Toe Tools To Tame Toe? Rim-brake pads need an adjustment called toe-in, or toe, for short. Achieving the correct adjustment has always been a challenge, so when tool companies make Toe tools to automate the process, here at BBI we are all eyes on. Some years ago, Tacx introduced a tool for the purpose (# T4580), but it suffered three major disadvantages: it only worked on narrow range of rim widths, it forced the pads to be too low on the braking surface, and it could create only one angle of toe. Similar versions of this tool, with all the same disadvantages, exist as the Super B Brake Shoe Tuner and the SunLite Pad Preset Tuner. More recently, Jagwire entered the field with their # WST029 Brake Pad Tuner Toe-in Tool, so we just ran it through its paces. Unlike the Tacx-style tools, which consist of a single hinged device that clamps onto the rim (which limits the range of compatible rim widths), the Jagwire version consists of two completely independent shims (which solves the rim-width issue). So with the universality issue addressed, we were anxious to see how the Jagwire tool addressed pad height and variable toe angle. In short, it doesnt address these issues in any way, so we still find it badly lacking. Are we just being picky? Well, with the Jagwire tool, the pads end up 2mm lower than the top edge of the braking surface. Considering that the majority of rims have braking surfaces that are no taller than the typical brake pad, this means 2mm of pad hits nothing but air from day one. Furthermore, with cantilever brakes and V-brakes, pad height may drop at least one more millimeter over the wear life of the pad. Yes, pad height matters. As far as toe-in angle, you want as little as .5mm heel clearance at the moment of toe contact, but you may want as much as 1.5mm heel clearance. This varies with the type and flexibility of the brake caliper. Basically, you want just enough toe to eliminate the tendency of the brake to squeal, but the more toe you have, the shorter the pad life becomes. So is it hopeless? Not at all. The lack of a good over-the-counter tool has not left BBI students fumbling in frustration when setting toe. In our classes, we use one of the two methods described in Barnetts Manual. Using common wire of the sort available at every hardware store, we have fashioned wire loops that go around the heel end of the pad (the loops are flattened on the side that goes between the pad and the rim). By varying the wire gauge, these toe ties can create varying amounts of toe. The other method described in Barnetts Manual involves using nothing more than those ubiquitous self-sticking 3 x 3 notes. Since each note paper measures .1mm thick, you can simply peel off a stack of 5, 10, or 15 sheets to equal .5mm, 1.0mm, or 1.5mm. To use the note stacks, fix the wheel from turning, clean the rim of contaminants to insure a good stick, then stick the stack of notes onto the rim where they will be located just under the heel end of the pad. Whichever of these homemade versions you use, simply make sure the device at the heel end of the pad contacts both the pad and the rim while also making sure the toe end of the pad simultaneously contacts the rim. With both ends in contact, secure the pad-retaining nut. Youve just gone toe-to-toe with toe, and you won. Here at BBI, we believe in having the right tool for the job. To that end, we evaluate every tool of interest, and sometimes when no tool company makes the right tool, then we design it, make it, and sell it. However, if the right tool consists of nothing more than a little instruction on how to use common and inexpensive materials, then thats how we help mechanics always have the right tool for the job.
Posted on: Mon, 10 Nov 2014 17:22:02 +0000
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