Adjusting brake bias - front/rear
Discussion
I am trying to adjust the brake bias from front to rear. When I brake, the fronts are grabbing MUCH harder than the rear, and the brake lights don't come on until I am really pushing the pedal hard (brake light switch is associated w/ the rear brakes).
So, I would like to accomplish two things:
1) Adjust the brakes so the rears grab a bit harder in order to balance the front/rear bias.
2) Get the brake light to come on earlier with less pedal pushing effort.
It seems that even if you adjust the master cylinder pins where they attach to the pedal bias bar, that when you press the pedal the bias bar just pivots within the brake pedal and ends up applying the same pressure to front/rear as before the adjustment???
Is the master cylinder pins = longer (ie out from pedal) more braking power, or is it shorter for more braking power???
????
So, I would like to accomplish two things:
1) Adjust the brakes so the rears grab a bit harder in order to balance the front/rear bias.
2) Get the brake light to come on earlier with less pedal pushing effort.
It seems that even if you adjust the master cylinder pins where they attach to the pedal bias bar, that when you press the pedal the bias bar just pivots within the brake pedal and ends up applying the same pressure to front/rear as before the adjustment???
Is the master cylinder pins = longer (ie out from pedal) more braking power, or is it shorter for more braking power???
????
Regarding the brake lights, have you checked the new switch solution in the factory update? http://www.pistonheads.com/xforums/topic.asp?h=0&a...
Sounds like you are adjusting the wrong bit.
The shafts from the master cylinder should be the same length and only moved in and out together to put the pedal in a position fore and aft that is comfortable for you and puts the pedal in the correct position for toe/heel if that is what you want.
Brake bias is adjusted by screwing the cross shaft that passes through the pedal. This will result in the pedal pushing on a shorter arm for one cylinder and a longer arm for the other.
bias bar
The brake switch will likely only be solved by fitting the factory pedal switch or an adjustable pressure switch which I have details.
Steve
The shafts from the master cylinder should be the same length and only moved in and out together to put the pedal in a position fore and aft that is comfortable for you and puts the pedal in the correct position for toe/heel if that is what you want.
Brake bias is adjusted by screwing the cross shaft that passes through the pedal. This will result in the pedal pushing on a shorter arm for one cylinder and a longer arm for the other.
bias bar
The brake switch will likely only be solved by fitting the factory pedal switch or an adjustable pressure switch which I have details.
Steve
Edited by Steve_D on Thursday 18th June 16:30
Ok, ...... I see now that I was adjusting the wrong bits. Before I got the responses here I had called Ultima, and they said the same thing!!!
So, the 'bias bar' that runs between the pedal........ how do you get it adjusted properly? The guys at Ultima claimed that it should be sticking out by approximately 21mm, but how do I know how to get the front/rear bias exactly right??? Just running the car and slamming on the brakes and/or using the digital thermometer??
So, the 'bias bar' that runs between the pedal........ how do you get it adjusted properly? The guys at Ultima claimed that it should be sticking out by approximately 21mm, but how do I know how to get the front/rear bias exactly right??? Just running the car and slamming on the brakes and/or using the digital thermometer??
"The guys at Ultima claimed that it should be sticking out by approximately 21mm, but how do I know how to get the front/rear bias exactly right??? "
Maybe, being as how they spend every day of their working lives designing, building and developing these machines, 21mm IS what will give you the correct brake balance. Just a thought .....maybe they have earned the right to make such a "claim".
Maybe, being as how they spend every day of their working lives designing, building and developing these machines, 21mm IS what will give you the correct brake balance. Just a thought .....maybe they have earned the right to make such a "claim".
ILuv4REs said:
I am trying to adjust the brake bias from front to rear. When I brake, the fronts are grabbing MUCH harder than the rear, and the brake lights don't come on until I am really pushing the pedal hard (brake light switch is associated w/ the rear brakes).
So, I would like to accomplish two things:
1) Adjust the brakes so the rears grab a bit harder in order to balance the front/rear bias.
2) Get the brake light to come on earlier with less pedal pushing effort.
It seems that even if you adjust the master cylinder pins where they attach to the pedal bias bar, that when you press the pedal the bias bar just pivots within the brake pedal and ends up applying the same pressure to front/rear as before the adjustment???
Is the master cylinder pins = longer (ie out from pedal) more braking power, or is it shorter for more braking power???
????
The balance bar adjusts the static balance. This determines the brake distribution under very gentle braking. You can feel the effects of the static balance by cornering at moderate speed fairly close to the limit of grip and gently applying the brakes. If the front tends to wash out, you have too much braking at the front. If the front tucks in and the back starts to run wide, you have too much to the rear. If the car just gently drifts sideways the balance is spot on.So, I would like to accomplish two things:
1) Adjust the brakes so the rears grab a bit harder in order to balance the front/rear bias.
2) Get the brake light to come on earlier with less pedal pushing effort.
It seems that even if you adjust the master cylinder pins where they attach to the pedal bias bar, that when you press the pedal the bias bar just pivots within the brake pedal and ends up applying the same pressure to front/rear as before the adjustment???
Is the master cylinder pins = longer (ie out from pedal) more braking power, or is it shorter for more braking power???
????
After setting the static balance you should set the dynamic balance using the bias valve. The procedure is similar but this time you brake firmly in almost a straight line. You'll need to apply the brakes a lot harder this time. Again if you feel the back try to step out there's too much at the rear; if the fronts lock or run wide there's too much at the front.
On the balance bar, the side with the shorter rod gets more braking force.
If your car only has a balance bar and doesn't have a bias valve then you can't get the static and dynamic balance both right; you will have to decide which you want to get right and set the balance bar accordingly.
Quote: "If your car only has a balance bar and doesn't have a bias valve then you can't get the static and dynamic balance both right; you will have to decide which you want to get right and set the balance bar accordingly."
This would be true IF the bias bar had infinate travel, but it doesnt. All braking systems contain flexible components: calipers, seals, hoses etc. They all allow the pedal to travel. Its thru the travel that dynamic balance is gained. All the prop valve does is try to compensate for a poor initial setup. This does require some adjustment of the push-rods as well as the bias bar, but you will only ever get it spot on on the track. Even then you need to continually re-adjust the bias bar to account for tyre wear/temperature, fuel burn wind direction, incline and all the other variables you face in competition.
If the factory say 21mm, trust them, its their job to know. Thats what I would set the car up with, then if my driver wasnt happy, then we would start to tune it.
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
This would be true IF the bias bar had infinate travel, but it doesnt. All braking systems contain flexible components: calipers, seals, hoses etc. They all allow the pedal to travel. Its thru the travel that dynamic balance is gained. All the prop valve does is try to compensate for a poor initial setup. This does require some adjustment of the push-rods as well as the bias bar, but you will only ever get it spot on on the track. Even then you need to continually re-adjust the bias bar to account for tyre wear/temperature, fuel burn wind direction, incline and all the other variables you face in competition.
If the factory say 21mm, trust them, its their job to know. Thats what I would set the car up with, then if my driver wasnt happy, then we would start to tune it.
http://www.pistonheads.com/gassing/topic.asp?h=0&a...
Steve_D said:
Sounds like you are adjusting the wrong bit.
The shafts from the master cylinder should be the same length and only moved in and out together to put the pedal in a position fore and aft that is comfortable for you and puts the pedal in the correct position for toe/heel if that is what you want.
Brake bias is adjusted by screwing the cross shaft that passes through the pedal. This will result in the pedal pushing on a shorter arm for one cylinder and a longer arm for the other.
bias bar
The brake switch will likely only be solved by fitting the factory pedal switch or an adjustable pressure switch which I have details.
Steve
So Steve, heres a thing.... Ever since my bias bar/assembly was new, the centre shaft (ie the bit that holds the threaded bolt/cross shaft and the central pivot, can move from left to right! IE it is not fixed within the assembly tube - if you get me. So is it defective?
The shafts from the master cylinder should be the same length and only moved in and out together to put the pedal in a position fore and aft that is comfortable for you and puts the pedal in the correct position for toe/heel if that is what you want.
Brake bias is adjusted by screwing the cross shaft that passes through the pedal. This will result in the pedal pushing on a shorter arm for one cylinder and a longer arm for the other.
bias bar
The brake switch will likely only be solved by fitting the factory pedal switch or an adjustable pressure switch which I have details.
Steve
So Steve, heres a thing.... Ever since my bias bar/assembly was new, the centre shaft (ie the bit that holds the threaded bolt/cross shaft and the central pivot, can move from left to right! IE it is not fixed within the assembly tube - if you get me. So is it defective?
Edited by Steve_D on Thursday 18th June 16:30
s
thotfast said:
thotfast said: So Steve, heres a thing.... Ever since my bias bar/assembly was new, the centre shaft (ie the bit that holds the threaded bolt/cross shaft and the central pivot, can move from left to right! IE it is not fixed within the assembly tube - if you get me. So is it defective?
Not sure I'm understanding you.The bias bar has a ball in the middle and thread each end.
On the threaded sections are the 'Nuts' which are attached to the master cylinder push rods.
The ball of the bias bar is free floating in the tubed hole in the pedal.
If you adjust the bias you in effect move the ball across the pedal tube. If it did not move in the tube it would make the push rods work at an angle which would not be good.
The bias bar should have a locknut at one end so it cannot rotate and change the bias.
Does that answer the question?
Steve
Steve_D said:
sthotfast said:
thotfast said: So Steve, heres a thing.... Ever since my bias bar/assembly was new, the centre shaft (ie the bit that holds the threaded bolt/cross shaft and the central pivot, can move from left to right! IE it is not fixed within the assembly tube - if you get me. So is it defective?
Not sure I'm understanding you.The bias bar has a ball in the middle and thread each end.
On the threaded sections are the 'Nuts' which are attached to the master cylinder push rods.
The ball of the bias bar is free floating in the tubed hole in the pedal.
If you adjust the bias you in effect move the ball across the pedal tube. If it did not move in the tube it would make the push rods work at an angle which would not be good.
The bias bar should have a locknut at one end so it cannot rotate and change the bias.
Does that answer the question?
Steve
This bit isn't happening! so not good, I dont think the ball is moving left or right on adjustment. I will remove it and see.
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