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Posted by: Halfnelson Apr 23 2024, 05:03 AM

Hi, maybe a stupid question but I have a set of rebuilt calipers from PMB and they look excellent. Before I do the rebuild, do I need to include the clips from the old calipers. I guess not for the clip that attaches to the face of the piston as recon piston had a hard rubber seal and I can't see how they would fit but do the brake pads need the square backing clips? The pads are Porterfield R4-s.
Thanks.

Posted by: Geezer914 Apr 23 2024, 05:13 AM

You need the triangle shaped clips to orient the brake caliper pistons.

Posted by: Halfnelson Apr 23 2024, 06:10 AM

How do the triangular clips fit the new piston face? I can see how the work with the old pistons as they clip into place.

Posted by: PatMc Apr 23 2024, 11:50 AM

The triangle clips go on the front calipers. The caliper in your picture is a rear caliper...

No clips on the rear, since the piston can rotate a bit with parking brake mechanism...

The front pistons need to be oriented (or should be oriented) a certain way to concentrate the pressure on the trailing end of the pad in an effort to reduce pad chatter and noise.

Ironically, the angle on these clips is not exactly the 20° that Ate calls out in their literature, but it doesn't really matter, as long as they're close and all 4 pistons mirror each other's position. The clip doesn't need to be there once the position is set.

In order to reduce leading edge bite and control noise on the rear pads, Ate originally ground the pads on a slight angle....one end was about .5mm thicker than the other...which is why you see the 2 different sized pins, and the 2 different sized holes in the pads.

The rear pads available today are the standard D30 pad shape and have 2 of the same sized holes....and are not ground on a taper. Noise is typically not a concern with modern friction materials, but you still have to drill out one hole in each pad or buy a set of PMB's new hardware kit that has skinny pins for all 4 positions.

Posted by: Halfnelson Apr 24 2024, 04:51 AM

[/quote]

The triangle clips go on the front calipers. The caliper in your picture is a rear caliper...

No clips on the rear, since the piston can rotate a bit with parking brake mechanism...

The front pistons need to be oriented (or should be oriented) a certain way to concentrate the pressure on the trailing end of the pad in an effort to reduce pad chatter and noise.

Ironically, the angle on these clips is not exactly the 20° that Ate calls out in their literature, but it doesn't really matter, as long as they're close and all 4 pistons mirror each other's position. The clip doesn't need to be there once the position is set.

In order to reduce leading edge bite and control noise on the rear pads, Ate originally ground the pads on a slight angle....one end was about .5mm thicker than the other...which is why you see the 2 different sized pins, and the 2 different sized holes in the pads.

The rear pads available today are the standard D30 pad shape and have 2 of the same sized holes....and are not ground on a taper. Noise is typically not a concern with modern friction materials, but you still have to drill out one hole in each pad or buy a set of PMB's new hardware kit that has skinny pins for all 4 positions.
[/quote]

OK, thanks. I messaged PMB and they explained the clips were there to ensure they are clocked properly but that they do this during the rebuild so the clips aren't needed.

Thanks for explaining why though. All makes sense.

Cheers

Chris