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PostPosted: Mon Mar 18, 2019 2:18 pm 
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Hey everyone,

First time positing here, pre project.

I plan on creating an AWD, Morris Mini with the heart of a B18C Civic Type R engine. I'm also picking up a set if 12" SSR MK1 three piece wheels to put on the project and didn't really wanna go any larger. Not a fan of massive rims on minis.

I was wondering what people think about running 8.4" brakes, is this enough stopping power to account for the engine? Can I go larger with that rim size?

Any advice would be great,

Thanks!


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PostPosted: Mon Mar 18, 2019 5:06 pm 
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How wide are the 12" SSR MK1 three piece wheels?

The car is going to GO...

So you should have the best 4 potters or whatever you can fit inside the wheels to STOP...

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PostPosted: Mon Mar 18, 2019 6:11 pm 
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Location: SE Melbourne
I have 8.4” vented 4-pots on my B16 mini- they have no problems coping with the performance / weight of the car. If i were to upgrade the car to B18 I’d probably stick with them to try, that said if I was building a car from scratch with the extra power and weight I’d probably look into my options for bigger brakes for efficiency under the 13” wheels.

If you want to stick with 12” wheels and 8.4s thats your call- if you run a performance pad on the front and minifins or similar on the back it will have as much stopping power as it needs.

Just consider if the look of the 12” wheels outweighs the wider tyre options and bigger brake options you could get from 13” wheels.


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PostPosted: Mon Mar 18, 2019 7:52 pm 
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848cc
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9YaTaH wrote:
How wide are the 12" SSR MK1 three piece wheels?

The car is going to GO...

So you should have the best 4 potters or whatever you can fit inside the wheels to STOP...


The wheels are 12x5 at the moment but since they're three piece I intend to get Barrel Bros here in Sydney to make some wider lips for them so I can get more tyre to the ground.

And oh yea! She's gonna fly!

Harley wrote:
I have 8.4” vented 4-pots on my B16 mini- they have no problems coping with the performance / weight of the car. If i were to upgrade the car to B18 I’d probably stick with them to try, that said if I was building a car from scratch with the extra power and weight I’d probably look into my options for bigger brakes for efficiency under the 13” wheels.

If you want to stick with 12” wheels and 8.4s thats your call- if you run a performance pad on the front and minifins or similar on the back it will have as much stopping power as it needs.

Just consider if the look of the 12” wheels outweighs the wider tyre options and bigger brake options you could get from 13” wheels.


Thanks for all that info, greatly appreciated. Happy to hear that you get enough stopping power on the 8.4" disks. I think I will definitely take your advice and grab some performance pads to help it stop quicker. If I find once I build the car the 8.4" disks just aren't cutting it I guess I can just swap out the wheels and disks too. Although I am hopeful since the car is going to weigh so little.

Any particular brand of brakes you'd recommend?


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PostPosted: Mon Mar 18, 2019 9:04 pm 
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I’m running the minisport alloy ones. Good value and use the same pads and discs as a metro turbo so a few compounds to choose from. From memory i bought some greenstuff pads and some cheaper standard compound ones- i put the cheapies in first and find they’re pretty good so havent upgraded yet!


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PostPosted: Tue Mar 19, 2019 8:27 am 
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Location: St. George Area, New South Wales
An interesting little tidbit I found when looking at my disk conversion for my 998, preparing for when I actually find a 1275.

https://www.sgi.sk.ca/air-brake/-/knowl ... t-distance

The distance required to stop a vehicle depends on its speed and weight in addition to the factors of energy, heat and friction. The brake power required to stop a vehicle varies directly with its weight and the “square” of its speed. For example, if weight is doubled, stopping power must be doubled to stop in the same distance. If speed is doubled, stopping power must be increased four times to stop in the same distance. When weight and speed are both doubled, stopping power must be increased eight times to stop in the same distance.

Example: A vehicle carrying a load of 14,000 kg down a grade at 16 km/h is brought to a stop in a distance of 30 metres by normal brake application. If the same vehicle carried 28,000 kg down the same grade at 32 km/h, it would require eight times the braking power to stop the vehicle in 30 metres. This would be more braking power than the brakes could provide. No vehicle has enough braking power when it exceeds its limitations.

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PostPosted: Tue Mar 19, 2019 8:50 am 
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Hobson wrote:
An interesting little tidbit I found when looking at my disk conversion for my 998, preparing for when I actually find a 1275.

https://www.sgi.sk.ca/air-brake/-/knowl ... t-distance

The distance required to stop a vehicle depends on its speed and weight in addition to the factors of energy, heat and friction. The brake power required to stop a vehicle varies directly with its weight and the “square” of its speed. For example, if weight is doubled, stopping power must be doubled to stop in the same distance. If speed is doubled, stopping power must be increased four times to stop in the same distance. When weight and speed are both doubled, stopping power must be increased eight times to stop in the same distance.

Example: A vehicle carrying a load of 14,000 kg down a grade at 16 km/h is brought to a stop in a distance of 30 metres by normal brake application. If the same vehicle carried 28,000 kg down the same grade at 32 km/h, it would require eight times the braking power to stop the vehicle in 30 metres. This would be more braking power than the brakes could provide. No vehicle has enough braking power when it exceeds its limitations.


It's not just the stopping power that's important, it's how it can handle heat. The standard cooper 7.5" discs will very comfortably stop a mini from 160kph. Even the old drums on my 998 would very effectively stop from 100kph. But once you do it two, three times in a row, things will very quickly start to fade, and then fail.

8.4" discs with good pads will stop any mini from any speed they can reach. But if the brakes are going to go onto the track or see any amount of consistent, heavy braking, you'll want to move up to ventilated brakes. I've never heard anyone say that their ventilated 8.4" brakes were not up to the job.


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PostPosted: Tue Mar 19, 2019 7:51 pm 
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848cc
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Harley wrote:
I’m running the minisport alloy ones. Good value and use the same pads and discs as a metro turbo so a few compounds to choose from. From memory i bought some greenstuff pads and some cheaper standard compound ones- i put the cheapies in first and find they’re pretty good so havent upgraded yet!


Awesome! I was looking into that setup, glad to hear they do the job.

Hobson wrote:
An interesting little tidbit I found when looking at my disk conversion for my 998, preparing for when I actually find a 1275.

https://www.sgi.sk.ca/air-brake/-/knowl ... t-distance

The distance required to stop a vehicle depends on its speed and weight in addition to the factors of energy, heat and friction. The brake power required to stop a vehicle varies directly with its weight and the “square” of its speed. For example, if weight is doubled, stopping power must be doubled to stop in the same distance. If speed is doubled, stopping power must be increased four times to stop in the same distance. When weight and speed are both doubled, stopping power must be increased eight times to stop in the same distance.

Example: A vehicle carrying a load of 14,000 kg down a grade at 16 km/h is brought to a stop in a distance of 30 metres by normal brake application. If the same vehicle carried 28,000 kg down the same grade at 32 km/h, it would require eight times the braking power to stop the vehicle in 30 metres. This would be more braking power than the brakes could provide. No vehicle has enough braking power when it exceeds its limitations.


Thanks a bunch for that link and information. Regarding whats written, I think I will definitely need to go chat to an engineer and get their seal of approval before I go ahead with anything. That way I can take it to them when its complete and have no issues.


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PostPosted: Tue Mar 19, 2019 7:53 pm 
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848cc
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Irish Yobbo wrote:

It's not just the stopping power that's important, it's how it can handle heat. The standard cooper 7.5" discs will very comfortably stop a mini from 160kph. Even the old drums on my 998 would very effectively stop from 100kph. But once you do it two, three times in a row, things will very quickly start to fade, and then fail.

8.4" discs with good pads will stop any mini from any speed they can reach. But if the brakes are going to go onto the track or see any amount of consistent, heavy braking, you'll want to move up to ventilated brakes. I've never heard anyone say that their ventilated 8.4" brakes were not up to the job.


I will cough up the extra $$ for sure for vented disks based on what you said.


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PostPosted: Fri Mar 22, 2019 7:53 pm 
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Vented is a must
But as above you are stopping weight not power.


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 Post subject: Re: Vented Disks
PostPosted: Sat Mar 23, 2019 6:41 am 
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I wouldn't get too wrapped about the axles over it unless you are going to race it...

the trade off is weight, counting both as unsprung weight and rotational mass and inertial losses (horsepower loss).

On the road, solids will heat up quicker...pads will work quicker...

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