Vauxhall Agila - Brakes

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Mon 19 Aug 2024 19:27
Vauxhall Agila - Brakes - Rebecca Bagnall

I have an intermittent brake issue. My Agila has recently visited two local garages who both say the brakes are fine - but they aren't. Most of the time, the brakes respond as they should but, every couple of weeks, I have to press the pedal right to the floor if I'm braking as the car goes over a bump/grate/pothole. The foot brake loses its 'thread' and presses right to the floor (I'm not sure how I actually stop...). As I proceed over even ground without braking, the pedal eventually regains its thread (I don't know what else to call the engagement/resistance response of a normal brake pedal). What can I do as it doesn't seem possible for garages to identify the issue?

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Mon 19 Aug 2024 19:51
Vauxhall Agila - Brakes - paul 1963

Sounds to me like a vacuum issue with the servo, presume the brake fluid level is correct and it looks clean?

Take it to a garage that has a brake test roller ( mot station), obviously for the safety of yourself and others it really does need sorting, please get back to us if you get it sorted, it all adds to the knowledge base of the forum..

Edit: just had a thought, get the wheel bearings checked, it could be the pads are getting pushed back in the calipers, not being rude but if that goes over your head show the garage this post..

Edited by paul 1963 on 19/08/2024 at 19:58

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Mon 19 Aug 2024 21:18
Vauxhall Agila - Brakes - elekie&a/c doctor
Don’t think it’ll be the vacuum servo fault. A problem here would cause a hard pedal and you would have trouble pushing it down. Sounds more like air is being drawn into the system . I would also get the flexible brake hoses inspected.
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Tue 20 Aug 2024 10:20
Vauxhall Agila - Brakes - edlithgow

Bump sensitivity is a bit puzzling, and I suppose is why bearings and pad knockback are suggested above.

I cant really picture how this could lead to air (consistent with the "foot to the floor" description) being drawn in to the system, but that doesn't mean it couldn't happen.

Maybe a master cylinder seal everting could lead to sudden and temporary loss of brake function but I wouldn't expect it to be bump sensitive.

Similarly I wouldn't expect the classic explanation of this symptom, boiling wet brake fluid, to be bump sensitive either. I've had this symptom in combination with a detached brake shoe (I dunno if your car has rear drum brakes) which COULD be bump-sensitive but wouldnt be likely to respond as immediately as you describe.

Some stray debris or a collapsing hose could perhaps seal off pistons or even leak air in a G-sensitive manner. I've had a single piston fail due to a collapsed hose, picked up when flushing the brakes, so I'd do that first as part of a complete brake overhaul, and see what, if anything, you find.

Edited by edlithgow on 20/08/2024 at 10:30

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Tue 20 Aug 2024 11:53
Vauxhall Agila - Brakes - blindspot

I HAD A PROBLEM LIKE THAT YEARS BACK. IT WAS SOMETING TO DO WITH MASTER CYLINDER SEAL

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