Mechanical brake disc problems

[Shmigy02]

Hello all,

I've been having issues with my mechanical disc brake. It's your standard lever brake caliper and disc that you can buy on pretty much any go kart website and even Amazon. I cant seem to get it to function properly, but I believe it to be operator error.

I've watched every YouTube video about mounting and adjusting it to the right spot, but it just doesnt have enough clamping force to slow down the kart. When the kart is off and in my garage and I roll it around the brake kinda works, but as soon as I turn the engine on it will not squeeze hard enough.

When I ride the kart around my neighborhood and get going in the 20s the brakes will do, and I mean it when I say, nothing. Even sitting at idle on a small incline with the brake fully engaged the kart will start to slowly roll back. I cant imagine it being a weight problem because my kart with me in it is probably in the low 400s and I think it should at least do something when i slam on the brakes.

Actually, the only way I've been able to slow the car down is the "engine braking" which is just the wheels having to turn the engine when I don't give it gas. Is there a simple fix or troubleshooting list to this that most beginners don't understand to these mechanical brake discs, is this a weight problem, is this operator error, or is this post to long. Haha, thanks for the feedback.

 

[mckutzy]

Hi.. please post some pics of what you have and other details.. so we can better assess the situation...

 

[snowjob]

I have been relatively disappointed with mechanical calipers. We have a light kart with two calipers on the rear axle and at first it barely slowed it down. I replaced and adjusted the calipers and it now stops adequately, but not great. A few pointers I received:

Adjust caliper side to side
Ensure rotor is square
Ensure brake pads have plenty of life
Ensure best leverage to apply maximum force with cable
Deglaze rotors/pads

Even then, I am guessing your setup is 50% heavier than mine with 50% of the braking force....I wouldn't expect too much from it. Hydraulic is the only way to go IMO.

 

[itsid]

With most purely mechanical setups around (single piston) you will eventually face one issue:
i.e. the caliper is fixed and not allowed to float in it's bracket! (seized, bracket no longer straight)

if the caliper doesn't float, you will have 50% of the max possible braking force at best
(frankly I say 30% is more realistic)

That's the reason mac asked for a pic of the setup, I'd bet

And since you didn't showed us, I say it'll be what's stops you from slowing down (giggle )

'sid

 

[snowjob]

I largely agree on the floating caliper point. Our new calipers can move slightly side to side if they are not fully adjusted in or out. That was the reason for shortening our spacers, to get them in this range.


Sent from my iPhone using Tapatalk

 

[Bosch]

And since you didn't showed us, I say it'll be what's stops you from slowing down (giggle )

'sid

Well played, sir.

 

[Shmigy02]

Hello again, was camping all weekend and couldnt take pictures or respond to any comments. I think I have found how to attach pictures so hopefully it isn't to late to still get help.

 

[Shmigy02]

The pictures aren't that great, but you might be able to see that I have actually snapped a brand new brake cable trying to apply enough pressure to get the pads to pinch the rotor. I have a return spring on there as well to help it return, and like a previous comment above stated, when I apply pressure on the brake the caliper seems to move side to side when pinching down on the rotor. I also cant seem to find the sweet spot to adjust that outer bolt for the correct force needed to actually move the pad inward.

 

[mckutzy]

First..
Did you try to weld the caliper onto the bracket???
And the brake cable should never be welded onto the caliper...

 

[Shmigy02]

Yea a friend didnt think it should be moving so much so he tried welding it down before checking the metal and after he tried he realized its not steel.

And Yea I didnt have the right connection on the end of the brake cable so welding it was the only option.

 

[itsid]

yeah there's your problem for sure..

I admit I haven't seen someone -uhhhm- *peeep* enough to try to weld a caliper to its bracket,
since it's clearly slotted and if one doesn't know, one can look it up on the internets first..
but hey.. that bracket is clearly NOT FLOATING

You might be able to whack it off and grind it all smooth again,
otherwise
get a new caliper and maybe a new bracket and you'll be good.
(new bracket will have to be welded on I'm afraid..
I would suggest you ask someone OTHER than that friend

'sid

 

[Shmigy02]

So if I understood you correctly, the caliper is being blocked from moving side to side in its bracket, resulting it it not being able to fully clamp down on the rotor. So I just need to free it by grinding off the weld and making a more smooth bracket?

 

[itsid]

yes you understood correctly;

if the caliper is allowed to move freely side to side, it'll more than double it's force on the rotor.
(the welded cable might need to be fixed as well tbh... but you got the idea )

'sid

 

[mckutzy]

That would help...