Front Brake Problems

[dhunt]

Well I've been complaining about my front brakes for a while now so on the weekend I finally got round to trying to do something about it. The problem is no braking occurs until I pull the leaver in half way so I thought putting some weld on the leaver to remove that inital no braking would fix the problem.

So I tried that and took the bike for a little cane to test the brakes and the carbs (cause I'd done some work on them as well) was cranking along at ~160km when the bike started slowing down, which I thought was the carbs or something so I dropped it down a gear and gave it some more revs but it continued slowing and me busy changing down gears which finally ended up with me stopped in middle of my lane with the front brakes locked on

Had to remove the leaver to free up the brakes so rode back to the house with no front brakes so off came the weld that gave me nice 2 finger brakes.

Then after bleeding brakes again (got it down a couple months ago) which didn't help it's back to what it was at. I know my lines stretch a bit but this is different. I'm thinking it's the master cyclinder but wondering if anyone else has any suggestions :spudwhat:

[XTC]

LMAO

No I'm sorry i can't help with your brake prob..... But you will look back on this and laugh...maybe.

[vifferman]

The fact that when the brakes had got hot they came on more and more by themselves suggests to me that there's still some moisture or air in the fluid.

Also, how are your pads? I overhauled my calipers and that helped. Then I replaced my brake lines with braided s/steel ones, and it improved them heaps. But when I replaced the pads, it decreased the lever travel, improved the feel, and made as big a difference as the new lines had made.

[Paul in NZ]

Usually, there will be a specified (and often adjustable) amount of free play before the lever starts to move the m/c piston. Never a good idead to remove this. (as you found out)

Have a look at the fluid (should be changed regularly) and the hoses. They age and are better off replaced with braided lines. The original rubber ones were deliberately chosen to allow for some swell to give some feel at the lever. Over time, they degrade.....

I'd really recommend a proper overhaul. Clean the calipers, new pads, new lines and a kit in the m/C. Should not cost too much... If it were a Guzzi

Paul N

btw - I damn near pissed myself. Thats a bloody great story.... I might steal that one day!

[dhunt]

Pads are maybe half worn, had new fluid put in about Nov last year, pretty sure it's not flex in the lines as once the brakes start biting there is a bit of flex there that feels like flex.

Will have to admit It was sort of funny - not everyday one's brakes tell you to slow down.

[Motu]

Heh heh,done that before myself - not enough freeplay on the lever holding the compensating port closed....as the fluid heats up and expands the brakes slowly start coming on.do it again,just removing a little at a time till you have some freeplay.

[vifferman]

When you bled them, did you use new fluid (as opposed to some stuff that'd been sitting around in the bottle)? Brake fluid is highly hygroscopic - sucks moisture out of the air. If it's not fresh fluid you used when bleeding, then it's ferked.

What're your brake lines like? On the VTR, the brake line from the master cylinder went to a T above the mudguard, where it split into two lines. The one to the left caliper had a hump in it, and because of this, air bubbles tended to gather there. It made it almost impossible to bleed all the air (and sponginess, and lever travel) out of the brakes, which is why I went to braided lines - one from the M/C to each caliper. Also: joints, connections, bends etc tend to be good places for those sneaky little bubbles to gather. If you can eliminate them (joints etc) as much as possible, it helps a lot. Alternatively, tap the lines and any fittings with a small spanner or a screwdriver to get the bubbles to migrate upwards to the M/C.

But, as Paul said, the only way to get the brakes really good is a total overhaul/revamp. You're looking at ~$200-$250 for braided lines, maybe $110 for pads, and about $50-$100 for caliper seals. You can do it yourself, if you know what you're doing, take your time, and a lot of care.

[sedge]

Find a mate with a spare master cylinder, swap it in, be amazed, bloody Suzukis...

Sedge.

[dhunt]

When you bled them, did you use new fluid (as opposed to some stuff that'd been sitting around in the bottle)? Brake fluid is highly hygroscopic - sucks moisture out of the air. If it's not fresh fluid you used when bleeding, then it's ferked.

When I got it done in nov I got all new fluid put in so shouldn't have been old stuff and then when I did it on saturday it would have been older stuff.

What're your brake lines like? On the VTR, the brake line from the master cylinder went to a T above the mudguard, where it split into two lines. The one to the left caliper had a hump in it, and because of this, air bubbles tended to gather there. It made it almost impossible to bleed all the air (and sponginess, and lever travel) out of the brakes, which is why I went to braided lines - one from the M/C to each caliper. Also: joints, connections, bends etc tend to be good places for those sneaky little bubbles to gather. If you can eliminate them (joints etc) as much as possible, it helps a lot. Alternatively, tap the lines and any fittings with a small spanner or a screwdriver to get the bubbles to migrate upwards to the M/C.

But, as Paul said, the only way to get the brakes really good is a total overhaul/revamp. You're looking at ~$200-$250 for braided lines, maybe $110 for pads, and about $50-$100 for caliper seals. You can do it yourself, if you know what you're doing, take your time, and a lot of care.

Yeah it is like your VTR with the T above the mudguard. I've been thinking about putting in a master cyclinder kit and maybe braided lines at the same time, where'd you get your lines from? Were they premade or made to fit your bike?

[vifferman]

Yeah it is like your VTR with the T above the mudguard. I've been thinking about putting in a master cyclinder kit and maybe braided lines at the same time, where'd you get your lines from? Were they premade or made to fit your bike?

Weeeellll.... the first set were bought on TradeMe - they were BSR Aerotek ones and cost me $150, if I recall. Had to be ordered from the UK to fit the VTR. They were beatifully-made lines, and looked nicer than what I replaced them with, but unfortunately, they didn't have the all-important DOT markings on the sides. My first posting on KB was about these, and their legality. So, they were on the bike 4 days, then I took 'em off and got my money back. Kerry at Motohaus replaced them with some LTSA-approved ones, which cost me ~$250, but that included having all my hydraulics (incl. clutch) bled, and the lines fitted. Can't remember what brand they were, but they were ex-stock, Kerry just measured up the lengths, grabbed 'em from his rack, bolted 'em on.

Other places here make them to measure. The important thing is that whatever you put on must be WOFable.

[Storm]

Paul- was even funnier when you came over the rise behind him and found the bike sitting in the middle of the lane while a car was heading straight for him

[dhunt]

Paul- was even funnier when you came over the rise behind him and found the bike sitting in the middle of the lane while a car was heading straight for him

Yeah it was a good thing you were following cause I didn't have my cellphone on me so I would have had to walk a couple k's back. I really should get a toolkit for my bike so I don't have to bludge tools off everyone then maybe your bike might not have blown over either. while you come help me.

[FROSTY:Me]

Mate just do one thing at a time. first off is there too much free play in the lever as stock? There needs to be a very small amount of movement before it touches the master cylinder.
definitely pump all the brake fluid out of the system and replace it with new stuff.
Polish your pistons getting rid of all or and gunge built up around them
lube your piston seals
On lil trick once youve done that stuff is to pull the calipers off and give one pump on the brake lever. Refit the calipers--theyll be tight
sometimes itll improve ya brakes because it lets the piston seals settle into a relaxed state with the brakes off rather than trying to pull the pads back half a mm

[Milky]

I agree with Motu there - the return port will be blocked now that you have taken the free play out of the system. The return port could be blocked by corrosion if the freeplay doesnt explain it.
The no braking until the lever is half way in is likely to be the caliper seals pulling the pistons back as Frosty says. I would recommend taking them apart and cleaning + using brake fluid compatible grease on the seal faces. His quick fix may well work, but why not fix the cause of the problem, not the symptoms?

[dhunt]

Well It looks like I'll leave them as is for the time being as I don't have the $$ or the time to spend on them at the moment. Maybe in the rainy season (winter) I'll spend some $$ on them and pull everything apart. Should be fun but I'm currently saving all my $$ to get me through my last year at uni.