Underwhelming brake upgrade - why?
#26
05-08-2008, 08:46 PM
Join Date: Oct 2005
Location: Car Nut Since 1987, Owner Since Fall 2005, Vendor Since Fall 2007
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I'm wondering how you know the CT - TSW combo has greater CoF than stock. CoF for brakes is not a simple one-number thing -- it depends at least on temp and pressure. OEM brakes, and MINI is no exception, tend to be optimized for high CoF at low temp/press, at the expense of higher temp/press performance.
I'm betting the OP will get the car back from service unimproved wrt pedal feel.
I'm betting the OP will get the car back from service unimproved wrt pedal feel.
I'll address the CoF issue. AXC and CT will not release CoF numbers because there is no agreed baseline number in the industry to give you our customers true numbers. If there every is an agreed baseline we would welcome the CoF numbers into the market, I think you know why 
.Can I get some butter for my
#27
05-09-2008, 09:59 AM
I installed speed bleeders so I could bleed the brakes by myself. Others have pressurized Brake bleeder gizmos which fasten to the reservoir and work well, maybe faster, too. I would think "gravity bleeding" would be really slow.
http://speedbleeder.com/
Just carrying hose and empty water bottle to the track permits easy bleading.
http://speedbleeder.com/
Just carrying hose and empty water bottle to the track permits easy bleading.
#28
05-09-2008, 10:12 AM
Verdict is... I wasn't getting all the air myself despite the lines appearing free o' bubbles. Local shop redid, found air, and it's better than before doing the work / bleeding myself. Lesson learned. Cheap one too - glad I didn't end up taking to the dealer.
I'm inclined to agree with you, inimmini, but I think your point can really vary from pad to pad. The Carbotech Bobcats aren't requiring more effort than the stockers do (from what I remember) and are significantly better, although in an ideal world I'd like more linearity and less travel to get them biting more. Although it's just about perfect for heel-toeing now, unless you're really mashing the brake...
Thumbs up for the brake combo, thumbs down for nooby topics.
I'm inclined to agree with you, inimmini, but I think your point can really vary from pad to pad. The Carbotech Bobcats aren't requiring more effort than the stockers do (from what I remember) and are significantly better, although in an ideal world I'd like more linearity and less travel to get them biting more. Although it's just about perfect for heel-toeing now, unless you're really mashing the brake...
Thumbs up for the brake combo, thumbs down for nooby topics.
Installing a set of Tyrolsport bushings *should* firm up the pedal a bit, and remove some of that squish. It also helps make the brakes more "Linear". I forget, did you say you have SS brake lines as well?
#29
05-09-2008, 10:18 AM
The perception of pedal squishiness indeed has a lot to do with the CoF between rotor and pad. Agreed, the pedal is not truly more squishy with the higher performance rotor & pad, but because this set-up likely needs greater pedal force than stock for the same braking power, it seems squishier. I experienced the same thing as the OP when I switched from stock to TSW rotors/Hawk HPS. Without even bleeding the brakes (no possibility of air entrapment) I had to press harder to get the same braking power, which brought the brake pedal below the gas pedal for decent stopping. Not good for heel-toe. Brake bleeding did not help, but SS lines did, as well as simply more time for additional break-in.
I'm wondering how you know the CT - TSW combo has greater CoF than stock. CoF for brakes is not a simple one-number thing -- it depends at least on temp and pressure. OEM brakes, and MINI is no exception, tend to be optimized for high CoF at low temp/press, at the expense of higher temp/press performance.
I'm betting the OP will get the car back from service unimproved wrt pedal feel.
I'm wondering how you know the CT - TSW combo has greater CoF than stock. CoF for brakes is not a simple one-number thing -- it depends at least on temp and pressure. OEM brakes, and MINI is no exception, tend to be optimized for high CoF at low temp/press, at the expense of higher temp/press performance.
I'm betting the OP will get the car back from service unimproved wrt pedal feel.
I'm well aware that CoF is a graph like dynamic number, not a simple X + Y = Z calculation. I was saying that given equal pedal input, and assuming all else is equal, once within their "Temperature range" (Carbotech Bobcats have a stock like temperature curve, except it goes much higher before dropping off due to the ceramic content) the CT Bobcats will have a higher CoF than the stockers. It's rather easy to measure brake torque, just put your foot down, if it feels like it's biting harder, it is!
Last edited by Guest; 05-09-2008 at 10:21 AM.
#30
05-09-2008, 10:43 AM
Join Date: Sep 2005
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#31
05-09-2008, 10:53 AM
#32
05-09-2008, 07:52 PM
The haynes manual may be incorrect, but it states that the mini's brakes are self bleeding.
An interesting statement. And I'm reasonably certain that it refers to the basic gravity bleed where simply opening a caliper will purge said caliper of air as the bleeder nipple is higher than the inlet port. However pumping a brake system while the nipple is open is asking for problems...as the pedal is released and brought up the vacuum in the system will draw air back INTO the caliper thus requiring the whole process be done all over.
There remains absolutely NO reason for air to be in an ABS system or any part of the braking system other than bad procedures being employed. Even replacing a hose is no differet than changing the hose on a beer bong- the beer is flowing and so long as the funnel is full it's not going to stop and air is not going up. Connect the new hose, fill the caliper, keep the reservoir (the beer funnel) full and there shall remain no air in your system.
Bleeding is not about pressure, it's only displacement. Some procedures make it appear far more complex than it really is.
An interesting statement. And I'm reasonably certain that it refers to the basic gravity bleed where simply opening a caliper will purge said caliper of air as the bleeder nipple is higher than the inlet port. However pumping a brake system while the nipple is open is asking for problems...as the pedal is released and brought up the vacuum in the system will draw air back INTO the caliper thus requiring the whole process be done all over.
There remains absolutely NO reason for air to be in an ABS system or any part of the braking system other than bad procedures being employed. Even replacing a hose is no differet than changing the hose on a beer bong- the beer is flowing and so long as the funnel is full it's not going to stop and air is not going up. Connect the new hose, fill the caliper, keep the reservoir (the beer funnel) full and there shall remain no air in your system.
Bleeding is not about pressure, it's only displacement. Some procedures make it appear far more complex than it really is.
That may be what they mean, I'm not sure...I was definitely not saying to pump the brakes with the valve opened! That would obviously suck air into the system. I was referring to the fact that the air will rise through the system just as the fluid will drain. I was also referring to pumping in the sense of pushing fluid back and forth through the closed system, not the actual pressure. The movement and turbulance through the system may cause the air to float to the top. I am also curious how the air got into the system without changing brake lines or something like that. I have never had to bleed my brakes unless I am actually changing the fluid.
#33
05-09-2008, 08:02 PM
I'm happy to be shown wrong in this case, glad it worked out well for you. Maybe I'll try the CT pads after these Hawks are gone.
#34
05-09-2008, 08:03 PM
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