Evo 9 to X Brake Swap

Thanks to the chatter on the forums, even after getting brand new rebuilt calipers in 2016, and finally fixing the soft brake issue (titanium shim bending due to poor design), I was convinced to again revamp the entire braking system, this time to the X brakes setup, in the front only. Aside from one minor modification, this is the direct swap. I had briefly considered doing the rears as well, both for aesthetic reasons as well as performance reasons, but as it turns out, despite the small size of the 9’s rear calipers, they are strangely overbuilt. Track owners that have done this swap cite the rear ABS still kicking in before the fronts, and as it turns out, it is a better match for the 9 than doing all 4 corners. This is due to the weight distribution of the 9 – despite being much lighter than the X, it is slightly more front-heavy, and thus requires more braking in the front.

One of the reasons I decided to pull the trigger on this swap was because I was still unsatisfied with the braking power on my setup. To be fair, this was likely related to the pads (Girodisc S/S), which just didn’t seem to provide a lot of  bite. Regardless, even when others drove the car, they commented that the brakes just felt weak overall. Finally, given the high praises of how well the X brakes performed on the 9 (outbraking Lotuses sold me), I decided to pull the trigger.

The main benefit of moving from the 9 brakes to the X brakes is the increased rotor size – – 320mm to 350mm.

The caliper itself uses the exact same pistons, and even takes the exact same pads. The difference is entirely in the larger rotor, which provides increased clamping force while also serving as a larger heat sink for the track.

Apparently this is enough to overcome the weight disadvantage – I measured a difference of nearly 4lbs (9 DBA5000: 18.6lbs; X DBA5000: 22.4lbs) in the rotors alone. Of note however, the 9 stock calipers are roughly 22lbs. The wheels, from what I’ve measured, will be nearly a wash (Wedsport TC105N 17×9.5 +32: 16.3lbs; CE28N 18×9.5 +34s, 18lbs). The tires, however, will be a big jump, both in cost & weight (~4lbs). The size of the rotors & the positioning of the calipers require 18s, which was one of my main hesitations with doing this swap, along with the weight increase.

The other hesitation was that this required a modification to the mounting points in order to fit. I had to drill the mounting holes on my stock bracket to fit the X calipers. The 9 calipers mount using 12mm bolts, but the X calipers mount with 14mm bolts. Otherwise, the mounting position for the bolts is exactly the same. I used a 14mm McMaster reamer drill bit (https://www.mcmaster.com/#8851A29) to enlarge the mounting holes. It bites strong and cuts straight. Given that I’m a novice with drilling, it was ideal for me to use this drill bit. I also used Tap Magic to lubricate the drill to preserve the bit as much as possible, given that I would be cutting through steel.

I unmounted my evo 9 calipers and zip tied them up and out of the way. Then, I removed the old DBA5000s, and cleaned the new ones with Brake Kleen.

I then drilled the 4 mounting bolt holes:

I was recommended to take my time with this, slowly enlarging the holes. I tested the fitment with the mounting bolts, and fortunately it lined up perfectly. After I verified the fitment, I removed the brake line from the 9 calipers with a 14mm socket in my case, and quickly swapped crush washers and remounted the line to the X calipers. Finally, I remounted the new rotors and mounted the calipers on.

vs old setup:

The position of the X calipers looked a little odd to my eye – the bottom of the caliper seems to jut out a little further, and it seemed like the rotor was way too big for the caliper, like  it was unlikely that the pads would be in full contact with the rotors – however, after installing the pads, it seems all is well:

Perfect fit, with the pads entirely in contact with the outer edge of the rotors! Overall, it actually ended up being a fairly straightforward swap, especially since I’ve now become well experienced swapping pads, rotors, and calipers on this car.

I did make one important change to my usual formula of installing the pads – I usually slather copper antiseize between every surface and every contact point, including between the shims and the pistons – this time, I used much, much less antiseize on the whole, and forgoed adding any at all between the shim & the piston. The reason for this was because I again purchased the vented pistons & high temp seals from Racing Brake, the same setup as on my 9 calipers. However, with so much antiseize getting gunked up on my 9 calipers, it seemed to practically block the venting on the pistons, defeating the purpose. I would still get brake squeal anyway as well, so for cleanliness I decided this time around to try less antiseize.

For now, I’m going with the same pads that I was using on the 9 calipers, so I can get a better 1 to 1 comparison of how much difference the X brakes make. I went ahead and bled the calipers, and already the pedal feels much firmer. However, it will likely not be until spring that I test these brakes out on the road, given the salty conditions & the fact that I’m still searching for sets of wheels and tires. Looking forward to trying out the brakes, and hopefully they live up to the hype!

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One thought on “Evo 9 to X Brake Swap

  1. Pingback: Winter Projects 2017 | Motorsports Blog

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