Hi. I'm new to this forum and I've been searching with no luck. I have a 2014 FLHXS. I've had it about 3 months so far. A month ago the front brake got really spongy on my ride home, and it had obviously been leaking from the master cylinder gasket. The reservoir was almost empty. I replace the gasket - no more leaks - and bled the brakes with a vacuum pump. I also flushed enough new fluid through it the change most of it, front and rear.
Since then the rear brake is fine, but the front keeps getting air in the line. I bough the tool to cycle the ABS and that helps, but still after about 50 miles the lever is getting spongy, after 75 miles it's pulling to the handlebar and after 100 miles it doesn't work at all. I can vacuum bleed them and after about 6 oz of fluid I get several large bubbles. Then the brake is firm again, for another 50 miles.
Obviously air is getting in somewhere. The front brake pads are new and there is no evidence of a leak in the lines or calipers. I can't find any signs of a leak on the ABS module. I don't know enough about how this ABS system operates to figure out what to check next or how to check it. Any advice would be appreciated.

 

ABS once you get air in the system pretty much ABS needs to be cycled. Safe bet the bike was never been flushed as required every two years. That includes cycling the ABS. A service often skipped until something goes wrong.
There are those that will tell you can get away with this or that with ABS . They are wrong.
if you keep getting air in the system you have a leak and or are doing it wrong.

 

Which tool are you using to cycle the ABS module?

 

I have the Twin Tech scan tool to cycle the ABS. It's pretty simple to use and does activate the ABS module. I've literally been bleeding brakes for 50 years and have no doubt that I'm doing it correctly. If I was doing something wrong I wouldn't have a firm lever when I finished. The fact that it takes a while to fail indicates that even though I'm starting with a properly bled system, air is getting in. The question is where? I hate to just spend the money on a new ABS pump and then find that wasn't the problem.

 

It would seem to me if air is getting in, assuming there is no air in the system after bleeding, you would see signs of brake fluid leaking somewhere. So that part has me a little baffled.

So, my thinking is if you aren't showing any signs of fluid leaks, I'd say you've still got air in the lines. I would do another manual bleed. Then, another bleed using the Twin Tech. Finally, I would do another manual bleed.

 

I've bleed over two quarts of fluid through the system so far. Generally manual bleed, ABS cycle, and another manual bleed.

 

Your riding it and using the front brake also Correct ?
If you are sure of no visible leaks I have had a similar problem.
After finally rebuilding a single front caliper and the spongy brake problem was gone we guessed it was the seal.
When apply the brake the piston is forced out and the seal kinda rolls some (very little) with the piston.
When released the the seal rolling back is to help move the piston back to aid brake release.
We think upon release the seal was sucking in ever so little air with each apply and release.

This was one of those things that we didn't know for sure till we tried.
With the caliper disassembled we never found anything to point a finger at but the spongy brake problem went away.

Just passing along a PIA experience I had awhile back 3-4 yrs ago

WP

 

Thanks! I'll try that. It's a lot cheaper rebuilding a caliper than the ABS.

 

The odds of this problem being in the ABS unit is very very remote.
Brake fluid is hard to see especially when it's clean fluid.

If you have any doubt double ck for leak. Tie the brake lever back and let it sit..
If the line going into the caliper is just barley leaking the wind when riding can blow the fluid off. What's left could be very hard to see

Good Luck WP

 

Good idea. I'll try it. I have a caliper rebuild kit ordered in the meantime.