For those with 4-pot front & rear on their Elise/Exige. - LotusTalk - The Lotus Cars Community
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post #1 of 33 (permalink) Old 05-28-2019, 12:00 PM Thread Starter
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For those with 4-pot front & rear on their Elise/Exige.

I know this isn't a popular modification, and that the Elise/Exige brakes just fine from the factory yada yada yada, so if you guys running stock brakes or different configurations could please spare us all the diatribe.

I should have my factory 7624 308 BBK fitted front and rear within the next few weeks, so I'm interested in the thoughts of those that actually have the 4-pots F&R. I've got pictures of 20+ cars with this mod (most with the AP Racing 5950 kit) and if you have them, I'd like your take on a few things.

1. What size are your rotors F&R? 308/315?
2. Did you do any other modifications, like a different master cylinder, or a brake balance controller?
3. Are you running stainless lines or stock?
4. How is your street driving braking feel?
5. If you track your car, how has that worked out?
6. Did you retain an e-brake? If so, which one did you use?

Please feel free to provide any additional information and/or pictures.

This is my front kit, and the rear will be exactly the same very shortly.


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post #2 of 33 (permalink) Old 05-28-2019, 12:22 PM
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I'm not running the same setup but I do have 4 pots on all corners. I'm running Elise parts calipers with smaller pistons on the rear with 304mm AP discs all around. I am also using EP uprights all around, which allows me to retain a parking brake. I run DS2500 on the street and CL RC5+ on track. No problems at all with brake balance or master cylinder and installed SS lines on all corners. Braking on street and track is bonkers, just incredible!! No ice mode, great modulation and I'm very happy with the balance, I can certainly feel the backs working. No overheating or fade but do run Motul. I currently use the stock parking brake, likely move to a lighter version when I get around to it.

For you, running a matched set up on all four corners I'm not sure if you will have a problem with brake balance and the backs causing a problem but I'm sure others with your setup will chime in.
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post #3 of 33 (permalink) Old 05-28-2019, 12:30 PM Thread Starter
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Originally Posted by Zink View Post
I'm not running the same setup but I do have 4 pots on all corners. I'm running Elise parts calipers with smaller pistons on the rear with 304mm AP discs all around. I am also using EP uprights all around, which allows me to retain a parking brake. I run DS2500 on the street and CL RC5+ on track. No problems at all with brake balance or master cylinder and installed SS lines on all corners. Braking on street and track is bonkers, just incredible!! No ice mode, great modulation and I'm very happy with the balance, I can certainly feel the backs working. No overheating or fade but do run Motul. I currently use the stock parking brake, likely move to a lighter version when I get around to it.

For you, running a matched set up on all four corners I'm not sure if you will have a problem with brake balance and the backs causing a problem but I'm sure others with your setup will chime in.
Man, what a great response, thank you!

I know the AP kit uses 308/315, but I'm not sure about the piston size.

I intend to run the OEM 7624 caliper and 308 rotor front and rear. This will be in a pure street capacity, no racing at all.

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Last edited by VisualEchos; 05-28-2019 at 01:24 PM.
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post #4 of 33 (permalink) Old 05-28-2019, 02:20 PM
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I have no knowledge, but since the same calipers front and rear is regarded as a hot setup, I see no reason that the same [larger] calipers front and rear would not work acceptably

I wonder if with larger piston diameter front and rear if it might be possible to remove the booster, which I hear also is an improvement when it is possible, although I love the feel of the stock system on the street, 'they' say it is an improvement
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post #5 of 33 (permalink) Old 05-28-2019, 02:52 PM
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I have the AP Racing 4-wheel BBK with the 315mm front rotors and 330mm rear rotors (all slotted). Stainless lines all around. No bias controller and stock master cylinder. Carbotech Bobcats in the front and Mintex Extremes in the rear. Very little pedal input is needed. Painted locally with high-heat Porsche Speed Yellow and black.



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post #6 of 33 (permalink) Old 05-28-2019, 05:17 PM Thread Starter
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Originally Posted by exigegus View Post
I have no knowledge, but since the same calipers front and rear is regarded as a hot setup, I see no reason that the same [larger] calipers front and rear would not work acceptably

I wonder if with larger piston diameter front and rear if it might be possible to remove the booster, which I hear also is an improvement when it is possible, although I love the feel of the stock system on the street, 'they' say it is an improvement
I have never even considered such. Sounds pretty cool.

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I have the AP Racing 4-wheel BBK with the 315mm front rotors and 330mm rear rotors (all slotted). Stainless lines all around. No bias controller and stock master cylinder. Carbotech Bobcats in the front and Mintex Extremes in the rear. Very little pedal input is needed. Painted locally with high-heat Porsche Speed Yellow and black.[/IMG]

San
I've read a few times that some guys don't like the feel of the brakes when they put the 2-pot front and rear. I'm wondering if you like the feel of your BBK front and rear?

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post #7 of 33 (permalink) Old 05-28-2019, 10:31 PM
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I've read a few times that some guys don't like the feel of the brakes when they put the 2-pot front and rear. I'm wondering if you like the feel of your BBK front and rear?
I can't comment on the 2-pots as I didn't have the stock brakes for long. I have 4-pots (4 pistons) front and rear. The fronts I purchased from this forum and the rears I picked up from Stillen locally. The fronts are shown below. The rears have the 330mm rotors and the same calipers, with different piston sizes.

https://www.stillen.com/media/PDF/AP5920~broch.pdf

With the Mintex Extreme pads front and rear the bias was too much towards the front brakes. The Carbotech Bobcat pads in the front balanced out the bias nicely. The Eliges feel better with more bias towards the rear brakes than the stock front-heavy bias IMHO.

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post #8 of 33 (permalink) Old 05-29-2019, 04:45 AM Thread Starter
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With the Mintex Extreme pads front and rear the bias was too much towards the front brakes. The Carbotech Bobcat pads in the front balanced out the bias nicely. The Eliges feel better with more bias towards the rear brakes than the stock front-heavy bias IMHO.

San
Interesting. I'm hoping I don't have problems with the 50/50 set-up that I'm doing, but as @Zink suggested, I'm going to test them thoroughly to make sure there are no surprises. I have a set of RS14's that I could add to the rear if needed.

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post #9 of 33 (permalink) Old 05-30-2019, 12:01 PM
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Check out this thread if you haven't already: https://www.lotustalk.com/forums/f91...36/index3.html
Yes, it's about the 2 pots, but you're effectively getting the same bias (or slightly worse by running a larger rear rotor) with the 4 pots.

"I think that under a lot of circumstances... having the same braking on all 4 corners yields a car with too much rear bias (speaking for the S2)."

"I think my 2-pot all round setup is too rear-biased even with a less-aggressive compound on the rear. "

"So after switching the 2 pots all around. Running CL RC8 front, RC6 rear (per BOE recommendation). I'm also experiencing what I think is too much of a rear bias. I feel the rears locking up easily. The rear will lock up and try to slide out on me even in hard straight-line braking."

YMMV
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post #10 of 33 (permalink) Old 05-30-2019, 12:30 PM Thread Starter
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Originally Posted by Scott M View Post
Check out this thread if you haven't already: https://www.lotustalk.com/forums/f91...36/index3.html
Yes, it's about the 2 pots, but you're effectively getting the same bias (or slightly worse by running a larger rear rotor) with the 4 pots.

"I think that under a lot of circumstances... having the same braking on all 4 corners yields a car with too much rear bias (speaking for the S2)."

"I think my 2-pot all round setup is too rear-biased even with a less-aggressive compound on the rear. "

"So after switching the 2 pots all around. Running CL RC8 front, RC6 rear (per BOE recommendation). I'm also experiencing what I think is too much of a rear bias. I feel the rears locking up easily. The rear will lock up and try to slide out on me even in hard straight-line braking."

YMMV
Thanks for the reply.

I was planning on running the same G-Loc GS1 street pads front and rear (low dust, low noise, rotor-friendly), since I don't race/auto-x. That's still my plan. I'll do some testing under hard straight-line braking, and if I have a problem, I'll swap my RS14's into the front. If I still have a problem then I'll contact BOE.

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post #11 of 33 (permalink) Old 05-30-2019, 08:45 PM
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Originally Posted by Scott M View Post
Check out this thread if you haven't already: https://www.lotustalk.com/forums/f91...36/index3.html
Yes, it's about the 2 pots, but you're effectively getting the same bias (or slightly worse by running a larger rear rotor) with the 4 pots.

"I think that under a lot of circumstances... having the same braking on all 4 corners yields a car with too much rear bias (speaking for the S2)."

"I think my 2-pot all round setup is too rear-biased even with a less-aggressive compound on the rear. "

"So after switching the 2 pots all around. Running CL RC8 front, RC6 rear (per BOE recommendation). I'm also experiencing what I think is too much of a rear bias. I feel the rears locking up easily. The rear will lock up and try to slide out on me even in hard straight-line braking."

YMMV
The problem with that is my 4-wheel BBK uses the same calipers, but different piston sizes front and rear. You're addressing running all four corners with the same calipers (and piston sizes). I can't comment on that.

All of the brakes on the Eliges from the factory and even the AP Racing non-stock 4-wheel sets have too much front-wheel bias IHMO. Moving more bias to the rear is advantageous IMHO.

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post #12 of 33 (permalink) Old 05-31-2019, 03:56 AM Thread Starter
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The problem with that is my 4-wheel BBK uses the same calipers, but different piston sizes front and rear. You're addressing running all four corners with the same calipers (and piston sizes). I can't comment on that.

All of the brakes on the Eliges from the factory and even the AP Racing non-stock 4-wheel sets have too much front-wheel bias IHMO. Moving more bias to the rear is advantageous IMHO.

San
Yeah, I think my best course of action (since I don't race my car) is to do some testing when I get them on, and if I have a problem then go from there. It's quite likely that for my application I won't have a problem at all.

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post #13 of 33 (permalink) Old 05-31-2019, 04:32 AM
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The upshot is that under a TBD amount of heavy braking, your rears will lock up first. If there is any kind of turning going on - think emergency/panic brake and a lane change - a spin is the result. Definitely make it a part of whatever testing you are planning. The effect will be more pronounced in low grip situations (ie wet pavement)

"Give a man a match, and he'll be warm for a minute, but set him on fire, and he'll be warm for the rest of his life."
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The upshot is that under a TBD amount of heavy braking, your rears will lock up first. If there is any kind of turning going on - think emergency/panic brake and a lane change - a spin is the result. Definitely make it a part of whatever testing you are planning. The effect will be more pronounced in low grip situations (ie wet pavement)
I will test it thoroughly for sure, I plan to induce ICE mode while turning as well, all of it. I've had the car 11 years without a single panic stop, but one never knows.

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post #15 of 33 (permalink) Old 05-31-2019, 11:57 AM
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The thread to which @Scott M pointed is worth a close read.

I have OEM 2-pots with 288mm rotors all round (PFC 13 front and PFC 11 rear), and OEM wheel/tire sizes.

I made the caliper change first. There was for sure too much rear bais to allow for correction with pad compounds. I got rear-first lock-up with attendant premature ABS kick-in and loss of overall stopping power (no ice-mode, which I believe comes more from tire-diameter mismatches out of range).

I went the whole way and deleted the booster and ABS and added the BOE bias cage. I find that 65/35 bias is required for stable braking (including some down-hill trail-braking at Sears Point). I can lock them all up (even on slicks) and have had no overheating issues.

I love my brakes now but they are really not suited to street use (I don't street-drive the car). The brakes barely work when cold.

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post #16 of 33 (permalink) Old 05-31-2019, 05:58 PM Thread Starter
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The thread to which @Scott M pointed is worth a close read.

I have OEM 2-pots with 288mm rotors all round (PFC 13 front and PFC 11 rear), and OEM wheel/tire sizes.

I made the caliper change first. There was for sure too much rear bais to allow for correction with pad compounds. I got rear-first lock-up with attendant premature ABS kick-in and loss of overall stopping power (no ice-mode, which I believe comes more from tire-diameter mismatches out of range).

I love my brakes now but they are really not suited to street use (I don't street-drive the car). The brakes barely work when cold.
Since my car is purely for the street I don't think the rear bias will cause an issue. As I said previous, I'll do some testing braking over bumps, braking mid-corner, hard panic stop, etc.

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post #17 of 33 (permalink) Old 05-31-2019, 06:03 PM
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I'd be very cautious of any assumption but you are promising to test so I'll just predict that you will find it to be freaking dangerous.

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post #18 of 33 (permalink) Old 05-31-2019, 06:12 PM Thread Starter
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I'd be very cautious of any assumption but you are promising to test so I'll just predict that you will find it to be freaking dangerous.

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We shall soon see.

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post #19 of 33 (permalink) Old 05-31-2019, 06:21 PM
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Since my car is purely for the street I don't think the rear bias will cause an issue. As I said previous, I'll do some testing braking over bumps, braking mid-corner, hard panic stop, etc.
I'm guessing you're doing this more for the looks than the performance, and based on your preference for 17-inch wheels on all corners, you probably would enjoy the caliper symmetry as well. You also probably wouldn't opt for a Volk CE28 8-spoke wheel in the front paired with a 10-spoke in the rear, right? I know I wouldn't.

I like the RAC Monolites because they're strong and light. I am not particularly fond of the spoke pattern as it isn't as symmetrically pleasing to me than other wheels. The weight-weenie side of my brain overrules the symmetrical side.

I'm also guessing that the rotors being of similar size will appeal to your symmetrical 'bias' with regards to looks. I had to throw bias in there with an opposite context than others are using.

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post #20 of 33 (permalink) Old 05-31-2019, 06:52 PM Thread Starter
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I'm guessing you're doing this more for the looks than the performance, and based on your preference for 17-inch wheels on all corners, you probably would enjoy the caliper symmetry as well. You also probably wouldn't opt for a Volk CE28 8-spoke wheel in the front paired with a 10-spoke in the rear, right? I know I wouldn't.

I like the RAC Monolites because they're strong and light. I am not particularly fond of the spoke pattern as it isn't as symmetrically pleasing to me than other wheels. The weight-weenie side of my brain overrules the symmetrical side.

I'm also guessing that the rotors being of similar size will appeal to your symmetrical 'bias' with regards to looks. I had to throw bias in there with an opposite context than others are using.

San
You are correct on all counts. It's all about aesthetics with me, it just so happens that race-car bits are usually more interesting, and more aesthetically pleasing to my eye. It's more about balance than anything, and the stock brakes are terribly ugly compared to the rest of the car, as are those horrid balloon front tires. I'm just correcting the imbalance at the expense of outright performance because I don't use the car in an outright performance capacity.

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