No rear brake pressure - 696 w/ abs

[Kev M]

Hey all.

Woke up Jenn's 11 696 from an extra long winter slumber today for a ride together. She immediately noticed too much travel and lack of pressure in the rear brake.

~9k miles, new pads last year after dealer flushed and changed fluid.

So ABS error light, system initializes and light goes out as normal. Front brakes normal.

Fluid level at top.

Plenty of meat on pads.

No visible signs of leaks.

Can sorta get a little brake action at an extreme travel on the pedal, but never really get a firm pedal, definitely not normal.

First guess would be failure of the cups on the pistons in the MC?

UNLESS there's something in the ABS system that could do this without a code​light?


Any thoughts?


Kev


PS this is the bike you see occasionally with some of my RevZilla articles.

[DarkMonster620]

Just rebleed the rear brake . . .

I used to open the bleed nipple and pump about halfway thru the reservoir and then close the nipple, then I would pump 3 times and hold on the 4th . . . If your wife can help with pumping, even better

[Kev M]

Just rebleed the rear brake . . .

I used to open the bleed nipple and pump about halfway thru the reservoir and then close the nipple, then I would pump 3 times and hold on the 4th . . . If your wife can help with pumping, even better

Might be worth a try. Jenn's used to helping me with bleeding.

But why would it work fine all last season and develop a problem in storage?

Also,  is there any problem bleeding ABS bikes without a scan tool to cycle the modulator?

[jasonub]

No problems with bleeding an abs equipped bike

Sent from my SM-N9208 using Tapatalk

[Kev M]

No problems with bleeding an abs equipped bike

Sent from my SM-N9208 using Tapatalk

Good to know, sounds like I have diagnostic step 1!

[DarkMonster620]

Might be worth a try. Jenn's used to helping me with bleeding.

But why would it work fine all last season and develop a problem in storage?

Also,  is there any problem bleeding ABS bikes without a scan tool to cycle the modulator?

Maybe humidity got to the fluid . . . Just saying and NO issues bleeding

[Kev M]

Maybe humidity got to the fluid . . . Just saying and NO issues bleeding

Nah, I'm not buying that. Insulated garage with a bunch of other bikes and cars in it. Not the slightest problem on any other vehicle in there.

Can't see how moisture suddenly got in when we had no problem the first 5 years and no fluid change.

I'm still thinking master cylinder piston cups stuck over the winter and failed taking most pressure out of the stroke.

[DarkMonster620]

Nah, I'm not buying that. Insulated garage with a bunch of other bikes and cars in it. Not the slightest problem on any other vehicle in there.

Can't see how moisture suddenly got in when we had no problem the first 5 years and no fluid change.

I'm still thinking master cylinder piston cups stuck over the winter and failed taking most pressure out of the stroke.

was just an opinion . . humidity here is to blame for way too many things .. .

[Kev M]

was just an opinion . . humidity here is to blame for way too many things .. .

No it's cool I appreciate the thoughts.

Around here we see little humidity until summer and even then...

[ducpainter]

This comment might seem off topic,the wall, which is fine by me...

but...

I have a condensing boiler in my house. All winter and spring the thing runs and you hear basically nothing other than fans and pumps whirring. Then...in the summer, when the heat doesn't run and things cool down, relatively, the thing starts banging away every time the hot water is called for. It goes away in the fall when the heat starts running again.

I think the fluid contracts over the winter and creates an airspace, which requires bleeding.

Carry on.

[Kev M]

This comment might seem off topic,the wall, which is fine by me...

but...

I have a condensing boiler in my house. All winter and spring the thing runs and you hear basically nothing other than fans and pumps whirring. Then...in the summer, when the heat doesn't run and things cool down, relatively, the thing starts banging away every time the hot water is called for. It goes away in the fall when the heat starts running again.

I think the fluid contracts over the winter and creates an airspace, which requires bleeding.

Carry on.

It's an interesting theory.

My question would be if that's true why didn't it happen the first 5 years of winters?

And why doesn't it happen to the rest of the fleet?

But I'm just thinking it through, I obviously don't KNOW yet.

[ducpainter]

I know little.

Doesn't make me wrong.

[Speeddog]

Possibly some not-up-to-par fluid was used at the dealer.

Flush and bleed is first step, and nearly free.

Occam's razor.....

[Kev M]

I know little.

Doesn't make me wrong.

I know even less, and I'm usually wrong, just ask Jenn.

[Kev M]

Possibly some not-up-to-par fluid was used at the dealer.

Flush and bleed is first step, and nearly free.

Occam's razor.....

Then should I expect the clutch and front brake to fail next?

I like Occam's Razor, which is why I checked for leaks and checked pads first.