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VTR fighter
1,391 Posts
Discussion Starter · #1 ·
Got a customer telling me he's back brake is weak and it binds when not applied, so i thought i'll do a little how to.

Before removing anything i checked the little wear limit marker on the lever arm, then adjusted the rod, still binds when not applied so i thought it will either be drum ovality (warpage on the steel drum) or rough edges on the shoes.

First i got my clean area (always get a clean area to put clean parts)

Next i removed the shoes and clamped them in the vice.

The edges were pretty rough and would cause binding so i decided to shamfer them (file a little angle on them) Before


After, as you can see there's a nice little angle on them to grab onto.

If you noticed you can see that there is actual silver paint on the shoe friction surface ^^ This won't help braking so i gently took it off with a scouring pad

Next i checked the drum, it was very rusty so i took some wire wool to it, cleaned up much better, no wonder brakes were crap!

Next i checked ovality on the drums, you can use a ruler (not soo accurate) a verrnier caliper (pictured) or a dial test indicator (best way in my opinion). To test how much off it can be, check your service manual, over 1mm and i'd say they are no good.

next i greased the post (at the top) and the cam (at the bottom) if i had time, i'd also clean the back, but it will just cost the customer more money for something that won't affect performance. Blast everything with brake cleaner, shoes, drum etc.. get all that muck off! Don't buy brake cleaner in that expensive spray, you can get a 5L bottle and brake cleaner applicator for £20 on ebay! better and loads more for your money.

Next where many go wrong! they try to stretch the return springs to pull the shoes out over the cam + post, no need, its easy to just push them in on an angle!

While it's apart you might as well check wheel bearings and seals. I also checked runout + balancing on the wheel, putting it on a wheel balancer and using a DTI, it was all true, and brakes worked well once back together. It's an old single leading drum brake so will never be great!
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