Thumping noise when breaking ???

[solarstu13]

Hi Guys ,

I finally got the turbo problem sorted , after changing cat the turbo pipework the lot, it was the n75 valve that was faulty,

i have a new problem now, ( my wife thinks i have deep pockets ) back to the problem , when breaking i have a thumping noise coming from the front of the car, i have just put new discs and pads on and had a mechanic check the driveshafts for any wear, but couldnt see anything wrong, the noise is starting to get on my wick now, could someone please help ,

thanks stuart

audi a4 1.8t quattro sport

 

[Chriscooke]

Check the wheel nuts

 

[solarstu13]

Thanks chris,

checked the wheel nuts and all fine, noise still there, has anyone got any other ideas ?? abs rings are fine also , the noise is like the abs coming on at low speed, there is no warnings showing, ???????

 

[Dimokslis]

I'd try to check brake pads and calipers also engine and gearbox mounts. It is hard to say anything when have not heard the actual noise.

 

[Bradderz_1988]

What discs do you have fitted standard/drilled&grooved ??

 

[solarstu13]

Thanks guys,

I have checked the pads and discs they are all new, the discs are drilled and grooved, all engine and gearbox mounts are ok, when im driving at high speed then braking hard the noise is gone, its just at low speed this happens, hope this helps,

 

[Bradderz_1988]

Check the grooves of the discs are in the right rotation and also the chamfer of the pad is correct to the rotation other than that id say it was abs related is the noise the same at low speeds when clutched/declutched ??

 

[Bradderz_1988]

http://www.eclipseracing.co.uk/images/ebc/3gddiscdirection.jpg

then the chamfer of the pads should be facing the road due to the trailing caliper setup.

 

[solarstu13]

Hi thanks for the reply,

I have checked the discs and pad and all ok, the noise is only at low speed, and its coming through the brake pedal, is also louder when turning when braking , i really cant understand it ???

 

[Bradderz_1988]

CV joint ???

 

[solarstu13]

cv joints have just been done a couple of months ago, thanks for tryin bradderz

 

[Dimokslis]

Any of the control arm??

 

[NineNails]

and its coming through the brake pedal

Can you really feel it through the pedal? Is the pedal banging against your foot? If so, then that's the abs. At slow speeds the ecu can interpret a faulty sensor as wheel slip and kick in the abs. You will only get a abs warning if the sensor fails open or closed circuit if I remember right

 

[aragorn]

ABS activation feels more like a vibration though, the pedal just rapidly pulses, it doesnt "thump"?

You can get an ABS warning with an iffy sensor, but it depends how it fails. The signal gets stronger/clearer the faster the wheel turns, so a manky sensor/reluctor will often cause the signal to drop out as it appoaches 0mph. At higher speeds, the signal strength improves, and the system works normally. However if the sensor still continues providing incorrect data at speed, the warning light will come on and the ABS will be deactivated.

 

[solarstu13]

Thanks guys ,

you really have been a great help, i will change the abs sensors see if that helps, i will keep u all informed cheers again

stuart.

 

[Bradderz_1988]

When you remove the abs sensors spin the disc/hub and check each reluctor on the shafts for any cracks or corrosion build up !!

 

[solarstu13]

Thanks Bradderz,

i will do i will let you know the outcome cheers again buddy.

stuart

 

[Steve_D]

I know your pain!! i have the same problem.. its kind of a thumping noise too (hard to describe) and at low speeds only!

Mine is the Rear Drivers ABS Sensor vcds tells me, but i broke that myself heating the caliper carrier bolts up and still havent replaced it.

So if all the other things that could be have been replaced or are nearly new then it will definatly be this.

IIRC i read somewhere trapped air in the ABS Module can create a noise also... maybe try cycling it and bleeding the front brakes