What’s causing this one...

 

A garage fitted rear discs and pads to my VRS about 2 weeks ago as it failed it’s MOT and they said they needed done. 
 

Since then when I move from P (Parked) to D (Drive) on my DSG and then let the car start to move - if I then hit the brake pedal I get a clunk coming from the rear of the car from the brake area. 
 

When I stop completely and go from D to R (reverse) when going into a parking space and touch the brake pedal I also get the clunk.

 

When driving normal as in when in D and just going forward there is no noise when braking. Only when moving from D > R and back to D. 
 

Checked the Caliper and all seems tight. I don’t want to back to the garage who fitted them as they damaged my alloy and damaged my locking wheel nut key and had to argue with them to get it sorted and I don’t have faith in them. I’m thinking of naming and shaming but would never use them again. 
 

Would appreciate ideas....

 

They are drivetec branded discs and pads (I know they aren’t the best but I’m thinking of changing car next year so they will do until the next MOT)

Some pads aren’t quite to the same tolerance as the oem ones so can move slightly in the carrier. 

I was moving the car while someone was watching the calliper and I'm sure the rear side pad moves slightly. Is it anything to be worried about or should I just get use to the noise? 

You can get a suitable grease for the back of the pad that usually deals with this. It used to be copper grease but more modern alternatives are nicer to the rubbers etc.

11 hours ago, StuFan said:

I was moving the car while someone was watching the calliper and I'm sure the rear side pad moves slightly. Is it anything to be worried about or should I just get use to the noise? 

 

Ceratec is what I use, but that is generally for squeal not clunking. There is a bit of play in the system but even the cheapest pads should fit correctly.

 

To replace the disks they would have had to take the carrier off. Carrier and caliper bolts are stretch bolts and should be replaced each use. They have a specific torque and angle sequence for tightening. Did the garage do this?

 

It would not be the first time someone has put the bolts in finger tight and not torqued them up. That would probably be the first thing to look at.

No idea if they torqued the caliper to be honest. Do you have the torque settings to hand? I did check the bolts and they did seem tight but I didn’t check the torque. 
 

thanks for the reply. 

5 hours ago, StuFan said:

No idea if they torqued the caliper to be honest. Do you have the torque settings to hand? I did check the bolts and they did seem tight but I didn’t check the torque. 
 

thanks for the reply. 

 

The problem is the carrier to bearing housing bolts are stretch bolts with a torque setting and then an angle. You cannot check them like a standard bolt.

 

They are 90nm then 90 degrees (quite difficult to do with everything around them)

 

They should be replaced as they have already stretched. I am not advocating it but sometimes you can get a second use out of them but it has to be done by feel.

 

If they have re-used the old bolts and torqued them to 90nm (or what felt tight) then I would say that is your problem

 

If they have re-used the caliper to carrier bolts they should at least be cleaned and re thread-locked they are not stretch and 35nm

 

 

 

Thanks for taking the time to explain this to me. I’ve got it booked into a reputable VAG specialist in Glasgow that I’ve used before so will let him have a look and advise the bolts you are talking about. 

No problem 

 

Let us know what he finds

Sometimes if the pads are noisy and also if they squeal, you can get shims fitted that stop the pad movement.

Hi, it’s def a metal clunk when the brake pedal is pressed. Sometimes it’s louder than other times. Will report back with findings. 

Does it happen when you brake going forward for the first time after you have braked going backwards?

Especially if you backed in to a parking space,  braked, and then parked up for a while?

And vice versa?

 

This can be the brake pads moving in the calipers.

The original pads can have a self adhesive backing on them that helps to stop this.

The new set of pads might not have this adhesive but have been greased up.

 

Thanks, AG Falco

I've just encountered this issue after having new discs and pads fitted.  Took it back to the garage and the inner pads are moving about .5mm causing the clunk.  Waiting on a different brand of pads to be fitted next week.

On 07/10/2020 at 20:36, Guest said:

Thanks for taking the time to explain this to me. I’ve got it booked into a reputable VAG specialist in Glasgow that I’ve used before so will let him have a look and advise the bolts you are talking about. 

Who is the VAG specialist? I need a Glasgow based VAG specialist to look at my car. 

21 hours ago, tawke said:

I've just encountered this issue after having new discs and pads fitted.  Took it back to the garage and the inner pads are moving about .5mm causing the clunk.  Waiting on a different brand of pads to be fitted next week.

I've seen that a lot of 'budget' branded brakes and discs aren't as good as tolerance as the OEMs - and therefore the pads clonk as they move around in the carrier.  Probably best sticking with new OEM pads and discs....