Front brake master cylinder rebuild - piston stuck

[staves]

Hello,

 

I am rebuilding the front brake master cylinder on my 1999 RT. The piston is stuck in the cylinder. There was quite a bit of crusty brake fluid in the area. The set screw is removed and I'm able to push the piston down in the cylinder.

 

I've read that compressed air might be helpful. The thing is, I have no idea where to shoot the air into. Maybe obvious, but not to me! Is it the hole for the set screw?

 

Besides compressed air, any other ideas?

 

Thanks.

 

 

[TSConver]

usually shoot the air via where the bleeder or the brake line attaches with a rubber tipped air gun.  Have to block off all other openings so that the one you want to move is pushed out.

[dirtrider]

9 minutes ago, staves said:

Hello,

 

I am rebuilding the front brake master cylinder on my 1999 RT. The piston is stuck in the cylinder. There was quite a bit of crusty brake fluid in the area. The set screw is removed and I'm able to push the piston down in the cylinder.

 

I've read that compressed air might be helpful. The thing is, I have no idea where to shoot the air into. Maybe obvious, but not to me! Is it the hole for the set screw?

 

Besides compressed air, any other ideas?

 

Thanks.

 

 

Afternoon  staves

 

If the master cylinder is still on the motorcycle then using compressed air is very risky as brake fluid will flat out ruin paint and/or dash plastics. 

 

Maybe try a duckbill snap ring plies in the push rod depression in the piston. 

[staves]

 

23 minutes ago, TSConver said:

usually shoot the air via where the bleeder or the brake line attaches with a rubber tipped air gun.  Have to block off all other openings so that the one you want to move is pushed out.

 

To confirm - are you referring to where the brake line is attached to the master cylinder or the caliper?

[staves]

16 minutes ago, dirtrider said:

Afternoon  staves

 

If the master cylinder is still on the motorcycle then using compressed air is very risky as brake fluid will flat out ruin paint and/or dash plastics. 

 

Maybe try a duckbill snap ring plies in the push rod depression in the piston. 

 

Yes, it's still on the bar. Good thing I'm not worried about the paint! 

 

Any chance you have a link to a pair of duckbill snap ring pliers? I'm not familiar and my Web searching is coming up short.

[dirtrider]

3 minutes ago, staves said:

 

Yes, it's still on the bar. Good thing I'm not worried about the paint! 

 

Any chance you have a link to a pair of duckbill snap ring pliers? I'm not familiar and my Web searching is coming up short.

 

 

But do worry about the dash plastic as brake fluid can ruin & cloud that & that is unrepairable. 

[staves]

21 minutes ago, dirtrider said:

 

 

But do worry about the dash plastic as brake fluid can ruin & cloud that & that is unrepairable. 

 

Thank you. I appreciate your point about the dash plastic.

[9Mary7]

And if you do go the compressed air route, the piston will probably shoot across the garage.....FWIW

[Jim Moore]

44 minutes ago, 9Mary7 said:

And if you do go the compressed air route, the piston will probably shoot across the garage.....FWIW

Yeah, keep body parts out of the path of travel.

[dirtrider]

59 minutes ago, 9Mary7 said:

And if you do go the compressed air route, the piston will probably shoot across the garage.....FWIW

As well a brake fluid shooting out so other vehicles in the area are at risk of brake fluid damage. 

 

I usually toss a double shop rag over the open end of the master cylinder to catch the piston plus hopefully catch most of the blown out fluid. 

 

If the pocket in the piston is deep enough I can usually get the piston out using those snap ring pliers shown above.  

[Skywagon]

Hold my beer and watch this...

[Lowndes]

Please be sure to video tape this episode with full audio!!   I'd give anything to be there.