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If you’ve been following this build you know this car was originally built for the purpose of competing in the long forgotten NASA SE-R Cup. The rules from that bygone era – written on stone tablets by Moses Kojima, and brought down from the mountain – prohibited the use of ABS or traction control systems of any kind. Since our car came with ABS from the factory, completely removing the ABS system was on our agenda. The ABS computer, and all of its related wiring, were removed when we put the interior’s wire harness on a diet, so that alone took care of that section of the rule book. For those of you who still drive your vehicles on the street, and want to get used to your cars without ABS, you may want to simply pull the ABS fuse to disable the system. Since it is safe to say that we will never purposely be driving our car on a public road ever again, we took our ABS removal a step further by replacing the ABS system’s spaghetti factory of hard lines running through the engine bay, as well as removing the heavy ABS motor from the passenger side’s front corner. Like many other parts of this project, this was nearly impossible with the engine still in the bay, so we waited until our original motor gave up the ghost, which happened during the first practice session of our second race event…. Rut roh!
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| The ABS system is bulky, heavy, and in a horrible location. |
The G20 uses a 4 channel ABS system, which means that each corner can be individually controlled by the system. This also means there are a bunch of lines, six to be exact, going to and from the ABS motor – 2 in and 4 out. Though it may seem like a daunting task to re-plumb your entire braking system, careful planning and the right tools makes this a pretty simple job to accomplish. By following the lines you can decipher what each line is responsible for. The G20 had 2 lines attached to the master cylinder which went to the ABS pump. These lines were the fluid feed lines for the Front and Rear brakes. The remaining 4 lines were the feed lines for each individual caliper. Our solution was a simple one; T both of the front and rear main feeds from the master cylinder to directly feed the front and rear sets of calipers.
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You mechanically inclined folks are probably asking yourselves, “If you’re feeding the calipers directly from the master cylinder, what controls front and rear brake bias?” If you look at the diagram above, you will notice there is an external proportioning valve between the ABS pump and the rear calipers. Well, oddly enough, that proportioning valve found its way into the trash. Proportioning is set from the factory for the 99.999% of G20 owners who use their car for its intended grocery gathering purposes. Nissan apparently also did not want to ever replace rear brake pads under warranty, since they were almost never used with the stock proportioning. In order to have full control of how much work our rear brakes were doing, we installed an adjustable Wilwood proportioning valve on the dash. The Wilwood adjustable proportioning valve is a very useful tool for any race car as it gives you the ability to control lock up as well as make changes according to the track and conditions.
