1991 Mustang Rallycross Car

Why?

Fall 2013: I had been rallycrossing for a few seasons, I knew my way around a course (at least in a rear wheel drive car), but I had a vehicle predicament. My modified class MR2 was fast, but I sold it after it blew the engine for the second time. My stock class Celica was too boring- the 22re is not an exciting engine. So what to do? Get an e30 like everyone else? An RX7 like that years’ MR winner? Was the answer Miata?

No. berkeley every last one of those options. I like power, and in over a dozen cars, not a single one I had owned was American- it was time for a pony car. But which? Step one was to hit the junkyard- I had to know my options: the 3rd gen F-body was too old school, with its’ steering box and flimsy chassis; the Fox/SN95 chassis cars seemed weak and poorly designed, but had good axles and large wheel wells; the 4th gen F-Body was the best engineered with the most tire clearance, but good god was it big and heavy; G-Body cars were out, I did NOT like what I saw when I got under them.

After the junkyard trip, my thought was Mustang or 4th gen F-Body was the answer, but I figured I should ask a pro: so I called Sam Strano, an expert on such things. He told me neither car was a particularly good choice, but the Mustang was far more likely to make a competitive and robust vehicle due to the suspension travel and axle limitations of the GM products. OK- I was in the market for a Mustang.

A Pile of Parts

A few weeks of scouring craigslist and the 20 or 30 Mustang forums had given me a clear picture of what I wanted- someone else’s money pit. Cars with thousands of dollars in parts cost the same as clapped out stock ones, so why in the hell would I start with Ford’s awful engineering everywhere? I wanted something that barely had a single stock part left, and in late November, I found it:

A former C-Prepared autocross car, with all sorts of goodies. It had been for sale at $4k for months, so I figured the seller would be willing to drop the price significantly- talking to him on the phone confirmed as much, so I bribed my friend for the use of his rollback, and went to pick it up 3.5 hrs away.

When I got there, this is what I found:

The good:
-Fancy engine. Aluminum heads, fancy intake, roller rockers, headers, etc.
-It was STRONG, the seller claimed 350 hp, the butt dyno said closer to 300, but either way it would be plenty for dirt.
-The differential (Torsen T2R) was fully functional, confirmed by doing a donut in a cul-de-sac.
-Subframe connectors, bump steer correction kit, some sort of race springs, Steeda rear 5-link, and Tokico dampers all in good working order.
-Kirkey seats, 3 sets of wheels, and stock springs included in sale.
-It sounded AMAZING.

The not so good:
-The battery was dead and didn’t seem to be charging when running.
-The power steering was not only dead, but had a ton of resistance making it incredibly difficult to turn the wheel.
-Slight grind when downshifting into second gear.
-Terrible blue repaint (car was originally red) with overspray everywhere. The paint is nearly 1/8” thick!
-Some of the gauges didn’t work.
-A very noisy fuel pump.
-The seller repeatedly changed his story: the car had been sitting for either a 1, 2, or 4 years according to different points in our conversation.

The DOWNRIGHT berkeleyING TERRIFYING:
-Lead acid battery, without a box, mounted just behind the driver.
-Kirkey seats mounted with 4 sheet metal screws each and NO WASHERS.
-The positive battery cable was touching the exhaust in 3 places and had no grommets where it passed through the floor.
-Harnesses mounted to the floor, again with no washers.

In the end, my friend convinced me to buy it- I left $1900 poorer, and one terrible Mustang richer. On the way home, when asked why he pushed me to buy the car, his response was, “Anything to make your life just a little bit more miserable.”

Shenanigans

When we got it back to my place, the car wouldn’t start. Battery fully charged, we tried bypassing the awful “relocation kit” the PO had installed but to no avail. The car was pushed into the garage, and I was left with a bad feeling about the entire project.
A couple of “before” pics:

The next day, it was time to rotate the tires on my girlfriend’s Jeep before the snow started to get much worse: shenanigans ensued.

So, it looks like the Mustang won’t quite be able to fit 33s, but my measurements show with some a hammering I should be able to clear up to a 29” tall tire in the rear. Also, to this day I still occasionally beg to lower the Jeep and stick some wide steelies on it permanently- for some reason I haven’t gotten an affirmative answer yet, but I’ll keep trying.

I've been waiting for this.
Please, go on.....

We have the same kind of friends, tell us more.

Make it sweet with a real 4-link like every successful RWD rally car ever had, and ditch that V8 for a proper 4-popper that makes easy to drive power, and you'll really be in business.

I drool over the Esslinger "400hp from 4 cylinders" 3-liter engines. Really, though, it'd be easy to get excessive power from the 2.3 without mortgaging your kidneys/firstborn.

Finish the berkeleying STORY!!!

In reply to The_Jed:

TELL US ABOUT THE BERKING GOLF SHOES

Why the hell would I bother with a Mustang if I wanted a 4 cylinder? There are far better platforms out there. In fact, there are far better platforms for the V8 as well, but this is one of the cheapest that comes with it pre-installed

As for the rear suspension, I'm keeping what its' currently got. I'm cheap and it seems to work well enough,

Teardown

Let me first apologize for the lack of pictures in the upcoming sections- my garage is a barn with holes in the walls. It was berkeleying COLD for the entirety of this build. The wind sounded like the lost souls of a thousand Detroit E36 M3boxes seeking vengeance on me for what I was doing to their kin, and I had no real plans to make a build thread until only recently, so the camera rarely made it out to the car.

I decided the entire car had to come apart- the PO gave off a distinct air of ineptitude, and I didn’t trust anything he had touched. Except the motor and trans, berkeley tearing those down. They can come apart if they break. The entire suspension and interior were disassembled, and all removable body panels were pulled. A few things were discovered at this point:
-The exhaust had a turn down on one side, but not the other.
-The 5-link rear was set up ALL KINDS of wonky.
-The steering rack was leaking into one of its’ boots.
-The wheel studs had been cut down to fit inside of 1” spacers, and cross threaded. I’m not sure how the wheels even stayed on for the test drive.
-The quarter panels had been filled with Great Stuff foam.
So, all in all, not too many new terrible things were discovered. I also decided something very important when taking the rear hatch off- that motherberkeleyer is HEAVY. It will never be put back on. This mustang will be a ute.

Hotlinked from Irish44J's build thread:

In reply to The_Jed: Way to go off and ruin the suspense

Magic Smoke and the Oil Snorkus

First order of business once the car was apart: fix the starter. The first step of that was to fix the god-awful battery relocation performed by the PO. I picked up a 15 lb Braille on sale and, using the cut up remains of the previously installed 20ft of battery cable (seriously, look at the excess coiled up in the “before” engine bay pic), and the top piece of the old battery bracket, I installed the battery in the original location for the sake of simplicity.

As a result, the snazzy aftermarket coolant tank could no longer live in that spot, so I relocated that as well. It turns out that the hood latch bolts lined up perfectly with the mounts for the tank, so…

Cool, now the starter should work, right? I turned the key, and the starter promptly let the smoke out. Upon removal, I noted that the starter appeared to be the oldest part of the entire car, so I ordered a new (lightweight) one for $60. That one didn’t fit (surprise), and appeared to be hewn from pure Chineseum, so I returned it, got my money back, and then spent roughly twice as much on one from Latemodel Restoration which was even lighter and actually fit the car. Turned the key again and… let the smoke out of the starter wire. It turns out the genius PO had routed to starter wire VERY close to the header, so it had cooked and disintegrated. After replacing that, the car fired to life! I only idled it for a few seconds, since it felt like it wanted to vibrate off the jack stands… something about a cam and motor mounts made out of polytransmitsaE36 M3loadofvibrationethane.

The other glaring weirdness in the engine bay was a tube JB Welded into the driver’s side valve cover. Apparently, upon realizing that the strut tower bar blocks the oil fill, this was the improvement the PO chose to make.

This tube, known as the oil snorkus, had no plug, cap, or cover. I concluded that uncapped snorkus+dirt=bad day, so a $3 plug, visible in the engine bay shot below, was my solution to the PO’s solution. A clean snorkus is a happy snorkus.

Sorry. That occurred to me after I hotlinked the pic but only after I turned the computer over to the kids, so I couldn't ninja edit.

Where's the front sway bar?

In reply to The_Jed:

In the scrap pile, want it?

Big Knobby Tahrs

I needed to get the ground clearance, tire clearance, and suspension travel for rallycross, which meant I should probably pick a wheel and tire package. My first step was to get the steering and suspension in roughly working order so I could see what I was working with. The leaky, crunchy old steering rack was replaced with a unit that was on sale on RockAuto- it was cheap and claimed a faster ratio than the others they offered (SVO rack?). Before installation, I removed the limiters at either end of the rack. My goal was to use the entire steering angle the rack would give me by any means necessary.

At the rear of the car, there was some sort of awful pinion snubber setup. I removed that, which brought the rear suspension travel from about 2” to more like 6”. Then, with some fiddling with the 5 link and spacing of the shocks, I found another 2”. Cycling the suspension with no springs, the car had roughly 6” front travel and 8” rear, and that looked to be all I was getting without major modifications.

Measurements indicated that running even the tallest rally tire in the rear would put the pumpkin of the 8.8” axle very close to the ground. Luckily, Mustangs have large rear wheel wells, so after some quality hammer time, I made enough room to run the common small offroad sizes of 215/75r15 and 235/75r15. This would give me good clearance under the pumpkin and a variety of A/T and M/T tires to buy for cheap off craigslist. I needed a +10mm offset or lower for this whole plan to work with 7” wide wheels.

Up front, I found that with a careful application of the BFH to strategic points in the wheel well, I could use the full steering rack travel as long as I kept the toe-out sane, my tires under 25” tall, and aimed for zero offset on a 7” wide wheel. Any further out and the tire hits the chassis, any further in and the wheel hits the control arm. At this point I ordered some 15”x7”, 3.75” backspace Basset racing wheels because they’re cheap, they’re tough, they come in the dimensions I need, and seriously, they’re really berkeleying cheap.

Then it was off to the forums/craigslist to find some tires. I found some cheap Hankook rally take-offs on SpecialStage, and a set of 215/75r15 Hankook Dynapro M/Ts on craigslist. Would they fit in the wheel well as anticipated?

Damn right they did. The next order of business for the suspension was spring selection. I figured the rear was light enough that I needed the softest springs I could get, so I put in the stock springs with all of the isolators removed to reduce preload as much as possible (Mustangs have a E36 M3load of preload at both ends of the suspension), and removed the sway bar. Up front, I had already decided I didn’t want to use the sway bar- it was massive and heavy, and with enough front camber and caster shouldn’t be necessary. I put the race springs that came with the car back on with their isolators, and actually ran my first event like that (more on that later) but the car was too high- apparently all the weight I has taken out made a significant difference! With the isolators removed, the car sits pretty much level, and has plenty of clearance up front, although I still feel like it needs stiffer front springs.

NONACK wrote: In reply to The_Jed: In the scrap pile, want it?

Yes but shipping would be a bit much.

Interior? We Don’t Need No Stinkin’ Interior

The Kirkeys were sold, the steering wheel that came with the car was disintegrating, and there was a big berkeleying jagged hole in the floor with a shifter coming out of it (either this car used to be an automatic, or Ford cut their shifter passthroughs with a chisel). After gutting the car, that tar poop that everything comes with all over the floor was still there smirking at me- for the first time in the build, the hootus-shrinking temperatures became my ally. Liberal application of the Harbor Freight Orange BFH bounced the majority of the garbage off the floor, and the remainder was easily handled with a screwdriver.

I had a Sparco Sprint sitting in my house from a friend’s former project (he was only looking for 2 and somehow found three- meanwhile, I haven’t been able to find one for a passenger for 4 months now!) and a Momo wheel. The Sprint was adapted to the seat bases that came with the car easily, requiring only 2 new holes to be drilled. There was a quick release hub on the car, but it was only for 3-bolt steering wheels. Luckily, MiataCage makes these really cool lightweight steering wheel adapters, so I bought one, and now I have a fancy wheel that comes off easily for people to steal.

The many holes in the floor (from bolts, not rust) as well as the shifter hole were then patched with my favorite bodywork supply after zipties- aluminum tape. A generic lap belt was installed to meet the incredibly lenient rallycross safety rules.

I also needed a replacement for my rear quarter windows. 1/16” Lexan is FAR cheaper to ship if you buy in 24x48” sheets instead of 4x8’, and luckily the quarter windows fit that profile. Interesting note: if you fab Lexan windows when it’s 20 degrees out, they get all funhouse-mirror when it’s above 40.

That car looks like 10 lbs of fun in a 5 lb bag!

NONACK wrote:

Lololol. I like it a lot.

Ute the Bastard

I mentioned previously that the hatch was not going back on the car. But, I wanted something to keep the minor storm systems generated by the rear tires out of the cabin, so some more 1/16” Lexan, angle aluminum from home depot, and a box of pop rivets later, I had a rear bulkhead. Fun times were had by all as I had a friend drill through the Lexan while I braced the other side so that we could install plastic rivets at the overlap in the middle. Then, I Plasti-Dipped most of it black, leaving just a small window at the top- the idea being to keep the car from becoming a greenhouse in summer events. There is an opening to either side of the bulkhead which I had planned to close up if dust came in, but it seems to be out of the danger zone so I left it for additional ventilation.

As you can see in the hatch-less image a few posts up, the car was still missing something. But what? Style? Downforce? Redneck NASCAR Craftsman Truck imitation? YES to ALL of those things. And so, from a couple dollars of plastic, several scraps of angle aluminum, and another box of pop rivets, a spoiler was made. The plastic portion is riveted in behind the taillights, and uses the license plate mounts as its’ primary fasteners. The aluminum pieces were riveted to the tail panel in the former trunk (now a bed) while it was still vertical, then bent to the proper angle and riveted to the plastic. It was finished with el cheapo Autozone edge trim.

I can't tell if you ruined it or made it better. I'm conflicted.

In reply to mazdeuce:

Can't it be both?

Let me be the first to say two things:

To Chris: About damn time you made a thread on this.

To everyone else: This car is every bit as scary in person (both sitting still and at full-throttle) as it appears to be in the pictures. Scary looking. Scary fast. Scary mean-sounding. And very scary to cones

Since I'm sure Chris is pounding away at the keyboard with some discussion of the first few events, I'll hold off on posting any additional pics or vids of this beast for the moment :)