Brake problem

[Zackschiffler]

Hey guys new to the forum, I bought a half built go kart and have everything put together except the brakes. It came with a caliper on disc set up that didn’t function and I tried to order a few different new caliper set ups but can’t get anything except the original to fit. I’ve looked everywhere for a new version of this caliper that I could buy and can’t find anything figured I would post it here and see if anyone had an idea about the part number possibly?

 

[madprofessor]

That's a great-looking frame, really liking that! So, firstly why do other calipers not fit, is that not fitting onto the disc, or how the calipers fit to mount to the frame? Secondly, why doesn't the existing function? Do you just mean the pads won't squeeze down to grab the disc when you depress the brake pedal?
Firstly: There are different thicknesses of brake discs, and of the calipers to use with them. If the new calipers are too tight to fit onto the disc properly, then the disc is too thick for them...........(and it's pretty tiny, for example I'm running an 8" diameter). If it just doesn't use the same bolt holes, then you have to make new bolt holes or whatever mods necessary to mount one of the new calipers.
Secondly: Does the caliper move when the brake pedal's depressed if it's not mounted on the disc? Until there's no doubt whatsoever that every cubic nanoliter of air has been purged from the system, you can't condemn the caliper. I'll make a gentlemen's bet with you right now that air in the system is all that's wrong with those brakes. At least I hope so.

 

[Denny]

You know that may not be a kart brake caliper at all. It may just be a scooter brake caliper.

 

[panchothedog]

if you have air in the line it needs to be bled. It can be a real pain bleeding the line in the conventional way of pumping up pressure and then cracking the bleeder due to the tiny size of the master cylinder. I messed with it for hours one day and still didn't get it. Went to harbor freight and bought a bleeder, 1/2 hour later line was bled.

 

[madprofessor]

Pancho, great call on getting a bleeder kit. If I'd had any idea there was an inexpensive bleeder like that, it could've saved me a huge amount of headache when I swapped out an 18" brake line for an 84" one. Just looked it up, is this one linked below the one you used? Reviews say it'll pull and hold 10" of vacuum, sounds like a lifesaver for $25.
Brake Bleeder and Vacuum Pump Kit (harborfreight.com)

 

[Zackschiffler]

I did already try bleeding the system with no luck but the brake lines like 6ft so there’s a good chance that I just didn’t try for long enough before. I also already happen to own one of the mini vacuum pumps so that’s good! I didn’t realize you could use that as a bleeder as well though I just used it to test vacuum so to bleed the system would I just crack the bleeder and start pumping? As far as why the new calipers won’t fit they just won’t cover the distance from the mounting bracket to the actual brake disc, but fortunately I think I found a brand new exact replacement to use. Sorry for the late response I’m back at school right now.

 

[panchothedog]

Yes Mad that is the one I bought. I had never used one before. Always did it the old fashioned way with someone sitting in the car and pumping the pedal. Now I know.

 

[madprofessor]

Now I know.

Ditto, and thanks for the pointer. Ordering it in a day or two with some other stuff. Not needed right now, but want it ready to go when I do.

 

[Snaker]

Those caliper setups have some pretty small diameter passages.

I had a air operated vacuum bleeder that was pretty hardcore.
The cart I bought had a 6' hose to rear caliper and was bone dry at the bleeder.
The bleeder could not get fluid to show after several minutes of constant vacuum.

I ended up putting a open ended hose on the open bleeder and started hard pumping on the pedal.
No pump and stop at all, just a open bleeder and aggressive pedal pumping.

After maybe a dozen pumps, fluid showed up at the bleeder and I was able to do a proper bleed.
I don't know if there was debris in the system that got blown out or what.

On the caliper, I found that many of these calipers are the same but they use different mounting adapter brackets to fit different frames.
Maybe your old mounting bracket will fit on the new caliper?
Or maybe the old setup works and just needs some bleeding persuasion.

 

[Denny]

I used to use an old (new) garden sprayer as a pressure pot bleeder for brakes. It had a flat plate with a piece of conveyor belt for a gasket and a big worm type hose clamp for a clamp. Worked great on cars. Just pump it up for pressure and unscrew the top to release pressure. Couple small brass valves and good to go.

 

[DukeKL]

if you have air in the line it needs to be bled. It can be a real pain bleeding the line in the conventional way of pumping up pressure and then cracking the bleeder due to the tiny size of the master cylinder. I messed with it for hours one day and still didn't get it. Went to harbor freight and bought a bleeder, 1/2 hour later line was bled.

Ok, we might deal with this brake with the tiny size of the master cylinder. The previous owner of the kart didn't finish the bleeding may be due to unsuccessful attempts. I'll just finish installing the rack and jeep accessories on the Wrangler before we can start working on it. Gonna look for a bleeder tomorrow.