Brakes - cleaning and bleeding; Blogger trouble

Today I've been trying to get my self back in the groove of working on the go-kart; it's been very long days at work for the past several weeks.

This post is quite long, and I apologize for the lack of pretty pictures. My hands were so black that there was no way I was holding a camera!

I decided to take another stab at bleeding the front brakes I got from my pal Chris.
They were in a motorcycle accident so they look a little worse for wear, and I've been having a really hard time trying to get the slave cylinders to move.

It's tricky holding the master cylinder and the brake line, then squeezing the handle to pump some brake fluid with only two hands. Fortunately I have access to a vice that rotates, so I turned the jaws so they face the floor, and used them to grab onto the top edges of the reservoir, thus holding it upright (so the fluid doesn't all run on the floor - you have to do this with the reservoir open!)

So, I held the hose with one hand and pumped with the other. Of course the fluid must go somewhere, so I held the open end of the brake line over the reservoir! At first, mostly air will come out.
Once fluid starts coming out regularly, I found the trick was to hold the banjo in the reservoir, so that the fluid was covering the hole in the banjo (the end of the brake line).

This way, when you release the brake handle, instead of sucking air back down the brake line it sucks fluid instead. Pump many (a dozen at least) more times to ensure the air is out of the master cylinder and lines. I found that when I fully depressed the handle I would still get a little air pumping out of the banjo. This happened over 100 times so I'm certain there wasn't really air in the system, though I can't quite convince myself where it is coming from.

Anyways, bolt the banjo back on the slave cylinder assembly (brake assembly? - whatever it's called, the part with the pads in it) and continue bleeding by carefully following these steps in order:
1. Hold slave such that bleed valve is the highest point (so air heads towards it, very important)
2. Open bleed valve
3. Cover bleed valve with a rag (to not make a mess when fluid jets out)
4. Fully depress handle of master cylinder
5. Tighten bleed valve
6. Release handle
7. Repeat steps 2 to 6 until only fluid comes out, no air at all.
8. Do it once more for good measure.
9. Refill your master cylinder!

I would also recommend doing this procedure with something (screwdriver, etc) in the jaws of the calipers - preferably the brake disk you will be using, though that may or may not be the easiest way.


I finally managed to feel some resistance on the handle once I finished bleeding, but the pistons wouldn't move! I pushed a little harder and I saw they were really just stuck with black grime and brake dust.
Pushing them out with the master cylinder and forcing them back in with a screwdriver (by slooowly but forcefully prying between the piston and the steel side of one brake pad, NOT between both pads or you will wreck the brake pads) you can eventually work them loose.

I decided I needed to take the brake assembly apart to really clean the pistons as they were still sticky after working them back and forth a few times. Taking them apart was a snap, undo one bolt and tap the two pins out; both brake pads fall out and you can clean the pistons freely.

However I noticed something odd inside the housing! My brake assembly has two pistons. A flat steel spring inside the housing pushes the brake pads up and out of the housing (against the two pins) - but it was not symmetrical!
The left piston had a perfectly flat side of the spring, while the right side was folded nearly in half.
I judged that the bending was not intentional, and hammered it (sort of) flat so that each side acted on the brake pads symmetrically.

I cleaned up everything I could get a rag on, especially the two pins, and thew it all back together.

The pads are much more free to slide along the pins now, opening and closing as the pistons move.
Before they were binding so hard to the pins that I could barely move them by prying with a screwdriver; now they can be forced around, I'm guessing it's good now.


Secondly, Blogger troubles -
Today when I tried to log in to write a post, it only gave me the option to Publicly or Privately follow my own blog, no editing options like usual, no homepage, etc. Logging out and in several times, trying different accounts to log in with (google, yahoo, etc) finally it opened normally.
Now I am following my own blog - and since I am successfully logged in, I have no option to stop following it!
Hilarious but more frustrating when you just want to make a post.

Axle has arrived; upcoming plans

After a battle with a nasty 48 hour bug this week I managed to snap this photo of the new axle I bought from McMaster-Carr.

Axle
It is partially keyed - 14" on one side, 4" on the other. So, more then enough space for a wheel, drive sprocket and brake sprocket. It is made of 303 Stainless Steel - I'm darned happy because it is shiny, and it's going to stay that way. I would hate having a rusty steel axle and be fighting to remove all the sprockets from it in the future. The disadvantage is that the tensile strength is much lower, but still around 70,000lbs - It seems like a lot to me, but I'm sure the forces in this kind of system are intense.




For scale, the 1" bar in front is 12" long (30cm). The drive motor is properly aligned with the axle sprocket but perhaps too close together, I really need a frame to mock that up properly.

Frame
Speaking of frame, that's my task for this week, to go shopping at Metal Supermarkets, and to get a red flag or something to hang off the metal I'm sure will be sticking from the rear of my car. Thinking 1 1/2 square rather than 1 1/4 most (gas karts) use because of the extra weight I'll be lugging around in batteries.

Batteries
Still waiting for my contact at a certain battery company to get back to me. I have a contact who put me in touch with the sales manager, so I'm hoping to swing a great deal from them. It would cut a lot off the purchase price.
Interestingly I was also told to consider using NiMH - either industrial packs or sub-C cells - and making my own battery pack. Well that's the advantage of talking to people in the know, I would never have considered such a plan.
Apparently on Monster Garage they converted an old Bel Air to run on cordless drill batteries! Have to check that out some time.

Brakes
I've been reading a lot on www.diygokarts.com and a lot of people have been helpful there. A certain member who lives relatively close to me not only offered me advice and pictures of his experience, but also offered to sell me a set of working hydraulic brakes for a steal, only $60! Remember the bike shop earlier quoted $150 for the same exact deal - one set of used brake parts. Different models I am sure, but in both cases, just whatever was lying around.
I'm ecstatic! It might be a pain getting over to see him but totally worth it. I'm sure I will get a lot of sage advice too. Anyone else considering a similar project to this *really* needs to spend time on forums, there are some awesome people on the internet (i.e. in real life, that you can communicate with on the internet hehe)

Trailer
On a completely different note, I have been considering how to move this kart around when it's finished. Most people are settled and build these in their back yards... seeing as I am in an apartment this is a problem.
I have recently realized that my go kart has trailer tires, and the front (will have) actual trailer stub axles. So - get the kart licensed as a trailer, and tow it backwards! I'm thinking to build a pin into the steering mechanism to lock the steering straight for towing, and leaving a place to attach a long trailer hitch arm to the rear of the kart.
The Ontario website does not indicate much in the way of requirements for trailers so I think it should be relatively easy to get it plated.

Until next time...

Welder plug installed, brakes make more sense now

 Welder:
$110 later, I have a 40A circuit hooked up for my welder. Plugged her in, and she welded first try.
Of course I checked voltages with a meter first :) I'm just glad the 240 to 208 conversion I did last week worked properly.

Brakes:
In other news, I've been bugging people on the forum diygokarts.com and I've gotten some great help in the hydraulic brakes area. More specifically, how to take hand brakes from a motorcycle, removing the hand lever and replacing it with a different lever, cable-driven by the brake pedal. Perfect!
Now I definitely know what I want to do, I just have to buy some brakes. The person who helped me out might also sell me some, or eBay has a decent selection.

Tires:
Still fuzzy in the tire selection arena. I only have a week left on that Princess Auto sale. Someone on the forum is using that particular kind of tire, but they installed tubes in the tubeless trailer tire, so that he could run a low pressure setup, compensating for having no suspension. According to him, these tires are capable of bending the go kart frame when off-roading at the recommended inflation pressure. Crazy! I have asked for clarification, we'll see what he says.