How Much force for bias valve?

[jayro]

So how much pressure does it take to keep the bias valve open? I zipped tied it up last year to give my rears maximum flow (or max w/o installin bias plugs). I have notices that when I bleed my brakes I get alot less flow at my passenger rear caliper than my drivers side rear. I also notices when I did my rear brakes after a number of track days that my driverside rear pads were much more worn than my passenger side. I have stainless lines and new calipers. I didn't see anywhere in the hardline that looked crushed or anything. Before I disassemble the valve I was wondering if maybe I didn't push the valve arm up hard enough to open it all the way. I just pushed up on it as hard as I could with my hand and zip tied it in place. Would it be worth using a c-clamp to apply more pressure to it?

I am not concerned about it adjusting bias, I just want good flow to both back calipers.

If it is messed up I was planning on taking out the stock plugs to see if I could modify them to be open all the time. This was mentioned in a couple of threads, but not much detail was given. I am thinking it shouldnt be a complicated procedure, but since I have never take one apart I dont know what the stock plugs look like. Does anyone have a pic they could post? Thanks

 

[intimdatr]

Just to check are you sure your rear caliper isnt stuck? Unlikely but something to check.

 

[jayro]

Just to check are you sure your rear caliper isnt stuck? Unlikely but something to check.

I am sure it is not stuck. I put on new calipers to make sure. Same flow.

 

[quikSHOilver]

Not sure if you want to retain abs system? However, to my understanding, only way to get equal full flow to rear would be to removing the whole bias valve block and install proportional valve in after mc then to "T" fitting in back. Again, That would be going abs-less.

 

[jayro]

Not sure if you want to retain abs system? However, to my understanding, only way to get equal full flow to rear would be to removing the whole bias valve block and install proportional valve in after mc then to "T" fitting in back. Again, That would be going abs-less.

I guess I don't follow. I am talking about the stock bias valve that is controled by the lever attached to the rear control arm. It is supposed to be open when the car is level. I dont have it connected to the RCA, I am just ziptieing the lever up so that it is open all the time. It doesnt have anything to do with the ABS system.

For 100% flow I could just add bias plugs, but I dont want to if it is not nessacary. The stock valve all the way open is about 60% flow....which is fine.....I just want my full 60%.

 

[93markVIII]

maybe the rubber brake line has collapsed or broken down internally.

 

[jayro]

maybe the rubber brake line has collapsed or broken down internally.

Stainless lines. I have gone through the system to eliminate the other possibilities. I was just wondering if maybe I didnt put enough pressure on the valve to open it all the way. I will clamp it with a c-clamp and see if that helps. If not I will go the bias plug route. Or disassemble the valve and see if I can modify it to stay open.

 

[Irish Pride]

The lever not being up all the way will not cause one caliper to brake more than the other. The Bias Valve does not decide which side brakes and which side doesnt. They both will get the same amount of flow regardless. Sounds like you have an issue further up the line. Might be time for a new Master Cylinder.

 

[K-Dawg]

So how much pressure does it take to keep the bias valve open? I zipped tied it up last year to give my rears maximum flow (or max w/o installin bias plugs). I have notices that when I bleed my brakes I get alot less flow at my passenger rear caliper than my drivers side rear. I also notices when I did my rear brakes after a number of track days that my driverside rear pads were much more worn than my passenger side. I have stainless lines and new calipers. I didn't see anywhere in the hardline that looked crushed or anything. Before I disassemble the valve I was wondering if maybe I didn't push the valve arm up hard enough to open it all the way. I just pushed up on it as hard as I could with my hand and zip tied it in place. Would it be worth using a c-clamp to apply more pressure to it?

I am not concerned about it adjusting bias, I just want good flow to both back calipers.

If it is messed up I was planning on taking out the stock plugs to see if I could modify them to be open all the time. This was mentioned in a couple of threads, but not much detail was given. I am thinking it shouldnt be a complicated procedure, but since I have never take one apart I dont know what the stock plugs look like. Does anyone have a pic they could post? Thanks

I've wondered this myself because I zip-tied up the arm once and couldn't tell a bit of difference. I also couldn't detect any kind of movement on the valves while I was under the car pressing on them.

If I understand how the Taurus braking system works, the bias valve(s) could absolutely cause a difference in brake fluid flow between the two sides. At that point they are two independent systems, each with their own bias valve.

 

[Irish Pride]

I've wondered this myself because I zip-tied up the arm once and couldn't tell a bit of difference. I also couldn't detect any kind of movement on the valves while I was under the car pressing on them.

If I understand how the Taurus braking system works, the bias valve(s) could absolutely cause a difference in brake fluid flow between the two sides. At that point they are two independent systems, each with their own bias valve.

The lever will work both valves equally. If the flow is restricted at the valve it wont be because of the lever not being up. If the valve is the problem you will need Bias Plugs to correct it.

 

[jayro]

The lever will work both valves equally. If the flow is restricted at the valve it wont be because of the lever not being up. If the valve is the problem you will need Bias Plugs to correct it.

I see what you are saying because the lever is designed to push both the valve equally at the same time. Though over time my lever has gotten some play/wobble/twist in it that could allow for it to favor one circuit over the other if one were easier to depress than the other. I will clamp it to see if it helps. If not I will check the flow at the valve entrance and exit.

I replaced the Master Cylinder this past summer. It didn't change the flow at all.

 

[cowboy0ne]

I have a 94 atx with same problem divers rear eats pads and ocasonaly locks. Im on my 3rd caliper all the lines are good jus have little to no presure to the rear. Jacked up or on the ground.

 

[jayro]

I have a 94 atx with same problem divers rear eats pads and ocasonaly locks. Im on my 3rd caliper all the lines are good jus have little to no presure to the rear. Jacked up or on the ground.

I haven't got to mess with mine to much. Been parked all winter. With the stock bias valve you are always going to have less flow in the rear. Full bias for the stock valve is about 60% if I remember correctly.

Is it possible that there is an issue with your ebrake cable that is not allowing your caliper to completely release?

 

[cowboy0ne]

Just put new hi pro calipers and drilled and sloted roaters all the way around and when I went to bleed I had zero fluid or presure in the back at all. I took both back lines off and pumped em up but nothing. Front blead fine. Drove it down the road a couple times and had some pres in the rear re blead and all seemed fine. But the LR still locks ocasonaly. Ive checked the ebrake and both release and go back to wear they should be.thats why I was curious about the bias valve im new to the crazy intriguing way the sho works lol

 

[jayro]

Just put new hi pro calipers and drilled and sloted roaters all the way around and when I went to bleed I had zero fluid or presure in the back at all. I took both back lines off and pumped em up but nothing. Front blead fine. Drove it down the road a couple times and had some pres in the rear re blead and all seemed fine. But the LR still locks ocasonaly. Ive checked the ebrake and both release and go back to wear they should be.thats why I was curious about the bias valve im new to the crazy intriguing way the sho works lol

It could be something with the bias valve if it s not letting fluid flow the way it should. Did you have it zip tied up when you tried to bleed the rear? If not, that would explain the zero flow while bleeding. Did you replace the soft brakelines along with the calipers? Over time they can cause flow issues ads well. You could always take the lines off before the bias valve to check flow and then after.