Rattling alcons - Page 1 - 911/Carrera GT - PistonHeads UK

I had alcon front disks on JZM bells on my 996GT3CS but they tended to make quite a noise over bumps and dodgy road surfaces. I'm toying with the idea of putting them on my 997.1 GT3, but don't want the aural side effects - can anyone shed any light on this and how to stop the banging and crashing if I do put them on? Cheers

Get perspex side windows with sliders. You won't hear the Alcons over the sound of rattling windows. HTH

Upnorthgt3 said: I had alcon front disks on JZM bells on my 996GT3CS but they tended to make quite a noise over bumps and dodgy road surfaces. I'm toying with the idea of putting them on my 997.1 GT3, but don't want the aural side effects - can anyone shed any light on this and how to stop the banging and crashing if I do put them on? Cheers How old are the discs and bells on the 996 ? I ask as Alcon have revised the mounting system at least once, the later versions are silent. I'd suggest the 997 items will be as quiet as the standard items. If you need any further info, speak to Matt at Fearnsport for advice on the Alcon products.

I've got Alcons with RS29 pads from JZM on my 997 and they are perfect, no noise or rattles at all, unlike the two pice floating discs i had on my 996 turbo which sounded like a bucket of old nails on each wing.

You can fit spring loaded bobins Alcons have quite a large float. (Unless they have changed the design)

Cheers guys The disks are new, well less than 12 months old but I suspect the bells which were acquired along the way and not bought as a package might be older

Upnorthgt3 said: Cheers guys The disks are new, well less than 12 months old but I suspect the bells which were acquired along the way and not bought as a package might be older People keep bells too long best advice is new bell for 3rd disk imo. Which means only one disk change on the same bell.

Ps the noise stops as soon as the brake is applied

PorscheGT4 said: Upnorthgt3 said: Cheers guys The disks are new, well less than 12 months old but I suspect the bells which were acquired along the way and not bought as a package might be older People keep bells too long best advice is new bell for 3rd disk imo. Which means only one disk change on the same bell. Understood!! Many thanks

Upnorthgt3 said: Ps the noise stops as soon as the brake is applied It's the float or the wear, you can fit spring loaded bobbins to stop the disks moving on the bell.

PorscheGT4 said: Upnorthgt3 said: Ps the noise stops as soon as the brake is applied It's the float or the wear, you can fit spring loaded bobbins to stop the disks moving on the bell. I'll give it a go - there's nothing wrong with the brakes themselves - really good stopping power and no deviation under full braking

Upnorthgt3 said: Ps the noise stops as soon as the brake is applied More than likely just the pads rattling in the callipers. I've had this loads of times on my 996 GT3 with solid discs and now have it on my 997 GTS. Always seems worse with Pagid pads and almost certain to be because new anti squeal shims with the adhesive backs weren't used when the new discs and pads were fitted. Nothing to worry about.

jackwood said: More than likely just the pads rattling in the callipers. I've had this loads of times on my 996 GT3 with solid discs and now have it on my 997 GTS. Always seems worse with Pagid pads and almost certain to be because new anti squeal shims with the adhesive backs weren't used when the new discs and pads were fitted. Nothing to worry about. Just rather annoying - sounds like there's a dwarf under the bonnet rattling a bag of spanners

It can be fixed very easily. There are little top hats that push into each of the Pistons in the calliper. These have a sticky backing on them that stick the top hat to the back of the pad, holding the pad in place in te calliper. Remove the pad, remove the old top hat, peel off backing paper from new top hat, insert into each piston, replace pad, apply brake pressure and viola. No more pad rattle. The only issue is if you track the car heavily the glue melts and you are back to square one. In normal road use they should stay stuck to the pads and be rattle-free.

jackwood said: It can be fixed very easily. There are little top hats that push into each of the Pistons in the calliper. These have a sticky backing on them that stick the top hat to the back of the pad, holding the pad in place in te calliper. Remove the pad, remove the old top hat, peel off backing paper from new top hat, insert into each piston, replace pad, apply brake pressure and viola. No more pad rattle. The only issue is if you track the car heavily the glue melts and you are back to square one. In normal road use they should stay stuck to the pads and be rattle-free. Cheers jack

Upnorthgt3 said: jackwood said: It can be fixed very easily. There are little top hats that push into each of the Pistons in the calliper. These have a sticky backing on them that stick the top hat to the back of the pad, holding the pad in place in te calliper. Remove the pad, remove the old top hat, peel off backing paper from new top hat, insert into each piston, replace pad, apply brake pressure and viola. No more pad rattle. The only issue is if you track the car heavily the glue melts and you are back to square one. In normal road use they should stay stuck to the pads and be rattle-free. Cheers jack And they cost something ridiculous, and additionally they hadn't used to fit with RS29s until they were part worn.

jackwood said: It can be fixed very easily. There are little top hats that push into each of the Pistons in the calliper. These have a sticky backing on them that stick the top hat to the back of the pad, holding the pad in place in te calliper. Remove the pad, remove the old top hat, peel off backing paper from new top hat, insert into each piston, replace pad, apply brake pressure and viola. No more pad rattle. The only issue is if you track the car heavily the glue melts and you are back to square one. In normal road use they should stay stuck to the pads and be rattle-free. I had this on my lotus Elise with AP calipers. The pad rattle was so loud one instructor requested to come back to the pits :-) It happened when calipers would get hot and expand and funnily when cornering would stop as sticky tires made sure the moving parts where under check with centrifugal force helping. Or when braking. Never managed to solve it but the above might indeed have cured it temporarily...

Had AP's on my CSL and 1 M Coupe, they never rattled. Ever. I'd suggest someone left the anti rattle springs out of your calipers. The springs can be seen in this drawing (part 9) : http://www.apracing.com/drawings/p12136.pdf

Or they've become weak over time due to all the heat cycles. Had that more than once. Eventually they will make contact with the outer edge of the disc & get worn away completely but to a cursory glance they seem OK.

rosino said: I had this on my lotus Elise with AP calipers. The pad rattle was so loud one instructor requested to come back to the pits :-) It happened when calipers would get hot and expand and funnily when cornering would stop as sticky tires made sure the moving parts where under check with centrifugal force helping. Or when braking. Never managed to solve it but the above might indeed have cured it temporarily... That was a known easy fix of caliper pad buffers ! Sold from every lotus spare part site.