Project Lexus SC300 Road Racer: Part 7 – Sealing the Things


The factory used all manner of plates that bolted to the firewall for harness pass-throughs, sometimes with gaskets or boots. In this case, one was still stuck to the car, so we quickly used it as a template.
It can keep water out of a boat, so…

3M marine adhesive is good enough to keep water outside of a boat in through-hull situations. It’s also extremely strong and fast-setting. It’s more than good enough for use to create an environmental seal between a panel and the firewall. The SC300 is filthy, so we made sure to clean the firewall well before attaching the panel. Make sure you do the same.

Well, you should probably have pulled the engine and all of the interior and all of the sound deadening and power washed the hell out of things before you started with ANY of this stuff, but that would only make sense in hindsight, right?


In addition to the epoxy, for this larger panel we also riveted it into place.

You can see the factory Lexus ABS unit in the foreground. It is going to be removed since it is no longer being controlled. An unused ABS unit is a great place for lots of air to get trapped in a brake system, so it really should go.

Some day in the future it will be replaced with an aftermarket, motorsport-focused unit. There are not many options, but factory ABS tends to misbehave once racing brakes and super sticky racing tires are involved. At the super high end is the Bosch M4, which may be the gold standard, but also can end up costing $10,000. A common mid-priced option is the Teves MK60 ABS unit, which came on the E46 M3. It is possible to use these in a stand-alone fashion, and higher-end configurations have some programmability. There are several vendors that deal in these systems, and we hope to review one in the future!


Here’s one of those into-the-fender holes on the driver side. Tom is tracing it out to prepare for making a panel.
In this case, both sides of the car have the same openings, so we can just make two copies of each panel- one small trapezoidal panel and one circular one. We happened to have a socket on-hand that was the perfect size for the circular panel.
3M epoxy again to the rescue. And, for the larger panel, factory bolt holes will be used for extra security. The smaller circular panel is simply epoxied in place.
All done!

Finally- many, many hours of labor and essentially all of the openings are sealed and all the devices are secured. Now what? You’ll have to come back and see.

XS Power

Haltech Engine Management Systems

Racepak Smartwire

Autosport Labs

AiM Sports

H Craft Customs

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