7.9" discs

Author
Discussion

haynes

Original Poster:

370 posts

249 months

Tuesday 2nd May 2006
quotequote all
With minispares 4 pot calipers on 7.5" discs ive found that the outside of the pads are positioned slightly outboard of the end of the disc. Ive got what look like a decent set of used 8.4 grooved discs and was thinking of having them machined down. Does anyone know if i just ask them to machine to 7.9", is that the exact dimmension?

Ive also found that the 7.5 minispares supplied discs suffer from a fair bit of corrosion yet the 8.4s ive had in my damp cellar all winter are untouched. Are there better quality 7.5" discs to be had?

cooperman

4,428 posts

257 months

Tuesday 2nd May 2006
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It's not the quality of the disc, it's the corrosion protection with which they are supplied that causes this. If you intend to store new discs you must make sure that you grease them properly beforehand.
I don't think you can machine the 8.4" discs down, but I could be wrong as I've never had reason to want to do it. I always run 7.5" standard 'S' calipers with Carbon-Metallic pads and the brakes are absolutely fantastic. Cold friction is fine and they will still lock up the wheels on tarmac with the discs glowing red hot. Excellent pedal feel, too, with a remote servo.
Personally I think 4-pots are a bit of a waste of money really.

love machine

7,609 posts

242 months

Wednesday 3rd May 2006
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Is swapping between 8.4 and 7.5 that difficult? I think it isn't simple. My old S brakes and S callipers do the job at some stupid speeds, if you do it right. I'm running green stuff pads.

I'd swap to 7.9 if you have the opportunity and probably flog the S stuff on ebay.

That reminds me, I have to get a new CV and wheel bearings as mine is behaving strangely. (the castle nut undoes itself, shears the pin and then proceeds to wear that washer out)

Interested in these carbon/metallic pads. Where do you get them and how do they compare to greenstuff? My wheels are getting covered in brake dust at an alarming rate which can only mean 1 thing.......

cooperman

4,428 posts

257 months

Thursday 4th May 2006
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No comparison between Green Stuff and Carbon Metallic. The closest EBC comparison to C-M may be their 'Yellow Stuff'. I get my C-M pads from Mini Spares, but they only do them for the 7.5" 'S' discs. On a rally tarmac stage I can fade out Green Stuff in about a mile, but the C-M never, ever fade at all, even when the discs are glowing red hot. I always use AP600 race brake fluid to prevent fluid boiling and I change it all every 12 months. With modern DOT 4 fluids this may no longer be a problem, I just don't want to take any risks with braking.The really good place for all brake pads is Questmead - tel: 01706 860088 - speak to Alan. They are so expert with pads for all sorts of applications and I always get the pads for my Rover 214 rally car from there.
I hope this helps,

Peter

guru_1071

2,768 posts

241 months

Thursday 4th May 2006
quotequote all
cooperman said:
No comparison between Green Stuff and Carbon Metallic. The closest EBC comparison to C-M may be their 'Yellow Stuff'. I get my C-M pads from Mini Spares, but they only do them for the 7.5" 'S' discs. On a rally tarmac stage I can fade out Green Stuff in about a mile, but the C-M never, ever fade at all, even when the discs are glowing red hot. I always use AP600 race brake fluid to prevent fluid boiling and I change it all every 12 months. With modern DOT 4 fluids this may no longer be a problem, I just don't want to take any risks with braking.The really good place for all brake pads is Questmead - tel: 01706 860088 - speak to Alan. They are so expert with pads for all sorts of applications and I always get the pads for my Rover 214 rally car from there.
I hope this helps,

Peter


they also do them in metro 4 pot size (to suit alloy 4 pots) as well

a mighty, mighty pad!

though they must be run on solid (i.e ungrooved) discs and be discarded when 2/3rds worn.

i wouldnt run anything else

haynes

Original Poster:

370 posts

249 months

Monday 8th May 2006
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Despite these amazing testamonials, and knowing Petes advice is spot on and free of BS, but somehow i'm still not convinced on a road car, even a fast one. Maybe because i'm not a heavy braker, and on the road or even a hill climb i'm not burning the brakes over a long period like you would on a rally. Would you chaps still recommend them for road use over green stuff?

I suppose i'm asking for more info on what they're like / suitability when cold, rather than when red hot.

>> Edited by haynes on Monday 8th May 13:13

cooperman

4,428 posts

257 months

Monday 8th May 2006
quotequote all
Modern friction material has improved so much. When asbestos was no longer allowed brake pads for high-performance use really did become worse than had been the case with the old Ferodo DS11 material. Brakes seemed to lose their 'feel' and even with so-called competition pads this was a real problem. The Minrex 171 was possibly the last of the really good 'old type' pads.
Now, however, their is a whole new range of pads for all types of use. When EBC started to offer their Green Stuff & Red Stuff pads a few years ago they did leave much to be desired. My friend Peter Horsborough who rallies a Cooper 'S' got through 2 sets of Red Stuff on the 'Ypres Rally' in 1999 (I think it was) and only finished because I had retired and gave him a spare set of M171's.
EBC have clearly improved since then and I have a set of Yellow Stuff in my Rover 214Si rally car, although I haven't done an event on them I lent the car to Jamie Turner and he won the SW Endurance Rally a few weeks ago with them. My son has EBC Green in his Peugeot Rally 1.3 Enduro rally Car and they work fine, but that car is very light and has vented discs as well, so they never get really hot.
For my Mini I use the Carbon-Metallic pads from Mini Spares and I can recommend them for all applications from fast road to full historic rally. The do work so well at all temperatures and wear rate is excellent.
Once you find a pad that suits you it is probably best to stick with it unless you find an even better specification to work with. There seem to be continual improvements and I have been recommended another make/type to try, but as I have no experience with them yet I can't comment.
Maybe pad material is more important to braking on a Mini than disc size or number of pots in each caliper. I certainly have no problems with standard Cooper 'S' 7.5" discs and calipers so long as i use an advanced pad material.

kjw911

49 posts

237 months

Monday 8th May 2006
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I have been running green stuff pads with 7.5 discs and alloy 4 pot calipers on my sprint car and it was very reluctant to slow down. By recommendation I changed to carbon metalic pads (minispares)and the brake are now excellent.

haynes

Original Poster:

370 posts

249 months

Tuesday 9th May 2006
quotequote all
So CM works well when cold, are they noisey /squealy by any chance?

Just found the following comments from a well known mini 'expert':

Carbon Metallic pads. Made in USA by Performance Industries, heralded as the latest and greatest in brake pad technology. And they were when they first arrived. Formed by combining carbon and iron particles, fused together by a special sintering process. Developed for ‘real’ race cars (the compound is the same irrespective of vehicle application) but used by one and all despite short-comings as they bettered the established marques (Ferodo, Mintex). Recommended to be used with non-drilled/grooved discs to try and maintain high operating temperatures. Pros - High friction coefficient, broad operating temperature range, no fade. Cons - savage disc wear, full potential rarely used on Mini (insufficient weight/speed), high heat transfer to caliper/fluid (causes fluid boiling), grabby in operation - especially in the wet! Can be very noisy, limited range, expensive.


>> Edited by haynes on Tuesday 9th May 13:25

guru_1071

2,768 posts

241 months

Tuesday 9th May 2006
quotequote all
haynes said:
So CM works well when cold, are they noisey /squealy by any chance?

Just found the following comments from a well known mini 'expert':

Carbon Metallic pads. Made in USA by Performance Industries, heralded as the latest and greatest in brake pad technology. And they were when they first arrived. Formed by combining carbon and iron particles, fused together by a special sintering process. Developed for ‘real’ race cars (the compound is the same irrespective of vehicle application) but used by one and all despite short-comings as they bettered the established marques (Ferodo, Mintex). Recommended to be used with non-drilled/grooved discs to try and maintain high operating temperatures. Pros - High friction coefficient, broad operating temperature range, no fade. Cons - savage disc wear, full potential rarely used on Mini (insufficient weight/speed), high heat transfer to caliper/fluid (causes fluid boiling), grabby in operation - especially in the wet! Can be very noisy, limited range, expensive.


>> Edited by haynes on Tuesday 9th May 13:25


there are a couple of compounds avalible for minis, the usual one that 99% of people use, and a super special one that is truely evil - the disc wear is horrific - 2 discs to one set of pads is the norm.

the normal set is fine - my discs have hardly worn, no squeals, no clattering, just monster brakes

cooperman

4,428 posts

257 months

Tuesday 9th May 2006
quotequote all
With the ones I get from Mini Spares, which are the ones 'guru1071' refers to, the disc wear is low, there is no squeal, the pedal pressure remains virtually the same at all temperatures, there is no grab at low temperatures and on the MoT rollers from cold the reading was identical for both sides on first application, I've had no fluid problems using AP600 fluid and the calipers are fine after many rallies.
I can't think of any downside. To think that years ago we used Ferodo DS11 with all its limitations when cold, squeal and high disc wear without complaining.

skyedriver

18,945 posts

289 months

Tuesday 9th May 2006
quotequote all
Re EBC Green stuff pads:
Fitted them onto a Caterham a few years ago and once warmed they were excellent HOWEVER, if you drove off cold from home say, and needed to use them in the first few miles you hit the pedal and prayed. You would honestly think the brakes had failed!

vrooom

3,763 posts

274 months

Tuesday 9th May 2006
quotequote all
I found EBC work best when they are hot, but not too hot. I cant wait to ditch them when they wear off, and will get carbon metallic ones.

haynes

Original Poster:

370 posts

249 months

Friday 12th May 2006
quotequote all
Last couple of questions as i'm pretty convinded i will go for CM pads, firstly do they give off much brake dust? Just out of curiosity as the EBC pads were billed as being pretty clean in the comics and thats b*******ks.

The other thing is as i'm using ally 4 port callipers which are supposed to dissipate heat better, just wondered if itll keep em too cold? Wonder if its not advised like using grooved discs?

cooperman

4,428 posts

257 months

Friday 12th May 2006
quotequote all
Some dust, of course. However, they are great and you'll find no problems.

haynes

Original Poster:

370 posts

249 months

Wednesday 17th May 2006
quotequote all
Agghhh, 'sblood. Went into local minispares agent and he was dead against using CM pads and told me i'm better off with grooved discs and green stuff, thats what he uses and he is a local hill climb champion, but i must admit not always got on well with his advice. He thought temp range was far too high, rallying being more demanding on brakes than a hillclimb and that they knacker your wheels as well. Still tempted to try them though because Pete Cooperman's recommendation is so emphatic.

I did a search and in a previous thread i noticed Guru was not recommending them for road use. My car is not particularly heavy, 600kg and i'm not using a servo, which again is different from a heavier servo'd rally machine. Mind you defination of road use is questionable, i should mean road legal, with a 296 cam and soon a webber etc its not a daily driver.

Anyone know if the compound of the S size pads is definately the same as used for the 4 pots?

cooperman

4,428 posts

257 months

Wednesday 17th May 2006
quotequote all
After DS11's were NLA I tried Mintex 171, Mintex 1144, 1155 and Ferodo 3000. All those gave mixed results (best were M171), except the 1144's which were completely b****y useless for rallying and faded on tarmac within about 5 miles from cold.
Then Peter Horsborough recommended the C-M pads from Mini Spares and I have just been amazed at how good they are across the entire speed and temperature range.I expected high disc wear, but it's not any sort of problem. With DS11's one used to have to warm them up before going for an MoT as they would 'grab' when cold and if one had to wait for the test to commence this could be a problem. The C-M just work - always and well.
There may be downsides, but I certainly haven't found any. I do use a servo as I can't seem to get on well without one, despite trying, but that applies to all pad materials and it's just my driving style (or my age), I guess.

Peter

fwdracer

3,564 posts

231 months

Wednesday 17th May 2006
quotequote all
I've watched this thread with interest and to save peopel a few pennies and some disappointment, I feel time is ripe to add my thoughts. CM pads aren't suitable for Road Mini's. Full Stop.

It is debatable whether they are any good for race applications (feel free to look at my profile) - due to low vehicle weight. I've used them, and quite frankly CM pads aren't up to much unles you value a dead pedal feel, poor modulation, and a new set of under pants every time you need to pull up with discs in cold/cool disc condition. Ideal for road... I think not.

There are better alternatives out there....

edited to add ...I don't use servo.

>> Edited by fwdracer on Wednesday 17th May 14:41

kjw911

49 posts

237 months

Wednesday 17th May 2006
quotequote all
I was recommended CM pads by a motorsport business that runs mini 7's and miglia's and they did seem a great improvement over the green stuff ones. However ever open minded I would be very interested if there was a better pad available (No Servo).

>> Edited by kjw911 on Wednesday 17th May 16:32

guru_1071

2,768 posts

241 months

Wednesday 17th May 2006
quotequote all
the first mini i drove on the road with cm pads hard the rock hard type - they where foul and coloured my judgment massivley.

ive since run the newer type ones in my race car and really like them - far better than the greenstuffs.

i wouldnt run them in a 100% road car, mind you i run green stuff in my road car and dont like them either.

i think that pads are a real personal choice think, they aint dear, buy a set of each and try them!