Project Lexus SC300 Road Racer: Part 10 – Finish Wiring the Back and Prep the Front Harness


The Toyota/Lexus ABS solenoid is pretty chunky.

Now that we’ve moved on to the engine bay, it’s time to address this monstrosity. When we say that we are removing the ABS, we really mean it. It’s all coming out. Since the ABS computer was removed, the solenoid is no longer being controlled. And, in general, when it comes to air or other junk getting caught up in a braking system, an unused ABS solenoid is a great place for it to happen. So, out it comes.

Keep track of which hydraulic line goes where for joining them later.

When we remove the ABS solenoid we are simply going to “bridge” the hydraulic lines together. The master cylinder only has two output ports (front/rear). The ABS solenoid had  two inputs and three outputs (front left/right and rear). Some work with tape and a Sharpie helps us keep track of what goes where.


Japanese cars use mostly metric plumbing, and unfortunately, Toyota uses a somewhat uncommon size.

The ports and lines are all M10x1 metric threaded. They also involve flared fittings. Obtaining the right parts to help us tie things together involved a few trips to the local hydraulics store and some unfortunate mis-ordered parts online.


Brakequip tees came to the rescue.

We ended up using Brakequip tees that I was able to purchase locally. We used one tee to split the front master cylinder output into the two front brake channels (left/right). Then we used another tee to split the rear master cylinder output to the one rear brake channel. You might be wondering how a tee splits something to one. Your confusion is right, as that would leave an empty port on the tee. However, we had something in mind for it. We were going to add a brake pressure sensor to the mix.  

A brake pressure sensor is another interesting driver tuning tool. For one, it tells you when you are applying the brakes. Secondly, it also tells you how hard you are applying the brakes. Lastly, it tells you how quickly you are applying the brakes. All of these data points can be used to improve braking technique. And, since we were adding sensors and wiring and all kinds of other things, it seemed like an opportune time.


This looks like a little bit of a mess right now. You definitely don’t want to just leave the hydraulic lines dangling. That means another bracket and some CAD.

You can see the empty brake port for the future sensor. We need to mount all of this gear to something so that it’s not just dangling. I don’t know if the engine bay electrics and hydraulics were completely reversed on the right-hand drive Z30 chassis, but on the left-hand drive version, you have the brake lines very close to the turbo and downpipe. Brake lines (and fluid) and heat don’t get along, so a heat shield is in order, too.


The brake tee mount is a little complicated, so Tom makes some sketches of his ideas.

The mount has to be strong but also needs to attach to something sturdy. We are also building the mount to where the lines ended up, as opposed to trying to modify or move the lines significantly. This made the mount a little bit complicated, as it has to change direction and is offset quite a bit from its attachment to the car.

Leave a Reply

Your email address will not be published. Required fields are marked *