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GP Underbody Panels

At the end of production for the first Generation new MINI came the GP. It was the fastest MINI to date at the time and had some interesting aero tweaks including full length under-body panels to smooth the airflow under the car. Those panels run at least $200 each if you can find them, but there is an alternative that is almost as good (but also at end of life.) The second generation (R56) Cooper S had optional underbody panels which were 90% the same shape as the original ones and only about $60 each.  Fitting them is fairly straight forward, but does require some modification of the panels and perhaps fabrication of one bracket.

The first Gen cars have two of the necessary mounting points already attached.  Just remove the air flaps ahead of the rear tires and the panels slip on.  Once you work to the front of the car you will see the bits that need to be trimmed away to make them fit. You will need to drill six new holes in the floor pan to attach the rest of the mounting points, but don’t worry, there is nothing in the way of the bolts on the other side. On the passenger side, you will need to use a thread cutting tool to capture a bolt for the outboard side and the bracket for the inboard side.  On the driver’s side you will need to thread the outboard side then figure out how to attach the bracket.  I had it welded in place.  Now move to the front.  You do not want air washing over the leading edge so get some 1/8th inch thick ABS plastic, bend it to fit and attach using screws or pop rivets.  That’s it.  If you have a lift, it could be done under 2 hours.  If you’re working on jack stands like I was, plan to double that and add a trip to chiropractor to the list.

The first parts list shows the R53GP part numbers.  The second one is from the R56. The next three are before, after, and the leading edge modification. The last photo is the Rennline Skidplate we installed the week before.

screen-shot-2016-09-12-at-1-58-16-pm screen-shot-2016-09-12-at-1-56-30-pm img_2003 img_2026 Rennline skid plate

MINI Front Splitter DIY

I’ve been thinking about making my own front splitter ever since I read this article in Special Projects Motorsports. This got me thinking that a good splitter should be: a). disposable and b). cheap. I then came across this thread about building your own splitter for the MINI. So I got the template and set about to make a splitter out of (mostly) found materials.

Here’s how I made it:

Start with this template.


Rough out the splitter out of light-weight plywood or ABS plastic. I used some spare under-layment that I sandwiched together with some waterproof glue. Cost: $3 for the glue.

Next I covered it in some resin and fiberglass I had from a previous project. Then I sanded it smooth. Cost: $0.00.


When the resin was dry, I used some automotive spray paint to paint it black and then cover with clearcoat. Cost: $0.00.

Since you have to think of the splitter as disposable (and your bumper cover not) I wanted the mount to support the load forces to be applied, but break away under shear force. I made some T-brackets out of spare metal stock and connected the splitter with snow-blower shear-bolts. Cost: $3.50 for the bolts.


At this point, the mount was strong enough for highway speeds, but it still had quite a bit of flex. It certainly wouldn’t be good enough for track speeds. I ordered some slick splitter turnbuckles, but they won’t be available in time for the track this weekend, so again I headed back to the hardware store.


This took some creativity to piece together. I started with a turnbuckle used to support a sagging gate. I replaced one end with an eye bolt. I attached it to another eye bolt attached to the splitter. At the other end of the turnbuckle, I heated and shaped the rod to form two 90-degree angles like a zig-zag and I cut it off about 6 inches from the threaded end. I drilled a hole in the bumper and threaded the zig-zag end like you do a tool hook in a peg-board — if that makes sense. Once I put tension on the turnbuckle, it pulled out the gap under the chin spoiler and would now support my weight when I tried to stand on it. The pair formed the most expensive parts of this whole project. Cost: $27.

Total Cost: $33.50 (and the better part of a 4-day weekend.) Now that I have the template, I’m going to work up a couple of spares.