Confusing experience with brakes

Confusing experience with brakes

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Discussion

JohnMcL

Original Poster:

146 posts

144 months

Sunday 25th June 2017
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The setup is twin Wilwood m/cs with ap discs and calipers. On Sunday 18th June in +30C, drove 130 odd miles out, parked for lunch, then set off for home. During the return journey the brake pedal went soft with long travel. System could be pumped up but braking effect seemed reduced. So I put the car away and planned to sort it out this weekend.

Before starting work I drove up and down the lane to refresh my memory. Pedal is rock firm and braking effect is perfect.

Anyone got any ideas as to what is happening?

GreenV8S

30,209 posts

285 months

Sunday 25th June 2017
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SWAG - bearings opening up when hot and causing pad knock-back?

E-bmw

9,240 posts

153 months

Tuesday 27th June 2017
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^^^^ Wot 'e said, alternatively pads dragging causing fluid to boil.

Boiled fluid is a gas, this causes a spongey long pedal, which when pumped works again.

Boiled fluid cools down & re-condenses & feels fine again the next day.

Either way you need to remove the calipers, clean & grease the sliders/pistons/pads to make sure everything is free, ditto the discs/hub interface etc.

It will probably then be fine, but a fluid change/full bleed wouldn't go amiss.

JohnMcL

Original Poster:

146 posts

144 months

Saturday 1st July 2017
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Thanks guys. Plenty to check but I haven't found an obvious smoking gun yet. Onwards.