Yerf dog 3203 Brake upgrade

[Weezil]

I've never fabricated anything so if you see an obvious flaw in my plan or a way to do it better please let me know.

My plan is to weld the new bracket to the side of the existing caliper bracket, the shaft support, and to the tubular frame above the caliper. I'll also bolt it using the existing holes in the caliper bracket and holes in my bracket drawn on the diagram. Its hard to explain and I don't have a program to draw on the pictures so hopefully you get the gist.

My only concern is that the lever on the caliper will be off center from the brake cable. It seems like pulling at an angle will wear on the caliper parts but I can't move the brake cable tab from the bottom of the frame to the side to compensate because the tire will rub the cable.

 

[Sgona101]

Put a cross bar from the left tire side to the engine.

 

[BigMark408]

just saw a video on this by CloinFurze on Youtube last week

 

[mckutzy]

I think what you have there will be fine... Take a look at my other bike, the Jimmy Rig.... Made up the exact same setup you were thinking...

http://www.diygokarts.com/vb/showpost.php?p=425458&postcount=177...

 

[Weezil]

Well, changed my design a little but its done. Keep the snickering about the welds to a minimum. New problem. My brand new rotor is warped. I can't find a machine shop or auto shop that can turn it. Any suggestions? Any of you guys able to do it?

 

[mckutzy]

Well... Im not going to get into the issue of weld quality of yours here just yet......

But the rotors are typically warped like that as they are welded onto a hub. The weld is wrapped around and not tacked first. Hence the wobble.....

A fix, is polish the shaft and the bore of the brake well. Get some shaft collars that fit the shaft.
Polish the keyway up on the brake hub. You may have to add a few punch marks to the key to make it stay put on the shaft, a slight hammering into the shaft to seat it will do, but dont pound it home....
Assemble and allow some movement of the disc latterly(about an 1/16-1/8").
This will allow the caliper and the disc to float well... dont forget to grease the ways of the caliper on the bracket(polishing the bracket "ears" helps alleviate a sticky caliper)...

Also welding the bracket on, makes it difficult to reinstall the caliper should/when it needs to be serviced again. Just to let you know.....

 

[Weezil]

Also welding the bracket on, makes it difficult to reinstall the caliper should/when it needs to be serviced again. Just to let you know.....

It probably is a mistake, I have made my share for sure. But I only welded the bracket, the caliper slides in and out freely as long as I slide the disc off the axle at the same time. I'm not entirely sure how the whole system works to be honest so hopefully it can be removed with a grinder if necessary.

As far as the welds go, I just picked up the welder this weekend. I practiced on scrap for a couple days before moving to the go kart but the kids are getting restless. I'm not letting them leave the yard till I'm certain it's safe.

 

[Weezil]

The new disk and caliper brakes work. They even work better than the band brake that came on it. It stops well enough in the yard but when I took it out on the street and really opened it up, it took me about 150-200 feet to get it stopped. That just isn't acceptable. Is the only option I have left to upgrade to hydraulic or is there a way to increase the leverage I get on the mechanical caliper? I thought about putting a pulley or something on the brake line but was wondering if anyone else had an easier fix. *edit Oh, and I removed the plate I welded and rewelded it. I think I'm getting better.

 

[mckutzy]

I had a ton of brake problem over the last years.. Take a look at my threads...

You can add a lever extension to try to add more clamp... However that really makes it difficult to setup the offset of the pads...
A good idea I found, was to sand the disc with a rough grit sanding disc. Also try sanding the pads to break of the initial glaze that sets in...
Wear a mask as this mostlikely contains asbestos.


Also... A big safety note.... I would highly recommend getting shaft collars on either side of the disc, as a minimal....
I have personally had 2 brake keys walk out on me, and both times barely managed to stop.
One time the wheel hub key went, and then welded itself to the main axle shaft. That's how I stopped.... Eventually.
Second time I was at speed on my other bike doing atleast 60kph, I was flintstoning to stop it... Wore a bit of a flat spot on my old pair of boots too.


Now I was on a bike but still remain a threat none the less.

 

[Weezil]

Also... A big safety note.... I would highly recommend getting shaft collars on either side of the disc, as a minimal....

I noticed the disk had moved when I took everything off to take that last pic. I just thought I needed to put some loctite on the hex things that keep it from sliding on the axle. Thanks for the tip. I will get a set.

 

[mckutzy]

If you use locktite on setscrews... Use the blue semi permanent stuff...
You'll need to break it down a few times...