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Who's running 2 pot calipers front and rear?

51K views 237 replies 47 participants last post by  thebuzzard 
#1 ·
Hi,

I'm curious who's running the AP 2pot calipers in the front AND rear, and what the noticed changes are. I'm considering running the same caliper front and rear, likely XP 12/10 or 10/8, with no other changes (stock abs, stock brake booster). I wouldn't say I'm disappointed with the braking I have, but I'm curious to explore improvements, and I will be messing with the front calipers anyway... so I'm contemplating "while you're at it" possibilities.

1. What pads do you run front/rear?
2. Any brake drag experienced, and if so what did you do about it?
3. Any change in pedal travel?
4. Are you running the stock brake booster?
5. Are you running ABS?
6. Any negative surprises?
7. Largest benefits observed?
 
#2 ·
I'm doing it and it's awesome.

1) CL8 front, CL6 rear
2) No drag
3) Yes, the pedal is a little longer but has more resolution... more accurate braking force
4) Yes
5) Yes
6) No... just that there is no e-brake if you don't make provisions for it. I used the EP Ultimate uprights. PS: I have 16mm EP dropped uprights that have the capability of having the 2 pots bolted to the front and the stock single pots on the rear that will allow you to keep your e-brake. I will sell them if there is interest.
7) Less ice-mode when driving aggressively (auto-x) and more resolution on the pedal for more controllable braking. It's rad.
 
#3 ·
This topic is right on time as I am strongly considering adding a set of front calipers to the rear of my car. I've been worried about messing with the brake bias, not having much adjustment, and regretting the change. It seems pretty much everyone staggers the pads, so I am planning that as part of the upgrade. BOE's brake bias cage looks like it would solve the dilemma but $$$.
@glagola1 , would you comment on your brake bias observations?
 
#5 ·
This topic is right on time as I am strongly considering adding a set of front calipers to the rear of my car. I've been worried about messing with the brake bias, not having much adjustment, and regretting the change. It seems pretty much everyone staggers the pads, so I am planning that as part of the upgrade. BOE's brake bias cage looks like it would solve the dilemma but $$$.

@glagola1 , would you comment on your brake bias observations?
Brake bias seems to be perfect with the pads I'm running. I wouldn't change it. CL8 might be a bit too aggressive on the street though. Works for what I do:

 
#4 · (Edited)
Matt is right with everything he said and suggested. Except 5, god no ABS EW. Also I gained 20 meters shorter stopping into 12 at COTA.

you do NEED more pad in the front IMO or this happens if you get aggressive:



I have the bias bar on now, will report back after the weekend.
 
#6 ·
#7 ·
Hi Phil, thanks for chiming in, I've already been out there. Did have one question for you though - is there ever a situation that makes sense to have radical up front, stock 2pot in back, but keep the stock brake booster? I'm guessing the stock brake booster probably doesn't configure well with brake changes on both ends but maybe some loonatic has already tried that and discovered otherwise. I understand the benefits of no boost on track, but I also want to be able to walk after my spouse and I do one of our road trips... so at this time looking to keep the stock booster.

On facebook I read a post from someone complaining about brake drag after this change- didn't seem it was an issue for all, but I do wonder what can be done if I put 2pot on the rear and was one of the "lucky" ones.
 
#12 · (Edited)
One last bump, and question.

When implementing this solution, the brake calipers are mounted backward compared to how they mount in the front. Has this caused issue for anyone? (Such as getting bent slider pins)
 
#16 ·
I think that is what I'm assuming. Here is a picture from the BOE website, with the OEM rear caliper removed, and the arrow indicating the direction of the rotor. When the brakes are applied, the pads will want to slide in the same direction the rotor is going, which is opposite compared to how things operate on the front.


 
#19 ·
I'm doing this modification this winter as well. I dropped off the 2 POT Calipers at BOE this week. I plan to run XP10 front and XP8 rear on the track and keep the emergency brake. I'll have to fill the hydraulic line with a bleed screw on the stock rear slide caliper. I've been running XP12 front and rear with the stock setup and it is not good on my short home track. (The brakes are basically analog.) This thread is making me wonder if I could run XP8 front and XP6 rear?

Andrew at BOE gave me a nice bit of advice, "use less brake";}
 
#22 ·
I plan to do this modification in 2018, but with a hydraulic e-brake setup to avoid mounting two calipers on the rear.

Has anyone actually tested this setup using the same pads front and rear with this setup? Seems to be a lot of conversation that the similar pads add too much rear brake bias, but not sure anyone has ever admitted to actually running such a setup.
 
#23 ·
I've not seen anyone saying same pads front and rear were a good idea, i did not plan to test it out either. I'm running carbotech/gloc pads, so planned on 10/8 or maybe 12/10, and on the street putting the autocross pad on the front and the street pad on the rear.
 
#24 ·
I did, it was not good. Way too much rear bias for my liking. I am running the BOE manual brakes now with the bias adjuster and using cobalt XP2 now all around and it's great. My brake sensors failed (thanks ****ty aim) so I don't know what my bias is right now, but I can report back later.
 
#25 ·
Okay thanks. It's just for the longest time everyone repeated that you should have one compound higher in front than rear for the stock calipers, but obviously we now know that's not optimal. I was wondering if the same was happening again.

Do you still think the unpowered brakes are "barely streetable?"
 
#26 ·
If you are referring to "unpowered brakes" as having the option of a balance bar and no brake booster, these cars really do not need a brake booster. I drive my car on the street and it is just fine. You just have to get use to a firmer pedal and a little more pedal effort.

Later,
Eldon
 
#27 ·
I am made larger diameter rotors(304mm) on the front to help with balance and will try the same compound pads this spring...the set up still fits under the stock wheels, saves about 12 lb. and the increased mass of the front/floating rotors should help with thermal capacity.
 
#29 ·
Does anyone know if this setup will fit with 15/16 wheels (Rota Slipstreams)?
 
#34 ·
P.S. I'm actually thinking of using the Wilwood mech spot caliper as a handbrake. It should still result in some weight savings over keeping the standard iron caliper and allows for me to retain a mechanical brake.
 
#46 ·
I find once ive got some heat into the rear tires then 2 pots all around are amazing, you can brake so much later and it actually gives your front brakes alot less stress.



works especially well when you have alot of rear downforce and stiff suspension so you get less dive under heard braking
 
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