Calliper sliding pins

[underwhelmist]

I want to replace the brake calliper sliding pins on my Honda CRV. The replacements have two different types of pin as shown in the pic - one is straight, the other has a notch for a soft plastic collar to fit in.

Does the one with the collar go on the top or the bottom? As far as I remember the old pins are both straight. Thanks in advance!

[Chris32345]

The one with the rubber bit on often goes on the bottom from what I've seen but never worked on that manufacturer

[E-bmw]

Just put them in the same way as you remove the old ones.

[TwinKam]

OP has said that his OE slides are both the same, ie neither have the dampener.
Tbh, I have never been 100% sure whether the dampener is there to stop rattle, or to crrate a bit if 'stiction' to cause a delay at that end of the caliper ie so that the leading or trailing edge of the pad kisses the disc first, presumably to avoid grab, judder or squeal or whatever. This is why I fastidiously replace them from whence they came. But I would love to have a definitive answer. Next brakes of this type I see I will make notes.
In response to the earlier reply, 'top' or 'bottom' is irrelevant as a caliper may be mounted ahead or behind the axle-line, meaning that the leading edge of the pad can be at the bottom or top accordingly.
I would suggest that the OP has been supplied with the 'wrong' parts here, and should seek ones identical to those he has removed.

[E-bmw]

TwinKam said:

OP has said that his OE slides are both the same, ie neither have the dampener.
Tbh, I have never been 100% sure whether the dampener is there to stop rattle, or to crrate a bit if 'stiction' to cause a delay at that end of the caliper ie so that the leading or trailing edge of the pad kisses the disc first, presumably to avoid grab, judder or squeal or whatever. This is why I fastidiously replace them from whence they came. But I would love to have a definitive answer. Next brakes of this type I see I will make notes.
In response to the earlier reply, 'top' or 'bottom' is irrelevant as a caliper may be mounted ahead or behind the axle-line, meaning that the leading edge of the pad can be at the bottom or top accordingly.
I would suggest that the OP has been supplied with the 'wrong' parts here, and should seek ones identical to those he has removed.

OP said "as far as I can remember" not "they are the same" so perhaps the start of the answer is still to check what is actually fitted where before going any further.

[tux850]

TwinKam said:

OP has said that his OE slides are both the same, ie neither have the dampener.
Tbh, I have never been 100% sure whether the dampener is there to stop rattle, or to crrate a bit if 'stiction' to cause a delay at that end of the caliper ie so that the leading or trailing edge of the pad kisses the disc first, presumably to avoid grab, judder or squeal or whatever. This is why I fastidiously replace them from whence they came. But I would love to have a definitive answer.

I remember reading the patent that covers these - or their first instantiation at least - and I seem to recall it only covered 1) dampening of rattle, and 2) aiding retraction through restoration of the square-edge deformation (similar to piston seals). I don't remember it claiming anything to do with it aiding how the friction surfaces are brought together, and whilst I can't authoritatively it couldn't be exploited in that way I personally can't see it having any meaningful effect given how insignificant it would be compared to the force and positioning of the piston on the back of the pad.

[TwinKam]

tux850 said:

TwinKam said:

OP has said that his OE slides are both the same, ie neither have the dampener.
Tbh, I have never been 100% sure whether the dampener is there to stop rattle, or to crrate a bit if 'stiction' to cause a delay at that end of the caliper ie so that the leading or trailing edge of the pad kisses the disc first, presumably to avoid grab, judder or squeal or whatever. This is why I fastidiously replace them from whence they came. But I would love to have a definitive answer.

I remember reading the patent that covers these - or their first instantiation at least - and I seem to recall it only covered 1) dampening of rattle, and 2) aiding retraction through restoration of the square-edge deformation (similar to piston seals). I don't remember it claiming anything to do with it aiding how the friction surfaces are brought together, and whilst I can't authoritatively it couldn't be exploited in that way I personally can't see it having any meaningful effect given how insignificant it would be compared to the force and positioning of the piston on the back of the pad.

Thanks for that, yes, makes sense. But which leaves the question, why on only one pin? And does it then matter which pin? ...
I sometimes see cut-outs in piston-side shims that would achieve the latter shall we say bias of presentation; all very well and good in theory, quite another when 20,000 miles worth of salty rust and cooked brake dust on the pad slides means that they only move in one direction now!

[tux850]

TwinKam said:

Thanks for that, yes, makes sense. But which leaves the question, why on only one pin?

Good question! Cost maybe?

TwinKam said:

And does it then matter which pin?

Yeah, dunno.

For what it's worth the service manual a 96-99 Hyundai Coupe shows it on the leading edge (bottom with them sitting forward of the axle):



Great! But then the 00-09 model service manual happens to show it on the trailing edge:



So I can only assume it doesn't actually matter (and also that one is sufficient).

TwinKam said:

I sometimes see cut-outs in piston-side shims that would achieve the latter shall we say bias of presentation; all very well and good in theory, quite another when 20,000 miles worth of salty rust and cooked brake dust on the pad slides means that they only move in one direction now!

Yeah quite. Perhaps this reality doesn't matter too much if you're in the business of making these things - if they can charge an extra 10p (or whatever) per pin for something that might just sound valid on paper then over millions of units it presents a nice little earner and one worthy of patenting.

[underwhelmist]

E-bmw said:

OP said "as far as I can remember" not "they are the same" so perhaps the start of the answer is still to check what is actually fitted where before going any further.

Fair point, it’s been a while since I checked them.

I contacted the manufacturer, they said the pin with the collar usually goes in the bottom position - the callipers are behind the wheel, not sure if that’s significant.

Interesting to read about the possible reasons for the collar, thanks for the responses all.