I have had my Super Glide Custom for three months and since day one the front brake has been MUSHY. I bled the line using the Harbor Freight Brake Bleeder and it got a little bit better. So yesterday I arrived home after a week away and when I pulled on the front brake lever it went waaaayyy down. Pumped it four or five times and it is high again. What gives? Why does it go soft and require pumping?

 

As long as the fluid level is correct and you have no fluid leaks, you still have air in the system that needs bled out.

 

Back to the dealer.....let them fix it.

 

I am not so sure the Harbor Freight bleeder didn't actually add some air to the system.

"Back to the dealer.....let them fix it."

I would love to tell the dealer to fix it but I just know they will spill brake fluid on the paint and ruin it. I have a sixth sense about it.

 

I am going to assume you put the Harbour vacuum pump on it. Not one that fits on to and pressures down. You really need to be careful if you use a vacuum on it that you do not pull but a very small amount and that the cover is on (to prevent splash) but loose since the system is not vented (the top of the cover or gasket has a small V to allow air on top of the gasket to allow inner bellow to drop in fluid when it is tight) Why you cannot put a lot of vacuum on it is the cup seals in the master are designed one way for tremendous pressure, but the other way allows air to come by in a high enough vacuum. That is probably what is happening. If you have ABS, and have gotten air in the system from up at master assembly, it will require the dealer to fire the ABS to get it out. If not, bleed it manually by breaking the bleed with a hose in fluid. Use a box wrench to open till lever drops and snug slightly before releasing the lever. Pump it up and repeat couple master cylinder full of fluid. If non ABS, the lever will be firm like it should be.

 

First, it is non-ABS. So you are saying that using the vacuum to suck from the caliper isn't good. I should do it the old fashioned way and start by running a tube from the bleeder to a container with fluid in it. Squeeze the brake lever and open the bleeder. Before the lever bottoms out tighten the bleeder. Fill resevoir and repeat until hard. Correct?

 

Occasionally I'll get one through here acting like yours and here's the steps I follow and I get solid brakes every time . Those Harbor Freight bleeders are a waste of time & money , I use the bottle to catch the bled fluid , about all it's worth .

Try to level the master cylinder angling the handlebars so you can take the top off without any spilling out . Next SLOWLY work the lever about 1/4 of the travel a few times and see if you get any tiny air bubbles , if so don't bother the bleeder just keep SLOWLY working the lever with maybe 30 seconds to a minute in between till the bubbles stop . At this point put the lid on and SLOWLY pump the lever till it comes up and crack the bleeder , do this a couple times . Top off the MC .

If the lever still feels mushy this is when I pull the caliper bolts and raise the caliper off the rotor with the line still sealed on it . Pump the lever till you see the brake pads move and you can see the piston moving out , then gently open the pads back up just enough to get the caliper back down over the rotor even if it's tight & dragging a bit . Bolt it all back down solid and hit the lever a few times to seat things again and you should a solid brake lever . Sometimes the piston in the caliper sticks a bit not pushing past a certain point so pads open an air gap against the rotor , this is the mushy lever you feel . By pushing the pads & piston past that point you take out the extra travel .

This doesn't do it I'd be looking at the MC bypassing internally .

 

Huge +1 to this.

If you don't have a bunch of air in there, your master cylinder seals sound shot.

 

Right On Advice To The T

 

Yes, vacuum is good especially for an old system, the vacuum can work only if you are very careful do just do a very little vacuum. On old system, it will prevent you running the pistons on the master cylinder down into rough areas. On yours, you should not have any rough areas. One thing I left out is to either torque the cover with a small inch lb torque wrench or do like I do and just snug to the gasket bulges ever so slightly. The gasket spring will preload the screws keeping them from getting loose and also you will not close up that v notch air gap on the top side. You need to check the screws in a few day also. Mine had dot 5. Sadly Harley went to 4 on all new bikes because the ABS unit require it and they did not want two types for model years.