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This is a SEAT ibiza 6l and not polo 9n, even though they're basically the same, so I'm trying my luck in this forum, maybe someone has dealt with the same issue here.

The car makes an annoying rattling sound over bumps and bad asphalt since I bought it a year ago and I've finally found the problem, the front brake caliper is loose and doesn't contact the brake carrier like it should, I've confirmed the issues by applying the brakes when driving and the noise stops. This car has the FS III brakes.

I found that there was slight play in the caliper, enough to cause the brake pad and caliper to bang against the carrier with every jostle and bump. The caliper should only be moving in and out along the sliding pins, but since there is a soft bushing around the pins it kind of pivots slightly up and down allowing a tiny bit of movement between the caliper and carrier which makes a huge racket when driving. All parts are genuine VW parts as the car was serviced at a dealership when the brakes were changed last.​

https://imgur.com/a/L9ml4wy

My initial thoughts were worn out or loose pins and bushing, but upon closer inspection the pins where correctly torqued (28 Nm) and they were in immaculate condition with no rust or gouging on the surface, they also had a very tight fit (almost interference) inside the bushing with no play so I doubt that's the problem. The official SEAT (VW) repair manual makes no mention of any lubricant whatsoever, neither on the sliding pins or the sliding surfaces of the brake pads, only a thorough cleaning and rust removal. The brake pads also fit snugly on the caliper with no movement so springs seem to be intact.​

https://imgur.com/a/IW6pPdE

Are these calipers designed to wiggle around a little? Any suggestions to fix the noise?​

they are floating calipers and should move laterally. if not fitted correctly or excessive wear noise could result. possibly noise could be coming from pad assy? some brands fit better than others.

PS. I always use the correct lube/grease on slide pins and pads.

These are genuine VW pads and calipers so there shouldn't be a fitment issue, I wonder if perhaps the springs on the brake pads are kind of loose? I've looked in other forums and this seems to be a reoccurring problem, altough the noise seems to be coming from the caliper banging on the carrier not the pads moving inside calipers but I'll double check.

Looking at the last picture in your original post you can clearly see some wear on the caliper at the bottom where the caliper/pad sits against the carrier area , this could lead to movement/noise.
also the brake discs look to be worn and have a lip around the edge ,have you measured the discs for thickness to see if they are below minimum thickness.
My first action would be to strip and clean the brakes and apply some copper grease on the contact areas and try again .

littlepolo wrote: ↑Wed Jul 12, 2023 9:49 am they are floating calipers and should move laterally. if not fitted correctly or excessive wear noise could result. possibly noise could be coming from pad assy? some brands fit better than others.

PS. I always use the correct lube/grease on slide pins and pads.

I'm quite sure there isn't a fitment issue as the pads and caliper are genuine VW parts for this car. The pads (JZW698151) have springs that are supposed to hold them in place within the caliper, and they do fit in the caliper, the issue seems to be excessive movement of the caliper up and down.

CarbonChaos wrote: ↑Wed Jul 12, 2023 12:22 pm Looking at the last picture in your original post you can clearly see some wear on the caliper at the bottom where the caliper/pad sits against the carrier area , this could lead to movement/noise.
also the brake discs look to be worn and have a lip around the edge ,have you measured the discs for thickness to see if they are below minimum thickness.
My first action would be to strip and clean the brakes and apply some copper grease on the contact areas and try again .

I did take apart the brakes to see if the springs where missing or something like that but everything fits well, I've had the noise for almost a year at this point so I'm not surprised all the clattering has worn the caliper causing even more noise. I've cleaned the brake with brakes cleaner/wire brush and put it all together with a strip of duct tape on the sliding surface of the caliper, what has eliminated the noise but obviously it won't work for long. I've ordered some Liqui moly brake anti-squeal paste, hopefully it gets rid of the clatter.

I'm going to answer the thread in case it might help someone in the future, the problem was a tiny gap between the caliper and brake carrier which caused it to clank with every bump (quite loud).

After noticing that the inner(piston side) brake pads were slightly loose unlike the outer, I did try to adjust and bend the brake pad clips so that they could fit better in the caliper hoping that it might solve the issue, but even after many adjustments and a snug fit the issue simply wouldn't go away. The caliper piston doesn't have a very pronounced edge/lip on the inside so the pad clips can't really grab on to it very well, no matter the adjustments the inner pad wouldn't sit rock solid like the outer pad, but I managed to make it fit snugly so it wouldn't just fall out. The original brake calipers supplied with the vehicle are unfortunately on the cheaper side and seem to develop a tendency for noise and play with age, similar model brakes have anti-rattle springs which attach between the caliper and carrier to prevent this exact problem but these don't have it.

The solution was simply to grease the contact points with Liqui Moly Brake Anti Squeal Paste, now the issue is gone (almost). I still hear slight clanking when driving over potholes and VERY rough surfaces like uneven gravel roads but otherwise the issue is gone so I'm satisfied. The paste is supposed to be very adherent and resistant to water splashes and corrosion, so in theory it should last come winter but only time will tell.