Traction in Action

Update by Scott Lear to the Mini Cooper S Club Racer project car
Jul 20, 2010

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With about 10 days left before the event, we decided to attend. That gave us only one weekend to go over the car and ensure everything was in good order—and it’s a good thing we did.

With our new OS Giken limited-slip differential, clutch and flywheel in place, it was time to do some real-world testing. Our friends at the NASA Southeast region had a full race weekend slated at Roebling Road Raceway, one of the closer tracks to our Holly Hill, Florida, headquarters. With about 10 days left before the event, we decided to attend. That gave us only one weekend to go over the car and ensure everything was in good order—and it’s a good thing we did.

Our first step in checking things over usually involves putting the car up on jackstands and removing the wheels. Our first snag ended up being a pretty serious one: the left-front wheel had a frozen lug, and no amount of convincing seemed to loosen the assembly.

The lug was fused to the stud securely enough that applying massive torque only spun the stud. We figured at first that we’d simply unscrew the stud from the hub, as we’ve done on many other BMW products, but the stud refused to come free. We attacked it with a huge lever, impact tools, a drill, a Dremel—the whole arsenal. All we got was a free-wheeling stud that wouldn’t come out and a properly stuck wheel.

We hypothesized—correctly, it turns out—that the stud had some kind of flange or spacer that was keeping it trapped behind the massive rotor hat of our AP brakes. Rather than continue hammering away and ending up with an car unable to even roll back on the trailer, we cut our losses, admitted defeat and put the wheel back on the three good remaining studs.

We were sure that we’d done some serious damage to the hub, so we loaded the car back onto the trailer and did not pass go as we went directly to Ian Stewart’s Maitland Importers shop in Orlando. With just a few days to prep the car, we didn’t have time to guess at a solution. Ian’s shop would have a replacement hub in stock and the know-how to fix the problem in a hurry.

Sure enough, they found that we’d stripped the threads on the hub completely in the affected stud mounting hole. The flanges on the studs that were preventing us from pulling the stud out past the hat were revealed as well.

We needed some extra-long, race-worthy studs in a hurry, so we called our friends at BimmerWorld. Since our MINI has but four studs on each hub, and we’re planning on moving up to an even wider tire in the near future, we figured quality and strength were of the utmost importance. Owner James Clay told us that their Premium Race Bulletnose Wheel Stud is the same part they use on their Grand-Am Continental Tire Challenge BMW race cars, and at $9.99 a piece, they’re not terribly expensive. We ordered a set of eight to take care of both front hubs. The studs are shot peened and double magnaflux inspected, and the bulletnose design makes starting the lugs on the threads a breeze. They’ve even got pre-applied threadlocker on the hub threads. We opted for the 92mm variant, but an 82mm option is available.

We lucked out with our timing, too, as Ian’s MINI computer guru, Jan Brueggermann of Revolution Mini in California, happened to be at the shop. He couldn’t resist plugging his laptop into our MINI, and he found that our JCW ECU flash was a much older version that was causing the car to run rich just about everywhere. He gave us the latest factory JCW flash and found that it leaned things out considerably; he said he wouldn’t be surprised if it were worth 15 or 20 horsepower.

Ian had the car ready with a day to spare, so we loaded up and headed to Roebling Road. The race weekend went without any major incidents, and the improved out-of-corner traction that our OS Giken differential was striving to provide was impressive. We say “striving to provide” because our old BFGoodrich R1 tires seemed to be at the end of their lifespan. The MINI was particularly twitchy on the back end, so we lowered our running pressures from about 39 psi to 35 psi in the rear, which seemed to help matters. (We kept the fronts at around 39 psi). We were uncontested in Performance Touring C, so we even came away from our weekend with a shiny trophy.

Our tires are toast, so it’s time to make the switch to a set of brand-new BFGoodrich R1s before our next race. We’ve also got a Sneed Speed Shop front splitter to see if we can’t get more grip on the nose of our front-wheel-drive beast. Look for another update from our HyperFest weekend soon, or check out a bit of a video teaser here:

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minimac SuperDork
7/20/10 11:21 a.m.

For future reference: temperature is measured in degrees, pressure is measured as psi.

Sarah Young
Sarah Young Editorial/Art Assistant
7/20/10 1:07 p.m.

Duly noted. This heat is getting to my brain--it must be, like, 100 psi outside.

7/27/10 6:03 a.m.

I didn't catch the name of the splitter you have installed. What was it?

Scott Lear
Scott Lear
7/28/10 8:35 a.m.

It's a Sneed Speed front splitter; we'll have a full update on that soon. It rocks.

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