Brake Pulsing

[Rockape]

I've got a mazda 2. It had new discs and pads last year say 8k ago.

Last few weeks I noticed that there was a slight pulse coming through the pedal. Noticeable at slow speed just as I was coming to a stop when brake like the brakes were grabbing on and off.

I have stripped the brakes down, cleaned everything off, slider pins cleaned and greased, calipers wound back in freely, discs appeared to be wearing evenly across front and back and the pads had plenty meat left on them.

I've still got the pulsing through the pedal. Im thinking the discs are warped slightly hence the sensation.

Any thoughts or pointers?

[Higgs boson]

'certainly sounds plausible.

[stevieturbo]

That sensation is a strange one ( but one I've experienced many times ), but in this instance I do not believe it is warping.
What the actual cause is I'm not so sure, but in pretty much all cases I've either just lived with it, or replaced the discs.

Skimming would be an option if the discs are particularly expensive, but not something I've done.

There is one online article about material buildup on the discs causing what many might feel are warped discs, and at every opportunity every fool seems to latch onto it for all manner of brake problems. This might actually be one possibility for the cause...but I'd still think it a long shot.

[Rockape]

I should have mentioned that there is no judder at all through the steering wheel. Just that on off sensation.

[9xxNick]

Were the rear brakes replaced as well? Have they been checked over?

[Rockape]

9xxNick said:

Were the rear brakes replaced as well? Have they been checked over?

It's has drums on the rear. I've not stripped this done to have a look.

[archie456]

It sounds like it my be pad deposits on the discs.

Try a few hard stops from high speed, say 80-100, this quite often sorts it.

[Boosted LS1]

Discs, ball joints perhaps? Anything where there could be play.

[9xxNick]

I certainly wouldn't ignore the rears, especially as you say you can't detect any vibration through the steering.

[tapkaJohnD]

Maybe this is the online article referred to above:
https://centricparts.com/getmedia/aff05081-b7c5-40...

Or this, by Carroll Smith, who knew a thing or two:
https://www.brakes-shop.com/brakepedia/general/myt...

John

[mickyh7]

As already suggested.
3 or 4 very hard stops from 80-100
Or until you lose your brakes!
Do it at night on an empty road!
It will be build up on your discs.
Warped discs are pretty rare to be honest.
I struggled with my car for months, even new discs felt warped after a couple of months.
Auto stop on modern autos dont help by holding hot pads onto the discs.

[Rockape]

So I stripped it all down again. I clamped a screwdriver to an axle stand and held the end of the screwdriver onto the face of the disc. I turned the disc and found some fluctuation as the disc was turned. So looks like a warped disc. I did notice that there was a shadow print pretty much at the section which was catching so wonder if the pads have been held on here after some heavy braking. £47 for new discs and pads so will see how I get on.

[stevieturbo]

A dial gauge would be better...pulsing and warpage are different things though. Warping you probably should be feeling something through the pedal.

the pulse feeling in retardation is different. Either way, the parts seem very cheap, why not change them.

Unless part of the problem is cheap parts.

[Rockape]

stevieturbo said:

A dial gauge would be better...pulsing and warpage are different things though. Warping you probably should be feeling something through the pedal.

the pulse feeling in retardation is different. Either way, the parts seem very cheap, why not change them.

Unless part of the problem is cheap parts.

Stevie I can feeling the pulsing effect through the pedal too. Cheap enough to change over and hopefully that'll do.

[mickyh7]

If your discs are not flat to the hub you would get a similar outcome to your test.
It may be cheap to swop out the parts.
It may not cure the problem. As already mentioned.
Cheap parts!

[Rollin]

Can you see the back side of the front discs? Have you had the discs off to look?
Back surface of my rears were rusty and lumpy as fk despite looking pristine on outer surface.
This caused a similar pulsation. Car was parked for 3 weeks after a drive on salted roads which I believe was the cause. I read that the outer surface can dry quicker and rust less due to it not being hidden behind shield.
I wire wheeled the disc and it's fixed the problem

[Rockape]

Rollin said:

Can you see the back side of the front discs? Have you had the discs off to look?
Back surface of my rears were rusty and lumpy as fk despite looking pristine on outer surface.
This caused a similar pulsation. Car was parked for 3 weeks after a drive on salted roads which I believe was the cause. I read that the outer surface can dry quicker and rust less due to it not being hidden behind shield.
I wire wheeled the disc and it's fixed the problem

Yep had them off. The discs and pads looked fine. The cars in use daily doing 80-100 commute. I gave everything a right good clean and grease where required but found the n/s disc warped. Have got new discs and pads ready to go on.

[Rollin]

Rockape said:

Rollin said:

Can you see the back side of the front discs? Have you had the discs off to look?
Back surface of my rears were rusty and lumpy as fk despite looking pristine on outer surface.
This caused a similar pulsation. Car was parked for 3 weeks after a drive on salted roads which I believe was the cause. I read that the outer surface can dry quicker and rust less due to it not being hidden behind shield.
I wire wheeled the disc and it's fixed the problem

Yep had them off. The discs and pads looked fine. The cars in use daily doing 80-100 commute. I gave everything a right good clean and grease where required but found the n/s disc warped. Have got new discs and pads ready to go on.