I recently changed the brake master cylinder on my 1991 Fiesta 1.6S.
It was a pretty straightforward job and I was feeling quite smug about having saved myself a few quid on garage fees. The trouble is, the brakes have felt rubbish ever since.
Firstly, the pedal feels much firmer than it did (OK, you might put that down to the fact that the old master cylinder was worn and had more travel). But it also requires more force to bring the car to a stop. I dont't think the brakes are unsafe, it's just that they don't feel as strong as before.
Plus - and this must be more than coincidence - the brakes don't feel progressive, i.e. a light press of the pedal doesn't do very much, but a firmer press causes the brakes to bite.
I've checked the servo and vacuum pipe non-return valve (as per the instructions in the Haynes manual) and they both seem fine.
Any ideas?
Ta very much.
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I had a similar problem on my 1996 fiesta. Did you take the servo out when replacing the master cylinder, the servo I took out of my fiesta was heavily corroded on the lower side (where you can't see without removing the damn thing) and therefore had a small leak (but it passed the Haynes tests). This turned turned out to the the source of my troubles.
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misterbarbel
I didn't take the servo out, I just removed and replaced the master cylinder, then bled the brakes.
You say you had a similar problem - was your problem that the pedal was firm, or was it that the brakes didn't feel progressive? Or both?
I still think it's an odd coincidence that the servo, or something else, should have developed a problem as soon as I changed the master cylinder.
Isn't there a device in the system that regulates pressure between the front and back brakes? I'm wondering if it's somehow developed a fault, i.e. the front brakes are fine but the back brakes are only being applied when the pedal is pressed harder than usual (or vice versa). It might account for the lack of a "progressive" feel in the pedal.
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When I change dthe front disks on son No 2's 1993 1.1 Fiesta, I discovered that the rubber flexible hoses to front disk calipers were shot and fluid came through intermittently. Changed them and brakes became perfect.
You may have a flap of rubber acting as a valve in one..
madf
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Riggers, I should have been clearer, my brakes didn't feel as progressive(as they had a few days earlier). I had to remove the master cyclinder to get at the servo so I wondered if you had distrurbed yours when undertaking the same process.
I had a look at the Ford TIS CD, it doesn't cover your car but for fiestas 96 and onwards there is now mention of any system that regulates pressure between the front and rear brakes. Is it possible you still have air in the system after bleeding?
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madf, I don't think there's a problem with fuid getting through as, when I bled the brakes, it was squirting through all the bleed nipples without any apparent restriction.
I'm sure there's no air in the system, either. The pedal's firm rather than spongy.
I don't know if this sheds any more light what's wrong, but I've had the car up on a jack and got someone to turn the front and back wheels by hand whilst I applied the brakes. The result was, with a fairly light foot, the front wheels locked whilst the rear ones still turned easily. It took a firmer push on the pedal to get the back brakes to bite. Does that sound normal?
Any advice appreciated.
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There should definitely be bias towards the front brakes, but how much (or how you'd check it) I couldn't say.
Did you change the pads too? If you did then it'd be normal to experience slightly reduced bite while they 'bed in'.
If there's no problem with fluid flow and all the wheel assemblies are fine, then the only thing that springs to mind is that it might not be getting enough vacumm.
Or even the new master cylinder. As Haynes will tell you, never leave a component out of a fault diagnosis just because it's new - it could be defective from the factory.
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As you have replaced master cylinder.It will feel different.But I would be inclined to check the rear brake adjustment.. as the rear self adjusters can fail.
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Steve
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