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MG MGF Technical - Excessive brake pedal travel

My '97 1.8MPi has recently had new brake pipes fitted front to rear, and new rear calipers (due to seized handbrake actuators) The front discs and pads were also renewed at the same time, so I have been using the brakes carefully while they bed in. The rear discs and pads were OK but they were removed, cleaned up and replaced.

Since this work was done I have noticed an excessive amount of travel on the brake pedal before the brakes begin to bite. The brakes have been re-bled carefully in the recommended sequence but this has not reduced the pedal travel. On the advice of colleagues I have fitted the B & G Servo brace - again without significant improvement.

The pedal feels quite firm at the bottom of its movement and doesn't seem to "pump up" to any significant extent. I have now completed about 100 miles without any noticable improvement in the pedal travel.

I am wondering whether the handbrake self adjustment mechanism in the new rear calipers may be malfunctioning in some way as there is very little movement in the hand brake - only one click from fully off to firmly on.

Is there a method for resetting this mechanism? Should I loosen the cable adjuster to give more slack in the handbrake? How many clicks?

Does anyone have any other suggestions?

Andy Dear
Andy Dear

sounds like the handbrake is working right, could it be that the sized calipers on the back were giving you a false impression of 'right travel' before - how far is 'a long way'.

take the wheels off and put your fingers on the sides of the pads- get a friend to push the brake, does one set move more than the others?
does the car pull at speed using the brakes hard?
does the car pull at speed using the brakes soft?
Will Munns

One or more discs may not be running true so that it/they push the pad/s further back causing more pad and hence pedal movement.
Remove the wheel/s Set a Dial Test Indicator on the disc face approx. 6mm from the outer edge. Runout must not exceed 0.05mm
Geoff F.
G. Farthing

Will,

I have owned the car for eight years, and it always had what I would call a 'normal' amount of pedal travel before this work was done.

Now, the pedal goes halfway down before it meets any resistance (I must measure the movement!) but there is no pulling to one side on braking, fast or slow.

Thanks for the suggestion for checking for unequal pad movement. I will try this.

Andy
Andy Dear

Geoff F,

Wouldn't excessive runout cause pulsing of the pedal? There isn't any detectable. However, that is something else I can check, thanks for the suggestion.

Andy

Andy Dear

Bump.

Is there anything critical about installing new rear calipers that if not carried out correctly might lead to excessive travel in the footbrake?

Andy
Andy Dear

First suspicion is that there is still air inside the system - a stubborn air lock somewhere in the system. It can and does happen. Very frustrating.

The next problem, if not excessive servo movement (seems unlikely if you have a B&G bracket and the pedal feel remains unchanged) is that the seals in the calipers (front) are in need of servicing. Kits are available, or you can replace with new reasonably simply - or indeed with reconditioned on exchange.
Rob Bell

Thanks for your suggestions. I will work through them and see what turns out to be the cause.

Andy

Andy Dear

This thread was discussed between 22/07/2006 and 25/07/2006

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