Braking up - is hard to do.

tz375 · Post by **tz375** » Fri Dec 05, 2008 4:28 pm

I pulled out the front wheel of the Buffalo Phat Trakka project bike and dropped it carefully on the bathroom scales.

Including axle, sleeves and nuts but missing 4 disk bolts and tabs, it weighed in as the heavyweight champ at 36.6 pounds.

Pulled off the pair of disks but still with the axle and everything on that, it was a svelte 23.4 pounds. That includes tire and tube, so it's not too bad.

Still some room to get a few more ounces out of that.

Then I added back a single CBR600F4 disk and a 3mm spacer and 6 Yamaha disk cap screws and it was back up to 26.0 pounds.

That's 10 pounds lighter than stock right there on one wheel.

I'm hoping that one disk with SV650/EX500 type sliding 2 piston caliper will be more than enough brakes. kawasaki triple riders swear that a single stock low friction stainless disk and EX500 caliper is enough to stand it on its nose.

Of course a GT750 is slightly more portly, I mean substantial, but it might just work.

rngdng · Post by **rngdng** » Fri Dec 05, 2008 7:14 pm

I tried my bike with a single ex500 caliper, and it worked fine, but I had already gotten used to the feel of two ex500 calipers. It stops.

Lane

tz375 · Post by **tz375** » Fri Dec 05, 2008 7:40 pm

LAne,

How bad is stock disk brake material? I was under the impression that teh Coefficient of friction on old stainless was a lot less than modern disk material or is it not enough of a difference to worry about?

In fact I was figuring a friction coeficient between HH pads and modern rusty disk to be almost twice as high as old stainless.

tz375 · Post by **tz375** » Wed Dec 10, 2008 5:05 pm

Lane, what sized master cylinder did you use with single or twin EX calipers?

tz375 · Post by **tz375** » Fri Dec 12, 2008 1:11 am

Well the welding looks fine, but now I have them mocked up more correctly, I think I'll have to move both calipers inwards slightly. maybe a washer between teh brackets and the fork sliders will be enough.

rngdng · Post by **rngdng** » Fri Dec 12, 2008 2:37 am

tz375 wrote:LAne,

How bad is stock disk brake material? I was under the impression that teh Coefficient of friction on old stainless was a lot less than modern disk material or is it not enough of a difference to worry about?

In fact I was figuring a friction coeficient between HH pads and modern rusty disk to be almost twice as high as old stainless.

I don't have any idea. The stock disks worked fine, but I didn't use the HH pads. I don't remember what pads I bought; whatever the dealer had in stock. I have Katana disks on it now. They're slightly smaller in diameter so I had to move one mounting bolt on each caliper mount to swing them down enough.

Lane

tz375 · Post by **tz375** » Mon Jan 19, 2009 10:41 pm

I'm going to start with one disk and see how that works out. As long as that experiment isn't a total disaster, I can always add the second disk later.

http://pinkpossum.com/GT750/phattrakka2/p5brakes.htm