Avid® Hydraulic Caliper Brake Installation & Hose Length Changes
This article will discuss the caliper alignment and adjustments to hose length.
Typical tools and supplies required:
4 and 5mm hex wrench
Rubber gloves, such as MG-1 (recommended)
8mm open end wrench
Avid® compression ring and barbed hose fittings
Clean shop rags, or paper towels
Isopropyl alcohol, or soap and water
Avid® disc calipers are mounted using a cup-and-cone washer system that allows the caliper to adjust to the rotor (Figure 1).
Figure 1. Adjustment washers of Avid® disc calipers
For frame or forks using the common "international standard" mounts (Figure 2), the caliper uses a mounting bracket. The mounting bracket attaches to the frame or fork, and the caliper body attaches to the mounting bracket.
Figure 2. IS mounts (international standard) of suspension fork
An alternative frame mounting system is the "post type" (Figure 3). The Avid® caliper bolts directly to the frame or fork posts, with no additional bracket required.
Figure 3. Post-type mounting system of suspension forks
Check that any mounting brackets are secure to the frame or fork mounts. Avid® recommended torque for bracket bolts is 70-80 inch pounds. Loosen the caliper body mounting bolts until body can move freely. Check the caliper is able to move laterally and center over the rotor when adjustment is loose (Figure 4).
Squeeze the lever firmly several times and hold. This should position the caliper pads parallel to the rotor. First snug one and then another caliper body bolt. Next fully secure caliper mounting bolts fully to 40-60 inch pounds.
See related article at Rotor Disc Service.
Figure 4. Check lateral motion before adjusting caliper body
Hydraulic Hose Length
The Avid® hydraulic brake system uses hydraulic hose (tubing) to connect the brake lever to the caliper. The hose length may be shortened as necessary. New compression rings and new barbed hose fittings will be required if the hosing is cut.
The length of hydraulic line should be similar to conventional wire brake housing. The housing should be as short as possible without any stressing or pulling on the housing ends. The hose should enter the levers and calipers in a straight line. For the rear brake, rotate the handlebars to test housing length. Housing should be as short as possible without stressing the hose connection to the lever during maximum bar rotation.
1. . Gently pry brake lever boot away from lever body using a plastic lever (Figure 5).
Figure 5. Remove rubber boot from lever body
2. Loosen hose compression nut counter-clockwise using a 8mm wrench (Figure 6). Slide nut compression nut away from the lever body.
Figure 6. Loosen compression fitting
3. Pull hose to remove it from the lever body (Figure 7). Wipe up any fluid spills or drips.
Figure 7. Tubing with compression fitting and nut pulled from lever body
4. Cut the hose to an appropriate length using a cable cutter such as the Park Tool CN-10 (Figure 8). Alternatively, use a razor blade or other sharp tool. Hose must be cut cleanly and squarely at the end.
Figure 8. Cut hosing end square and clean
5. Lever boot and compression nut must be in place on hose. Install a new compression ring onto hose. Thread a new hose-bard into end of hose using a 2.5mm hex wrench (Figure 9). Push the compression ring close to the new hose-bard at hose end.
Figure 9. Thread hose-barb into hydraulic hose.
6. Push the hose end firmly into the lever body to ensure the end of the hose seats into lever (Figure 10). Slide compression nut to lever body. Thread nut onto body and secure. For steel nuts, secure to 70 inch pounds. For aluminum fitting secure to 47 inch pounds. Push lever boot to cover compression nut.
Figure 10. Install new barbed fitting and compression ring into lever.
7. Bleed the system anytime it is opened.