OK, so within 30 minutes of posting on my local track club forum, I got a line on a great deal on a slightly used halo seat for the copilot position. I'll go see it (and probably buy it) next week. And parts arrived, from Stephen at eMINIparts.com. So I immediately cut them up and banged on them with a BFH and drilled some holes and stuff. Doesn't look like much, here... Looks better with a little paint. And even better on the car. "Stealth diffuser". OK, so it's not finned / compartmented. But it's a ton better than the giant open cavities in front of the rear bumper that used to be back there. With the track wheels and splitter installed, I have about 2.5" under the splitter in the front. And almost 9" out the back. I suspect it's gotta be better than the aero nightmare I had going on the last time I was at the track, with the mushed exhaust hanging down back there. If I get ambitious, I might add some fins to it. If I get really ambitious, I'll rework the exhaust and install the Group 4 diffusers I have coming. But I'll see how this does, first.
OK, that's fair. I got kinda busy after MOTD. So here's the Negasonic Teenage Warhead Update... I built a really crappy looking, but totally functional, bikini top prototype. The roof is surprisingly quiet and keeps the car surprisingly dry. Art and I drove for hours and hours in the rain around MOTD, and it was surprisingly civilized. MOTD was fantastic, as always. The car performed spectacularly, no issues. When Colin drove the car, he thought it was pretty well sorted, but might benefit from even stiffer springs. So we agreed to test that, later. I decided a couple of things at MOTD: I want a hard cover for the rear (to get rid of the flappy tonneau cover) and I want to create a removable hard top for the cabin. Thought about doing a fiberglass top for the rear, kinda RedBull-Mini-like... but then thought of maybe doing a hybrid that looks kinda like the canvas/vinyl tonneau, but rigid. I decided to take that route, at least initially. Made a template for the curved rear section... Transferred to 1/2" plywood... Cut and fit... Wrapped it in marine-grade vinyl... Mounted brackets... Installed. Seals with the factory weather strip. Cut and fitted the other two pieces around the cage. Wrapped and installed... Makes an excellent bar top, while retaining the general look of the tonneau. Still opens to allow access. Used it on the street and at the track, and it works very well. I'm gonna add some aluminum angle underneath to stiffen them and prevent sagging. I'm happy with this. Took a first shot at brake ducts. Cut the GP black grille piece behind the faux ducts, to accept 2.5" hose. Liberal use of racer tape. Got some brackets from Coleman Racing and initially mounted on the front of the A-arms. I wanted to try this routing, because there's so much stuff to work around on the back side of the A-arm (brake lines, sway bar end links, axle...) Flattened the hose just a bit to provide clearance at full steering lock with fat tires. This held up well at the track, but it's not providing as much air to the inner rotor as it could from the other side of the hub where it's more open. So I'm gonna make some different brackets and re-route them. I also got titanium brake pad shims to help with heat transfer to the brake pistons and fluid. Stiffer springs arrived (10kg/mm front and rear). I installed and re-corner-balanced... They were fantastic at the track. Suspension feels "right". Installed a bigger top-mount intercooler. And installed a GreenePerformance coolant tank. I mentioned a few times that I went to the track, yes? Dirty little track beast, with the track wheels. While at MOTD, Colin mentioned that he knew someone selling a GP2 rear diffuser setup for a decent price. I crawled around under Mark Dissen's GP2 looking at it, and thought I could probably make it work on my car with the Milltek rear section and the battery box in place. So I bought it. While the diffuser clears the milltek and the battery box with no problem, extensive fitment is required: Must cut slots for the tabs in the bumper. Must trim the edge on the diffuser that fits into bumper (it's too long to fit in the groove). Must notch that diffuser edge to go around protrusions in the groove. Must do major trimming to the tunnels to clear the control arms. Must fabricate brackets because the R56 brackets don't fit an R53 with normal exhaust. Must fab some other brackets to secure front of tunnels. Must do heat shield origami. Must cut rear trim to fit around diffuser. So it's not a trivial mod. But... It looks GOOD. And works well. I decided it will fit better with standard rear bumper trim, instead of the GP trim. So I bought a new set of that, and need to re-fit it. Also, the curvature of the R56 bumper is slightly different than the R52/R53 bumper, so the way the ends of the diffuser fascia fit is a little funky. I need to work on that a bit more to get it to stay put the way I want. Still, I love it. The car feels more stable at speed, and seems to have noticeably less wind noise, so I think this helped with some of the rear turbulence. We'll see how it does at the track. OK, we're caught up. Today, I'm re-fitting the rear trim and diffuser fascia, and re-working the brake ducts.
Yaaay update! Now I can go hibernate some more while I work on my own project piece. Hopefully I will have something to post about in a couple weeks. Thanks Paul!
Up on the Cherohala this year I saw you and a couple of other GPs hammering by, looked and sounded great!
Pulled the diffuser off, reworked the slots in the bumper, made some more brackets, and reinstalled. Fitted the new trim. Much better, now looks OEM and is solid enough, I could swing from it.
Oh yeah, I forgot to mention in the Negasonic Teenage Warhead post... I also bolted the driver's seat directly to the floor, no more sliders. The sliders had developed massive floppy play after just a few thousand miles. I hated the seat shifting around at the track. So, now it's SOLID. I am one with the car when driving. If anyone taller or shorter than me needs to drive the car, it's gonna seriously suck to be them.
Nice job and a fixed seat is better on track anyway! Makes for better harness adjustments. Looks like a fine set of changes since MOTD, nice! Don
At CMP, still had some brake cooling issues. Boiled my Super Blue one session ut: and had some pad fade on the next one. I think several things contributed: * I didn't do a fluid bleed after my last track event... probably wasn't as fresh as it should be. * I was trying to get all the use I could out of an old set of Carbotech XP10's... ran them down to 3-4mm. Thin pads transfer MUCH more heat to the pistons and fluid * The duct config wasn't as effective at delivering air to the rotor bowl as it could be * After boiling the fluid, I drove like a newb the next session and drug the brakes far too much because I didn't trust them * And it was 100F in the shade that day, on the toughest track on brakes that I run, with lots of high speed heavy braking and little cool down time. Anyway, I've made some changes, hopefully to ensure no more of this brake foolishness. Reworked the brake ducts, for much better air delivery to the rotor bowl. The key component of this was the 6" long 2.5" aluminum joiner tube, from Amazon https://amzn.com/B014GXQI16 I cut this in half, and flattened the open end of each half. Then cut a length of 1" wide galvanized steel, ground it with a die grinder to fit around the wheel bearing assembly, and drilled to bolt it to the factory rotor shield holes. Bent to shape, drilled and bolted to the 2.5" tube segment as shown. That should do it. Uses low-temp hose for most of the duct, only uses the high-temp silicone hose for the last 9" or so near the rotors. You can "screw" together segments of this hose, then secure it with racer tape. Also got a set of titanium brake pad shims from TCE (slip between the pads and pistons, and reduce heat transfer into the Pistons and fluid), and a liter of Castrol SRF fluid. Did a full brake and clutch flush with the SRF, including ABS bleed. We'll see how the SRF holds up for the rest of this track season. Many folks report that they don't need frequent bleeds when using SRF, since it has such a high wet boiling point.
Im really glad that deal on the diffuser worked out for you. Even if that guy is going to kill himself with his own set of harnesses at some point.
Built these in my shop for the owner of a racin BMW.... Gets the cooling air down into the hat and cooling air exits out through the internal fins inside the disc for good 360 cooling and with maximum surface area contact... Paper mockup Test fitting View down into the hat Finished, check for clearance Finished, check for clearance