Brakes. and brake bias.... Suggestions please?
Discussion
I have the older Ford brakes, but with both the front and rear clys the same size. I think the new larger brakes use 2 cly sizes for front and rears? My question is, it must be the same principle what ever type of brakes? My problem is - even with the brake bias bar fully over, I can never get the rears to lock-up, even on gravel. So is it because the bias is not enough (hence the mix of clys front and rears on the larger brakes??) The factory used to supply only 2 clys of the same size, and didnt really comment further... The fronts lock up if pushed fine... and I know I dont want the rears to lock up too soon, but worried I am not getting enough brake action from the rears... Any one got any ideas? I have though of trying a cly size change on the rears..?
Paul - You say the rears won't even lock on gravel! I would check that you have no kinks in the pipes leading to the rears, that the pistons are free and as suggested, try replacing the fluid and bleed the system.
You may also want to check the assembly of the bias bar. If not inserted right at the begining then it wont be effective. You may have started off with far too much front bias.
Paul.
You may also want to check the assembly of the bias bar. If not inserted right at the begining then it wont be effective. You may have started off with far too much front bias.
Paul.
Paul
As mentioned before, check operation of your bias mechanism. Make sure that you are adjusting it correctly. If you're sure that it's OK, here's the method to get the brake bias in the ball park (an American term meaning "getting it close") as recommended by the master Carroll Smith, who recently has driven off to that big race track in the sky!!.
Put the car on 4 jacks.
Have someone sit in the drivers seat, and hold the steering wheel so it can't turn.
Rotate the front wheel, and have the driver apply the brake until the wheel won't turn. Use a fair amount of effort.
Holding that brake pressure, the rear wheel should just be able to be rotated (almost locked) using the same effort as applied to the front wheel. Make bias adjustments until this condition can be achieved. If it can't, you have a mechanical or hydraulic problem.
This method is very easy to do on an open wheel car, more difficult on a closed wheel car, but is fairly easy on the Ultima since the clips can be opened.
Final adjustments are done on the street or track.
Jack
As mentioned before, check operation of your bias mechanism. Make sure that you are adjusting it correctly. If you're sure that it's OK, here's the method to get the brake bias in the ball park (an American term meaning "getting it close") as recommended by the master Carroll Smith, who recently has driven off to that big race track in the sky!!.
Put the car on 4 jacks.
Have someone sit in the drivers seat, and hold the steering wheel so it can't turn.
Rotate the front wheel, and have the driver apply the brake until the wheel won't turn. Use a fair amount of effort.
Holding that brake pressure, the rear wheel should just be able to be rotated (almost locked) using the same effort as applied to the front wheel. Make bias adjustments until this condition can be achieved. If it can't, you have a mechanical or hydraulic problem.
This method is very easy to do on an open wheel car, more difficult on a closed wheel car, but is fairly easy on the Ultima since the clips can be opened.
Final adjustments are done on the street or track.
Jack
thanks guys... I can get the rears to lock up on the stands, and can't rotate with my hands, so the general operation looks fine IE no air locks etc, I assume as the rear tyres are much wider that the amount of power needed is more to stop the rears. Question: is there any way I have fitted the bias bar wrong? Ie is it "handed". I guess a rolling road will tell me how much the rears are "stoping". What size clys do you guys fit on front and rear?
With equal size master cylinders, you may well be running out of mechnical travel on the balance bar. The slave cylinders will be very different sizes front and back so your balance bar will need to move a long way to allow for the extra displacement. Ideally the master cylinders would be sized to match the slaves so that both cylinder have similar travel if you see what I mean. Also, it would be worth going back for yet another check to make absolutely sure you are adjusting it the right way, in fact try adjusting it the other way just in case!
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