not desirable or optimal. We want the car to turn in crisply, quickly, and controllably. The easiest way to dial out some of the front understeer, is to change the rear sway bar…..to make it bigger, and adjustable. However, this is another area where going bigger does not mean go BIG, we just need a tad bit more torsional rigidity in the rear bar, not a lot. If you go BIG, you actually will make the MINI twitchy, and it will not feel confident inspiring. On the R53 MINI, you need an 19mm, solid, rear adjustable sway bar. There are lots of them out there, most are nearly the same, normally we would lead with the NM Engr rear adjustable sway bar (better mounts, bushings), but in this case, we went with the H Sport adjustable rear sway bar (mounts can be lubed externally).
Along the same line, if we want the car to rotate and turn in crisply, the other area on the MINI then needing attention would be the front lower inner control arm bushings. The stock bushings are soft, rubber, and allow too much deflection under load. There are a variety of options here…and thought needs to be applied to understand the need and application. Just because we want to upgrade the bushings, does not mean we have to go with the hardest, stiffest solution. That would induce noise, vibration, harshness, and yet, not really provide much of a difference in handling response. In our view, the proper upgrade here is to go with a polyurethane bushing. Much more solid than stock, but it does not induce any noise, vibration or harshness, and, they are warranted for a lifetiime, even better than stock. We do not believe that all the other suspension bushings need to be changed, nor the engine or transmission mounts. Changing most of the other bushings either does not return a lot, or induces negative aspects into the car.
Finally, the area that is most in need of change, are the shocks / springs. This is a difficult choice, as we mentioned earlier, the stock MINI is limited in the amount of natural suspension travel….mainly due to the front lower suspension interacting or being limited in travel due to the front lower subframe rail. So, changing out the MINI’s suspension with sport springs is usually not a good approach. The car will sit lower, but the ride is awful, and the car has such limited suspension travel that it just bounes down the road. Putting on just any coil-over isn’t the right choice necessarily either, and almost all, if they are adjustable, are NOT. Due to the location of the shock adjuster on most coil-overs on the rear…the rear adjustment knob is on TOP of the shock, where you can’t ever reach it or get to it once installed. Finally, you want….you need a shock that is adjustable, since indeed, this is a dual personality car, and you don’t want to be bouncing down the road, you want to enjoy driving your MINI. The only solution that we have found that works great is the Bilstein PSS (B16) solution. There used to be two versions, a PSS9 and a PSS10. Originally, Bilstein made the PSS9 for the R53 MINI Cooper….however, in 2018, Bilstein upgraded the coil-over for the R53 MINI, and now makes the B16 version in the PSS10 design.
Notice how on the Bilstein PSS10 there is the BIG shock adjustment knob on the bottom of both the front strut and the rear shock….this is the big difference. Big, easy to reach, can be adjusted softer or stiffer in seconds…versus others that are adjustable, but not reachable. Implementation makes all the difference.
The good news with either the MINI Cooper JCW or the GP model, is that both come with the JCW brake upgrade front and rear. The real benefit is in the front brakes…instead of the stock brakes, the JCW and GP come with a larger, 4-piston, full floating caliper and larger rotor. Due to the size of the caliper, the brake pad size is also increased. The stock MINI brakes, if driven hard, are just NOT up to the task. The good news is the JCW / GP brakes are…no need to move to a true big brake kit (BBK). So…does anything need to be done here? Always…the fluid needs to be upgraded (to one of seven different grades of brake fluid that are better than stock, and can take the heat abuse from either autocross or track use)(fluids like StopTech 600, StopTech 660, Motul 600, Motul 660, Brembo HTC-64t, or Endless….in this case, we would choose Brembo HTC-64t (the choice is more guided by frequency of abuse and budget)).
But, there is more…the rotors. The stock JCW /GP brake pads work well for the occassional street / autocross / track mixed use. High carbon content, stronger, harder brake rotors are what is needed to sustain the ongoing aggressive use.
The picture below is the complete JCW / GP brake kit…as this kit can be installed on a MINI Cooper S to upgrade the complete brake system.
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