not a pug problem but hopefully someone can help

[ianst28]

ok as i said not a pug issue but hopefully someone on here will come up with an idea

my mothers audi 80 has developed a rather interesting braking fault
when you brake at any speed over 15 mph the front right dips down and it feels like the brakes are only working on that side on the front this causes the car to pull to the right if you need to brake (i didn't know about this till i had to jam on after an idiot pulled out on me )
ok so the first thought i had was sticking or siezed caliper so i stripped it down and nope it ain't that
so then i took it to my local mot station (they're mates so it was at lunch and the missus had cream cakes to distract them)
stuck the car on the brake tester and as thought huge imbalance on left to right
so we think summat simple bulging flexi hose .................. get the car in the air with the work exp lad in it and nope it's not a bulging flexi
so then someone says ....... has anyone checked the tyre pressures ...... cue swearing as we check them and lo and behold the tyre pressures are all to hell so we correct them and then throw the car on the tester ................... nope wasn't that either

so anyone got any ideas ??????????

this thing is pretty dangerous to drive to the point where i've lent mum my car so she's not gonna crash head on into oncoming traffic

thanks all


ian

[Doggy]

Hydraulic fault on one circuit, e.g. one seal gone in master cylinder? Don't know how the Audi is split - if it's diagonally you probably wouldn't notice the rear brake imbalance.
Guess you can't rule out an ABS fault either
HTH

[jasper5]

Was the imbalance on the same axle, eg, front only or rear only?

On the mot brake tester, you should be able to ID which side is not working properly.

I have had brake hoses that have broken up inside not allowing the fluid to flow through correctly.

Are the pads free in their calipers? Are the pivots for the calipers free?

[ianst28]

ok you have to excuse the bad typing and spelling i'm on my mobile using predictive txt
Ok so on the tester it showed that the imbalance was only on the front the passenger side was running badly the driver's side was ok but a huge imbalance between the 2 sides
We checked all the sliders and pistons and they were all ok on it
The abs works if you do the usual test however the cv boot is split with all the usual mess and grease that that entails don't know if that will make any difference but better mention it huh

[djp30djp]

Grease from the CV joint on the disc Try giving the disc a good clean with brake cleaner & see if that helps.
Have you tested to see if the rears are balanced

Hydraulic fault on one circuit, e.g. one seal gone in master cylinder? Don't know how the Audi is split - if it's diagonally you probably wouldn't notice the rear brake imbalance.
Guess you can't rule out an ABS fault either
HTH

[ianst28]

yeah we thought that too but cleaning didn't help
I'm wondering if it is a collapsed flexi or an abs fault

[jasper5]

Have you got all the figures from the brake test? Out of the four, is there only low effort on the left hand front?
If so, there is definitley a problem with the left hand brake, my main suspect is a collapsed brake hose. Undo the bleed screw and see how the fluid flow is compared to the other side.

This should be a simple fault to ID if you have brake testing equipment.