Original Cooper S disc brakes VS new grooved discs

[Ratkiller]

Took my mini down a vey steep, long, and windy road last week. Towards to tale end I had major brake fade. Scared the hell out of me. Ended up haveing to use the e-brake when comeing to a stop.

So I ended up replacing the original Cooper S 7" discs with MiniSpare's 7.5" slotted discs. I have yet to take it on that same road, but I haven't noticed any difference. My questions is should I put the original Cooper S discs back on, or just leave the 7.5 grooved one on? Are the origianl Cooper S made with a better material or is it the other way around?

[vegar]

How old are your brake fluid??

[minimans]

Brake fade or pedal dropping to floor? as the last post I would flush and change the brake fluid first.............

[Gray]

Cooper discs were 7" and S were 7.5" and I think they may of been thicker too.

[Ratkiller]

Brake fade or pedal dropping to floor? as the last post I would flush and change the brake fluid first.............

I'm referring to brake fade due to exessive heat!!!! As I was braking like mad going down that hill.
Fluid is fine. Was replaced 6 months ago when I replaced the soft lines.

[Ratkiller]

Cooper discs were 7" and S were 7.5" and I think they may of been thicker too.

Thicker then a set of new style 7.5" discs?

I guess what I'm really asking is there a benifet for keeping original MK1 discs vs new discs. Are then thicker? Is the material different?

[pad4]

i think its the pads you need to focus on , the stock rotors will be made from similar materials , grooved discs have just been lobbed on a cnc machine, you can get better material discs from companies such as AP but probably not for minis anymore.

youre just simply overheating the pads to the point where theres no grip - grooved discs will help a little as they will let the gas escape from between the pad and rotor but not that much, they will also wipe the haze (gloss surface) of the overheated pad

what pads are you using ?

pad (lol)

[Smiffy]

Grooved disks create more friction and will heat your brakes up faster.

[Benny]

i think its the pads you need to focus on , the stock rotors will be made from similar materials , grooved discs have just been lobbed on a cnc machine

This advice is spot on. Make sure you've got GOOD pads, and stop worrying about the discs.

What type of fluid did you use when you changed it? Silicone fluid is known to boil.

[Ratkiller]

Pads are "Green Stuff" and the brake fliud is DOT3.

[mk1]

Go for carbon metallic pads, a bit slow to warm up, but once they are, they are perfect with almost anything thrown at them.

M

[Smiffy]

Pads are "Green Stuff" and the brake fliud is DOT3.

I'd start by changing to DOT4 to begin with.

[Ratkiller]

Go for carbon metallic pads, a bit slow to warm up, but once they are, they are perfect with almost anything thrown at them.

M

What brand do you recommend?

[mk1]

http://www.minispares.com/product/Class ... o%20search

M

[pad4]

Green stuff - lol theres your problem there shit - carbon mettalic from minispares are spot on - plenty of late braking from warp speed

Oh and smiffy - grooved discs actually reduce friction- if you have 50 grooves on a disc you effectively loose surface area - less surface area, less to grip on but extremely fast pad wear - its a very common mistake that people make - you only need the grooves to expell gas and wipe pad haze which happens at high temp

best thing you can do is moniter your pad heat then find a suitable pad that will cope with that heat range.

Silicon fluid doesnt go with mini seals- get a good motorsport fluid

and bed the pads in properly otherwise they will never work properly - ever

pad on pads

[pad4]

Remember Heat creates friction but friction creates heat - get the ratio wrong and it wont work

pad

[Ratkiller]

...bed the pads in properly otherwise they will never work properly - ever

Mk1 and pad4 - Thanks for the advice. what are your procedures on bedding the pads?

What I've done in the past, was to slightly rest my foot on the brake only to apply slight contact between the pad and disc. Drive around town -one block slight break pressure -one block no breaks -one block slight pressure -one block no breaks.... I would do this for about 10 blocks. Keep in mind I have very short blocks in my neighborhood and I would try to avoid any hard breaking for at least the first couple of weeks.
Does this sound like a good bedding procedure or am I doing it wrong.

[Benny]

For bedding in, I was always taught to go out, and do about three or four emergency stops from about 50 mph, with a little time for cool down between, then drive as normal....this has always worked for me.

Those carbon metallic pads may have specific requirements, but I'd imagine MS would include some instructions on that.

[InimiaD]

On that link to the recommended brake pads, scroll down and it explains the best way to bed the new pads in.

I had brake fade with an S brake set up during a stage rally on Eppynt ranges and it scared the life out of me. Those pads had been used for quite a few weeks before the event, but they obviously hadn't been bedded in properly.
Lesson learnt, any new pad sets were thoroughly bedded in after that episode.

Edit. As per Benny's post.

[Smiffy]

Oh and smiffy - grooved discs actually reduce friction- if you have 50 grooves on a disc you effectively loose surface area - less surface area, less to grip on but extremely fast pad wear - its a very common mistake that people make - you only need the grooves to expell gas and wipe pad haze which happens at high temp

You may loose surface area, but you gain friction with the multiple edges.