I finished my go kart!! But with a few problems...

[wblupton]

Hi everyone! I finally took the long stretch to make my go kart look like the final product. I think the project went pretty well besides how long it took D: The picture at the top is it, but I'm still running into some problems as you can see in the pictures below.
Problem #1 My brakes are on and the pedal moves the brake lever to the master cylinder just fine, and I know it's going all the way but if I'm driving, I still slow down, but it takes a pretty long time. When I'm rolling down a hill (not that fast) it will slow down a little but wont go to a complete stop. It almost feels like I don't have brakes! Any suggestions?
Problem #2 My gear ratio is around 1:5 but my main problem is that if i speed up too quickly or up a hill, the chain will slip and make a horrible sound. The chain is as tight as it can be and the two gears are lined up. I don't see how it can slip like that and it does it pretty often. Any ideas?

 

[Doc Sprocket]

Brakes- can't see too well. Are they hydraulic? I think your rotor is too small to have enough leverage.

Chain- the chain is skipping? Ouch. Either something is out of alignment, or there's just not enough wrap there. You might have to go to larger sprockets (and in turn, alter your jackshaft to axle spacing).

 

[ML-TOYS]

looks cool but as far as aerodynamics i think you built it backwards having that flat front on it

 

[Doc Sprocket]

With big honkin' tires and ground clearance like that- to heck with aerodynamics. This thing ain't built for the track!

 

[wblupton]

Yeah it's big but it goes! And yes the brakes are hydraulic and i do have a larger one for the jack shaft and more chain so ill see how that plays out. I'll think will have to get a bigger brake rotor though, when I got that one in the mail, it was a lot smaller than I thought.

 

[crazy4carts]

do you think the end of the shaft might be flexing, between the bearing, and the sprocket, itself? looks like a pretty good distance, there. maybe slide the shaft on over, and get some support on the end of the shaft might help.

 

[OzFab]

The massive bend in the brake cable won't help either, that adds loads of resistance to the pedal. A brake cable should be as straight as possible. You may need to reverse the whole setup. The small rotor won't help...

The chain isn't meant to be tight, it should have around 3/8" - 1/2" of movement in it; reducing the tension may just solve your problem...

Looking at the shaft mount, i'd say it's possible the whole mount may be flexing; I can't see what it's mounted to but, from what I can see, it doesn't look very solid

 

[wblupton]

To me, I think the shaft is pretty solid as far as i know. As for the sprocket, I may get a bigger one for the jack shaft so the chain can have more grab. Are you sure that the chain needs that much movement? I thing it could be subject to slide even more. As for the brake I may just have to get a new bigger rotor, it just bothers me that I have to re weld the mount higher but I guess thats the best I could do. You have any ideas where I could get a brake rotor locally because I really don't want wait two more weeks for it to come in. I' dont think my local tractor supply has one though. Any other suggestions?

 

[mysteryboy28]

the sprockets are too close together, and one is SO MUCH smaller than the other. so the chain is going to find the spot with the least resistance and SLIP! plus you can't mount a pillow block bearing to just a steel plate. it WILL bend/flex. period. that will cause slack in the chain. so the combination of the tiny sprocket being so close to the big sprocket, and the flexing bearing mount are your cause of chain slippage.

throw some square tube under the sheet metal where the bearing is, running the bolt holes THROUGH the square tubing. get another plillow block bearing so that you can run the jackshaft clear across and have support on BOTH sides of the sprocket. flex gone!

as for the big vs little sprocket: you're basically screwed there unless you can spread them farther apart somehow, or make a second jackshaft so that your sprockets that are chained together wont be so dramatically different in size. a gear ratio of anything higher than 6:1 (5:1 is HIGHER than 6:1, and worse for torque) with big knobby tires is generally asking for trouble. lol.

a 10 tooth to 60 tooth sprocket with say, 18 inch or smaller tires, is a decent recipe when there's a torque converter involved. but you want the sprockets spread out so the chain doesn't just slip over the little sprocket.

 

[mysteryboy28]

also, ditch the cable for the brake. the bend is bad, and cable just sucks for brakes IMO. flip the master cylinder around, and run a 1/4" rod straight from the brake pedal. it will work GOBBS better!

that brake rotor is WAY too small for sure!

live and learn, it sucks to have to find things out the hard way. lol.

 

[jamyers]

Have you bled the brakes?

 

[landuse]

I agree with all the above. Too late again. LOL

 

[FurFlyin]

do you think the end of the shaft might be flexing, between the bearing, and the sprocket, itself? looks like a pretty good distance, there. maybe slide the shaft on over, and get some support on the end of the shaft might help.

Winner! Problem solved.

 

[HaM551]

If the chain is too tight you will be loosing power, might be causing your chain issue as well

 

[landuse]

Winner! Problem solved.

Lets see what happens when he fixes it first

 

[wblupton]

Alright, I resolved the chain problem and now to the brakes. I'm probably going to get a new cable because the other one's basically toast at the bend i have it on. I'm also going to switch the master cylinder setup around. The only thing is that I'm trying to find a new, larger brake rotor. The one I have on there is around 6 in. in diameter. Would a 10 in do? I can show you guys some more pictures if you need to. Suggestions would be appreciated!

 

[Nodroz]

Are you guys sure it's the rotor size that is causing his problem? Might be some air in the system... did you bleed the brakes correctly?

 

[OzFab]

IMO, it's not just the rotor, but it's not helping

 

[wblupton]

Well they're brand new but I haven't bled them yet.

 

[wblupton]

Also, if it's not just the rotor, what do you think it could be? I have no clue.