Rear Brake Dragging

[MikesBike]

I just got a used sikk pit bike, because the tranny was messed up I only rode a few times around the block. Put in new engine and again few times around the block. Went on a longer ride off road yesterday and when I was done noticed the rear wheel wouldnt spin. The rotor was super hot and discolored.

So I happened to also have brand new lines to install and put those in, new dot4 fluid.
Rode around the neighborhood and it started to drag again and was very hot.
So I took off the caliper, was able to press in the pistons by hand and also greased the pins it slides on.

Went around the neighborhood again same route but this time it was good.
So today I go for long ride checking every once in a while, it was warm but still spun. I also tried not to use the rear but only when I had to.
Well later it happened again and I had to let it cool for 10 min. Then I rode back to the truck and left the area.

So do I need a new caliper? or the device that activates it?

Where can I find these parts cheap?


All I know is its a 2 piston caliper

 

[MikesBike]

I ended up finding the entire rear brake setup minus the rotor
from the pic the mounting bracket looks taller then mine, but the mounts for the caliper to go on look the same
If the pic is even accurate who knows, says 125-150cc pit bikes im sure they are all the same

So if thats true I can use my caliper mount with the whole new brake system
I think under $50 shipped
This way I replace alot of 7 year old parts all at once, maybe its easier that way

 

[Carlts]

Is the disc bent or even the brake mounting bracket? this may be causing it to rub unnecessarily? but yeah a new brake setup for cheap isn't a bad idea considering the bike age.

 

[sean01]

have you backed off the brake rod that connects the brake pedal to the master cylinder??? usually a 10mm spanner nut (undo it) and wind the brake rod clockwise to release some pressure..

sometimes its wound up too far and can cause this..

 

[MikesBike]

have you backed off the brake rod that connects the brake pedal to the master cylinder??? usually a 10mm spanner nut (undo it) and wind the brake rod clockwise to release some pressure..

sometimes its wound up too far and can cause this..

no I did not know you can adjust it at all

and the other poster I dont think its bent I can spin the wheel and it look fine, its not bent enough to show any movement

Sucks because even though I can get away crusising around the block here a few times once in a while it may not be enough to get a real test, and out in the field test if it starts to bind you have no way to do anything about it

I guess I need to get a long run with not using the rear at all, then same test using the rear

 

[sean01]

the problem your having is there draggin and then heating up... brake pads swell when really hot and so does the disk..
so the problem is there is too much pressure built up. sometimes the only way to fix it so the wheel turns again is to crack the bleed nipple to release pressure...

back that rod off and see how it goes..

 

[MikesBike]

the problem your having is there draggin and then heating up... brake pads swell when really hot and so does the disk..
so the problem is there is too much pressure built up. sometimes the only way to fix it so the wheel turns again is to crack the bleed nipple to release pressure...

back that rod off and see how it goes..

yes at the time off roading no one had any tools so we had to wait to cool down, lesson learned until its fixed

I did notice a few things today.
If I take off the axle nut, the metal suspension housing expands maybe 1/4 inch. Sorry not an expert on all the names

So that makes me think when I tighten the nut its bringing everything together
From the scooters ive ever worked on, the spacers usually are all the correct width where they are hard to get in
Where this bike they fall out because of the 1/4 inch play

So I did a few things
First I found out 2 spacers are the same height, one is a hair taller.
Now maybe that taller one belongs in a certain area. From the looks one tall one, one short one have marks where they belong in the sealed wheel bearing. The other short one is all messed up from the weather, little rust spots on it so I guess that would be the one on the far right outside.

Also when I got the bike the tire was a hair to the left, not centered. But im not sure what to expect on a china bike.
Maybe because I have that 1/4 play when loose, tire that isnt centered that could of all helped heat up the pads

spacers

I have the tall spacer all the way on the left side wheel, I figured I need to get the wheel over to the right anyways to be centered.

This is with the axle nut off, you can see how the metal spreads out and now I have that large 1/4 inch gap that should of been taken up with the correct size spacers

Found 2 washers that fill in the gap perfectly, not sure if that is the correct thing to do

I drew this line because I could not find my laser, but you can see the wheel is still off center but alto better then before, it was further to the left, which could of helped cause the brake issue

Since I have no idea if these bikes usually come with the rear tire centered I have nothing to go by
I have no idea if the previous owner took the tire off at one time, didnt put the spacers in the correct order (if there is one) so who knows

The chain looks to still be pretty straight, but its hard to tell with that black plastic thing it drags over since it already has alot of wear in it the chain seems to still want to sit on that spot

This is what I started with, not really centered

Ive also had to adjust those puller bolts that center the wheel vertically a touch too, but its hard to tell how level it is because any angle I look at it changes for whatever reason

not sure if your supposed to eyeball that or use a level or something


Thinking of running it on the stand in high gear to get it spinning really fast and check to see if im making any heat, pouring out rain right now

 

[sean01]

sometimes the tyre will appear to not be centered in the swinga, as long as the tyre is straight you should have no drama's..
drop the chain off and run a straight edge across the rear sprocket, it needs to be inline with the front sprocket...

another problem with brakes can be the slide pins seized which might mack 1 pad always rubbing on the disk harder than the other...

and now since you mentioned the wheel centering question you must also check the disk centering in the caliper.. maybe not the proper hub spacing for the swingarm or maybe not the correct brake setup for the hub...

just check everything lines up

 

[MikesBike]

Ive read some mention of adjusting the push rod on the brake lever
does that just screw in and unscrew to change length?

 

[MikesBike]

I found the adjuster nut on the brake lever rod
So I tightened the rod about 4 turns
this to me sucks up the lever, and when attached to the foot brake it then pulls it back down I guess
then making you press a little more to activate the rear brake

if im right then thats what I want to do, because it was very sensitive before and would lock very quick

I hope this will make me have to press harder to activate
I also ran it on the stand in 4th gear for over 5 min taking temp readings
temp only went up a couple degrees and was not warm to the touch

but I will have to ride it for the real test
I still have that whole new rear brake setup coming anyways but this way I can learn on the old one

Im still hoping it was the shims all along, not being in the correct place

 

[MikesBike]

Here is what came in, I ordered black
but look at the condition and finish
plus I noticed the push rod is way to small, so I will try to either first get the correct one sent or refund
I could always use the caliper and not anything else but who knows what will happen
Im pretty pissed because of the quality it came as, wrapped in a bag the mail man just threw it onto the porch too

 

[sean01]

who/where did you get that from?

the brake rod length should of be seen before you purchased it, but not that its an issue..

depending what master is on your bike you may be able to simply swap the rod over..or youll have to cut and weld the rod to make it longer...

 

[MikesBike]

who/where did you get that from?

the brake rod length should of be seen before you purchased it, but not that its an issue..

depending what master is on your bike you may be able to simply swap the rod over..or youll have to cut and weld the rod to make it longer...

The rod length was my fault I was so concerned with the mounting bracket and black color and 2 piston I forgot to check the pushrod length in the pic

So the one I got looks like you could take it out with those rusted nuts
but the one on my bike has no nuts looks all one machined body/piece
plus mine has a remote reservoir where the one I got has it built on the lever which im not a fan of either, another detail I missed

Got the brake from joestone11/black diamond cycle

Im really convinced its was more a spacer issue/ or push rod length issue
Since I did shorten the rod 4 turns, and fix my spacers im confident this weekend it will work out. But I will carry a wrench with me to pop the bleeder if it locks up again

It now seems my lever has almost 1 inch before the pads even start to catch when pressing the lever down, before it was instant
so maybe the pushrod was too long

I dont really use the rear brake unless going down very steep hills
and since I changed all the fluids and added braided lines the front feels great now, when I got it, it was very soft and weak

This is the 3rd ebay ordeal this month where im sent the incorrect item I purchased
still need to clear up all 3 too, waiting for the new parts to come in

I never remembered any problems in all the years, but then ive recently been buying china parts when I never have in the past

 

[sean01]

lol the parts themselves arent the issue, its either the buyer that fails to buy the correct part or the seller that fails to describe it properly...

jap bike spares are easier to buy for because of there model and year as reference..

some/most china bikes have no real model so unless its a decent brand name your left in the dark. but to get past that you just do your home work and check everything before purchasing...

^^thats the reason you pay more for a motovert or pitster or ciniworx bike.. they keep the same basic bike and as years go by they include newer parts. so as long as you know the year your right..

anyways let us know how the brakes go on the weekend

 

[MikesBike]

okay went on long rides today
probably 3-1hr rides and 1/2 hr ride
I would pull over every 10 min to feel brake rotor
1st 1hr ride I did not use rear brake. 2nd 1hr ride I had to because of all the down hills

I think it was the end of the last 1 hr ride I could feel it not coasting well so I checked, and it was too hot. Most of the ride was up hills too
So I just popped the bleeder and went on.
Last 1/2 ride most of it was down a 40% grade, really had to use the brake alot. When I got back to camp it was super cold????

So who knows, other then that bike worked great for its first hardcore test

I got video of it all but will be a day until I can get it all uploaded



Now I need to work on a better seat

 

[MikesBike]

After I detailed my bike I decided to give full effort into looking at the push rod adjustments

I found I was able to screw it in about 1 inch more, or 15 turns
I now see the brake lever hole, and the pushrod hole line up

So before there must of still been pressure if after 15 turns up gets them even

so there probably was always constant rubbing or enough at certain times to heat it up

Im going to have to wait until next time test it again

 

[MikesBike]

problem solved
it was the pushrod length
I notice I now have almost 1/4 inch of play before the brake lever activates the pushrod

does make me have to really angle down the foot to slow down, but I did bend the brake lever when the lock ups first started to happen thinking my foot was resting on the lever

but im fine with it, I only use the rear down steep hills