After much reading and thought, I decided to give Essex a call and have them build an AP brake kit for my GT4. I ordered them through my friend Ron at Discovery Parts.

Here are a few thoughts, and pictures. I hope you guys take something useful away, and enjoy!

The calipers are a masterpiece. The engineering, and function of the part is second to none. I have no worry about quick/easy pad changes and broken ceramic pucks anymore. That, for me, was worth the price of admission.

The rotors are also a masterpiece in their design (ability to expand outwards when hot, due to the free floating design). The ability to expand and avoid "curling" of the rotor was what sold me. I'm a concrete guy, and curling of a slab is a phenomenon that occurs with all slabs and causes a serious structural issue - anything to avoid this is a great thing. So, I could relate when I saw the image of the Essex website that spoke about rotors doing the same thing when they get hot, expand, and are restrained thus the "curl."

I decided to go with the DS2500 pads. They make no noise on the street. They feel good, but not great. The initial bite is vague, but the modulation is good. For the street, they will suite my needs just fine. But for the track, I'll swap out to something with more initial bite and better pedal feel.

The brake lines are a pain, and you should take your time and read the instructions twice. Again, take your time when clocking the brake lines. We found out the hard way that if you don't clock the rear lines just right you will cause a rub with the rear tire and it will wear through the black shielding. We quickly re-clocked the line to fit tight against the chassis so all seems to be good now.

We used a pressure bleeder for the first half bottle of SRF until we removed most of the air. Then, we switched to the good ole fashioned manual bleed with me on the brake pedal and a buddy on the bleed screw. We extracted a great deal of air that way, and made at least (3) rotations around the car and went through nearly 2 full bottles of SRF just for good measure - I'm a stickler about feeling good when it comes to brakes, and knowing that we took every measure to ensure the best outcome.

I would recommend going with the caliper bridge ("spring clips" so I call them) that hold the pads in nice and tight. This prevents any pad shift/clicking noise on the street.

And, spend the money and have Essex bed the rotors for you! It's very accurate, the kit is ready to go out of the box, and you don't take unnecessary risk on the street!

This link provides a ton of useful information and pictures of the actual brake kit. Scroll down and you will see plenty of pictures and explanation - https://www.essexparts.com/essex-des...61394mm-981gt4

Enough typing, here are some pics!

Good write up. I wish I could justify the price of this, but for me, it’s not financially worth it since I’m only doing 3-4 events per year. Definitely on my list if money was no object!

I have the AP kit on my GT4 as well. I’ve had the car on track for few events already with the kit installed and it has worked great. I strongly prefer it to the OE setup. It takes a few sessions to calibrate your foot to the pedal, as the AP kit requires less pedal force to get into ABS. After you realize that, it is pure bliss. Changing pads is also much easier than OEM. Once the wheels are off the car, it takes literally a few minutes to change the pads.

I prefer the pedal feel of the AP setup compared to the OE setup. The AP kit requires much less pedal force to slow the car and provides more control in my opinion. However, some drivers might feel differently about that than I do. Plenty of GT4 and GT3 owners are happy with the pedal feel on their cars.

As has been detailed by Jeff Ritter in other threads, the kit drops a lot of unsprung weight off the car and that undoubtedly improves performance. I would really have to drive the car back to back with a car that had OE brakes in order to say how much I can notice the difference in unsprung weight, so my comment above is mainly due to pedal feel, but I am sure that the unsprung weight reduction is helping. Separately I do like not having a reason to worry about the OE ceramic piston insulators cracking, and I like the much easier brake pad changes that are possible with the AP setup, but those are not really benefits that can be felt on the track. Hope this helps.

Please provide details on the 18” wheels and tires.