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I've used standard BMW (Jurid) brake pads on Vikki, and whilst she stops OK, some times I feel as if she could anchor up a bit better.
The easiest thing to swap out before doing anything more drastic would be the pads. I've heard that EBC do pads with a bit more bite to them - does anyone have any experience with them? Or with any other brand that might perform better?
I feel much the same about my Sportster. I have a theory. The BMW pads are designed to work with a servo with a big boost ratio - I suspect these means they are very hard. The Metro servo gives a lot less boost meaning the pads dont get the shove they need to make them start working in earnest. I think that some softer pads would work better - but how you get hold of some I don't know. I guess it would be worth trying to find a braking specialist - if such a thing exists.
As EBC are in Northampton, I've just sent this to them:
Hi,
I have a Marlin Sportster kit car:
[url]www.greatoldone.co.uk[/url]
Which is based on a BMW e30 325i. As such, the braking system has been retained from the donor car bar the servo, as it is physically too large.
This has been replaced with a Marlin supplied servo, which just happens to be a Rover Metro part - so there isn't much assistance.
The car weighs around 890kg, and makes around 160-170bhp. It currently has OEM brake discs and pads (JURID). Whilst the car stops, It doesn't stop as rapidly as i'd like.
Would different pads and discs help here? If so, what EBC pads (and discs if necessary) would you recommend to increase the brake performance? The car is used on the road, driven in a 'spirited manner' :-)
Interesting, greenstuff are the generally recommended EBC pads for fast road use by the motoring press. I think the yellowstuff ones are the next grade up the ladder and will be interested to hear how you get on if you take their advice.
Incidentally, I always thought that the brakes on my donor lacked bite but they did the job well enough. However, the brakes on the A4 Avant that followed felt much more "grippy" and the ones on my present E46 are certainly better than the E30. I wonder how the rear drum set-up feels?
I've been repeated recommended to steer clear of ebc, I've not tried them myself. Mintex get good recomendatioms and ferodo. I've sorely tempted by wilwood 4 pots but that's out of budget for now. I'm sticking with jurid for now - you can lock the wheel even at speed if you push hard enough
My brake travel has got a bit longer than it was. Not sure why?
As some of you may remember i've got drums on the back.
It's so many years since I fitted the rear brakes I can't remember if they are self adjusting or not. I'll have to dig out the old Haynes manual which I haven't used for ages....
hmm that's odd. Drums on the back shouldn't be much of a problem, my back brakes barely get used - they've got a pressure reducer in-line which the donor had.
You could try re-bleeding the system, maybe some air has gotten in somewhere?
I tried green stuff years ago, as they were cheaper and supposedly better than OEM pads. They were on the car a week (500 miles ish) before I got shot of them - poor cold bite, and made an awful noise when hot.
A few years later, and a different car, I thought in the interests of experimenting I'd try some red stuff pads. Again, they were on the car for approx 1000 miles before I sold them on.
I've since tried yellow stuff pads on the 5EXI and a Clio 182 cup..... they lasted less than a day on track on the Clio, and were inconsistent on the 5exi. I've now replaced them with DS2500 pads, and although much more expensive than the yellowstuffs, the performance is in a different league.
I've read of, and been told of good experiences with the yellowstuff, but I've found them poor.
By the way, I'm surprised about the braking power issue. The Sportster isn't massively heavy at 890kg, and from memory the E30 runs 260mm front discs, which is the same diamter as the Rover discs on the 5exi. My 5exi weighs ~700kg, and I don't have a servo! The brakes lack the over-assisted bite of many modern cars (VAG are particularly bad in this respect), but the power is there as proven by the way the car stops on track - I can lock up R888s on high friction runway tarmac.
I've used standard BMW (Jurid) brake pads on Vikki, and whilst she stops OK, some times I feel as if she could anchor up a bit better.
The easiest thing to swap out before doing anything more drastic would be the pads. I've heard that EBC do pads with a bit more bite to them - does anyone have any experience with them? Or with any other brand that might perform better?
GOO
What is it you don't like about your brakes? Having watched your build with great interest I have always been sceptical about you using flexible hose throughout. By their nature these will expand a little and with so much of it you are likely to get a soft pedal - that's why road going car have hard brake lines and only use a short section of flexible hose to connect to each wheel.
Changing your brake lines to hard brake pipes will be the cheapest option.
If you change your pads, do not choose race pads: these are designed to work at high temperatures through continuous heavy braking, and are dangerous on general road use as they rarely reach operating temperature, and offer very limited braking effect.
I used flexible hoses everywhere as they where what where supplied from Marlin. They're well made stainless over-braided from HEL, and they do the job... However I'm not adverse to swapping to hard pipes if needs be, but from the sounds of it Robin has a similar issue - and he has hard pipes.
It's not that she won't stop. She does - It's probably just me being used to more assistance in my other cars.
That or I just haven't driven Vikki enough to get the pads and disks bedded in properly.
As Jason said - I am not impressed with the brakes - and I beleive the problem is caused by using standard BMW brake linings and a micky mouse Metro servo. I swapped my servo over the winter for a brand new one hoping things would improve. But as the car is still not fully re-assembled after painting I have nothing to report yet. Hopefully later this week :-)
I found the donor cars brakes a bit weak in the donor car but them I'm used to an over assisted modern car. I keep having to remind myself when I drive the Sportster that I need to push very hard on the brakes. Has worked OK for me so far but I have felt there is room for improvement on the initial bite. I have got copper pipes most of the way and braided flexy lines for the final bits.
I ran a 1989 318is while I was building the Sportster. The brakes on that were equal to any modern car. That's why I suspect the combination of Metro Servo and BMW linings. Like Jason, my brakes aren't bad - just not as good as I would have expected given my eperience driving the 318is and the reduced weight of the Sportster.
The brakes on that were equal to any modern car. That's why I suspect the combination of Metro Servo and BMW linings.
Robin
Robin
I am with you on the Metro servo - it only offers 2:1 boost. My A4 has, I beleive, over 4:1 boost, so the effort in the Marlin will be twice that of my A4. I have tried to locate a servo with a bigger boost, but am restricted by the diameter (as I guess the Sportster is)
During my searches I have been told some modern cars are running a pump off the engine to generate a vacuum (I guess to do away with the inlet manifold vacuum and help control emissions better?)
It therefore struck me that if the servo can not change in diameter, perhaps the vacuum pressure could be increased if there is a pump to contol it?
Is anyone aware of a car with its own vacuum pump? - and if so what pressure does it run at? - and could it be increased to offer a greater boost from the same sized servo?
Mike
Most diesels these days have an engine driven vacuum pump. The vacuum on petrol engines is generated when the throttle is shut and because diesel engines dont usually have a throttle they need a separate means of generating vacuum.
The problem will be that they are usually directly driven by the engine (sometimes of the back of the camshaft or an engine ancillary) and therefore will need some type of machining / fabrication to connect up to a different engine.
Like I replied, I guess my problem is the amount of force required to get the desired effect. I'm waiting to see what the combined wisdom of the zone (or at least brian) has to say.
but that's out of budget for now. I'm sticking with jurid for now - you can lock the wheel even at speed if you push hard enough 
