Brakes that don't Brake?
10 January 2003, 03:50 PM
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Broken? You mean warped? If so, it's probably not the pads causing it, more the disc construction and usage.
Best way to avoid warpage is to go for a couple of slow laps to allow the airflow to cool the discs at the end of each run. Also make sure you avoid sitting with your foot on the brake pedal when the discs are warm and the car is at a standstill. The heatsinking effect of the pads will set up temperature differentials in the discs which cause warpage.
Treated properly, you should be able to get a set of OE discs red hot on a repeated basis and still not have them warp. Quinton Hazell ones are very good for this.
Speaking of which, strictly IMO, most of these so-called "Group N+" discs are a complete waste of money. They still suffer from the poorly designed joint between the "disc" and "bell" sections, and if anything, they are more prone to warpage than OE discs thanks to material removed for grooving, dimpling etc.
The best solution is a separate disc/bell assembly like DBA's, or the forthcoming Performance Braking kit. Even then, the 24mm discs are thinner than ideal for grooving.
Anyway, back to the pads. For a mix of track and road use on the standard calipers, Pagid RS4-2 (Blue) is very difficult to beat. The "roadified" version, RS4-2.1, has better wear characteristics and less squeal in return for slightly less friction.
There's also an RS4-4 (Orange) compound which while still carbon based, provides even better high temperature performance - but at the expense of cold bite. For a car that gets used on the road it's probably not a good compromise.
[Edited by greasemonkey - 10/1/2003 3:53:07 PM]
Best way to avoid warpage is to go for a couple of slow laps to allow the airflow to cool the discs at the end of each run. Also make sure you avoid sitting with your foot on the brake pedal when the discs are warm and the car is at a standstill. The heatsinking effect of the pads will set up temperature differentials in the discs which cause warpage.
Treated properly, you should be able to get a set of OE discs red hot on a repeated basis and still not have them warp. Quinton Hazell ones are very good for this.
Speaking of which, strictly IMO, most of these so-called "Group N+" discs are a complete waste of money. They still suffer from the poorly designed joint between the "disc" and "bell" sections, and if anything, they are more prone to warpage than OE discs thanks to material removed for grooving, dimpling etc.
The best solution is a separate disc/bell assembly like DBA's, or the forthcoming Performance Braking kit. Even then, the 24mm discs are thinner than ideal for grooving.
Anyway, back to the pads. For a mix of track and road use on the standard calipers, Pagid RS4-2 (Blue) is very difficult to beat. The "roadified" version, RS4-2.1, has better wear characteristics and less squeal in return for slightly less friction.
There's also an RS4-4 (Orange) compound which while still carbon based, provides even better high temperature performance - but at the expense of cold bite. For a car that gets used on the road it's probably not a good compromise.
[Edited by greasemonkey - 10/1/2003 3:53:07 PM]
01 October 2003, 03:22 PM
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Have broken many front brake disks this year from over heating on track days. Now using standard callipers and GroupN Disks. Can anyone recommend some decent pads? Not Standard or Metalic. Please
01 October 2003, 04:43 PM
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I love the Ferodo DS3000's - atmittedly not used them on a track yet - but no fade even braking from VERY high speeds .... and they still work from cold!
01 October 2003, 10:14 PM
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greasemonkey, a couple of points frm my experience as the northern Pagid distributor......
"grpN" discs are NOT grooved or drilled as this relates to production" racing and the discs must remain as original but can be made from upgraded castings/ material. A lot of suppliers misuse this moniker to infer that their product is something else, but normally they are simply "fashion" discs.........
wouldn't recomend rs4.2.1 for track use unless you are really light on the brakes, as it doesn't have the temp. ability...........
rs4.4 has only a marginal dfference in cold bite compared to rs4.2, but more than rs4.2.1 so this would generally not be an issue.......
normally use rs15 with a "pukka" grpN disc on track or rally cars with great success, and would normally suggest/ supply this for track use.....
completely agree with your comments about "cooling" laps and not holding the brakes at standstill, often amazed by the number of people that overlook this important point...........
alyn - asperformance.com
"grpN" discs are NOT grooved or drilled as this relates to production" racing and the discs must remain as original but can be made from upgraded castings/ material. A lot of suppliers misuse this moniker to infer that their product is something else, but normally they are simply "fashion" discs.........
wouldn't recomend rs4.2.1 for track use unless you are really light on the brakes, as it doesn't have the temp. ability...........
rs4.4 has only a marginal dfference in cold bite compared to rs4.2, but more than rs4.2.1 so this would generally not be an issue.......
normally use rs15 with a "pukka" grpN disc on track or rally cars with great success, and would normally suggest/ supply this for track use.....
completely agree with your comments about "cooling" laps and not holding the brakes at standstill, often amazed by the number of people that overlook this important point...........
alyn - asperformance.com
02 October 2003, 10:19 AM
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Thanks for your replies.
I always do a cooling down lap, never keep my foot on the pedal when stopped and never use the hand brake but still I have cracked a set of original front disks and 2 sets of Tarox drilled and grooved in one season. The disks I am using now are Tarox GroupN (not grooved or drilled but heat treated) with standard pads. They haven't cracked yet but I just cant stop.
I always do a cooling down lap, never keep my foot on the pedal when stopped and never use the hand brake but still I have cracked a set of original front disks and 2 sets of Tarox drilled and grooved in one season. The disks I am using now are Tarox GroupN (not grooved or drilled but heat treated) with standard pads. They haven't cracked yet but I just cant stop.
02 October 2003, 11:43 AM
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Weird, cracking is (more often than not) caused by really sudden differential cooling of the discs - like driving through a ford or deep puddles.
As mentioned earlier, the best option in your position is probably a separate disc and bell setup like the DBA 5000 or Performance Braking (01600 713117)'s soon to be available one. One-piece rotors by their nature have a compromised design, and the OE pattern (and by definition Grp N/"Group N+" parts particularly so.
BTW - Alyn, agree with you 100%. Know true "Group N" discs can't be drilled/grooved etc. Was referring to the so-called "Group N+" items that use the same shape basic casting but with additional material removal. As you say, fashion discs.
As mentioned earlier, the best option in your position is probably a separate disc and bell setup like the DBA 5000 or Performance Braking (01600 713117)'s soon to be available one. One-piece rotors by their nature have a compromised design, and the OE pattern (and by definition Grp N/"Group N+" parts particularly so.
BTW - Alyn, agree with you 100%. Know true "Group N" discs can't be drilled/grooved etc. Was referring to the so-called "Group N+" items that use the same shape basic casting but with additional material removal. As you say, fashion discs.
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