[jsmith24]

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Hi all,

I dropped my bike last week, as most know. I trailered it home yesterday, and noticed that the brakes feel mushy. About a week before the wreck I replaced all pads, rebuilt the calipers, and bled both front and rear lines. Any ideas?

Also, I've heard people talking about bleeding the front master cylinder separately, then the line. How is that done?

Thanks,

Jack

 

[Hobie1]

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Bleed all the brakes. You probably have air in the systemif nothing else was damaged. I don't know how far over your bike tipped but the bubble of air on the top of both master cylinders probably traveled intoyour brake lines.

Or I could be wrong.:baffled:

Hobie

BTW, glad you and your bike are alive.:waving:

 

[jsmith24]

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Hobie1 wrote:

Bleed all the brakes. You probably have air in the systemif nothing else was damaged. I don't know how far over your bike tipped but the bubble of air on the top of both master cylinders probably traveled intoyour brake lines.

Or I could be wrong.:baffled:

Hobie

BTW, glad you and your bike are alive.:waving:

Well the impact wasn't that bad, cost me a left saddlebag, windscreen, set of forks,and front fairing, but the bike was laid over on its side so far that it was sort of tipped wheels up (wrecked on a banked curve on a mountain road.) The air in the lines from the masters makes sense, since there is no damage as far as I have been able to discern.

Thanks Hobie!

Any others with master cylinder bleeding advice?

Jack

 

[Jason]

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jsmith24 wrote:

Hi all,

I dropped my bike last week, as most know. I trailered it home yesterday, and noticed that the brakes feel mushy. About a week before the wreck I replaced all pads, rebuilt the calipers, and bled both front and rear lines. Any ideas?

Also, I've heard people talking about bleeding the front master cylinder separately, then the line. How is that done?

Jack, just disconnect the brake line from the MC and let the fluid run out until it's free of bubbles, keping it topped up with new fluid. Then reconnect the brake line and bleed that.

 

[corneo]

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let me know if this does work. Mine are mushy too. I've used a power bleeder on them, rebuilt them and still are mushy. I'm starting to think the rubber lines got damage and I need to replace them. If I do that will be a complete brake system change out.

 

[Goldwinger1984]

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If you have a stuck slider on the caliper or a stuck pistonit can give you a feeling of mushy brakes even though there is no air in the system.

vIC

 

[jsmith24]

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Goldwinger1984 wrote:

If you have a stuck slider on the caliper or a stuck pistonit can give you a feeling of mushy brakes even though there is no air in the system.

vIC

I rebuilt the whole slider assembly on each caliper, too. New rubber and lithium all around.

Jack

 

[Hobie1]

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First of all, is it possible that you got dirt or sand in the calipers causing the pistons to hang, even though you just rebuilt them the week before? If you had lubed the pistons, it would be possible I'd think.

As far as rebleeding them, I had a mechanic give me an inexpensive way to make sure you've got all the air out: Break loose and lightly snug upthe bleeder valve on the caliper you're going to bleed, attach a length of tubing to the valve, run the tubing into a partially filled with new brake fluid clear bottle, open the valve and pump the pedal/lever while maintaining fluid level in the reservoir. Keep pumping until you don't see any bubbles coming out of the hose in the bottle. When you let go of the pedal/lever, the fluid goes back up the hose without having to worry about sucking any air. When you're satisfied that the system is air free, close the bleeder valve, top off the reservoirs and your done. I have heard of air in the banjo bolt, but I didn't run into this particular problem when I did my system. I wouldn't think it would hurt to crack the banjo bolt loose when you first start to bleed down the system, give the pedal/lever a pump or two, remembering to close the bolt before you release the lever/pedal each time(takes three hands:cheeky1, then bleed away.

 

[Dave Campbell]

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Seen several with air in the banjo at the master cylinder, a real toughie to bleed, have to remove the master, point the brake lever up and bleed the bubble out. The banjo fitting is the highest point in the system.

Jack, dumping it over and squeezing the brake lever while its down can put air in the system if the ports in the master cylinder are exposed to air. The hand lever controls the front drivers left caliper, the foot pedal controls the front right and rear calipers. Also its possible to damage a caliper pin by bending it, but not as likely. Its a natural reaction to clamp on the brake hand lever when picking a GL up in anticipation of it rolling ahead.