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Unread 07-05-2012, 05:46 PM
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Fair! Fair! is offline
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Join Date: Jul 2004
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Default Re: Vorshlag $2010 GRM Challenge car - BMW E30 V8

Project Update for July 5, 2012: While other work was being performed on the E30 in the past two months, I kept seeing little things that bugged me - various fluid leaks that were easy to ignore on a $2000 race car, corners that were cut during construction to meet the budget, etc. Since this car has long surpassed any hopes of returning to $20XX GRM Challenge, I have held up the sale of the car so we could fix all of these issues.

In late May, after a small fuel leak was temporarily fixed, I test drove the E30 around town (with a fire extinguisher inside) and it was... interesting. The car gets a LOT of looks on the street, as you could imagine. Whoever buys this car shouldn't be a shy introvert. After some miles around town I decided to soften the spring rates (900# is a bit much on the street) and found a few little things I wanted to tweak before we try to get the state safety inspection. We did some of these things and then the car passed with flying colors - its street legal now and never has to have another emissions check (at least in Texas) since its 25 years old.

After the inspection was passed we knew there was still more to update. We've addressed all of the big stuff (new T5, fresh aluminum L33 5.3L V8, AST suspension, CCW wheels, second seat added, etc) and have been focusing on the little things. And of course, the "little list of little things" has snowballed into two months of work, to the point that we've gone overboard. But as I keep saying, for as much as this car is going to likely sell for (I've turned down three different offers for $15,000 so far) it's going to be worth it to the new buyer, in the end. Gone are the $10 shocks and $2000 worth of new ASTs are in their place. The 15x10" steel wheels have been replaced with 18x11" CCW 3-piece wheels. And on and on until we've got a substantial chunk of money invested into this car well beyond the "$2011" moniker. And I don't even want to contemplate how much work we did to the car before (with the volunteer crew of 15 workers) or after the Challenge event (at Vorshlag, by our technicians)... it's too painful to try to put a value on 1000+ man hours.

Driveability and Reliability Updates

As I mentioned in my last post, the steering rack was replaced with a remanufactured E36 unit, along with the tie rods and is now 100% leak free. While the steering rack work was going on, we put in some more reasonable spring rates. The 800 #/in front and 900 #/in rears were pulled in favor of some 450 #/in fronts and 550 #/in rears, almost cutting the spring rate in half. We don't know who the next owner will be, or what he will use this car for, but I didn't want this the E30 leaving our shop sprung so stiffly; it was "unpleasant" on the 18x10s with 285/30/18 street tires and the old spring rates. In case you are wondering, 900#/in rates are outside of what off-the-shelf-valving AST 4100s can deal with effectively (duh!). With the new springs (Hyperco front, Swift rear) the street ride has improved immensely.

There was also a small fuel leak that had started earlier this year, which come to find out stemmed from re-using some 25 year old fuel hose, to meet that insane $2011 budget. This is one of the areas that I think could be improved in the GRM Challenge rules - a little flexibility when it comes to safety items. The various CrapCan road racing series don't ding their $500 cars for fuel or brake parts, and now I see why. So many compromises have to be made on such a strict "dollar budget" build, but we can go back and fix all of that now - and we have.

My buddy Ed owns a hose and fitting shop and he came by, worked with Ryan on the list of parts needed, and ordered a gaggle of AN fittings and a couple dozen of feet of -6 and -8 braided line. So after a day of measuring, cutting, fitting the hoses into the fittings, installing new fire sleeve to both engine bay lines, and then attaching the completed assemblies to the car with P-clamps, the E30 now has a fuel system "done right". Safe, leak free, good looking, and rugged as hell.

Another thing I learned from my street driving in May, when I drove the E30 across town in stop-and-go traffic to get the safety inspection, was a tendency to run warm. It was almost 100F out and the little OEM a/c auxiliary fan just wasn't moving enough air to cool the E36 radiator in the car.

We ordered a single 2800 CFM electric fan, Ryan made custom aluminum mounting brackets to get it spaced close to the radiator, then wired it into the car with GM style weatherpack connectors, new wiring, a proper relay and a dash-mounted switch. It is wired to run when the ignition is on, but you can switch it off manually if needed. That puppy moves some air! The old evap fan went into the dumpster, where it belonged. There are tons of GM weatherpack connectors on this car now - everything Ryan has re-wired has been done so with these modern, water-tight connectors (these are the standard for use on race car wiring).

Above you can see the new fan wiring work being completed as well as a shot of the interior (from a few weeks ago). Every auxiliary gauge is plumbed and working, and an oil leak was found and fixed on the engine during the process (the car is now 100% leak free - a first!). The bundles of OEM wiring visible under the driver's side of the dash will soon be covered by a replacement OEM lower "knee pad" dash piece and brace, which were missing on our car for the past two years that we've had it. This and some other interior clean-up work will be shown in our next update. The original dash is in PERFECT condition, as are the door panels - this was why I bought this particular car way back when, and we've managed to keep them in this condition through two years of thrashing.

A Cosmetic Tweak + a Little Bit of Aero

While the interior work will be shown in the next update, some exterior updates have also happened lately. Of course the "Art Car" theme improved the looks from 2010 to 2011, but we've been doing some other little bits as well. One thing that always seemed "unfinished" to me was the underside...

Here you can see the massive expanse of "exposed underbelly". This makes for extremely poor under-car aerodynamics and an overall incomplete look. Since this E30 has an E36 front (and rear) bumper cover, and it has an LSx V8 underhood, there wasn't an easy off-the-shelf aluminum undertray or splitter we could just buy and slap onto this car. So I decided that we should make an undertray, and while we were at it, let's go ahead and make it extend past the bottom of the bumper cover to create a splitter.

The 2011-2012 Leguna Seca splitter is $700 and made from ABS plastic

What material to use? We looked at aluminum, Alumilite, composite, and even ABS plastic. The splitter on my 2011 Mustang is a 3/8" thick sheet of ABS (from the factory Leguna Seca), and it has held up remarkably well after many many months of street driving, autocrossing, and road course lapping. It only scrapes on an extreme driveway entrance angle, but so far this material has been completely unharmed by the occasional road scrapes, or crashing into cones at an autocross.

So we priced a 4'x8' sheet of 3/8" thick ABS from multiple local sources... but when I saw the $450 price tag I nearly choked. When it comes to splitters, don't discount the low cost, rigidity, ruggedness, wear resistance, and ease of manufacture of PLYWOOD. I picked up a 4'x8' sheet of 5/16" thick plywood, and might even suffer the extra weight of 3/8" if we were to do this again. Splurge the extra couple of bucks and get one that's finished smooth on both sides. I have seen plywood splitters in club racing and pro racing paddocks for years... there is some stigma attached to it, so just call it "carbon-based, multilayer composite!"

Step-by-Step Splitter Construction:

Using plumb bob, mark the outline of the bumper on some corrugated cardboard.

Mark the mounting holes by piercing the corrugated cardboard at any factory holes you can find, while mocked up on the car.

We welded some nuts to open holes in the subframe.

Transfer the corrugated template to the plywood, then cut it to shape using a jig saw. There is a small rectangular hole cut-out to clear the E36 steering rack, which has a slight protrusion.

Paint or stain the wood in the color of your choice...

Here the four mounting struts are shown, bolted in place. Two mount to the front core support and two were hung on some aluminum angle brackets Ryan made.

The bumper cover was notched around the struts and re-installed.

The lower mounting brackets that came with the struts were bolted to the splitter and the lengths adjusted.

The final look worked out great! There is still a gap at the front from the bottom of the bumper cover to the splitter that needs to be covered up. We will use sheet metal to cover the gap from the splitter to the bumper, and I'll show this step in a later post. In the end this will clean up the underside airflow greatly, improve radiator airflow, and should even provide some front downforce at speed.

Getting close!

Last edited by Fair!; 07-21-2012 at 03:32 PM.
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