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brake bias adjustment
timf - 30/5/03 at 01:16 PM

I found this http://www.stockcarproducts.com/tech1k.htm

it may be useful for those with biar bars and how to roughly set them up


Findlay234 - 31/5/03 at 12:33 PM

Cheers, recieved my pedal box and bias bar yesterday, so thatl be very usefull. one of the reasons for logging on now was to ask how to do it.


fastenuff - 31/5/03 at 05:41 PM

nicely copied from Wilwood, thank you very much.
Looked very familiar so had a look at wilwood, very much the same


macbrew - 3/6/03 at 07:50 PM

I think I know what a bias bar does but will somebody explain how, what, why and do I need one ?


Findlay234 - 4/6/03 at 08:25 AM

the front brakes need more force than the rears to pass SVA. IE the fronts should lock up first in harsh braking. When you have a single master cylinder like the one out of your donor escort or sierra you will need a valve in the rear brake line to limit the force going to the rear drums/discs. this get fiddly to use and if you use the sierra one you have to mount it just right or it wont work. The other way is to have 2 master cylinders. one larger than the other (smaller one for the rear) then for any minor changes you use the bias bar, which just acts as a lever between the two MC's. you push with the pedal at a point along the the bias bar between the MC's. the closer to one of the MC's the more force it gets. Really bad description but hey, its free.

A picture would clear things up, if you want

[Edited on 4/6/03 by Findlay234]


Alan B - 4/6/03 at 03:23 PM

I'll just add here that often the the two MC's are the same bore....in my experience....but otherwise agree with that...


Findlay234 - 4/6/03 at 03:50 PM

I didnt think the bias bar gave enough of a difference between the front and the rear. Im just about to get my MC's and was gonna get .75 for the front and .70 for the rear but now your making me wonder......


Chazzy - 4/6/03 at 03:56 PM

If you assume for the momet that all pistons are same size and the bias bar is set to give equal force then you need the smaller MC going to the front brakes.

Smaller area = larger pressure in fluid giving more resultant force from piston(s)
(Force = Pressure X Area)
Most rear brakes have a smaller piston as well to decrease the force.
As you say the Bias bar gives fine adjustment.
The stuart taylor kit has different sizes MC's.


Chazzy - 4/6/03 at 03:59 PM

Sorry re reading that, it looks a bit ambiguous, the piston in the first sentence is the brake calliper piston.

Good luck!


Alan B - 4/6/03 at 05:10 PM

Findlay.....you should find the bar will give quite a lot of adjustment, however it is worth checking what others have done....I have seen it both ways, just more often with 2 the same......although in lots of applications, not just Locost....

Worth asking I guess?

I could be wrong......it does happen...


Alan B - 4/6/03 at 05:22 PM

I've just read my Tilton instructions for my brake bias bar....mine is for 2.5" centres...it says 3/8" off centre will give that side 65% and the other 35%.....IOW one can get nearly double the force of the other......

It does also say that if this isn't enough then go ahead and change sizes.


HTH



craig1410 - 4/6/03 at 11:20 PM

Alan,
I like you floor mounted pedals but won't you have trouble with fluid draining back into the MC from the calipers. Are you planning to put a light pressure non-return valve in there? I'm not being critical but I am trying to decide between floor mounted and swinging pedals and have been waying up the pro's and con's of late.

If you had the MC's with the remote reservoir that would probably help.

Cheers,
Craig.


craig1410 - 4/6/03 at 11:21 PM

sorry for my dodgy spelling...
weighing, not waying! Doh!


Alan B - 5/6/03 at 01:43 AM

Craig, yes you are correct, I'll be doing one of those things.......whichever is cheapest I'd suspect..

The master cylinders were very cheap, but I imagine remote res. replacements won't be........so the low pressure NR valve is the favourite..