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 :brick:

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. :whocares:

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 :lol:

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. :bash: :argh:

[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.:doh: 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 :done:

[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 :done:
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. :doh: while you come help me.

[FROSTY]

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.

[F5 Dave]

Gee I’m confused. Is Motu on your ignore list? :confused: It is 90% likely to be free to fix.

Type in bigger font Motu, people can’t read your sage advice.

Ride the bike until the brakes lock up. Remove brake lever. Marvel at how this fixes the problem. Adjust or replace lever with genuine article so there is some freeplay.

Seen it again & again.

PS: saw a sign saying ‘Motu Enterprises’ when I was in Motuaka, almost took a pic to post but didn’t have the digital with me.

[dhunt]

Gee I’m confused. Is Motu on your ignore list? :confused: It is 90% likely to be free to fix.

Like I said earlier I don't have time at the moment to do this, I might have a go at playing around with it next time I'm out at my uncles as I don't have a tig welder either.

[Pickle]

Take your calipers off and clean the pistons, takes about 10minutes & you dont have the time?? Think about it next time you go for a ride! :brick:

Motu & F5 Dave have both given sound advice, stop complaining and do something about it.

[Motu]

Gee I’m confused. Is Motu on your ignore list? :confused: It is 90% likely to be free to fix.

Type in bigger font Motu, people can’t read your sage advice.


Ha - you make me laugh...fair dinkum,years ago I used to answer the phone on sundays with (insert my real name)'' Motu's free mechanical advisory service''...my mates wouldn't blink an eye and go right on - 'hey I've just pulled the head off,what's the head torque and tappet setting?'

It's an easy,and I think fun thing to do - go for a blast,using the brake hard till you feel it come on,back off the bleed screw,or remove the lever,go home and file some more off.Now I've got a tool on my belt that can solve the worlds problems,I'd rip it out and file away on the spot.

[dhunt]

Take your calipers off and clean the pistons, takes about 10minutes & you dont have the time?? Think about it next time you go for a ride! :brick:

Motu & F5 Dave have both given sound advice, stop complaining and do something about it.
Well I might give it go on the weekend then If I'm not busy, I'll have to go get some brake fluid sometime then. :done:

Thanks guys for all your advice. :2thumbsup

[Timber020]

I put an RF900 front on my GSXR750 and had the exact same problem with the brake locking up. with mine it was due to the brake lever being bent in such a way that it put just a tiny bit of pressure on the booster and as you rode it pumped the brakes up. Gave me the shits the first few times until it was worked out. GSX and GSXR brakes can be a pain in the ass.

[F5 Dave]

. . . next time I'm out at my uncles as I don't have a tig welder either.


That’s funny I don’t have a tig welder either.

I was going to mow the lawn, but I don’t have a Brazilian fishing licence.




What the???

[dhunt]

That’s funny I don’t have a tig welder either.

I was going to mow the lawn, but I don’t have a Brazilian fishing licence.

What the???
:niceone: :lol: Need the tig welder to build up the weld so I don't have to pull my leaver in so far. I thought that's what you were on about me doing???

Why I'm at it, if you pull your calipiers apart do you have to replace the o ring seals or can you normally get away with using the old ones.

[F5 Dave]

Um, no, the exact opposite, if the lever is slightly pushing in the master cylinder piston then you need to file it. Or you could file the stop so the lever opens more which is preferable if your hands are big enough to grab a lever that is a little further away.

Usually the seals are good, but be prepared to by new ones if any doubt.

Really I’d try the lever first.

[dhunt]

Um, no, the exact opposite, if the lever is slightly pushing in the master cylinder piston then you need to file it. Or you could file the stop so the lever opens more which is preferable if your hands are big enough to grab a lever that is a little further away.

Usually the seals are good, but be prepared to by new ones if any doubt.

Really I’d try the lever first.
Ok now I understand what you're trying to say. I've already filed it down so it doesn't lock up anymore, So I was thinking you ment put more weld on and then slowly file that away, hence the need for a welder. Also filed it so the leaver is slightly further away.

Yeah that's what I'm a little worried about pulling the calipiers apart but I guess if it has to be done it has to be done.

[Motu]

On my XLV750 I changed the lever to bring the lever in closer for my dainty girl like hands...but I filed a bit too much on the last attempt.As a temp fix I folded a peice of stainless cut from an old hose clip and used it as a shim - it was still there 3 yrs later when I sold the bike,never did bother to modify another lever,if it works,it works

Seals can often be used again,but I'd get some anyway - you don't want to be standing there with your calipers spread over the bench saying...''shit!,now I need some seals and they have to come from Japan!''

[dhunt]

Seals can often be used again,but I'd get some anyway - you don't want to be standing there with your calipers spread over the bench saying...''shit!,now I need some seals and they have to come from Japan!''
Yeah that's what I'm afraid of. So I might leave playing round with them until I can afford to buy some new seals.

[imdying]

Didn't read the whole thread, so hope I'm not repeating too much. What you did by adding the weld, was take the free play out of the master cylinder, which means the brakes were essentially on all the time (which you probably gathered). Because your brakes are ineffective till about half pull, you wouldn't have noticed initially. No foul though, seen plenty of people (even mechanics) do it.

If the bike is getting on, it's probably a combination of things causing the 'squish'.
- Hoses are buggered (either new ones from the manufacturer, or Safe R Brakes in Chch can make new ones with low expansion hose).
- Calipers are gummed up, and the caliper seals are worn. The caliper seals are a square section that skews under brakes, so they might be knackered and worn out. They're almost always an 1/8" section oring, availble from any brake specialists (I have a list of them if you're stuck, I'll even give you the part number if you measure the piston diameter)
- Master cylinder seals are poked. Needs a new kit, probably from the manufacturer. Although if the bore is poked, it'll need resleeving. A few places in NZ do that, the better ones will rekit it as well as sleeving it, saving you the trouble (and probably the $100 a genuine kit costs, because they've had seals made to fit).
- It isn't bled right, or the fluid is old. Air compresses, fluid won't. Master cylinders must be primed (get the air out) before hooking up the hoses. They're like oil pumps, they won't pump air. Bleeding bikes is a pain. The air has a long way to go down, and it wants to keep floating back up. You need someone who can do it, or the easiest way for someone who is new to bikes is to make the calipers higher than the master cylinder whilst they bleed. There's other tricks, but that's easiest for Mr I've No Tools.
- Pads/discs are poked. Doesn't help when the brakes are taking up heaps of space where ridged/lipped discs and pads are meeting.

A combination of these in small amounts is enough to turn good systems into poo. I hope something here helps.

/edit: Can't think of a good reason to ever start modifying levers if the brakes are in good nick. Most levers have that sort of adjustment built in (sometimes a screw, sometimes a span adjuster, cause lets face it, the only thing you can really adjust there is the span.... And a good tip is always always clean your caliper pistons when you change pads. They're sticking out, and you're about to push them in. The dirt on the pistons is all bad news for the seals. Just use a tooth brush and hot soap water (or brakekleen if you've got it). Takes 5 extra minutes, and most bikes don't have the dust seals that cars do. Don't ever use anything petroleum based on brakes though (like CRC, kero, petrol etc), just hot soapy water will do it :)

[moko]

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.

I hope your not going to ride it like that,never take any chances with brakes or tyres,could well cost a whole lot more further on down the road,you`ll be anacident waiting to happen.

[Dodgyiti]

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!

Yeah, and if you do go to stainless- make sure they are DOT approved lines as next WOF you might get knocked back.
Good advce about using new fluid, always crack a new bottle when doing the bike, use the leftover for the cage.
Rubber hoses are OK for a reasonable lifespan, they will expand over time and hard leaver input.
The M/cyl freeplay will be listed in the manual, and is vital you get it correct.
For the price of a few cups and dust seals [ try to get general ones from a Brake and Clutch outlet before you go 'Factory' replacements] it would be worth pulling it down for an inspection. If only to check the movement of the pistons and if any lips have formed in the bores. Then at least you know it is all good afterwards, surgically clean, new fluid, blead up, and then see....

[DEATH_INC.]

I think the prob is the calipers too.Easy fix,spray some cleaner to get rid of the crud on the pistons where they protrude from the calipers,then push 'em all the way back in,then pump 'em back out (with the caliper over the disc),repeat a couple of times.Give it a try it'll only take a few minutes.
One other question,are they firm once they take up the freeplay,or are they spongy?

[dhunt]

Well my brakes are on the fix it list still, it seems they pump up slightly better than they use to do after a few minutes riding. So will try and get a M/C kit and pull the calipiers apart one weekend soon and see if I can get too the bottom of the problem.