10 replies to this topic

[Reidbook]

I have a standard 91 Cooper that I'm looking to convert to 10" wheels. I've considered buying the 7.9 vented setup from Mini Sport (too skint for KAD) not so much for the braking performance but cooling instead. The reason for this is my Dad runs two identical British Opens on standard 8.4s and both with aftermarket pads have warped the discs after doing one Swiss mountain pass. Tough, yes but warped and smelly brakes is not what I'm after.

In short; is it worth going for the vented setup over the 7.5s to ensure that the discs don't warp? Can a good pad and disc be enough for 7.5s?

TIA, Adam

Edit: Spelling

Edited by Reidbook, 01 July 2021 - 08:28 AM.

[cal844]

Bare in mind that 7.9 inch brakes give a very limited wheel choice, personally go for vented 7.5 with 4 pot calipers. Use standard pads for general driving and Mintex 1144 for the mountain pass, use AP600(?) fluid.

Just my opinion so await someone with more experience than me.

[Dusky]

Brake disc diameter has nothing to do with overheating. It'll be even worse with smaller discs as there is less material for the heat to act as heat sink. Engine braking does wonders. If you're competing you can fit ventilated discs.

[Midas Mk1]

I’ve got both vented 7.9’s and drilled 7.5 4 pots with m1144 and the 7.9s are the better option. Still boiled fluid on both setups.

You’ll get comments along shortly saying minis are too light for vented discs and std 7.5 are the best, it’s utter bull.

[sonscar]

I was taught that hub/disc/wheel contact area was important for heat dissipation also.The wheel choice is also a factor in cooling.This may not apply to minis as I sometimes think fashion beats function or"we always did it like that so why change"

I am not an engineer so these are just my thoughts,Steve..

[Cooperman]

I have always run standard 7.5" discs in my rally Cooper 'S's over many years. 

With the Carbon-Metallic pads and, before them the old DS11 and Mintex 1166 pads I have never had any issues with discs warping, even though I have often had them glowing a dull red. 

If you buy top quality solid 7.5" discs with C-M pads and competition brake fluid you will have no problems, even on the most demanding roads.

In historic competiton it is not usual for vented discs to be allowed.

[Reidbook]

I’ve got both vented 7.9’s and drilled 7.5 4 pots with m1144 and the 7.9s are the better option. Still boiled fluid on both setups.

You’ll get comments along shortly saying minis are too light for vented discs and std 7.5 are the best, it’s utter bull.

I'm inclined to agree with you. After our Euro adventure we done the Duke's Pass as a Mini day out. With fresh discs and new pads once again were they warped, and we weren't even pushing hard at all. My Dad is also considering vented 7.9s as he's fed up with smelly and warped brakes. I'm looking to avoid this hence my post here but I'm looking to convert to 10s.

I was starting to think maybe standard 7.5s would be adequate after looking through dozens of braking related posts but didn't really find what I was looking for. It was mostly people asking about the vented stuff in relation to braking performance, not cooling. Again, most answers were discouraging vented and just stick with good solid discs and pads. I don't see how this would be better for cooling but I'm open to being proved wrong.

Edited by Reidbook, 01 July 2021 - 08:27 AM.

[Reidbook]

I have always run standard 7.5" discs in my rally Cooper 'S's over many years. 
With the Carbon-Metallic pads and, before them the old DS11 and Mintex 1166 pads I have never had any issues with discs warping, even though I have often had them glowing a dull red. 
If you buy top quality solid 7.5" discs with C-M pads and competition brake fluid you will have no problems, even on the most demanding roads.
In historic competiton it is not usual for vented discs to be allowed.

I imagine this sort of setup would be far less expensive to convert to and maintain than even a Minisport vented kit? I've seen your replies on other threads similar to this one and this is what made me reconsider before committing to 7.9s. I'm not looking for a performance increase just better cooling so they don't warp. I've failed to mention that my Dad was running the dreaded EBC Greenstuff when we were abroad and that surely contributed. The discs were also £30 Minispares ones... Can you get decent discs from Minispares?

[Dusky]

I have always run standard 7.5" discs in my rally Cooper 'S's over many years.
With the Carbon-Metallic pads and, before them the old DS11 and Mintex 1166 pads I have never had any issues with discs warping, even though I have often had them glowing a dull red.
If you buy top quality solid 7.5" discs with C-M pads and competition brake fluid you will have no problems, even on the most demanding roads.
In historic competiton it is not usual for vented discs to be allowed.

I imagine this sort of setup would be far less expensive to convert to and maintain than even a Minisport vented kit? I've seen your replies on other threads similar to this one and this is what made me reconsider before committing to 7.9s. I'm not looking for a performance increase just better cooling so they don't warp. I've failed to mention that my Dad was running the dreaded EBC Greenstuff when we were abroad and that surely contributed. The discs were also £30 Minispares ones... Can you get decent discs from Minispares?

If you just want good discs that don't warp buy 2x 08.5464.10 and 1x P 52 002. It's all you'll ever need and will be quite a lot cheaper than getting new wheels.

[Reidbook]

I have always run standard 7.5" discs in my rally Cooper 'S's over many years.
With the Carbon-Metallic pads and, before them the old DS11 and Mintex 1166 pads I have never had any issues with discs warping, even though I have often had them glowing a dull red.
If you buy top quality solid 7.5" discs with C-M pads and competition brake fluid you will have no problems, even on the most demanding roads.
In historic competiton it is not usual for vented discs to be allowed.

I imagine this sort of setup would be far less expensive to convert to and maintain than even a Minisport vented kit? I've seen your replies on other threads similar to this one and this is what made me reconsider before committing to 7.9s. I'm not looking for a performance increase just better cooling so they don't warp. I've failed to mention that my Dad was running the dreaded EBC Greenstuff when we were abroad and that surely contributed. The discs were also £30 Minispares ones... Can you get decent discs from Minispares?

If you just want good discs that don't warp buy 2x 08.5464.10 and 1x P 52 002. It's all you'll ever need and will be quite a lot cheaper than getting new wheels.

Is that discs and a set of pads from Minispares? I would be getting new wheels anyway as I want to convert to 10s but saving money that could be spent elsewhere would be great. I'd probably get AP600 brake fluid as well just to make sure that there are no heat related issues.

[rww]

    Millers 300 brake fluid looks to be half the price of AP. I have used it for the last 8 years on our Kad  7.5" vented set up in 40 min races with absolutely no problems, just change it every year.

 

 Warped discs is surely down to poor quality materials , possibly coupled with using EBC Greenstuff pads. Again, buy quality and you will have no further problems.