Audi s4 1999 brake problems

Fit like everyone... am new to this but have been a great admirer for months now just browsing through the forum... Looking for tips and ideas...

I have a braking problem on my early april 1999 s4... It doesnt happen all of the time.
When you apply the brake you feel a put, put put through the pedal. Its like a dimple on the disc or something. I have replaced the discs and pads on all corners, the front cv joints and the cv boots but it still does it. The discs and pads were after market parts but all other parst are genuine, but it did this when the original parts were on the car, so i dont think its the after market parts thats the problem.

I am taking off the front dics tomorrow and cleaning the calipers and re-applying some copper slip to the pads... but i think its the calipers thats causing this but any info on the subject will be greatly appreciated...

Many thanks... Andy

Hi ogg,
I have a similar problem with my A4, it does'nt happen all the time and its seems to happen under soft braking, my problem is the abs keeps activating and making the brake pedal go on and off quickly when coming to a stop but under hard braking it never seems to happen.
I think it must be a faulty abs sensor on one of the wheels ? i would be grateful if anyone had any ideas on how to resolve this fault too.

you need to get it checked with vag com or another code reader to find out which wheel is causing the problem, once you know you can check the position of the sensor and give it a clean to start. if that doesn't work then it needs replacing....

Thanks for your reply bigengines... I had thoughts of it being one of the abs sensors but it doesnt feel like its that. I am having a look tomorrow to see if i can see anything... By the way i fitted a new air mass sensor while it was on the rolling road on friday morning and its transformed the car. I am so delighted with the results. It will be going back on to the rolling road next tuesday to finish the tests. Hopefully it will show around the 320bhp

Andy

I have been down to the local garage yesterday to have the Vag-Com diagnostics done. It came up with no fault codes... None... so it looks like i will just have to live with it for now because i think it will need some investigating at Audi.. and the prices they charge arent cheap.

Thanks to every one who helped me... If i do find out what the problem was i will post it on here for future reference...

Andy

Well, wouldnt you know it... I removed the rear passenger wheel hub today to change over the wheel bearing only to find that the ABS ring was cracked... I thought it didnt feel like the abs was at fault but we all can get it wrong sometimes.. just very chuffed that it was that one and no another one as its very time consuming...

I have ordered one this morning and it will be here on Monday... I know what am doing on Monday nicht noo... 2 birds - 1 stone!!