Problems With Ap Racing Brakes.

[Baz man]

Hi

Looking for some help / info on AP Racing Brakes.

Got a big conversion done about 4 years ago - New AP 6 pots with 350mm groved discs & Ferodo Pads.

Have a fair bit of feeling on the pedal (Up & down) when pressing the brake at all times . Think it might be a warped disc. Had the calipers off and had a look at the pads and discs and both to the eye looked fine. I gave both a clean up but didnt help.

I have not had it confirmed yet but i am 99% sure it is coming from the front and is getting worse as the days pass.

These discs are a bob or 2 as most of you will know so was hoping to fix rather than replace with new.

Is this a common problem ???

If a disc is warped can it be skimmed to correct ???

If so does anybody know a place that will do the job & how much ???

Any info will be appreciated.

[euan_r]

i would think after 4 years discs have served their life span. then again its dependant on mileage and use. done much mileage? if in doubt measure the thickness of discs. if they were grooved discs are the grooves still visible?

[Baz man]

i would think after 4 years discs have served their life span. then again its dependant on mileage and use. done much mileage? if in doubt measure the thickness of discs. if they were grooved discs are the grooves still visible?

The discs still look as good as they did.

All grooves are fine and visible

Only done about 4000 miles per year.

Normal use on brakes. And i mean normal everyday driving use. Not going from 80 mph into emergency stops. Not that there is anything up with that

[euan_r]

if grooves are still there, the discs will still be over minimum thickness spec.

i had a slight vibration with my front brakes last year. a clean and regrease of caliper bores did the trick. i would have expected uneven worn pads though if it was the same in your case.

perhaps your getting pad deposists on discs, with no using brakes the same in icy conditions.

[thewelsho]

Normal use on brakes. And i mean normal everyday driving use. Not going from 80 mph into emergency stops. Not that there is anything up with that

I'm wondering why you splashed all that dosh for big brakes to use them normally.

Hope you get them sorted.

[Baz man]

I'm wondering why you splashed all that dosh for big brakes to use them normally.

Hope you get them sorted.

Some things you gotta have mate.

Boys and there toys. You know what its like

Simple as that

[stuarted]

Are they 2 piece discs i.e. bell and rotor?

If so, I thought the point in having a 2 piece unit was to eliminate warping?

[Baz man]

Are they 2 piece discs i.e. bell and rotor?

If so, I thought the point in having a 2 piece unit was to eliminate warping?

Yes mate

[des_curran]

Hi m8,

Warped discs are more pronounced through the steering than the pedal, a pulsing through the pedal when braking sounds more like ABS, did it suddenly start doing it or did it get worse over time ?

I have AP 6 pots on my current car and had them on my last subaru with no problems, and im very hard on the brakes.

You said you had the caliper off and everything seemed ok, are the pads worn even ? are all the hex bolts securing the bell to the rotor tight ?

How much wear is on the discs do they have a lip ?

Does the pedal travel get any longer if you make some hard left and right turns (ie: throwing the car about) ?

Is there any vibration under normal driving or only when braking ?

Des

[Baz man]

Hi m8,

Warped discs are more pronounced through the steering than the pedal, a pulsing through the pedal when braking sounds more like ABS, did it suddenly start doing it or did it get worse over time ?

I have AP 6 pots on my current car and had them on my last subaru with no problems, and im very hard on the brakes.

You said you had the caliper off and everything seemed ok, are the pads worn even ? are all the hex bolts securing the bell to the rotor tight ?

How much wear is on the discs do they have a lip ?

Does the pedal travel get any longer if you make some hard left and right turns (ie: throwing the car about) ?

Is there any vibration under normal driving or only when braking ?

Des

I first felt it on the pedal about 3 months ago. Just a pulse feeling as you say. Wasnt that bad but knew it wasnt right so got it into the garage a few weeks after.

Thought at the time the pads where gone and was going to replace with the same ferodo ones. The guy at the garage gave me a shout to have a look at the pads as there was plenty still on them and didnt need replaced. He sayed there might have been something caught in the pad and that a clean up might be all it was needing as there was no obvious sings of any other problem.

Ye mate the pads looked fine and the bells where fine.

Over the last two months the pulse feeling has got worse and i am getting a bit concerned with the weather conditions.

There was a small lip on the disc so the guy at the garage took it off just to rule it out. Didnt make any difference.

The discs still have plenty on them and all the grooves are there.

Took it back to the garage a short time after and the guy sayed all he could think of was a warped disc.

Will need to get back to you about the breaking when hard turning as i have never really noticed.

No other feeling apart from when breaking.

Was just not wanting to go out and spend crazy money again on pads or discs that doesnt solve my problem.

[des_curran]

As you say new pads and rotors aint cheap so you want to know for sure it is warped discs before splashing out on them

To check for warped discs you need to get a garage to check them with a run out gauge, they will remove each wheel and secure your disc to the hub with the wheel nuts and some washers, then they will fit a magnetic arm/clamp to your strut with a dial indicator gauge on the end and preload the gauge slightly against the disc, then they will turn the disc and any disc warpage will show on the dial indicator.

The other way to check for warpage but not advised on a 4 x 4 like a subaru is to get a garage with a roller brake tester (any mot test station will have one) to start both rbt rollers and press the brake pedal down but not enough to lock the wheels then hold the pressure on the pedal very steady and if one or both rbt gauges are fluctuating then you know that disc is warped, but again roller brake testers are not advised for constant 4 wheel drive vehicles as it can wind up the diffs.

The reason i ask about hard left and right turns is to rule out any play in the wheel bearing causing pad knock off, which is normaly noticed as a long brake pedal travel the first time you press the brakes after hard turns.

Edited December 4, 2008 by Des

[Baz man]

As you say new pads and rotors aint cheap so you want to know for sure it is warped discs before splashing out on them

To check for warped discs you need to get a garage to check them with a run out gauge, they will remove each wheel and secure your disc to the hub with the wheel nuts and some washers, then they will fit a magnetic arm/clamp to your strut with a dial indicator gauge on the end and preload the gauge slightly against the disc, then they will turn the disc and any disc warpage will show on the dial indicator.

The other way to check for warpage but not advised on a 4 x 4 like a subaru is to get a garage with a roller brake tester (any mot test station will have one) to start both rbt rollers and press the brake pedal down but not enough to lock the wheels then hold the pressure on the pedal very steady and if one or both rbt gauges are fluctuating then you know that disc is warped, but again roller brake testers are not advised for constant 4 wheel drive vehicles as it can wind up the diffs.

The reason i ask about hard left and right turns is to rule out any play in the wheel bearing causing pad knock off, which is normaly noticed as a long brake pedal travel the first time you press the brakes after hard turns.

Thanks for your help and info Des.

Think i will take your advise and get it into a place that can use a machine to check if they are warped.

Will get the wheel bearings checked first as this will be easier to rule out.

Thanks again