Thursday, August 11, 2016


I haven't posted for some time because I've just been driving and the car has, for the most part, has performed beautifully. The one exception has been the front brakes. The calipers I got with all the parts were from Wilwood, an aftermarket supplier. They have turned out to be not up to the job. They will stop Ok but in a panic stop I have to really push hard on the pedal and the calipers over heat, boil the brake fluid and then tend to lock up. Following that they start to leak fluid. The calipers I got are described on the JZRUSA page.

So, I have had enough and have bought new calipers.
These are from a Suzuki 600, 750 and 1300 Hayabusa bike on ebay. They have 4 pistons with 32mm pistons, similar area to the  Wilwood units and larger pad area than the Wilwood units.

Some notes on caliper area/pad area.
A single piston floating caliper with a piston area of, say 2.4 sq. in., is the same as a caliper with 2 pistons with 2.4 sq. in. area each. A 4 piston caliper with a single piston area of 1.4 sq. in is still the same as all the above. You take the number of the pistons on one side of the caliper and figure their area to find the force the caliper can create. A 4 piston caliper will have larger pads due to the larger spread of the 2 pistons on each side. Look at the width of the caliper on the web site above and look at the calipers I just bought. The piston area of the new ones is 2.5 sq. in. but are much wider.

Now for the myth of pad area. If you double the pad area you will not change the pedal effort required to stop the car!!! I know, this doesn't make sense but it is physics 101; trust me or look it up. So, what does happen by increasing the pad area is that heat is dissipated better and pad life is extended. Of course all the above requires the same master cylinder pad composition and the same pedal force. There are some other very small bits that affect pedal pressure but the above are the main areas of concern.

I'll post photos as I make the brackets and mount the new calipers. BTW the brake hose hookup will be really simple.


  1. Do you know which wilwood calipers you had that didnt work out?

  2. Yes, Billet Spot Caliper Caliper – Part No: 120-1064
    They are intended for ATV's. Don't use them.