Joined: Jul 2010
Location: Gatineau, Quebec
Well, its taken research. but I think I understand how the caliper pins are supposed to work.
Basically, there is a leading side pin and a trailing side pin. The lead pin will absorb more heat and needs to dissipate it. The trailing side pin has the rubber bushing on it to absorb vibration and chatter and won't get as hot.
Now here is where it gets fun. The lead pin will be the one that the rotor rotates into rather than the end pad from which the rotor rotates away from. If you picture a dot on the left rear rotor and imagine it going counterclockwise, where that dot first touches the brake pad is the lead edge, and the other end of the pad it emerges from is the trailing side.
What this means is, depending upon where the caliper assembly is placed on the rotor, the lead and trailing edges will change.
On the X trail, the rear left caliper is positioned to contact the left side of the rotor, or you could say it's on the right when facing it.
This means when the car is driving forward the left rear wheel is turning counterclockwise. Consequently, the leading edge of the pad would be the bottom, and the trailing end the top.
Conversely, the front left caliper is positioned on the left when facing it. So for it when the wheel is turning counter clockwise the lead edge will be the top end of the pad and the trailing edge will be the bottom.
You can do the same exercise for the right-hand side. You just need to remember on that side the wheel would be turning in a clockwise direction.
What this means in practice is that for the rear of the X trail the lead pin should be on the bottom and the trailing pin with the rubber in the upper position. For the front, it would be the opposite and the lead pin would go on top and the trailing pin with the rubber bushing on the bottom.
So I concluded AC Delco had it right, and I figured I must have flipped them at some point on the left side. However, what is weird is that the Nissan parts diagram has the rubber tipped one as going on the bottom. Furthermore, a quick scan of rear brake videos one for the X trail and 3 for the Rogue which uses the same rear caliper, showed all 4 having the rubber tipped caliper pin going in the bottom position which should be the lead side.
That had me curious so I looked at an Altima video where the rear caliper was on the left or inside, and it had the pin with the rubber boot on the bottom which would be the trailing side and correct as per my theory above. And when I look at the pins for the front calipers on the X trail which are also to the left, the lead pin is the solid one and goes on top and the trailing pin with the rubber goes on the bottom.
So, sorry for the long post, but I cannot figure out why the parts diagram shows the pin with the rubber tip going on the bottom for the X trail, when due to the orientation of the caliper that is the lead end. Could Nissan engineers have gotten this wrong, or does it really make no difference in practice which pin is up or down?
I will put out there that it seems a lot of X trails and Rogues for that matter have had rear brake issues. Could the rubber tipped caliper pins in the lead pins which supposedly experience more heat be causing part of the issues?
Should I just leave mine alone, or change them as per Nissan spec or change them as I think they should go?