How did 4 piston Brembos make your car feel?
04-23-2016, 01:08 PM
#1
How did 4 piston Brembos make your car feel? How good are the 4 piston Brembos suppose to be? Mine felt decent after I installed them but squishy due to trapped air. I didn't drive the car much, but after a short time my pedal started going really soft and bottoming out. I've bled all 4 corners and inside/outsides multiple times with the same result. I pinned it as a bad master cylinder and bench bled the replacement. I also replaced the brake booster while I was at it and the pedal really didn't improve at all. I heard I needed to manually force trapped air out of the ABS unit by activating it by slamming on the brakes which I've done and re-bled everything.
Something still just didn't feel right, then I somewhat realized what it was. The pedal still feels softer and doesn't seem to grab well, but the actual pedal travel is shorter by a good inch or 2". I don't feel the brakes bite as well as they should due to the lack of pedal. I might add, with the car off, the pedal is hard as a rock.
I'm wondering if that has something to do with less vacuum from the cam or maybe the stock master isn't big enough to feed the extra pistons? Would glazed rotors/pads make the pedal feel bad even at real low speeds?
I'm comparing pedal feel and stopping distance between my 2 TA's. My daily has 13" C5 Z06 rotors with the stock calipers. That car stops on a dime and the pedal feels great.
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Something still just didn't feel right, then I somewhat realized what it was. The pedal still feels softer and doesn't seem to grab well, but the actual pedal travel is shorter by a good inch or 2". I don't feel the brakes bite as well as they should due to the lack of pedal. I might add, with the car off, the pedal is hard as a rock.
I'm wondering if that has something to do with less vacuum from the cam or maybe the stock master isn't big enough to feed the extra pistons? Would glazed rotors/pads make the pedal feel bad even at real low speeds?
I'm comparing pedal feel and stopping distance between my 2 TA's. My daily has 13" C5 Z06 rotors with the stock calipers. That car stops on a dime and the pedal feels great.
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Last edited by HotWhipT/A; 04-25-2016 at 08:11 PM.
04-23-2016, 03:15 PM
#2
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Good or bad is so subjective for brakes. Sounds like you're looking for a high hard pedal. If that's the case then the brembo's are the wrong choice.
In comparison to stock brakes, there is more piston area to fill so the pedal will have more soft travel before it bites, but once it bites it will bite harder (create more stopping force) for the same pedal force since the piston area is so much greater. At the same time the brake pedal will feel softer, because it's requiring less pedal force for the same amount of braking vs stock.
Hope that helped, but much of what you're describing is exactly what you should expect from increasing caliper piston area without increasing the master piston diameter.
In comparison to stock brakes, there is more piston area to fill so the pedal will have more soft travel before it bites, but once it bites it will bite harder (create more stopping force) for the same pedal force since the piston area is so much greater. At the same time the brake pedal will feel softer, because it's requiring less pedal force for the same amount of braking vs stock.
Hope that helped, but much of what you're describing is exactly what you should expect from increasing caliper piston area without increasing the master piston diameter.
04-23-2016, 04:52 PM
#3
That does make sense. That's what I figured, so thanks for confirming my thoughts. However, they still feel more spongy than I think they should. It definitely doesn't have the bite it should. When it does have some bite, its only because I'm putting extra force into the pedal only to almost bottom out since its so short. I'm running AC Delco Ceramic pads if that means anything. My daily with lesser brakes stops quicker and with more confidence for sure.
Last edited by HotWhipT/A; 04-25-2016 at 08:12 PM.
04-23-2016, 06:48 PM
#5
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That does make sense. That's what I figured, so thanks for confirming my thoughts. However, they still feel more spongy than I think they should. It definitely doesn't have the bite it should. When it does have some bite, its only because I'm putting extra force into the pedal. I'm running AC Delco Ceramic pads if that means anything. My daily with lesser brakes stops quicker and with more confidence for sure.
04-23-2016, 11:11 PM
#6
http://powerbrakeservice.net/new-198...ydroboost.html
So the first time I pressure bled the system after the install, then again after it was still spongy, then once more manually with a friend for good measure. After changing the bad master and booster, we manually bled it and all was coming out solid. I drove it to test it out and force the ABS on to free trapped air in the unit and bled the brakes manually again.
I got a chance to start bleeding the brakes again tonight. This time I tried a third method. I'm using my MityVac and packing grease around the bleeder screw so there is ZERO chance of air getting in. You can tell when the grease isn't sealing up while under vacuum. I'm going to the parts store in the morning to get 2 new bottles of brake fluid and I'll finish it all up hopefully.
Last edited by HotWhipT/A; 04-25-2016 at 08:16 PM.
04-24-2016, 08:55 PM
#7
So I vacuum bled all the lines in the right order and all fresh fluid coming out solid. I ran 2 full bottle through the system. It made zero difference. My problem isn't with air, at least not anymore. The pedal barely moves and rock hard with the engine off.
I noticed the pedal doesn't go down nearly as far as it should and it has been like that since the install of the calipers I think. I'm not entirely sure. It literally bottoms out half way into what feels like a brick wall. My good working car has much better pedal travel and the pedal with the car off does have some give.
I took off the master off of the brake booster and pushed the pedal and it'll literally go all the way to the floor, so it's not the booster, pushrod adjustment, or the actual pedal.
Does your pedal travel stay the same with Brembo calipers?
If so, I either have a bad brand new master cylinder or maybe the ABS block??? When I bench bled the master, it had plenty of travel so I don't know what gives. The booster with no master pushed to the floor, that pin from the booster comes out a good 1.5", but with the master attached it feels like it only moves .5". That would cause **** brakes for sure. I guess I'll pull the master off and bench test it again to see if the piston will travel the full length it should, but I'll probably swap it out under warranty again. If that is okay, I'm going to assume its the ABS block.
I noticed the pedal doesn't go down nearly as far as it should and it has been like that since the install of the calipers I think. I'm not entirely sure. It literally bottoms out half way into what feels like a brick wall. My good working car has much better pedal travel and the pedal with the car off does have some give.
I took off the master off of the brake booster and pushed the pedal and it'll literally go all the way to the floor, so it's not the booster, pushrod adjustment, or the actual pedal.
Does your pedal travel stay the same with Brembo calipers?
If so, I either have a bad brand new master cylinder or maybe the ABS block??? When I bench bled the master, it had plenty of travel so I don't know what gives. The booster with no master pushed to the floor, that pin from the booster comes out a good 1.5", but with the master attached it feels like it only moves .5". That would cause **** brakes for sure. I guess I'll pull the master off and bench test it again to see if the piston will travel the full length it should, but I'll probably swap it out under warranty again. If that is okay, I'm going to assume its the ABS block.
Last edited by HotWhipT/A; 04-25-2016 at 06:42 PM.
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04-24-2016, 11:50 PM
#8
Check for play in your front hubs. Those calipers are fixed where the stock ones are floating. Any side to side movement of the rotor is going to cause piston "knock back".
What calipers do you have in the rear? C-clip axles can move enough to cause knock back on fixed calipers. Even guys with a 9" with tapered bearings have issues with fixed calipers and manual brakes, though it's usually ok with power brakes. A lot of the pro-touring crowd has switched to some form of full floating rear for this reason. If you have stock rear calipers they should be fine.
What calipers do you have in the rear? C-clip axles can move enough to cause knock back on fixed calipers. Even guys with a 9" with tapered bearings have issues with fixed calipers and manual brakes, though it's usually ok with power brakes. A lot of the pro-touring crowd has switched to some form of full floating rear for this reason. If you have stock rear calipers they should be fine.
04-25-2016, 12:51 AM
#9
Stock rears.
I'm familiar with knock back. I'll check the hubs, but that wouldn't explain why my pedal is always short.
My pedal physically will not go down as far as it should. The little bit that it moves is soft when running. Off, the pedal is rock hard.
I'm familiar with knock back. I'll check the hubs, but that wouldn't explain why my pedal is always short.
My pedal physically will not go down as far as it should. The little bit that it moves is soft when running. Off, the pedal is rock hard.
04-25-2016, 07:59 AM
#10
In the first post you said the pedal still feels soft and goes down further than it should. Assuming there's no air I'd have to think maybe you're getting a little pad knock back.
If it feels firm at a stand still and gets soft after moving forward a little, I'd be looking for play in the hubs.
If you're saying it's not going down far enough and it's too hard, the piston area of the Brembos is smaller. That'll cause less pedal travel and more effort.
If this chart is right, then it looks like 4.29 vs the stock 4.81. (Edit: I'm not sure if that 4.29 needs to be doubled or if it accounts for all 4 pistons)
I'm no expert on this stuff so Idk how much difference in pedal travel/feel that would make, but if that's your problem (or part of it) the ways to fix it would be a smaller bore master, or if there's not a bolt on that would work, you could change the pedal ratio. Anyone know what size master the CTSV and SS use with these calipers?
If it feels firm at a stand still and gets soft after moving forward a little, I'd be looking for play in the hubs.
If you're saying it's not going down far enough and it's too hard, the piston area of the Brembos is smaller. That'll cause less pedal travel and more effort.
If this chart is right, then it looks like 4.29 vs the stock 4.81. (Edit: I'm not sure if that 4.29 needs to be doubled or if it accounts for all 4 pistons)
I'm no expert on this stuff so Idk how much difference in pedal travel/feel that would make, but if that's your problem (or part of it) the ways to fix it would be a smaller bore master, or if there's not a bolt on that would work, you could change the pedal ratio. Anyone know what size master the CTSV and SS use with these calipers?
Last edited by t_raven; 04-25-2016 at 08:18 AM.
04-25-2016, 01:40 PM
#11
I just installed the cts-v brakes this weekend. I have yet to drive it yet as I just finished reinstalling my transmission too... I was going to test it but didn't want to wake the neighbors at midnight. I'll post results of pedal travel after I drive it later today.
04-25-2016, 06:50 PM
#12
In the first post you said the pedal still feels soft and goes down further than it should. Assuming there's no air I'd have to think maybe you're getting a little pad knock back.
If it feels firm at a stand still and gets soft after moving forward a little, I'd be looking for play in the hubs.
If you're saying it's not going down far enough and it's too hard, the piston area of the Brembos is smaller. That'll cause less pedal travel and more effort.
If it feels firm at a stand still and gets soft after moving forward a little, I'd be looking for play in the hubs.
If you're saying it's not going down far enough and it's too hard, the piston area of the Brembos is smaller. That'll cause less pedal travel and more effort.
I guess let me be more specific... With the car on, the pedal feels soft and short even when I'm parked and pressing the pedal which leads me to think that has nothing to do with pad knock back. I have to press further with more effort to get the brakes to feel like they are half working when I'm moving, but by that point, I'm about bottomed out on pedal travel. Now with the car off, after you pump the vacuum out, the pedal is like a rock and barely moves unlike my working car that still has some pedal feel that you can push. I think something is wrong with the new master, because the booster is working for sure. A rock hard pedal also leads me to think their is no air in the lines and of course no external leaks.
04-26-2016, 10:41 AM
#13
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In the first post you said the pedal still feels soft and goes down further than it should. Assuming there's no air I'd have to think maybe you're getting a little pad knock back.
If it feels firm at a stand still and gets soft after moving forward a little, I'd be looking for play in the hubs.
If you're saying it's not going down far enough and it's too hard, the piston area of the Brembos is smaller. That'll cause less pedal travel and more effort.
If this chart is right, then it looks like 4.29 vs the stock 4.81. (Edit: I'm not sure if that 4.29 needs to be doubled or if it accounts for all 4 pistons)
I'm no expert on this stuff so Idk how much difference in pedal travel/feel that would make, but if that's your problem (or part of it) the ways to fix it would be a smaller bore master, or if there's not a bolt on that would work, you could change the pedal ratio. Anyone know what size master the CTSV and SS use with these calipers?
If it feels firm at a stand still and gets soft after moving forward a little, I'd be looking for play in the hubs.
If you're saying it's not going down far enough and it's too hard, the piston area of the Brembos is smaller. That'll cause less pedal travel and more effort.
If this chart is right, then it looks like 4.29 vs the stock 4.81. (Edit: I'm not sure if that 4.29 needs to be doubled or if it accounts for all 4 pistons)
I'm no expert on this stuff so Idk how much difference in pedal travel/feel that would make, but if that's your problem (or part of it) the ways to fix it would be a smaller bore master, or if there's not a bolt on that would work, you could change the pedal ratio. Anyone know what size master the CTSV and SS use with these calipers?
There are 4 pistons per caliper in the brembo gen1's and 6 piston per caliper in the gen2.
Also Pad knockback is definitely an issue on a track with sticky tires, but I haven't suffered from it on the street. If the problem goes away when you pump the pedal. It might be knockback.
04-28-2016, 11:36 PM
#15
I checked my hubs and they are solid. They should be considering they are pretty new.
I changed out the new master cylinder a second time and that actually helped out with the pedal travel some I feel. Without re-bleeding the brakes I tested it again. What I noticed was the pedal and stopping power got better after every hard stop while activating the ABS. I did however check and clean all the fuses for the ABS and put dielectric grease on the connector harness. So maybe it was a combination of a bad master and some air or valves not working right in the ABS block?
Either way, the pedal feels better and is way more responsive. I bled the front lines again due to possible trapped air from the ABS. I did get some tiny bubbles. I want to bleed the rear lines once more, go for a hard drive and recheck all the lines again. I think by then, all the air will be out for sure. Then I believe the pedal and performance will be as they should.
I changed out the new master cylinder a second time and that actually helped out with the pedal travel some I feel. Without re-bleeding the brakes I tested it again. What I noticed was the pedal and stopping power got better after every hard stop while activating the ABS. I did however check and clean all the fuses for the ABS and put dielectric grease on the connector harness. So maybe it was a combination of a bad master and some air or valves not working right in the ABS block?
Either way, the pedal feels better and is way more responsive. I bled the front lines again due to possible trapped air from the ABS. I did get some tiny bubbles. I want to bleed the rear lines once more, go for a hard drive and recheck all the lines again. I think by then, all the air will be out for sure. Then I believe the pedal and performance will be as they should.
04-29-2016, 09:48 AM
#17
Sorry for the late response but I have had a chance to test my brakes and the pedal feel is actually pretty much the same, only difference is that I can lockup the front brakes quicker and the ABS kicks in earlier. It doesn't require any extra force so I don't know what's going on with OP brakes 
04-30-2016, 03:54 PM
#18
