Front caliper guide pins
 

I'm rebuilding my front brake calipers, and I noticed the two caliper guide pins are different lengths.

Upper pin: 34111157041 (shorter)
Lower pin: 34116757036 (longer)


When I go to most vendor web sites to try to buy these pins, the sites only list one pin. I've checked Pelican, ECS, AutohausAZ, and BavAuto, and they all only list one the upper pin, but not the lower pin. Pelican and Turner Motorsports say that they can special order the lower pin. ECS used to carry the lower pin, but no longer do.

Does anybody know why it is so hard for me to find the lower pin? I might have to go to the dealership and pay $25 per pin, while I can order the upper pin for <$10 at Autohaus. Has the lower, longer pin been replaced by the shorter pin?

The reason why is because they do not go bad. The only reason to replace them if the thread is bad which almost never happens. The retail shops do not stock them because it would just sit in the warehouse and potentially they would loose money. The pin just needs to be greased. If they are not stripped or bent I would not try to find it. Just my opinion. You have your reasons

You only need two of them for the whole car. I'd just get them from the local dealer. When I did my wife's X5 I replaced the guide pins. The old pins were fine when I got them out and I could have just reused them. Have you cleaned them up to see how they look? Are you also changing the rubber boots?

There are manufacturers that say grease the pins and those that say don't grease the pins. I've done both. BMW says don't grease the pins. It does look like your rubber boots have suffered or the cap came off or something to have the pin that dirty. The main thing is how shiny and smooth it is after you clean it off.

What's wrong with the old pins?

The old pins were dirty. After I cleaned them up, they have a few marks, but nothing too bad. I could reuse them, but I figured that since I have them off (and if they are only $8 each), I don't mind replacing them.

I wasn't planning on replacing the boots that surround the pins, but I may end up doing it.

Clean them, lube them and re-use them.

Permatex 24125 Ceramic Extreme Brake Parts Lubricant is good stuff to use for this purpose.

if the old pins are pitted after cleaning, I'd replace them. if they have marks and you can buff the marks out, just reuse them. I'd replace the rubber.

BTW, according to the Realoem diagram the readily available 34111157041 pin is the top pin.

I'm guessing on average, the boot is going to fail before the pin does and if the pin fails, it's because of the boot failing first. You're probably better off replacing the boot than the pin.