Improving OEM brakes for track

I tried stock setup at Bresse track, i did only 2 laps before the brakes have completely faded out ! Very scary... Air temparature was cold.

After that, meanwhile my AP 6P/4P kit arrives, I put Motul RBF660 brake fluid and Pagid RS-29 (yellow) endurance pads leaving stock discs and lines, and I did not recognized my brakes at Charade track (temperature was hotter than at Bresse). Even if I had some fading 3 or 4 times, it was a waaaaay better. If you go track only occasionnally and you are not too heavy with your right foot (that I am), it will maybe fit your needs ;).
 
exocet said:
I tried stock setup at Bresse track, i did only 2 laps before the brakes have completely faded out ! Very scary... Air temparature was cold.

After that, meanwhile my AP 6P/4P kit arrives, I put Motul RBF660 brake fluid and Pagid RS-29 (yellow) endurance pads leaving stock discs and lines, and I did not recognized my brakes at Charade track (temperature was hotter than at Bresse). Even if I had some fading 3 or 4 times, it was a waaaaay better. If you go track only occasionnally and you are not too heavy with your left foot (that I am), it will maybe fit your needs ;).
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Did you order new AP brakes? How long did you have to wait? I'm waiting for some now and apparently they can take up to four weeks to be shipped from AP :cry:
 
Yes I ordered the kit 1 month ago and still waiting, I've read somewhere that the delay is between 6 and 10 weeks (they are manufactured on request). That's why I've purchased Pagid RS29 and RBF660 for my stock calipers. I will be all next week at the Ring, my stepfather also gave me used Mintex 1144, used Carbone-Lorraine and I still have my stock pads, so I hope that will be enough before my APs arrives at home.
 
oops sorry my RIGHT foot of course :rofl: !
(even if sometimes I use my left foot to brake with FWD on snow).
 
playa have you ordered your kit?? what size did you go with??

you will not believe the size of the parts when they are in your hands, also interestly every single part was lighter than the stock items bar the rear calipers....... pretty amazing if you ask me, you'll loose a good few lbs with this setup!

byron
 
ChawenHalo said:
:thumbsup: Good post mate, a fellow geek! :) What you say makes sense. Its supposed to be the CSL's weakpoint too. The disks are too thin and prone toi crack when over heated. Thats why I'm a little weary of mucking about with components over the OEM.

Anyone else on specific pads please?
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I'd be interested to know what pads are available for the Z4M standard calipers and discs and what people have had success/no success with in the past.

The drilled holes in the discs won't help with the cracking as the provide a perfect crack propagation point. The fact that the discs float will help, but if i were upgrading my discs i'd go for plain discs rather than drilled. Slots don't do anything either other than wear your pads out quicker. Modern pads don't need the deglazing effect that slots are designed to give.

Just out of interest the picture below was a Spoon disc (curved rather than straight cooling vanes) used with DS2500 pads on my S2000 after a 2 sessions on track at Rockingham.

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I'm surprised no one has mentioned cooling, there are good ducts on the front of the car but they don't connect to the back plates on the hub,a bit of flex hose and a few well thought out mods to the back plate should see a proper flow of air over the rotors and callipers
On a lot of cars it's not the brakes that are the problem it's getting rid of the heat they generate
 
Beedub said:
playa have you ordered your kit?? what size did you go with??

you will not believe the size of the parts when they are in your hands, also interestly every single part was lighter than the stock items bar the rear calipers....... pretty amazing if you ask me, you'll loose a good few lbs with this setup!

byron
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Just waiting for Simpsons to get back to me with my booking in date! I told them I use CSLs for road and will use 18s for track so I assume they'll go with the slimmer calipers. Can't wait to get them on and back on the track for some comparison.
 
alfamale said:
I'm surprised no one has mentioned cooling, there are good ducts on the front of the car but they don't connect to the back plates on the hub,a bit of flex hose and a few well thought out mods to the back plate should see a proper flow of air over the rotors and callipers
On a lot of cars it's not the brakes that are the problem it's getting rid of the heat they generate
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Is that something you have done to yours? I wish I had known when we was on the track as I could have had a nosey... With regard to your last comment that doesn't apply to the ZM thanks to the absolutely pony stock calipers :cry:
 
I also removed a piece of platic just on top of the brakes holes in front of the wheels. Maybe that helps cooling brakes ?
 
Lower said:
Just out of interest the picture below was a Spoon disc (curved rather than straight cooling vanes) used with DS2500 pads on my S2000 after a 2 sessions on track at Rockingham.
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I may be wrong, but those look like blank discs that have been drilled after being cast, rather than being discs that have been cast with the holes in place (I believe BMW use the former option though, as cast ones can cost upwards of £500 each).

When the blank disc is made it has a specific structural integrity based on the materials & method of manufacture. Once you start drilling holes, you start reducing it's structural integrity, and start getting little fracture lines which can (in extreme cases) crack the whole disc. The cast ones don't lose any integrity as the structure doesn't change. However, in about 20 years of doing track days and marshalling, I've only ever seen a dozen occurrences, and they've either been down to a manufacturing defect, or abuse.

You've just got to weigh up whether the small amount of extra fade resistance the drilled disc gives outweighs the slightly decreased surface area due to the drilled holes.

The drilled holes on the current ///M cars are for show only - as otherwise they'd not have put a puny single pot calliper on it. My e34 M5 had similarly-sized, but solid, discs with 4-pot calipers (2 pistons on each side of disc) and floating discs, and they coped very well, even with an extra 250kg aboard.

ETA, the M5 callipers are £900 a piece, compared with the £270 a piece of the Z4M's. Personally I'd have thought someone buying a £40-£48k car wouldn't care if it was £1k more expensive if it had proper brakes. I suppose it just shows that BMW consider the ///M cars as purely a marketing/money-making exercise now.
 
Not on this car but I have on others with good results, lots of this type of discussion on the S2000 forum and something simple like removing the backplate helps, I will try to have a look at the set up this weekend from memory the front vents feed out through a grill in the arch liner but not sure after that
I obviously wasn't trying hard enough at Bedford as I had no problem with 5 lap sessions.
Are you unhappy with brakes when not overheated? I think you said it pulled to one side so could be one of the callipers doing all the work hence the fluid boil
 
mmm-five said:
Lower said:
Just out of interest the picture below was a Spoon disc (curved rather than straight cooling vanes) used with DS2500 pads on my S2000 after a 2 sessions on track at Rockingham.
Click to expand...
I may be wrong, but those look like blank discs that have been drilled after being cast, rather than being discs that have been cast with the holes in place (I believe BMW use the former option though, as cast ones can cost upwards of £500 each).

When the blank disc is made it has a specific structural integrity based on the materials & method of manufacture. Once you start drilling holes, you start reducing it's structural integrity, and start getting little fracture lines which can (in extreme cases) crack the whole disc. The cast ones don't lose any integrity as the structure doesn't change. However, in about 20 years of doing track days and marshalling, I've only ever seen a dozen occurrences, and they've either been down to a manufacturing defect, or abuse.

You've just got to weigh up whether the small amount of extra fade resistance the drilled disc gives outweighs the slightly decreased surface area due to the drilled holes.

The drilled holes on the current ///M cars are for show only - as otherwise they'd not have put a puny single pot calliper on it. My e34 M5 had similarly-sized, but solid, discs with 4-pot calipers (2 pistons on each side of disc) and floating discs, and they coped very well, even with an extra 250kg aboard.

ETA, the M5 callipers are £900 a piece, compared with the £270 a piece of the Z4M's. Personally I'd have thought someone buying a £40-£48k car wouldn't care if it was £1k more expensive if it had proper brakes. I suppose it just shows that BMW consider the ///M cars as purely a marketing/money-making exercise now.
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They're not plain drilled blanks. Spoon is one of the higher end Japanese racing brands and i specifically chose these discs because they were the only ones i could find on the market at the time that had curved cooling vanes (as opposed to straight to improve the airflow through the disc) that were designed as cross drilled discs and appeared to be properly developed and proven rather than just OEM type discs drilled to look good.

As long as the discs are designed to be drilled and the edges of the holes are appropriately chamfered after drilling it really doesn't make any difference whether they are cast in or drilled in. There is a different grain structure if the holes are cast in, but properly heat treated discs have a small, uniform grain structure anyway so its not significant. Its the sharp edge of the hole that creates the crack propagation point. Proper chamfering or abrasive flow machining removes the sharp edge and removes the specific crack propagation point.

The fact that the holes are there that makes the disc weaker and more likely to crack in the same way that a piece of perforated paper will tear along the line of perforation. Holes were originally put in discs to allow the gases trapped between the pad and the disc to vent rather to increase cooling. Nowadays they are just there for looks and in vented discs don't give any significant increase in cooling. You rarely see proper racecars with drilled discs for that reason.

I've seen lots of cracked discs, its a common problem with the S2000 with the wrong type of uprated pads. If the pads don't fade as the disc start to overheat then the driver doesn't know back off and the disc gets even hotter. Anything over 650 degrees and you're into disc cracking territory.

But going back to my original point, with the correct pads selection you can lower disc temperature which in turn reduced the fluid fade problem. Hence my interest in what uprated pads are available. The importance of good pad selection remains even if you've gone for a big brake kit.
 
alfamale said:
Not on this car but I have on others with good results, lots of this type of discussion on the S2000 forum and something simple like removing the backplate helps, I will try to have a look at the set up this weekend from memory the front vents feed out through a grill in the arch liner but not sure after that
I obviously wasn't trying hard enough at Bedford as I had no problem with 5 lap sessions.
Are you unhappy with brakes when not overheated? I think you said it pulled to one side so could be one of the callipers doing all the work hence the fluid boil
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The pulling developed after a few sessions on the track. I was on a meet the day before and did some big stops and plenty of spirited driving over 150 miles distance without incident so whatever happened occurred at Bedford it would seem. Either way, I'm getting AP kit now so we'll see how that works out next time round ! 8)
 
This week refection of front calipers with the kits bmw,
test again with the EBC yellow 1h Mountain (0> 1400) 3 passes, down the famous road .... Napoleon!
perfect matches for the quick way and cheap, is okay!
 
exocet said:
Yes I ordered the kit 1 month ago and still waiting, I've read somewhere that the delay is between 6 and 10 weeks (they are manufactured on request).
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They are manufactured on request? Does somebody know if you can order the calipers without AP logo or full black (the AP logo is now yellow).
 
Yep they're built to order. I guess our cars aren't the most popular of applications for those brakes although aren't they common with the CSL? Anyway, I was told to expect a slightly longer wait as it's the motorsport season and they take precedence :O
 
A quick feed back regarding brakes as I did my second track day at my local "grind & trash" circuit (saw an F3000 1990's with 3L Alfa engine totally trash his baby to bits).

Followed MMM5's advice further and did 3 proper cooling laps and no squeel after a 15 mins session. Used more TC off too which helps not trigger the ESP :)

Did go a little mushy after the 2nd session though.

difinately going to ditch the whole set OEM wheels and brake set up once I've worned the disks out and improved my level :roll:
 
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