Golf MK8 brake issue

[keeno88]

Hi all just joined up to see if owners alike are experiencing any similar issues or have any suggestions.

A few months ago I bought a 2021 VW Golf R-Line Estate. I love it apart from one issue which is brake squeal from the front brakes. This always happens after driving for about 5 minutes and only when light braking. Its very annoying!

The noise occurred on the original VW standard disc and pad set which were only 50% worn (car has only done 23K).

I have changed the discs, pads and the 8 metal calliper shims for genuine VW parts. I have also cleaned/ wire brushed/ re-greased the brake calliper and slide pins but the squealing noise still happens (new pads have been bedded in and discs are not glazed)

In additional to this my brake pedal seems to 'clunk' twice when coming off the brakes. It feels like the master cylinder/ booster attached to the pedal isn't returning as quick as the pedal itself. There's also a slight grinding noise when driving.

Anyone have any suggestion on what it could be? ...... calliper sticking?.

 

 

[Volkswagen Owners Club]

Generally, I tend to encounter such issues and squealing or grinding brakes and can attribute it to poorly fitted pads, incorrect or missing shims and more importantly, lack of compound between the pads and caliper carrier bracket.
By not applying a compound such as copperslip (which is not so necessary on stainless shims) you would have a corrosion factor with dissimilar metals.

You have done everything exactly as it should be done (and believe me, most of the issues I have encountered with dragging and squealing brakes are when those who fit the brakes do not do this).
Also, a lot of pads (if supplied from a dubious source of origin) may sometimes be slightly larger due to excess paint on the pads, which sometimes needs scraping back to fit correctly and this leads to the pads 'grabbing' and not retracting once applied.

Outside of the pads and calipers, issues such as a faulty brake servo, ABS and other related hydraulic issues it may be worth checking all wheels spin freely when jacked up and see if you can isolate the faulty component.
Also, check the brake hoses are okay and not damaged in any way

Let us know how you get on with it

[keeno88]

6 hours ago, Volkswagen Owners Club said:

Generally, I tend to encounter such issues and squealing or grinding brakes and can attribute it to poorly fitted pads, incorrect or missing shims and more importantly, lack of compound between the pads and caliper carrier bracket.
By not applying a compound such as copperslip (which is not so necessary on stainless shims) you would have a corrosion factor with dissimilar metals.

You have done everything exactly as it should be done (and believe me, most of the issues I have encountered with dragging and squealing brakes are when those who fit the brakes do not do this).
Also, a lot of pads (if supplied from a dubious source of origin) may sometimes be slightly larger due to excess paint on the pads, which sometimes needs scraping back to fit correctly and this leads to the pads 'grabbing' and not retracting once applied.

Outside of the pads and calipers, issues such as a faulty brake servo, ABS and other related hydraulic issues it may be worth checking all wheels spin freely when jacked up and see if you can isolate the faulty component.
Also, check the brake hoses are okay and not damaged in any way

Let us know how you get on with it

6 hours ago, Volkswagen Owners Club said:

 

 

Thanks for the info.

I didnt mention it but I first replaced with Bosch discs and pads and the noise still happened. VW garage basically put it down to non approved parts so I took a gamble and fitted genuine parts only to find still issue.

Just seen a video regarding testing the brake booster. Whilst car is off you pump the brake until it goes hard, then start the car with foot on the brake pedal. If the booster is working the pedal should gently sink further down. Testing this on my wife’s Polo this happens as stated, however, on my golf the pedal doesn’t go hard when pumping the brake (when off) nor does it move when staring the car. Wondering if this points toward a booster issue.

At first, when the car was up on the jack and I had just put on new discs and pads the wheels spun freely. However after a quick test drive and jacking up after the wheels didn’t spin as freely and it sounded like the pads were catch slightly. 
 

Taking it to a local garage tomorrow whom I’ve used many times before. Hopefully they can have a look and give their thoughts.

[Volkswagen Owners Club]

Well thats certainly an odd one!
I do wonder if the brake servo is a new generation of electronic braking assistance and these tests wouldn't necessarily apply. Another possible cause could be a brake hose collapsing internally, although very rare but does give similar issues.

It is okay for the pads to catch assuming the brakes work fine until everything beds in nicely (circa 100 miles to be on the safe side)

As long as the braking efficiency is there then it should be fine to drive.
A quick test to see if any of the brakes are dragging is to get a digital infared temperature gun and measure each disc after a good run of hard braking, etc.
Another way to accurately determine the efficiency of the brakes and if any of them are binding is to put it on an MOT Brake Test rollers and see if the needle or digital reading picks up any drag or deficiency on any of the wheels

Let us know how you get on with the garage