Rear brake upgrade
Discussion
Well it's finally time to bring the rear brakes up to spec following last years front upgrade. I've gone for the Compbrake kit as it bolts straight on and takes the rear brakes up from 273 to 300, more in line with what's now on the front.
Here they are on the bench, not a massive increase but hopefully worthwhile. You can also see the bracket that spaces the std caliper out radially.
Next you can see how it all bolts together
And finally loose fitted to the car.
Thus far it's been a doddle, if I wasn't doing the diff bushes at the same time I'd say it's an easy mornings work.
All I need now is a set of Mintex 1144 compound rear brake pads to provide some quality grippage
Here they are on the bench, not a massive increase but hopefully worthwhile. You can also see the bracket that spaces the std caliper out radially.
Next you can see how it all bolts together
And finally loose fitted to the car.
Thus far it's been a doddle, if I wasn't doing the diff bushes at the same time I'd say it's an easy mornings work.
All I need now is a set of Mintex 1144 compound rear brake pads to provide some quality grippage
Yup, all it's doing is increasing the mechanical advantage slightly. I did loads of maths (well when I say me I mean people on PH 
) and it turned out the four pot solutions would overwhelm the rear and lead to more unplanned backwards hedge visits!
I have got the ratios somewhere, from original, with just the four pots and how it will be now.
) and it turned out the four pot solutions would overwhelm the rear and lead to more unplanned backwards hedge visits!I have got the ratios somewhere, from original, with just the four pots and how it will be now.
That's the next step if it's necessary, I want to see how the inertial valve copes first. If I get the mechanical ratio about right I can tweak the line pressures if I'm still not happy. I may even reduce the master cylinder ratio at some point, but that'll probably be 2010's project
spend said:
Slowly slowly catchy monkey 
Shouldn't affect balance too much, still think I'd have tried an adjustable bias valve first, faced with that dilemma
The bias valve will affect the dynamic balance but first you need to get the static balance right and the bias valve doesn't do that. You need a balance bar, or to physically change the overall mechanical leverage of the front or rear brakes until they match the static weight distribution. Shouldn't affect balance too much, still think I'd have tried an adjustable bias valve first, faced with that dilemma That's the one, you're welcome to come and see it being fitted if you want, she'll be up in the air for the next two weeks or so depending on the weather
If your front set up is as efficient as mine (the big yellow Compbrake set up) it'll probably feel like it lacks mechanical bite at the rear...
If your front set up is as efficient as mine (the big yellow Compbrake set up) it'll probably feel like it lacks mechanical bite at the rear...
HRG said:
Well it's finally time to bring the rear brakes up to spec following last years front upgrade. I've gone for the Compbrake kit as it bolts straight on and takes the rear brakes up from 273 to 300, more in line with what's now on the front.
Here they are on the bench, not a massive increase but hopefully worthwhile. You can also see the bracket that spaces the std caliper out radially.
Next you can see how it all bolts together
And finally loose fitted to the car.
Thus far it's been a doddle, if I wasn't doing the diff bushes at the same time I'd say it's an easy mornings work.
All I need now is a set of Mintex 1144 compound rear brake pads to provide some quality grippage
Rob out of interest why did you think this upgrade was necessary buddy ?Here they are on the bench, not a massive increase but hopefully worthwhile. You can also see the bracket that spaces the std caliper out radially.
Next you can see how it all bolts together
And finally loose fitted to the car.
Thus far it's been a doddle, if I wasn't doing the diff bushes at the same time I'd say it's an easy mornings work.
All I need now is a set of Mintex 1144 compound rear brake pads to provide some quality grippage
I like the look of them but i can not get my head around what benefit they will give you
Not being critical just wanting to justify the expense that's all mate 
On my front I have AP racing 330 grooved discs... 4 pot callipers and standard rear Griff 500 brakes so what improvement should i expect over my current setup i wonder
Paul Daniels springs to mind Ok, first, it's not easy to translate "seat of the pants" to words, so what I'm trying to convey may not come across perfectly, but you'll get the idea
And in this case 'you' means the reader, not necessarily 'you' Pasco
The big front brake setup is fantastic, but when you throw the anchors out big time on the approach to a corner you can feel the rear end is unsettled and 'loose'. It's hard to describe, but the sensation is exactly the same as on a bike with it's infinitely front/rear setup when you're not applying enough retardation to settle the back end.
The maths bears out the theory that the upgrade will move the bias slightly to the rear again although nowhere near as far as in the stock setup.
Also the rear now carries 265 tyres, so I believe it can cope with additional retardation without lockup (weight transfer excepted) which should shorten my stopping distances.
I'm quite happy to be my own guinea pig on this, it'll either be bloody brilliant or I'll disappear into a hedge backwards
Phase three if I still want more stoppage will be to replace the master cylinder with a dual setup with a mechanical balance bar... Hopefully this will achieve what I want though.
And in this case 'you' means the reader, not necessarily 'you' Pasco
The big front brake setup is fantastic, but when you throw the anchors out big time on the approach to a corner you can feel the rear end is unsettled and 'loose'. It's hard to describe, but the sensation is exactly the same as on a bike with it's infinitely front/rear setup when you're not applying enough retardation to settle the back end.
The maths bears out the theory that the upgrade will move the bias slightly to the rear again although nowhere near as far as in the stock setup.
Also the rear now carries 265 tyres, so I believe it can cope with additional retardation without lockup (weight transfer excepted) which should shorten my stopping distances.
I'm quite happy to be my own guinea pig on this, it'll either be bloody brilliant or I'll disappear into a hedge backwards
Phase three if I still want more stoppage will be to replace the master cylinder with a dual setup with a mechanical balance bar... Hopefully this will achieve what I want though.
HRG said:
I'm quite happy to be my own guinea pig on this, it'll either be bloody brilliant or I'll disappear into a hedge backwards
Don't worry about being a guinea pig - this is pretty well what I did to mine 7 or 8 years ago, and the braking I have is excellent. I could go into the details converstaions I had at the time with people like Steve Heath, Pete (V8S) and Neill Anderson but the upshot of it all was, std. calipers with slightly bigger discs works fine. p.s. what do you have on the front?http://www.greenbear.org.uk/The%20Brakes.htm
HRG said:
Ok, first, it's not easy to translate "seat of the pants" to words, so what I'm trying to convey may not come across perfectly, but you'll get the idea
And in this case 'you' means the reader, not necessarily 'you' Pasco
The big front brake setup is fantastic, but when you throw the anchors out big time on the approach to a corner you can feel the rear end is unsettled and 'loose'. It's hard to describe, but the sensation is exactly the same as on a bike with it's infinitely front/rear setup when you're not applying enough retardation to settle the back end.
The maths bears out the theory that the upgrade will move the bias slightly to the rear again although nowhere near as far as in the stock setup.
Also the rear now carries 265 tyres, so I believe it can cope with additional retardation without lockup (weight transfer excepted) which should shorten my stopping distances.
I'm quite happy to be my own guinea pig on this, it'll either be bloody brilliant or I'll disappear into a hedge backwards
Phase three if I still want more stoppage will be to replace the master cylinder with a dual setup with a mechanical balance bar... Hopefully this will achieve what I want though.
Thanks Rob..... Makes sense does your explanation And in this case 'you' means the reader, not necessarily 'you' Pasco
The big front brake setup is fantastic, but when you throw the anchors out big time on the approach to a corner you can feel the rear end is unsettled and 'loose'. It's hard to describe, but the sensation is exactly the same as on a bike with it's infinitely front/rear setup when you're not applying enough retardation to settle the back end.
The maths bears out the theory that the upgrade will move the bias slightly to the rear again although nowhere near as far as in the stock setup.
Also the rear now carries 265 tyres, so I believe it can cope with additional retardation without lockup (weight transfer excepted) which should shorten my stopping distances.
I'm quite happy to be my own guinea pig on this, it'll either be bloody brilliant or I'll disappear into a hedge backwards
Phase three if I still want more stoppage will be to replace the master cylinder with a dual setup with a mechanical balance bar... Hopefully this will achieve what I want though.
So a cheeky one now......Supplier and how much
Pm me if you prefer Rob 
RichB said:
HRG said:
I'm quite happy to be my own guinea pig on this, it'll either be bloody brilliant or I'll disappear into a hedge backwards
Don't worry about being a guinea pig - this is pretty well what I did to mine 7 or 8 years ago, and the braking I have is excellent. I could go into the details converstaions I had at the time with people like Steve Heath, Pete (V8S) and Neill Anderson but the upshot of it all was, std. calipers with slightly bigger discs works fine. p.s. what do you have on the front?http://www.greenbear.org.uk/The%20Brakes.htm
Did you find the rear upgrade balanced the car more under heavy braking?
HRG said:
Did you find the rear upgrade balanced the car more under heavy braking?
Nope... and I've done several track days and many enthusiastic drives, not that I'd call myself an expert in handling by any means but I know how the car feels and it's good. I have 315mm and AP Racing 4 x pots calipers at the front but 15mm is not a lot is it? Of course, because all four corners were done at the same time I never drove it with just the fronts for comparison but for me it was probably one of the best improvements I ever made. Pasco said:
HRG said:
Ok, first, it's not easy to translate "seat of the pants" to words, so what I'm trying to convey may not come across perfectly, but you'll get the idea
And in this case 'you' means the reader, not necessarily 'you' Pasco
The big front brake setup is fantastic, but when you throw the anchors out big time on the approach to a corner you can feel the rear end is unsettled and 'loose'. It's hard to describe, but the sensation is exactly the same as on a bike with it's infinitely front/rear setup when you're not applying enough retardation to settle the back end.
The maths bears out the theory that the upgrade will move the bias slightly to the rear again although nowhere near as far as in the stock setup.
Also the rear now carries 265 tyres, so I believe it can cope with additional retardation without lockup (weight transfer excepted) which should shorten my stopping distances.
I'm quite happy to be my own guinea pig on this, it'll either be bloody brilliant or I'll disappear into a hedge backwards
Phase three if I still want more stoppage will be to replace the master cylinder with a dual setup with a mechanical balance bar... Hopefully this will achieve what I want though.
Thanks Rob..... Makes sense does your explanation And in this case 'you' means the reader, not necessarily 'you' Pasco
The big front brake setup is fantastic, but when you throw the anchors out big time on the approach to a corner you can feel the rear end is unsettled and 'loose'. It's hard to describe, but the sensation is exactly the same as on a bike with it's infinitely front/rear setup when you're not applying enough retardation to settle the back end.
The maths bears out the theory that the upgrade will move the bias slightly to the rear again although nowhere near as far as in the stock setup.
Also the rear now carries 265 tyres, so I believe it can cope with additional retardation without lockup (weight transfer excepted) which should shorten my stopping distances.
I'm quite happy to be my own guinea pig on this, it'll either be bloody brilliant or I'll disappear into a hedge backwards
Phase three if I still want more stoppage will be to replace the master cylinder with a dual setup with a mechanical balance bar... Hopefully this will achieve what I want though.
So a cheeky one now......Supplier and how much
Pm me if you prefer Rob HRG said:
It's the Compbrake CMB0124 kit. Comes in at £400 delivered inc VAT but doesn't include any upgraded pads. I still need to source some Mintex 1144 pads which will be about an extra £60...
Can also fully recommend Ferodo DS2500's if you want a hot pad. Have tem all round on mine now and they are superb, certainly the best pads I've had on the front and rear on mine without a doubt.That includes track work and enthusiastic driving in the mountains. In fact I boiled the brake fluid in France last year without realising any brake fade at all. It does run Dot 5.1 . . .
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