dt125 brake caliper

[wizzer]

Hi guys

I have a dt125lc3 (disc)and im having problems with the brake caliper piston.My Problem is that when i replaced the pads i decided to remove the piston, when i tried to refit it it wouldn,t go back in so i used a C clamp (i think this was a bad mistake)now the caliper piston is kind of halfway in and it won't come out or go in any more.

What do you guys sugest, do you think i should try to find a new caliper. In the manual it describes it as if the piston should just like slide in but mine doesn't

I feel a bit stupid that i have probobly broken something now but i am a teenager and still learning.

Thanks

[Vez]

Hi guys

I have a dt125lc3 (disc)and im having problems with the brake caliper piston.My Problem is that when i replaced the pads i decided to remove the piston, when i tried to refit it it wouldn,t go back in so i used a C clamp (i think this was a bad mistake)now the caliper piston is kind of halfway in and it won't come out or go in any more.

What do you guys sugest, do you think i should try to find a new caliper. In the manual it describes it as if the piston should just like slide in but mine doesn't

I feel a bit stupid that i have probobly broken something now but i am a teenager and still learning.

Thanks

Sounds like you have possibly trapped the seal when you have reinserted the piston. If this is the case, then a new seal kit would be a better option than a replacement caliper.

Maybe try and get the piston back out by fitting the brake hose and lever back on, refilling/bleeding the system and using the force of the lever to move it. Or there is the option of connecting it to a compressed air line and trying that way, although not heard alot of success stories with this method. If all else fails, get a bigger G cramp .

We all had to start somewhere, so don't feel stupid for trying .

[wizzer]

Ok thanks for replying vez.

In my manual it metions removing the piston using hydralic pressure from the brake but how would i do this once i connect it up how do i bleed the system?

[barkwindjammer]

Could be a 'hydraulic lock', have you tried loosening the bleed nipple (ooer missus) then squeezing it with your c clamp?

[Vez]

Ok thanks for replying vez.

In my manual it metions removing the piston using hydralic pressure from the brake but how would i do this once i connect it up how do i bleed the system?

To remove the piston once connected, you just keep pumping the lever/pedal until the piston drops out.

The way I bleed the system is: ( may require assistance from someone else depending how long your arms are).

You will need: 8mm spanner for bleed nipple ( iirc) a piece of clear hose that fits the bleed nipple snuggly about 2-300mm long and some brake fluid

1. Remove cap from fluid reservoir and fill to full mark with fluid. 
2. Run the hose from the nipple and into a jar half filled with water or brake fluid if you have any old stuff. ( this helps stop the air traveling back up the hose)
3. Pump on the lever/pedal 3 times and hold the lever/pedal in, keeping pressure on it.
4. Whilst maintaining the pressure on lever/pedal, undo the bleed nipple (you will feel the pressure weaken in the lever, keep pulling the lever) and the fluid will flow along the pipe and into the jar, along with any air trapped in the system, which will appear as bubbles in the hose and also in the jar.
5. Just before the lever gets to the end of its travel close the nipple again. ( You may want to get a feel for where the lever stops while the system is empty of fluid).

Repeat this process until no more air is released from the nipple into the hose and jar. BUT, make sure to keep the reservoir topped up with fluid or you will have to start the process over again. The lever should feel firm with very little sponginess when all the air is gone. ( If you have the standard rubber brake hose it will always feel a little spongy because the hose itself expands under pressure).

There are other methods and tools to aid in bleeding the brakes, but this method has always worked for me.

HTH

Vez.

Note: mmmmm nipples .

[wizzer]

To remove the piston once connected, you just keep pumping the lever/pedal until the piston drops out.

The way I bleed the system is: ( may require assistance from someone else depending how long your arms are).

You will need: 8mm spanner for bleed nipple ( iirc) a piece of clear hose that fits the bleed nipple snuggly about 2-300mm long and some brake fluid

1. Remove cap from fluid reservoir and fill to full mark with fluid. 
2. Run the hose from the nipple and into a jar half filled with water or brake fluid if you have any old stuff. ( this helps stop the air traveling back up the hose)
3. Pump on the lever/pedal 3 times and hold the lever/pedal in, keeping pressure on it.
4. Whilst maintaining the pressure on lever/pedal, undo the bleed nipple (you will feel the pressure weaken in the lever, keep pulling the lever) and the fluid will flow along the pipe and into the jar, along with any air trapped in the system, which will appear as bubbles in the hose and also in the jar.
5. Just before the lever gets to the end of its travel close the nipple again. ( You may want to get a feel for where the lever stops while the system is empty of fluid).

Repeat this process until no more air is released from the nipple into the hose and jar. BUT, make sure to keep the reservoir topped up with fluid or you will have to start the process over again. The lever should feel firm with very little sponginess when all the air is gone. ( If you have the standard rubber brake hose it will always feel a little spongy because the hose itself expands under pressure).

There are other methods and tools to aid in bleeding the brakes, but this method has always worked for me.

HTH

Vez.

Note: mmmmm nipples .

I tried to bleed the brakes and remove the piston by hydralic pressure but it didn't seem to work. When i sqeezed the lever fluid flows down the brake line a little then when i release the lever flows back up into the master cylinder. I also tried to remove the piston with mole grips but it just damaged the soft metal. I'm starting to think i should try and find a new caliper.

[Vez]

I tried to bleed the brakes and remove the piston by hydralic pressure but it didn't seem to work. When i sqeezed the lever fluid flows down the brake line a little then when i release the lever flows back up into the master cylinder. I also tried to remove the piston with mole grips but it just damaged the soft metal. I'm starting to think i should try and find a new caliper.

Well you could try and leave the lever under pressure overnight, cable tie etc the lever against the bar. Just a thought.

A pic may give us a better idea of how bad it is also.

Calipers ain't hard to find though.

http://cgi.ebay.co.uk/dt-125r-2003-full-front-braking-system-everything-/320595712241?pt=UK_Motorcycle_Parts&hash=item4aa4fe58f1

http://cgi.ebay.co.uk/YAMAHA-DT125R-FRONT-BRAKE-CALIPER-DT125-DT-125-R-MOTO-X-/260668742464?pt=UK_Motorcycle_Parts&hash=item3cb1115b40

[wizzer]

Thanks vez i found a piston and seals kit on bitz for bikes so i'm just going to try and force the piston out. do you think those calipers you listed will fit my bike?

I will take some pics and post them

[wizzer]

Managed to free the piston, vez you were correct i had trapped the seal when trying to insert the piston. I'm now going to order up a new set of seals and maybe piston however it doesn't look to badly damaged so might reuse it baring in mind my bike is only used off road.

Thanks vez for the help