Are front brakes overated?

**Str8 Jacket** · 2nd April 2009, 15:30

My lil FXR has had a dodgy master cylinder for a little while now. The brake has been bled plenty of times, the line is fine and there is nothing else wrong with the brake except for the master cylinder, which is obviously dodgy.
As Murphy's Law dictates my front brake completely failed on my way home today - We were always going to be replacing the master cylinder (thanks to Bren) tonight. When I got home, 5 mins later my brake was working, albeit not very well.

So this got me thinking, what makes the brake fail one minute and then work again the next? Has it got something to do with the seals, pressure what? This is not the first time it has done it so I have been a bit paranoid have been keeping my revs relatively high so I can drop down and use the engine braking to help me stop in a hurry if I need too. Also I have started using the back brake which has been a foreign concept to me for awhile! What the heck would you do if you were on a bigger bike or just not expecting this at all?!?

**bungbung** · 2nd April 2009, 15:34

Originally Posted by Str8 Jacket

Murphy's Law dictates my front brake completely failed on my way home today

Murphy's Law dictates bad things unless you get that sorted out.

It's not worth the risk

**mattian** · 2nd April 2009, 15:38

When you have to stop quickly. You will not want your front brake to fail

. get it sorted asap.

**Str8 Jacket** · 2nd April 2009, 15:40

For the record:

Originally Posted by str8 jacket

we were always going to be replacing the master cylinder (thanks to bren) tonight.

**bungbung** · 2nd April 2009, 15:47

Originally Posted by Str8 Jacket

My lil FXR has had a dodgy master cylinder for a little while now.

Sorry, didn't read your post correctly.

Cause?

Lack of sealing (bore, or piston), air bubbles

**Quasievil** · 2nd April 2009, 15:55

Could have some dirt or something in the line, may have a issue with the pistions on the calipers, thats what I would think if its irregular, seals and things would be consistant in that the performance would always suck.
thats my un mechaniclly minded opinion anyway

**Str8 Jacket** · 2nd April 2009, 15:58

Originally Posted by bungbung

Sorry, didn't read your post correctly.

Cause?

Lack of sealing (bore, or piston), air bubbles

All good!

yeah, there are always tiny bubbles rising to the air when fiddling with the master cylinder. No major though, only $45 to replace!

**AllanB** · 2nd April 2009, 16:12

Originally Posted by Str8 Jacket

only $45 to replace!

Famous last words....... hopefully not.

If only I'd replaced it before I ran that 5 year old over.....

If only I'd replaced it before smacking up the rear of that 2009 BMW.....

If only I'd replaced it before ripping off my 'bits' on the speedo on impact with the BMW...........

**FROSTY:Me** · 2nd April 2009, 16:14

Piston seals are fucked.
Not a good plan riding with no front brakes long term but shit happens sometimes.To be honest you are the first person who I've heard to have SUDDEN and unexpected brake failure for internal reasons.
Your front brakes supply up to 75 percent of your available brakes
That said I think new riders should practice NOT having front brakes. The brakes themselves are unlikely to fail but their effectiveness can be reduced to fark all if theres diesel on the road or a DEEP load of roadworks gravel.

**Str8 Jacket** · 2nd April 2009, 16:30

Originally Posted by AllanB

Famous last words....... hopefully not.

If only I'd replaced it before I ran that 5 year old over.....

If only I'd replaced it before smacking up the rear of that 2009 BMW.....

If only I'd replaced it before ripping off my 'bits' on the speedo on impact with the BMW...........

As soon as I knew it was fucked I ordered a new one. It had been fixed last weekend and was working absolutely fine all week so I had'nt been concerned about riding it - with caution! I also practiced stopping without using my front brake at varying speed often this week, its a small bike so alot easier to manouvere!

**quallman1234** · 2nd April 2009, 17:27

Still probabaly wasn't the smartest thing, but hey every does these things!.

**vindy500** · 2nd April 2009, 17:29

Originally Posted by Str8 Jacket

I also practiced stopping without using my front brake at varying speed often this week, its a small bike so alot easier to manouvere!

try it in the wet

**Number One** · 2nd April 2009, 17:35

Geebus woman! I hope that gets sorted pronto - as to your question...overrated hell no! I love my front brakes I wouldn't want to be without them and hate the feeling of them not working so good let alone worrying about them working at all. Hope you get it sussed chicky

**Squiggles** · 2nd April 2009, 18:18

If its the master cyl im thinking its letting air in, so you get nothing, but after a few pulls it'll prime and then you're back in business

**Str8 Jacket** · 2nd April 2009, 18:49

Yeah, it was wierd.
It didn't really 'pump up' there was no sponginess at all, the grab point would just move closer and closer to the bar untill it didn't grab because it hit the bar before it grabbed.

Its sorted now tho, bleeding it was a prick and a half and just wasn't working until we figured out the lever wasn't giving full stroke in place. - we took it off and used an allen key to push the piston in instead and she was bled in a whizzle.

Front caliper rebuild is on the to do list too.