Ok, i have searched through the more important (anti rant) threads on this subject and nothing really relates to what I wanna know. So here goes mine...

Running 1.8 ZVH with a few mods to get me the 200bhp mark (maybe - untested as yet), I have standard front brakes and a set of modified Mondeo (2001) rear calipers and discs ready to fit. I dont do track, and to be fair, I dont race around my streets like a boyracer on speed!

So would i need a bias valve fitted, or is there no real point? Admittedly, the conversion is more for looks and ease than anything.

The guy I got the set up off said that he didnt use a bias valve when he had them fitted, but his was a S1 and said that the S2 maybe different.....

Could it just be a case of trial and error?

 

yeh but what happens when you are on the motorway and someone pulls out in front of you and you have to go hard on the brakes.specially with standard ones up front.could be a disaster waiting to happen like a huys series one not that long ago who didnt have one.

 

Well yea, that was one of my thoughts.....

 

If you fit rear discs, no question. You NEED one.

 

For the money they cost in comparison to crash repair (if not worse!) i suppose theres no question... which does kinda render my original question pointless lol. But why is it that loads of people can quite happily and safely run without the valve, while others cant? Is it also down to the individual car itself and not just that of the set-up?

 

No, its ignorance.

once they need to brake hard and crash, then they'll know they needed one.

 

yip i agree i thought id get away with it on my old one.braked hard on the bypass and the back end swung round.luckily i caught it.needless to say i have used one since

 

IMO unless you brake hard enough (emergency stop) your not going to know if your rears lock up before your fronts, and as a rule most of us dont brake that hard day to day, but if they do it's like pulling your handbrake on at whatever speed you happen to be doing!
My car came with the rear disc conversion already done but if it was my choice i'd of stayed with drums and just fitted bigger front brakes.
As it is now i'm fitting 300mm Focus ST front brakes and going to see if that balances it out enough for the fronts to lock before the back (and i wanted better front brakes anyway), if it doesnt then a bias valve will be next on my shopping list.

 

So far then, Im getting one... Although this thread is turning out making me look a bit daft asking in the first place, maybe it will help others out later.

Theyre were some wilwood bias valves going on ebay yesterday for 30 notes... but theyve all gone this morning - typical lol... I'll go shopping now, thanks

 

Karlos, thanks.

My rears are playing up since i messed with them anyway, hence another reason for wanting to changing them. They sometimes feel like they are locking up, and thats at slow speeds! But i can imagine pulling the handbrake up at 70.... Not good

 

LOL It's that very thought that's made me look at my own setup!

 

dont think you are daft.loads of people will think/have no rear bias valve on for the rear.i hate the look of rear drums.simple as that.thats the only reason i fitted a big disc conversion.nothing to do with braking performance.i have focus rs front set up to do that.

 

Fronts are on the list... but at the minute, because im just running the engine in, and my town is the size of a pin head!, the standards will do just fine.... I just cant keep looking at the car and seeing the drums. They just stick out like a sore bloody thumb! I know they are very capable of the job in hand, but, well, nah

 

compbrake sell some nicely priced bias valves, ive got myself 1 of them, good quality piece of kit too

for the sake of Ł30 or there abouts, u get to tweak the rear brakes to EXACTLY the point where you are comfortable, and that peace of mind thats its sorted.

 

How do you set a bias valve up? and where do you put it? and where?

 

That was going to be my next question actually, Andy... what valve is best to get. Theres obviously differences in each brand/type. I looked at the compbrake ones cos someone was selling one on here the other day, but i got beaten to it (again, typical lol), but then wilwood is wilwood innit.... Are they all similar and just do the job in hand, or are there some that are really worth avoiding?

None seem to come with the t-piece bit either... but i guess thats readily available too?

 

As far as I have learned recently, it goes near the master cylinder and one line goes in one end, then you branch out the remaining lines with a t-piece from the other end.... something like that. Then its a case of adjusting as needed... blipping up the road and slamming on the anchors until it feels as it should

 

Hi mate, if your putting disks on the rear, my advise would be to use a bias valve. But what I am doing, and what some others have done on here, is to remove your rear compensators & ABS, and supply a fixed pressure to the rears. Admittedly, this is a more track set up, as you don’t need to consider rear passengers, which will increase the weight. But if you hardly ever take back seat drivers then no probs.

Some people will say don’t use one, and for them, it probably works, as physically it will work without one, but the percentage of braking to the rear will increase the moment you put the rear disks on, so you need to allow for that, hence the bias valve.
Admittedly i was going to do my set up with out a bias valve, until i decided i was going to go for the set up which is taking place!

Also i would suggest upgrading the fronts as well. Maybe to the cossie stuff at a minimum. As having bigger stuff up the front will help to lower the percentage braking at the rear, helping to keep the balance.

Good luck mate, hope it all goes well, get some pics up when your done.

Cheers

 

Then you've got the problem of where to put the bias valve! The RST brakes are piped diagonally.

That's why I always suggest sticking with the standard drums on the rear, road-going RST's just don't need anything better.

 

i put my bias valve here

 

I didn't mean where to physically put it, I more meant where in the system to put it! Of course really the whole system will need to be re-piped.

 

yeh pipin them up is another matter.i have new pedal box so mines is piped totally different.front together and rears the same.all i have is a line coming off my pedal box to bias valve then to t peice at rear to each caliper.

 

my reply wasnt really aimed at your comment,just used for reference

my system was re piped

 

As Mr C said, they are piped diagnally so you will need to get around this. I re-piped my system like this. Front outlet on master cylinder goes round front of engine bay and goes into bais valve which sits on the engine mount plate, it the pipes into a standard brass T peice which then feeds off going to each of the rear calipers.

 

I always have rear seat passengers... Thanks for the reply too. And yup, if i do eventually get fitted what ive had stored for what seems an eternity, i will post pics

I just dont like the look of the drums... Im guessing its just a personal thing really. I know there are no performance gains or anything like, but its just i really dont like the look of them... I even painted them black so they couldnt be seen as much lol

As for all this diagonal stuff and removing abs etc etc... i think i'll leave that to the guy fitting them

JamboRST aint you concerned of that valve getting caught by your foot being there?
Looks good there tho

 

Thanks for the pics, Muz. Always better to see pics than having it described

 

its not really at your feet mate,its sits just at ur left knee as u can see in the pic below and never had any trouble of it gettin caught,AVA fit all there bias valves there on all there rs turbos and never had any probs with them

 

Fair Play mate, I looked at it wrongly. Looks tidy

 

if its a 2 outlet rst master cylinder, its an easy re-pipe fitment, im just gonna run my hose to the rear through the bulkhead into the cabin to the bias valve, then back out of the cabin and into a t-piece under the rear seat area, and then to each caliper

all the screw type bias valves available are essentially the same thing, just prices range from good value compbrake kit, to extortionate AP kit which can go up to 5 times the price for a part that does the same job to the same standard lol

 

thing is u need to find a setting for dry and wet,its not just something you fix to suit and hope it works for all conditions,by having it there its easily adjusted if u lock the backs up while out and about u just close it over so less force is going to the rears,never had any truble with my bias set up after binning my car sideways into a van when i didnt have a bias valve

 

exactly mate my AP bias valve cst me 130 quid when there was cheaper options that did the same thing

 

Heres mine:

So I guess it'd be easier to just swap the whole unit, remove the ABS and run a 2-outlet master cylinder instead?

I heard that yea....

Bloody hell, sounds more messing about than its worth now

 

I just used the front of the Master cylinder to do the front brakes, with a t-piece. Then the rear of the cylidner to do the rear brakes. Bias valve inline, job done.

My bias valve is mounted similarly to Jambo's, but more tucked under the seat. It's actually bracketed off the same chassis rail that the seat bolts to.

Incidentally (blatant plug), I'll probably be selling my entire Servo/Master Cylinder assembly soon. It has a 25mm recently rebuilt Master Cylinder (the 25mm cylinders are like rocking horse shit and I got one of the last rebuild kits before they were made obsolete). It also has the correct reservoir fitted without the additional ports on it.

 

Can the rear set up and bias valve still be used with the ABS still installed?

Im just trying to figure out all avenues now without having to strip my car to bits and change everything just for the sake of having a better sight thru my rear wheels lol

 

not really mate,once ur happy with it in dry and wet conditions just dot it with a permanant marker so u can adjust it to that depending on weather conditions,it really is just trial and error,just dont go testing it on the motorway at 70mph with traffic around u

 

I just can't believe you're prepared to go to these lengths for what they look like! Get over it! LOL.

Imagine how I feel? 350bhp, 170+mph, rocking up to an event with drums on the back.

 

This is just a off the top of my head though but............. You could fit a bias vavle to each rear brake line seperately, would just have to make sure you get them braking evenly! Maybe use a brake test machine at a local garage?
Than theres no mucking about repiping anything, although they would not be in-car!

 

@ JamboRST: So what i have there is ok then? Looking at how Muz set his up, I could do that?

@ Christian and Becky: LOL, Ive come this far.... And I wouldnt trust drums at 170+ Obviously they work at that, but ... ok

@ Karlos: And if one was accidently set at the wrong setting or knocked off its mark, one brake would be different to the rest that would cause mayhem! And sod having to adjust more of them every time it rained... man, im struggling to get one right in my head, let alone 2 of the buggers

 

How would i pipe mine on my s1 as i have 4 outlets on my master cylinder like karlos says? and do i bin my compensators on my inner wing? Mine recently locked up with no bias valve hence new build

 

Jambo are your pipes incar?