Caliper differences between fork sizes

[MtnBoy]

Do the brake tabs on the rear of the fork sliders have different spacing for the two different forks? My forks mic at 34.993, but I am not sure whether they are 34's or 35's.
Thanks, Bob

 

[lukeS]

what year is the bike?

 

[MtnBoy]

Hard to say. Engine is '73, frame is later. Not sure about the forks. They mic at 34.993 and the caliper mounting tabs on the rear of the slider are 4.5in center to center. Ordering a Bembro kit and need to know if forks are 34s or 35s. Thanks, Bob

 

[arcticXS]

MtnBoy,
If you measure the fork tubes, and the micrometer or caliper says 34.993, then the surely are 35 mm forks. I believe the 34 mm forks had the caliper on the RH side, and in front of the fork slider. The 35 mm forks had the caliper(s) behind the sliders. In any case, no Brembo 4-piston caliper will bolt up tho the stock KYB/ Yamaha fork slider.
Just call or email whoever you are ordering from, and tell them the caliper lug C-C (spacing), distance from wheel axle center, and the brake disc diameter and offset.
If you plan on using a Brembo 4-piston caliper, the disc needs to have 22-23 mm offset in order to clear the spokes, when using a 320 mm OD disc. This means the disc only has approx. 2 mm clearance to the fork slider.
Good luck with your brake upgrade, that is one of the areas on the XS that can be improved a lot!

 

[MtnBoy]

Thanks Arctic. I am ordering the MC and caliper from Pandemonium Choppers. Am already running braided steel lines. They have two mounting kits, one for 34s and one for 35s. The latter has a spacer to correct the offset. I spoke with the proprietor yesterday. He told me that the 35s used brake tabs that are 4.5in center to center. The 34s measure approx 3.25 inches--just a ball park measurement--but, never the less, over an inch less than the 35s. I am not sure, but the early 34s may have had the tabs on the rear of the sliders also. If anyone out there has 34s, can verify this and measure the tube diameter, I would appreciate it. Need to know if I have 35s. Thanks to all, Bob

 

[gggGary]

You do, you measured the tubes as 35mm order the kit already.
Tell us how the install goes with pictures!

 

[MtnBoy]

Will do. Thanks Guys. Bob

 

[MtnBoy]

Brake upgrade done--and what a difference. Best upgrade for the XS, IMHO. The folks at Pandemonium Choppers hooked me up with their kit for 35mm forks, a Bembro 4 piston caliper and MC. You can imagine my surprise when I opened the box and found what appeared to be a beautiful, new Bembro caliper. The one with the large letters and no logo. The only thing that gave it away as being used were the old pads. They included a magazine article with detailed instructions. I had a few questions and the guy at Pandemonium was most helpful. Excellent customer service. When modifying the caliper, I recommend starting with a new file. Time consuming, but very easy. Just go slow and recheck often. If upgrading from a stock system, you will need a different lower brake line. I started with braided steel lines, so all I needed was the lower. The AMA pro I pit for recommended yoyodyne in New Jersey. I gave Fred the length, the banjo config and my VISA on a Thursday afternoon and received the line the following Wednesday. I live in the mountains of NE Georgia where the only straight road is my driveway. Took the maiden ride with the new system on my short loop, about 30 min. What a difference. Give the guys at Pandemonium a call.