Brake Issue

[Jezzy]

Learned opinions please:

I've had 314mm front brakes on my 2.0T for a while now, seemed like overkill when it was running 175 bhp, but a necessity now that I've had it remapped to 220 bhp. The brakes have performed really well for months, but since 3 or 4 days ago it feels like pressing the pedal initially doesn't seem to slow the car at all, you have to press a little harder than usual to get braking. The pedal isn't spongy at all. The pads are about 6 months old, the disks look almost new, the rear pads and disks were replaced in April, I bled the front calipers when I fitted the 314's, and renewed all the brake fluid in April this year.

I did do a couple of high-speed decelerations last week - nothing drastic, just the sort of thing where a passenger might have thought to themselves "wow, great brakes", rather than "OMG he's trying to kill me"; so I'm wondering if maybe I've glazed the pads. Seems unlikely as they were well bedded in already, and as I said, the deceleration wasn't humungous, just "considerable" lol.

I've given the disks a clean with halfords brake cleaner today, but no improvement. I've got a new set of police-spec pads lying around, which I suppose I could fit, but if it isn't the pads I'll have wasted them and will have to go through a bedding-in period again.

Any thoughts please?

[m8internet]

How many miles are on the front pads?
How much material is letf / how worn are they?

I usually get 25K miles out of front pads, between 6 and 9 months

[Jezzy]

Front pads are no more than one-third worn.

[m8internet]

Has the brake bias on the master cylinders been adjusted?

[Jezzy]

Has the brake bias on the master cylinders been adjusted?

Not since I've had the car (2 years).

[m8internet]

It's not much of an upgrade to the front discs, 302mm to 314mm
The rears are the same as mine, 292mm

It may be worth having the brake bias checked, due to the larger front calipers, as it may be slightly towards the rear after modification

I have to agree that when new the 314mm brakes and discs have great "bite" and after about 5000 miles (2 months) they tend to need more brake pressure to be effective, especially for light braking applications
However, when they are near the end of their life it can be quite scary!
Mine are getting to that stage now, just waiting for the brake sensor to come on which should be any day now

[davidjameswest]

why wait for the wear indecator to come on to have to buy one when you know there gettin low any way , false econamy if you ask me

[Craig1985]

i have had the 314mm set up done also and always felt like the brake have felt softer, ive had them almost 2 years and have had them bleed and fluid changed too. should i have had the bia adjusted then?

[Deztroyer]

Jezzy,

take the pads back out and then using emery cloth on a flat surface rekey the face of all of the pads - then refit and retest - i think the surfaces are probably glazed and brake cleaner will only remove the dust and not the glaze - but remember they will need to bed back in again

regards

Dez

[m8internet]

why wait for the wear indecator to come on to have to buy one when you know there gettin low any way , false econamy if you ask me

It's part of the warranty contract
I have to wait until the indicator comes on (as that is more than the material minimum on the front pads)
I did report them previously, but the claim was declined
Spoke to Vauxhall Retailer Warranties and they would not pay out unless the brake pad material was below the minimum OR the indicator was on

Towards the end of their life I try to accelerate the wear, where safe to do so, without damaging the discs

Don't get me wrong, once the warranty expires at the end of November then I am going back to my usual method of visual inspection and wallet
I'm not paying for pads at £150, I'm paying for the pads and discs set instead
Equally, I am going to try and synchronise the front and rear replacements together
Expensive, but the difference in performance is quite staggering