R100S Front brake caliper identification

[SGTBILL]

Hello all. I have a 1978 R100S. It is one of the bikes built for the European market(build month 06/1978 according to RealOEM) but then allegedly shipped to the US when the Euro economy tanked and Austria couldn't sell them. A previous owner has "upgraded" the front brakes to use the later Brembo brakes. This apparently was done by switching the fork lowers to the ones needed for the Brembo calipers. I want to install new brake pads and while I'm at it clean and freshen up the calipers. I see several kits offered at EME and other places. Since I don't have documentation from this upgrade to know what model/year lowers/calipers were used I'm looking for a way to determine which ones I have. Any guidance would be helpful.

 

[88bmwjeff]

I'm no real expert here, but here it goes. Most of the seals are sized depending on the caliper piston size, so the best way to be sure is to measure one of the pistons. If you're going to disassemble them anyway, you might as well separate them, inspect what you have, measure the piston, then order the parts needed. EME is great. Call them once you have measured the pistons and they will point you in the right direction. Also, they have great customer service including their return policy.

Edit: removed comment about the brake pins. See Post #5

 

[stevenrankin]

The Brembo forks, brakes and such used for your conversion are limited to Brembo style forks and brake calipers found only on twin shock RT, RS or S bikes. So about 81 to 84 years. After 85, the front forks changed radically along with the Brembo brake calipers.
So if you check the fitment chart on EME or the BMW microfiche, you would want the Brembo repair kit to fit the 81 to 84 year bikes.

Good luck, St.

 

[SGTBILL]

Thank you both for your quick replies. That should narrow it down for me.

 

[88bmwjeff]

BTW, if you haven’t done this before, you might want to check out Brook Reams’s website. He goes through rebuilding the calipers. https://brook.reams.me/bmw-motorcyc...semble-inspect-rebuild-brembo-brake-calipers/

After taking a look at Brook’s website and with what Steve said, I’m going to update what I said about the brake pins from EME. I have a 1988 R100 RT, which has an updated fork set up. The brake pins that EME sells are not correct for my bike, but looking at Brook’s website, it appears that the pins EME sells might be correct for the 81-84 vintage Brembo’s. I would look at your pins and see if they are compatible. See the photo below for the difference (click on the photo to see my comments that are not showing). Note the shoulder difference between the top and the bottom pins. Motobins sells the correct pins for the bottom one in the photo. https://www.motobins.co.uk/

 

[stevenrankin]

I mis ordered Brembo brake pins from EME myself. There are different variations one for the 84 to 81 bikes and one for the 85 and newer bikes. The wrong pins for my application were the longer pins found on the 85 and newer bikes. I see now in the EME website there is a note to measure the small center roll pin for length to help identify what you need.

SO, double check with the fitment chart or, call the gang at EME to verify what you have to replace.

By the way, my current restoration project is a 79 RT. I am removing the fairing to make a naked bike as well as switching the brakes from ATE to Brembo.
All has been going smoothly until I found a vendor on Ebay sold me two right calipers instead of a r and l pair. Any one need a rebuilt right caliper? LOL, St.

 

[SGTBILL]

I was working on the calipers today and discovered I have a mis-matched set of pins. 3 X 65mm pins and 1 X 60mm pin. EME doesn't list the length of the pins in their kit. Max's fiche I only find 60mm pins. The difference is at the top of the pin. From the ring down the pins are the same. I guess I'll call EME and ask