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Datsun 510 Rally Beater: Part 3

Brakes, electrical, lighting and seats

Dave Coleman
Jul 16, 2002

It's amazing how having a rally car can focus your life. Even with the casual, half-hearted approach we have taken to building our rally beater, getting ready for an actual rally has forced us to do the unthinkable: We made checklists. Things to do, things to fix, things to pack, things to find, things to buy; we made so many checklists that we missed two rallies before they were all done. We did learn more valuable lessons, though. Like don't remove your vinyl top until the car is ready. A vinyl top is like a mobile workbench, notepad and fashion accessory all in one. You can throw parts on the roof without fear of scratching the paint, and you can write checklists on it with a permanent marker and not worry about losing the list.

Our checklist after our last installment included bigger brakes, some powerful lights so we could race at night, some re-wiring and a bigger alternator to handle the extra electrical load and two basic tools of rallying: a rally computer and an intercom.

The Datsun 510 had great brakes in its day. Unfortunately, its day was 30 years ago. Just having disc brakes on the front was an outstanding feature at the time, but caliper technology has come a long way in 30 years, and the 510's calipers are goofy contraptions better displayed in an industrial history museum than on the front of a rally car. With 95 hp, brakes might not seem that important and, in reality, they aren't used all that often, but in rallying, when the brakes matter, they really matter. The 15-minute uphill stage in 100-degree heat that we used to justify our oversized Fluidyne radiator could easily be run downhill, where it would very quickly justify some bigger brakes.

Besides having the strength and heat capacity to slow the car several times in a row, brake bias it the most important factor for a rally braking system. In general, rally cars need far more rear brake bias than any other street car or racecar. There are two reasons for this. First, rally cars are driven on slippery surfaces and with limited grip, there is less ultimate braking power and therefore less weight transfer to the front wheels. Because of the loose surface, the rear brakes end up with more of the braking duty than they normally would on pavement. The other reason, of course, is that unlike any other kind of car, you actually want the car to slide sideways every time you hit the brakes. Ralph Kosmides, the 1998 Group 5 national champion in his Toyota Supra Turbo, used the Supra's massive stock four-piston calipers in the front, but in the rear, well, he had another set of massive stock front brakes. Kosmides, of course, used an adjustable proportioning valve to adjust the brake bias, but that should give you some idea of how important rear brakes are.

What did we do? We upgraded just the front brakes. We actually settled on a front brake upgrade before finishing the suspension because, as it turns out, our brake and suspension choices are all interrelated. One of the 510's biggest strengths is that it can use parts from so many other cars. With a little bit of junkyard research and poking around Web sites like www.datsuns.com and www.dimequarterly.com, we learned 280ZX brakes would fit our 510 if we used the entire 280ZX strut assembly. There are only a few limitations keeping this from being a simple swap. First, the spring perches are different sizes, but since we cut the spring perch off to install Ground Control threaded spring perches in the last installment, that isn't an issue. Second, the 510's outer tie rod almost hits the back of the 280ZX caliper. If the brake pads are new, there is no problem, but as the pads wear, the caliper slides inboard and interference becomes an issue. Our solution here is simply to keep an eye on pad wear. Hey, it's a beater.

Naturally, putting bigger, stronger disc brakes on the front and keeping the same, weak drums in the rear will give us exactly the wrong brake bias, but being on a beater budget, that was about all we could do. In total, the front brake upgrade cost about $100 in the junkyard, including the $16 for lifetime warranty brake pads from Pep Boys. Switching to rear discs would involve at least another $100 in rear brake parts from the junkyard (there are several possible donor cars, all detailed on the aforementioned Web sites) plus custom-made brackets and some welding. Instead of jumping right to the welding part, we simply removed the stock proportioning valve that normally reduces rear brake pressure.

Surprisingly, this made almost no difference. The next step is to try bigger rear wheel cylinders and grippier rear shoes in an effort to strengthen the rear brakes, but we haven't tried any of this yet. Meanwhile, we simply have to drive around the problem. At low to moderate speeds, the car refuses to rotate under braking, meaning you have to brake in a straight line, lift off the brakes, pucker up and wait for the car to rotate, and then if it won't rotate, reach for the hand brake.

Oh yeah, the hand brake. If you are fortunate enough to have a car with a conventional parking brake handle, try this trick: Push the button in all the way, drill a hole through the handle and through the button, and use a cotter pin to hold the button in while you are driving. The hand brake can be an invaluable tool for exceptionally sharp turns, stubborn corners where the car won't rotate and for re-introducing rotation if the car hits a slippery spot in mid corner.

Unfortunately, the 510's parking brake is a truck-style T-handle under the dash. There is absolutely no way to use this kind of parking brake for turning. While hydraulic hand brakes are available, they cost actual money. Instead, we went to the hardware store and with a few sections of pipe, some closet door rollers, some steel cable, some scrap aluminum and a rivet gun, managed to rig a WRC-style pull handle next to the steering wheel. If your beater doesn't have a truck brake, you won't have to bother.

Before re-assembling the new braking system with old rubber brake lines, we decided to switch to Goodridge braided steel lines in an attempt to get some sort of pedal feel. The 510's non-power-assisted brakes are notoriously mushy thanks in not-so-equal parts to a small master cylinder, brake line flex, the rear drum brakes and a flexible firewall where the master cylinder is mounted. Braided steel lines address only one of these concerns, but since our lines were old and in need of replacement anyway, it was an easy call to make. The Goodridge lines have a clear plastic sheath over the braided steel layer to keep dirt from getting into the steel braid. This is especially important on a rally car, as dirt in the braid can accelerate wear and lead to premature brake line failure. After making lines for our car, Goodridge now makes lines for the 510, but if they don't have lines specifically made for your beater, they do have universal, build-it-yourself brake line kits.

Lights, Action, Electrical Fire!
Electricity has a bit of a hard time making its way though our 510's 30-year-old wiring. From an alternator capable of something like 30 amps, to a fuse box that has been sitting, exposed in the engine compartment for 30 years, to an electrical system for which there has never, ever been an accurate wiring diagram, the 510 is destined to have electrical problems.

While we're perfectly happy to deal with parking lights that come on when you hit the brakes, or turn signals that take a few seconds to warm up, there are a few mission critical systems that had to be re-wired. First, the ignition system must not be victimized by old, corroded wires, loose connectors or mysterious, mid-harness circuit interruptions. Second, we need the fan, wipers and probably even the horn to work every time we ask them to. Finally, we need lights; lots and lots of lights. To accomplish all this without having to troubleshoot a very troublesome electrical system, we simply started adding complete, new circuits for the critical systems and left the old wiring dangling.

Adding new circuits of your own isn't really that difficult. All you really have to know is that Watts=Amps x Volts. If you have two 100-watt headlights on a circuit and the car has a 12-volt electrical system, that circuit will draw 16.7 amps. Now you know to use a fuse of at least 20 amps and you know that the 50-amp relay you were planning to use will work just fine.

You should also have a basic idea of how a relay works and why you need one. Basically, a relay is just a big, beefy switch that can be activated remotely by a small, wimpy switch. Early in the Beater's development, we were running the electric fan's power through a switch mounted under the dash. Since none of the interior lights work (even the dash lights), you can imagine the surprise of seeing a faint glow under the dash while driving through a dark, remote desert road. At first it seemed a stray dash light had been knocked loose and was roaming free under the dash, but it was actually the back of the overloaded fan switch glowing white hot! This is why you need a relay.

Bosch automotive relays are widely available for between $5 and $10. They are capable of handling 50 amps, they have nice, automotive connectors and their plastic housing mounts to the car with a single screw or bolt. There are now six Bosch relays in a row on the firewall sending power to the stock headlights, the high beams, the driving lights, the wiper motor and the fan. Power for these relays comes straight off the alternator on an 8 gauge wire, through a six-fuse fuseblock from the local electrical supply store loaded with 30-amp fuses.

A good electrical supply store should have automotive-style double-crimp connectors that grab the conductor with one crimp and the insulation with another. These are far less prone to mechanical fatigue and breakage than single-crimp connectors. You should also look for locking spade connectors that won't pull off from jolts and vibration.

For lights we used 90/100 watt Hella H4 high/low beams in the outer headlight sockets, incredible 250-watt GE sealed beam aircraft landing lights in the high beam sockets, and 100-watt IPF SuperRally auxiliary lights on the bumper. Doing a little math, two 250-watt aircraft lights would pull 41.7 amps--more than the 30 amp fuses we were using in the new fuseblock. To keep from overloading the wiring, we ended up putting each landing light on its own circuit. Adding up all the lights, we had 900 watts of light on the front of the car, plus the wipers, fan, heater, brake lights and ignition system. The lights alone make a 75 amp electrical load, which is far more than our alternator could ever provide. There are some Z alternators that install fairly easily, but they still have outputs in the 60 amp range. To find something better, we took our stock alternator and the mounting bracket to a local alternator and starter rebuilder called Automotive Electric Industries. After poking through their books, they found an Eagle Premier alternator that would fit our bracket perfectly, was internally regulated (the 510 has an external regulator), and put out 105 amps. It cost just more than $100.

Seats
In any kind of performance car, seats serve two purposes. First, they are a critical handling aid. How's that? Try getting your left foot on the clutch, your left half of your right foot on the brake, the right half of your right food on the gas, your right hand alternately on the hand brake and the shifter and your left hand on the steering wheel all while resisting a side load that's wildly fluctuating between 0 and 1 g. Just a hint: It's nearly impossible. To accomplish this feat of driving--which, by the way, is just an everyday drive in a rally car--you need a seat with so much lateral support that you don't even notice the side loads.

The second purpose of a seat, of course, is safety. In anything but a straight head-on collision, the seat and its mounting brackets are the only things keeping you from bouncing around like a superball in a clothes dryer. Oh, there is a third function of a good racing seat: to suck your wallet dry. In the world of beaters, racing seats are one of the single biggest one-time expenses, but they are, unfortunately, an absolute necessity. If the handling and safety arguments aren't enough for you, consider comfort. During a rally, you spend a lot of time in your seat. There is a fairly simple formula to estimate how much time you will actually spend sitting in your seat in a typical rally. You simply take the number of days the rally covers, multiply by one, and that's your answer. So in a typical two-day rally, you spend (no calculators, please) two days in the seat. Remember, there are transit sections between the actual racing stages and they can stretch up to 100 miles in some cases. Add that to the time you spend sitting, strapped in, waiting in line to start each stage and you had better like your seat.

Poking around in what seemed like a fruitless search for a low-priced seat, we finally stumbled into the Scat Procar 2000 Type R seat in Summit Racing's Sport Compact catalog. Summit Racing is hardly a hotbed of rally parts, but in many cases, parts can cross over many racing disciplines. In fact, it is often worthwhile to look through the main Summit Racing catalog for generic items like heim joints, overflow bottles and the like. Don't let all the pushrods scare you away.

But back to the seats. At $450 a pair, the Scat Procar 2000 Type Rs cost about half what we expected to spend on seats. The Procar 2000 has a tubular steel frame with foam and springs making up the seating areas. In many ways, this is more comfortable than a Fiberglas or carbon fiber bucket, but in thin clothing you can actually feel the springs in the backrest. With a driving suit on, it is quite comfortable. In a crash, however, a bucket is probably safer, and if your budget allows, an FIA-approved bucket is best. Currently, the SCCA does not require FIA approval on seats, but they have been considering it and it would be worth a check before buying seats.

Most rally drivers prefer to sit very upright, and true rally seats tend to be designed with this in mind. The Scat seat is a bit reclined for a rally seat, but with my particularly long arms, that works out just fine. The seats also come with built-in sliders for easy fore-aft adjustment. This might not be critical in a rally car, but a true rally beater might still be used on the street for occasional airport duty or transportation when everything else is broken. Hey, you never know.

Rally Parts
Just when you think you are finally ready to rally, there's more. In a real rally, you'll have to find a sucker to ride in the navigator's seat, you'll have to get a rally computer so they'll have something to do and you'll have to get an intercom so you can hear when they tell you to slow down.

We went to Road/Race Engineering both to get the computer and intercom and for help installing them. The intercom is no big mystery, just bolt it to the floor or strap it to the roll cage, give it power, and start talking.

The rally computer, on the other hand, is a little more involved. First, you have to mount it somewhere the navigator can easily reach. We mounted it to the door with a cobbled-up sheet metal bracket. Then you have to provide nice, clean power. We tried several different power sources, but ultimately found that unless we pulled power directly from the positive battery terminal and ran the ground wire all the way back to the negative battery terminal, the computer would re-set itself every time we flipped the lights on or off. Finally, the rally computer has to have something to compute. You have to have a wheel speed signal. On a rear-wheel-drive car, you want the signal to come off a front wheel--even with 95 hp, the rears will be spinning most of the time. The Terratrip rally computer uses a simple, hall-effect sensor that can read any ferrous object going by. We mounted the sensor behind the hub where it could read the four bolt heads holding the brake rotor to the hub. The sensor has to be within a millimeter of the bolt heads, so we had to carefully file all the heads to the same height, but with surprisingly little effort, it worked.

And that's it. $6,216 later, we finally have a real rally car. It isn't pretty, but it will pass tech... barely. Next time, we race.

THE TOTAL RALLY BEATER PACKAGE:
Car:

Power
Engine and transmission :
Exhaust :
Automatic to manual conversion :
Shortened Driveshaft :
Radiator :
Hoses and cooling system brackets :

Safety Equipment
Autopower bolt-in cage :
Additional welding on gussets :
Autopower Pro Cam harnesses:
G-Force GF525 driving suit :
G-Force helmet :
G-Force driving shoes :
G-Force nomex gloves :
Scat Procar 2000 Type R Seats :

Handling and Braking
Ground Control threaded body kit :
Eibach Race Springs :
Rally Shocks :
Energy Suspension anti-roll bar bushings :
10 280ZX wheels :
10 used Silverstone rally tires :
280ZX Brakes :
Goodridge brake lines :

Rally-Only Parts
Hella H4 lights :
GE Landing Lights :
IPF {{{960}}} driving lights :
Relays, Wires, Connectors, etc. :
{{{Eagle}}} {{{Premier}}} Alternator :
Terratrip rally compter (used) :
Terraphone intercom :
Total :
$500


$500
$120
$50
$88
$435
$125


$629
${{{300}}}
$298
$330
${{{240}}}
$60
$30
$450


${{{80}}}
$246
Good Luck

$31
${{{200}}}
$240
$100
$140


$100
$unknown
$239
$150
$115
$200
$ 220
$6,216
By Dave Coleman
94 Articles

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