KX Riders

Maintenance & Technical => KX250 / KX125 => Topic started by: dinkyguitar on April 12, 2015, 06:26:18 AM

Title: Disc brake pads only contacting upper rotor? PIC ADDED *****
Post by: dinkyguitar on April 12, 2015, 06:26:18 AM
Hi All,

My rear brakes pads are contacting the entire rotor on the outside of the rotor.

However, when I look on the inside of the rotor, the brake pads only contact about 3/8" of the tip of the rotor?

I can see the inside pad doesn't sit flat...the lower part of the pad has a small gap at the bottom.

Anyone see this before?

I suppose the age of the bike has something to do with it...87 KX 250...

Also, rotor and pads are new, and caliper has been rebuilt.

The brakes are strong though.

dinky,
Title: Re: Disc brake pads only contacting upper rotor?
Post by: sandblaster on April 12, 2015, 08:00:52 AM
Is the brake rotor completely flat?
Sometimes they won't wobble when you spin them but they are bent a;; the way around.
Put a straightedge on both sides of the rotor and see.
Title: Re: Disc brake pads only contacting upper rotor?
Post by: dinkyguitar on April 12, 2015, 10:57:12 AM
Yes the rotor is flat..it's a brand new EBC rotor.

Plus the wear mark is consistent all the way around.

dinky,
Title: Re: Disc brake pads only contacting upper rotor?
Post by: sandblaster on April 12, 2015, 03:41:59 PM
How loose is the caliper mount?
Title: Re: Disc brake pads only contacting upper rotor?
Post by: dinkyguitar on April 13, 2015, 01:38:14 AM
Caliper is on pretty good.

If I hold the caliper, it doesn't feel loose at all.

The caliper mount to brand new:

http://www.ebay.com/itm/KX125-KAWASAKI-1988-LOT-A-KX-125-88-REAR-BRAKE-CALIPER-MOUNT-/371298493736?hash=item56731d6528&vxp=mtr

Is it possible that the part of the caliper that hold the outside pad is bent out.....though use and age?

Not sure if that's a common problem....

Eventually, the pad will wear in....but it should ride along the entire rotor area.

dinky,
Title: Re: Disc brake pads only contacting upper rotor?
Post by: sandblaster on April 13, 2015, 03:01:51 AM

Is it possible that the part of the caliper that hold the outside pad is bent out.....though use and age?


That was my next guess.
I'm not sure what else it could be...
Title: Re: Disc brake pads only contacting upper rotor?
Post by: dan580,95 moto on April 13, 2015, 09:33:10 AM
hello i can tell u what it was on my kx500 1995, some one had let the pad on non piston side of calliper run right out to nothing, the disc literally had eaten the calliper away, check that the alu face that the back of pad sits on is actually flat and not angled.(non piston side)
mine was bad as the wavy disc had really eaten it.
Title: Re: Disc brake pads only contacting upper rotor?
Post by: Foxx4Beaver on April 13, 2015, 09:33:40 AM
it's a long shot, but how's the carrier on the swing arm look?
Title: Re: Disc brake pads only contacting upper rotor?
Post by: dinkyguitar on April 13, 2015, 11:19:17 AM
Here's the problem...as I thought.

(http://i166.photobucket.com/albums/u84/kezard/a9210e09-aae1-478c-b895-d6615ce526ca_zpsimmrrbtw.jpg)

The outside is worn towards the lower portion of the caliper. I would say that I have about .050" space on the bottom.

I could make a shim and attach it to the back of the inside brake pad...or I could shave .050" off the top of the caliper.

I tried searching around for a used caliper, but I feel this will be an issue with them all...

Any have suggestions?

dinky,
Title: Re: Disc brake pads only contacting upper rotor? PIC ADDED *****
Post by: dan580,95 moto on April 13, 2015, 11:23:35 AM
exactly the same as mine, mine was caused wavy disc eating it once someone let the pad get that low :-o, i did as u said, removed the material at the upper part with a file to make it square to pad again
Title: Re: Disc brake pads only contacting upper rotor? PIC ADDED *****
Post by: dinkyguitar on April 13, 2015, 11:44:57 AM
Thanks dan,

How did you do it? so that it's straight?

BTW, I took some measurements...

When the rear brake is pressed, I have about .016" space between the bottom of the inside brake pad and rotor.

At rest I have almost a .050" gap between the steel on the back of the brake pad and caliper.

dinky,