54 replies to this topic

[Tweakz]

Hi there, im wondering is it possible to change rear drums to discs
And how would i go about this.



Cheers tweakz

[HarrysMini]

Yes it is possible but completely and utterly pointless, unless your goal is to lighten your car.

 

KAD do a kit, which I think is either £500 or £700, I can't remember.

 

You will not gain any more braking power from using rear discs, in fact, they may even become worse, as a disc setup relies on heat, and with a car that weighs 600KG, not much heat builds up. 

 

A standard, well maintained drum setup has more than enough braking power to lock up the rear wheels, at which point it's the tyres that become the limiting factor.

[Mini 360]

As above.  However, KAD rear discs look gorgeous.  Buy them!

[Tommyboy12]

Im sure ive heard of someone using a VW Golf setup on the rear of a Mini. Took some decent fabrication though.

[DomCr250]

People have used lots of different rear disc set-ups from a variety of cars, yes it takes some engineering skills and I have to agree it looks great.  Do a Google search or take a look at some of the stuff on the 16V mini forum.

 

Apart from ascetics, It all depends on what you are planning to use the car for and how much power you have.  Not much use having drums on the back of a rear engined mini as an example.

[Cooperman]

The problem with rear discs on a Mini is that the braking effort required on the rears is so low that a disc brake set-up would simply not get warm and would not work as well as the drums. With the fronts doing about 80% of the braking, the discs would need to be really tiny to get to operating efficiency and temperature. Then there is the issue of the handbrake. How could that be integrated into a tiny disc/calliper?

 

I'm sure that some companies would be happy to take the money for a completely useless piece of kit though  .

 

Why would anyone want to do this?

[HarrysMini]

The problem with rear discs on a Mini is that the braking effort required on the rears is so low that a disc brake set-up would simply not get warm and would not work as well as the drums. With the fronts doing about 80% of the braking, the discs would need to be really tiny to get to operating efficiency and temperature. Then there is the issue of the handbrake. How could that be integrated into a tiny disc/calliper?

 

I'm sure that some companies would be happy to take the money for a completely useless piece of kit though  .

 

Why would anyone want to do this?

For looks and weight reduction, I think are the main reasons.

 

I personally don't like the look of the KAD rear discs/callipers, as they remind me of bicycle disc brakes 

[Cooperman]

The idea of fitting something less efficient just for perceived 'looks' escapes me as an engineer.

 

With race cars it used to be possible to effectively blank off the rear brakes so you could fit very small discs on the back, so long as the regulations allowed it, then set them to do nothing and have a lower un-sprung weight. There are adjustable brake valves to take virtually all the brake pressure off the backs. No good on a road car as the MoT would be failed for 'ineffective rear brakes'. I guess the valve could be tweeked for the MoT, but wound back on again afterwards.

 

Probably better to fit alloy rear drums though as that is a lot easier and would not really make much difference to the lap times.

[KernowCooper]

The drums are more than up to the job, which is why they had to put in a pressure reducing valve, ever tried a mini without the valve? nope nor me but they swap ends quickly with the rears locking under normal braking force. I think if its a disc conversion your after you have the wrong car.

[HarrysMini]

The drums are more than up to the job, which is why they had to put in a pressure reducing valve, ever tried a mini without the valve? nope nor me but they swap ends quickly with the rears locking under normal braking force. I think if its a disc conversion your after you have the wrong car.

You can lock them up even with the pressure reducing valve!

[Cooperman]

I like a bit of rear end braking on a rally car as I can then get it set up a bit sideways under late braking, then balance it on the over-steer with full power on through a corner. If the corner tightens I can then lift off slightly to bring the back out some more and, in extremis, left foot brake to make it really over-steer. You do need a lot of power to prevent it from spinning when using this technique and even then it's easy to get it all wrong and end up off backwards!

 

There are two advantages to buying a rear disc conversion: 1. You reduce the un-sprung weight for racing and maybe save 1/10th of a second per lap and, 2. You give more profit to the sellers of the conversion, which they love you for!

[cradley-heathen]

if its looks or weight saving your looking for then i would still say go for alloy drums.

 

i have machined a few sets of alloy drums down and got them really light, i saved 1.5kg off a pair of alloy drums, i think they were only 3kg to start with. you can get alloy rear hubs too or have some made up, and you can modify the back plate a little too. with all the fins off those alloy drums you could mirror polish them and they would look fab behind some nice wheels!

[greggy50]

I have uprated alloy superfin drums on the rear and vented 4 pots on the front of my mini and to be honest I don't see why you would need any more braking performance on the road or track I think mine are a huge overkill as it is on my 998!

 

You can get rear disk conversions but talking well in excess of £500 for something that only does a small % of the braking anyway. I would just uprate the front brakes to 4 pots instead if you have not already :)

[Cooperman]

In fact standard brakes are fine for all Minis, even 120 bhp monsters. The car is light and with really good quality discs & drums and competition pads, such as Mintex 1177 for ultimate rally use, the brakes may get red hot, but they won't fade. The brake fluid for this sort of use needs to be AP600 race/rally fluid.

Save the money for other improvements like a better cylinder head/cam/induction/exhaust.

[HarrysMini]

In fact standard brakes are fine for all Minis, even 120 bhp monsters. The car is light and with really good quality discs & drums and competition pads, such as Mintex 1177 for ultimate rally use, the brakes may get red hot, but they won't fade. The brake fluid for this sort of use needs to be AP600 race/rally fluid.

Save the money for other improvements like a better cylinder head/cam/induction/exhaust.

To add to that, people seem to think that the more powerful your Mini is, the better brakes it needs. The truth is, whatever power your Mini has got, whether it be 30hp or 300hp, on the road, you'll never be going any faster in the more powerful car. The brakes stop the car, not the engine.

 

Of course, when talking about competition Minis, it's an entirely different story.