Braking problems?

Author
Discussion

Yadizzle1

Original Poster:

698 posts

132 months

Wednesday 22nd April 2015
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Hello everyone

I've been having some pretty poor brake performance from my car recently. Basically the problem is that you have to push the pedal down quite far for the brakes to actually do any work, but I have noticed that pumping or tapping the brake pedal before braking significantly improves the braking performance.

I've had a bit of a nightmare trying to find out what the problem is, at first I thought I had worn my pads out, however a quick check of the pads in situ showed that they still had plenty of life left. Brake fluid is at the right level within the reservoir and I have been told that it's not due to air in the lines. I took my car to a mechanic who road tested the car and suggested that the pads may have become glazed due to overheating.

Which of these seems most likely to be the culprit, I can't imagine that pumping the pedal before braking would do anything to improve braking performance if the pads are glazed?

Any help would be much appreciated

steveo3002

10,669 posts

181 months

Wednesday 22nd April 2015
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id say air or badly ajusted rears

glazed would most likley give a wooden feel to the pedal

andyiley

9,980 posts

159 months

Wednesday 22nd April 2015
quotequote all
Fully change the fluid via bleeding and that will probably make a significant difference.

Yadizzle1

Original Poster:

698 posts

132 months

Wednesday 22nd April 2015
quotequote all
I thought it would be air in the system too. Would pumping the brakes while the engine is off indicate any signs of air being in the system? When I do this my brake pedal firms up greatly and there is no spongy feeling or travel to the floor.

I started to bleed my brakes the other day with help from a couple of mates, however, when they were tightening the bleed nipple, they said that it was stuck and wouldn't tighten nor loosen and didn't want to risk damaging the nipple so gave up on that idea. That's when I took it to the mechanic who then said it's most likely brake glazing.

PaulKemp

979 posts

152 months

Wednesday 22nd April 2015
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Car stationary, stand on the brakes hard, if pedal creeps down its probably air in the system.
Bleed them closest to master cylinder first.
If no improvement then may be master cylinder seals.
Pumping the brakes to get a pedal is usually air in the system.
Glazing is usual less braking and break fade on a hard stop without loss of pedal pressure.

Mr2Mike

20,143 posts

262 months

Thursday 23rd April 2015
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PaulKemp said:
Car stationary, stand on the brakes hard, if pedal creeps down its probably air in the system.
The pedal creeping down would indicate a leak in the system, usualy master cylinder seals. A very small amount of air in the system would give a somewhat springy pedal, lots of air means the pedal will go to the floor.

Having to pump twice to get a firm pedal is a sign of either some air in the system, or it can also be caused by rear drum brakes with a faulty self adjusting mechanism.

brman

1,233 posts

116 months

Thursday 23rd April 2015
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could also be warped discs or worn wheel bearings I think?

(wheel rotating knocks back the pads so you have more travel before you get braking)

Normally you would feel warped discs though the pedal but possibly not dodgy bearings.

I also had something like this when the caliper slide pin was siezed and it was braking mostly with one pad.

Yadizzle1

Original Poster:

698 posts

132 months

Thursday 23rd April 2015
quotequote all
brman said:
could also be warped discs or worn wheel bearings I think?

(wheel rotating knocks back the pads so you have more travel before you get braking)

Normally you would feel warped discs though the pedal but possibly not dodgy bearings.

I also had something like this when the caliper slide pin was siezed and it was braking mostly with one pad.
Warped discs would give some sort of judder through the steering wheel as you brake I believe?

andyiley

9,980 posts

159 months

Saturday 25th April 2015
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Bleed from the furthest point from the master cylinder first, not the closest.

Yadizzle1

Original Poster:

698 posts

132 months

Saturday 25th April 2015
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Thanks for the help, pulled my pads out and they were extremely smooth and shiny. Put new pads in and it's made a world of difference, I do have to double pump sometimes to get the brakes to really bite so will get the brake fluid replaced and the system bled as soon as possible.

S0 What

3,358 posts

179 months

Sunday 26th April 2015
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Yadizzle1 said:
Warped discs would give some sort of judder through the steering wheel as you brake I believe?
Not if it's the rear discs wink

T1pper

275 posts

143 months

Monday 27th April 2015
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A seized piston or slider in the caliper will give those sort of problems.