To Much Front Brakes

[Longboarder]

You're a bit stuck basically with a hardware mismatch for your car. The servo is giving too high a pressure on too small a pedal movement to allow you to control the brakes. In this situation its difficult to know if the front/rear balance is OK or not.

You need more pedal effort to produce less hydraulic pressure.

Possible solutions assuming you are not going to be greasing the front pads!

1. Less servo assistance.

2. A bigger diameter mastercylinder with the same servo.

3. A smaller master cylinder and no servo. Might need to increase pedal ratio (leverage).

4. After market pedal box and twin cylinders. (Mine still isn't sorted)

My pinto setup with servo was fierce. Just got used to it by putting in the miles. Never did find pads of poor enough quality to reduce the braking power to less than emergency stop!

If I were doing it again I would ditch the servo, get a Tiger extension push rod to operate the remounted mastercylinder, increase the pedal ratio by moving the point the rod connects to the pedal up towards the pivot point about half an inch and get used to the greater pedal pressure but better control.

 

Nigel

[Guest dinger]

Wise words from Nigel there Dan,

 

It may well take some time to get right. lets see how you get on with the tyres.

[ibrooks]

Sierras with discs all around but no ABS have a bigger master cylinder which may help giving more pedal travel per pressure if your existing one is from a Sierra with discs and drums. What size are the current front discs? if they are 260mm discs then maybe dropping to 240mm discs (and associated calipers) would help. Failing that it's relatively easy to alter the Sierra pedal box to take a pair of Girling masters with a bias bar - no need to go for anything exotic in the way of floor mounted boxes.

 

Iain

[speedtripledan]

Sierras with discs all around but no ABS have a bigger master cylinder which may help giving more pedal travel per pressure if your existing one is from a Sierra with discs and drums. What size are the current front discs? if they are 260mm discs then maybe dropping to 240mm discs (and associated calipers) would help. Failing that it's relatively easy to alter the Sierra pedal box to take a pair of Girling masters with a bias bar - no need to go for anything exotic in the way of floor mounted boxes.

 

Iain

they are the 240mm i have the master cylinder you refer to but no servo for it any one got one for sale ?

[speedtripledan]

just to clarify a little the fronts don,t snatch as soon as the brakes are applied they are progresive to a point but when pushing they just lock a bit to easy under moderate braking pressure.

The tyres might rectify this enough as the former yoko 538s are hard! 3000 hard miles several track days and they have only worn by 1.5mm

i have a spare pedal box with a master cylinder off an abs sierra think i,m going to play with this to increase pedal leverage etc and see if i can find a happy medium

if the above don,t achive the required feel i,m going to have to spend money and get a custom pedal box set up.

 

Its the last thing on the car i want to improve.

 

Thanks for your input

[Bob Tucker]

Dont forget the basics too....

tyre pressures should be 20 or less any harder & the tyres will lock easily.

Spring rates & damper settings ...if theyre too hard/stiff the suspension can skip on a bump, take weight off a wheel & allow a lock up again.

Otherwise follow Nigel's wise words..

 

I also went from a standard servo setup to a single pedal without a servo & scared myself at first. A few mile under the wheeels & I wouldnt go back if you paid me. Far more feel & control to the pedal now.

[speedtripledan]

After all that, the new tyres have done it what a differance and they are not even properly scrubed in yet

 

Happy days