dave_s2_rst

iTrader: (2)

Evening all,

can't see to find the answer im after, question is


I've currently got 4pots upfront (325mm) & will soon put 300's on the rear, I want to ditch the shity adjuster thingys on the back and replace them, question is with what type?

Is the the mk5 escort I should buy or ka ?

Would i be better off with a bias valve

Finally picts will be very helpful

cheers & thanks in advance

Christian and Beccy

iTrader: (14)

Before I went to a pedal-box and for quite a few years, my brakes were entirely re-piped in a very simple way. Front of master cylinder supplied the front calipers, rear of master cylinder did the rears. A single hose headed for the front/rear in each case and split off in a t-piece. That way it is easy to add a bias valve in the rear line before the t-piece. Then you can ditch the compensators altogether.

dave_s2_rst

iTrader: (2)

ah, nice and simple method, but is this not risky not being diagonally set up.

I suppose, provided that the brakes are put on properly, I'd be ok?

cheers

AstoN_B

iTrader: (1)

I don't fully understand how the system works. Granted I've got an 89 xr3i but they shouldn't be too different.

Are the compensators mounted to the drivers chassis leg above the driveshaft? I had two devices there to do with brakes when I was stripping cab for rebuild but don't think they'll fit with blacktop in way.

dave_s2_rst

iTrader: (2)

has your car got abs? I think your referring to the abs modulators?

the compensators are on the rear of the car, follow the brake line and you will find they feed into a springy type thing and then into the drums. Those springy type things adjust the rear brake according to the load on the rear of the car.

Karlos G

iTrader: (4)

No, Aston is correct they are the compensators I have them there too.

dave_s2_rst

iTrader: (2)

apologies

Karlos G

iTrader: (4)

lol

Rob_DOHC

iTrader: (4)

The rst has rear proportioning/compensator valves acting off the swing arms, the xr3i have the valves on the chassis leg as above.

I am using the same set up as Christian above however a few others are using mk6 inline valves (do a search in restorations section for Puss) from a mk6 escort, nice and simple plus OEM, this keeps the diagonally split system, and bypasses the compensator's.

Here is my bias valve fitted on the strut tower/inner wing so i can adjust my back brakes.



Good luck

Rob,

AstoN_B

iTrader: (1)

cheers guys, if i ditch the compensator on 3i does that mean i'll have same braking effort on rear as i do on front? i may just relocate them to free up some room for blacktop and simplify pipework...

EssexMikeSi

iTrader: (3)

I wish someone would do a system and then do a simple step by step thread that could be made a sticky on here for us all to follow as myself and plenty of others are completely baffled by the amount of options etc. I just want working brakes ffs lmao!!!!

dave_s2_rst

iTrader: (2)

lol, that will never happen. Too many variations and differing views ! Im going to go for the above approach that has been mentioned.

EssexMikeSi

iTrader: (3)

Think i will to. What master cylinder are you going to use?

dave_s2_rst

iTrader: (2)

currently on standard rs, however if this gives up then i'll defo consider the one rob has done on his car. did consider a pedal box but opted against it as i dont want to loose servo assistance.

EssexMikeSi

iTrader: (3)

Exact same here mate. I was ready to buy a pedal box and couldnt understand why not many were wanting to get rid of their old servo etc and get one, but then i got told by a few about how you lose the servo assistance.

My current set up has the master cylinder and in engine bay compensators, the non abs set up but i want to lose that and have braided lines made up with a proper bias valve.

Where in essex are ya mate, we may be able to help each other here lol.

dave_s2_rst

iTrader: (2)

hi mate, im near chadwell heath, i've got most bits for the conversion, just need the lines, tpiece and bias valve.

Hopefully then im good to go ahead.

1 more question, in terms of the actual bias - what should it be set to (front/rear) and should i have people in the back would i then need to re adjust the bias?

Rob_DOHC

iTrader: (4)

In my opinion the bias should be adjusted by driving at 30mph and deliberately locking the fronts on a wet road, if the backs lock up or are close to locking back them off a bit and go again. This will probably give the safest road set up (do it with no passengers). Then you can check it at an MOT centre. Essentially you NEVER want the backs to lock under hard braking.

Regards to stickys etc, i don't think we have a particularly active moderator? I have all the photos from my build which i would be happy to put up with a step by step account of things and other options but i doubt it will be stickyed. There are different approaches but not that many.

Rob,

EssexMikeSi

iTrader: (3)

sounds good rob. I need to start collecting parts asap but dont know wot to get.

JesseT

Mind that if you do the setting on the wet, you will lock the rears more easily in the dry. The more deceleration you achieve, the more weight will be transferred to the front making the rear very light in comparison and suspect for locking up. This is why the standard mk3/mk4 conpensators reduce rear pressure based on deceleration. The S2 ABS system on the other hand reduces the rear pressure based on weight transfer (rear of the car going up and the front diving low).

Rob_DOHC

iTrader: (4)

Thats not untrue, i think it goes both ways a little.. and saying that i have never locked a rear wheel in the dry and have done it several times in the wet. But a good trial in both wet and dry wouldn't hurt.

Yep and thats why the backs lock up in the wet, same brake effort, less deceleration (less grip, fronts may have already locked), little/less rear pressure reduction and a lower coefficient of friction (wet road) means locked rear wheels and an embarrassing about turn

Standard cars always use a massive safety margin, i find cars of that era with no abs/crude abs have rear brakes that do very little, no where near as much as they could. Thats why i like the bias valve, on a dry track i suspect the shonky drums could do A LOT more than they do as standard...



Rob,

Rob_DOHC

iTrader: (4)

It also compensates for weight in the back.... all totally screwed up by lower and stiffer suspension.

Rob,

JesseT

Yes, it's a huge compromise from the factory. Therefore I always though it was a pitty that the ABS system was front only. Although it was a terrible mechanical system. I've been toying with the idea of actually using the ABS front&rear as I already have the Cossie ABS master cylinder and the electrohydraulic setup. Just can't be arsed to mount the sensors on all four wheels.

Rob_DOHC

iTrader: (4)

Yes i thought about this for a while, all the sierras i have had with abs have stopped really well, it would just be a total pain fabricating the sensor mounts and pick-ups, you could maybe use the front drive shaft abs pulley (re machined) as the front pick up with the abs sensors mounted either side of the gearbox, but im fairly sure there is only one sensor for the rear on a cosworth??? Other than that its custom drive shafts with the abs ring and drilled hub carriers.

Too much work to make it worth while really.

Rob,

AstoN_B

iTrader: (1)

How do the compensators on a 3i adjust according to deceleration?

do they have a valve inside them?

I'd like to relocate them to the rear somewhere underneath if i can, hopefully they wont need to be mounted in a certain position!

Rob_DOHC

iTrader: (4)

pretty sure they have a ball and spring inside, the angle of the compensator's is key. The deceleration lets the ball move up the barrel reducing pressure to the rear. You can adjust the braking effort to the rear by adjusting the angle they sit at. Not that i would recommend it.

Rob

EssexMikeSi

iTrader: (3)

rob do u reckon a standard rs turbo servo and master cylinder arent really man enough for rear discs etc. What made u decide to chance master cylinder etc? I can get brand new rs turbo master cylinder through work for Ł15 lol.

Rob_DOHC

iTrader: (4)

I changed really because i wanted a bigger master cylinder. Generally the master cylinders you can buy are 22.5mm or something where as the standard rst uses a 25mm master.... i couldn't get one as they aren't made any more. Even if they are advertised as being for an rst.

There are plenty of people who have fitted rear disks with standard master cylinders, but i suspect the pedal travel will increase making it feel a bit spongy. That added with cosworth fronts won't help.

My pedal should feel pretty good (i hope) as i am using standard rst front callipers with spacer plates, no abs, braided calliper lines, 25mm master and the correct rear slaves. The bigger servo will definitely help too.

Basically the bigger the pistons are in the callipers the more fluid you have to displace for the same travel (greater volume), so the further you have to press the pedal. Add this to the master cylinder, where the smaller the bore the greater the distance the piston has to travel to shift the same amount of fluid, again the further you have to press the pedal.

Rob,

AstoN_B

iTrader: (1)

Looks like I'm digging out compensators later to see if they still fit with blacktop in lol. I genuinely cannot be bothered with a bias valve, unless I can find a remote adjustable...

dave_s2_rst

iTrader: (2)

https://passionford.com/forum/ford-e...al-set-up.html

see jambos - adjust in car.

Im tempted but obviously these require tweeking depending on conditions, making it easier to set up for a track car rather than a road going car.

Im tempted to leave the rear brakes with drums and my car is simply a road going car and I dont think I can be bothered for continuously adjusting the bias depending on different variations.

e.g. rear passengers/no rear passengers.
dry road
wet road

etc

However saying that I could always mark the valve according to the above conditions with a dot making life easier.

Rob_DOHC

iTrader: (4)

Mate you really don't need to adjust it all the time,

You don't need to adjust your current set up according to weather conditions do you?

Set it to a safe setting and leave it, unless your on a track etc. Thats why i didn't buy the extra in car adjuster,

Rob,

AstoN_B

iTrader: (1)

I genuinely couldn't do that in my car, i like oem+ for a road car. If needs be i will put a bias valve in spare wheel well next to battery and adjust it as and when i need to. simpler piping then too.

Any bias valve suitable for bulkhead mounting? like mounted and piped underneath but adjuster knob through bulkhead/panel?

Rob_DOHC

iTrader: (4)

Just read the above link, pretty much covers what has been said here, still no conclusive arguments about proper set up... dry or wet so when my car is done i will give it a try.

Don't like where Jambos is mounted at all, and still stick by my argument that you adjust it once and leave it (unless you go for some track action), compromise between wet and dry etc, this also agrees with what Karlos said. Was a bit unfair of JamboRS to go off at a tangent...

If you want the best of both worlds, great brakes in the wet and dry get an in car adjuster. If you can live with out the 5% or so extra you will get out of the rear brakes in the dry then do the easy thing and fit it under the bonnet. Its really not that big of a deal. Its what manufacturers do, and what they do is 9/10 good enough for me.

Rob,

Rob_DOHC

iTrader: (4)

Yes they do remote linkages, i think for wilwood, you fit the main adjustable valve somewhere sensible and run the flexible cable to a position of your choice (like a speedo cable) maybe in the glove box for example?

Rob,

Rob_DOHC

iTrader: (4)

Puss2

iTrader: (5)

Ive got rear discs ditched the standard stuff and just used inline compensators for the rear and its been fine

Rob_DOHC

iTrader: (4)

Was hoping you would get on Puss really like your solution simple and no messing with brake lines!

Only thing that stopped me doing it was the price, but if I couldn't do brake lines I would have bought them.

Rob

dave_s2_rst

iTrader: (2)

puss did you take the compensators from a mk5 escort or was it from a ka?

12_Second_rst

iTrader: (1)

isnt there a way of adjusting the standard proportioning valve to apply less effort to the rears?

Puss2

iTrader: (5)

It might help also that i have 335mm 4 pot ap's on the front.

The price of them nearly put my off but apart from them the only other thing i needed to do was change one of the brake line ends from male to female.

I THINK they are from a ka i will see if i have the finis number still

Not sure about that but i never checked to be honest

Karlos G

iTrader: (4)

lol
Yeah I think that probably makes a big difference, there's no way the rear will lock up before those bad boys!