ATKustom: brakes

Sunday, August 24, 2014

REPAIR: Rear Brake Allen Bolt Failure

I packed up all my camping gear and took off to Shelter Cove last year, going the back way through Petrolia and Ettersburg. It was supposed to be a short 300 mile trip... Buuuuuttttt, the ATK decided to make that not the case.

All packed up in the middle of some Doug Firs that rival some of the bigger Redwoods.

One of the disc bolts decided to back itself out on the road. I heard a slight "tink...tink...tink," and I suspected a rock had worked itself into the disk...

But a sudden jolt stopped the bike in its tracks once it backed out enough to stop itself on the caliper and I got a quick introduction to the gravel.

When I got back to town after limping the last 120 miles trying to avoid using the back brake at all on some steep roads into Shelter Cove I got some replacement bolts. Here is the stripped and bent bolt compared to a new one.

The threads were stripped all to hell as well, So I took the wheel to a local machine shop and rather than re-tapping the threads the guys had the idea to pass a "blank" threaded rod through the aluminum hub that was of equal pitch from the back side where the threads were unaffected.

Passing a "blank"

All four replacement blots back in with a nice fresh application of blue Loctite

Back on the road ready for whatever.

COST:

Labor: Free

Bolts: 3.75

Replacing damaged plastics: Hell no!

Sunday, May 12, 2013

MODIFICATION: FORK SWAP STEP 4: BRAKES

On the recommendation of zaz696 was to keep the Brembro lever and braided cable from the stock ATK set-up, but to keep the stock CRF caliper (The brembro caliper WILL NOT mount to the stock CRF mount).

So everything mounted up nice, but after I wrestled with getting the Brembro master cylinder level multiple times, I could not get gravity to pull the brake fluid through the brake system. I fanagled a vacuum pump system with a reservoir to get enough pressure to get the fluid to overcome the resistance in the system. At this point I came to the horrible realization that fluid was pouring out of the gap between the caliper and the banjo bolt. I switched the copper washers to see if that was the problem, but on closer inspection, I realized that the banjo bolt on the caliper had been cross-threaded. My fault or the previous owner's? I would prefer to believe the latter, but I was left with the result, it was hemmorhaging brake fluid and would never retain pressure.

I started looking at new CRF calipers online, and used ones on ebay, then came to my senses and took the caliper to my local machine shop who managed to tap the threads. 25 bucks at a local machine shop was a much better alternative than a 50 dollar used caliper with who-knows what problems from ebay, or a 200 dollar new replacement.

COSTS:

$25 to machine shop for thread tapping

$5.95 for DOT 4 brake fluid to re-bleed