Front brake woe's

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redfalco · #1 Post by **redfalco** » Sat May 10, 2008 7:57 pm

Hi all, it seems that I only post when I have a problem. So here's the new one.

With only light presure on the front brake leaver and at low speed's when coming to a halt I can feel the leaver pulsing as if the front disc's are warped, after reading several old post's here and else where it seem's I had already done most of the things that have been sudjested. I've put new disc's and pads on, made sure the calipers and piston are clean but still the brakes aren't right.

I did read on a couple of posts that DOT 5 can eat the seal's in the master cylinder and those on the piston's,( yes you've guesed it ,I have dot 5 brake fluid front back and clutch).

So I've now changed all the fluid, brakes still not right so my next coarse of action is to change the seals in the master cylinder and brake pistons, only it seems brenbo don't seem to sell them.

That is unless any one knows different, or where I could send them to be overhauled ?

Falco9 · #2 Post by **Falco9** » Sat May 10, 2008 8:11 pm

Obvious question I know, but you have given the pads a chance to bed in to the discs?

If you have, what exactly is the problem? lack of stopping power? or poor feel? or............?

You should be able to buy new seals, Brembo don't manufacture them and often it's a case of taking the old ones to a specialist seal stockist, however unless you are actually losing fluid the seals should be still OK?

When I had my Falco I always fancied upgrading the calipers to the Mille 4 pad jobs so this might be a good opportunity for you??? The calipers from the Ducati 999 & 748 will also fit the Falco

F9

redfalco · #3 Post by **redfalco** » Sat May 10, 2008 8:27 pm

I've not had much of a chance to bed the pads in fully due to a lack of MOT, failed on front brakes, can't remember the term they used but said it may be warped disc's which I duly changed.

The problem is not a lack of stopping power, but a lack of final control at slow speeds and only gently squeezing the leaver.

Don't realy wont to go down the road of buying new calipers until I can cross off all the cheaper alternatives. But it is a thought that I shall now trawl ebay for, especialy now I know Ducati calipers fit. Might look for a radial master cylinder whilst I'm there.

Many thanx for the tip.

Falco9 · #4 Post by **Falco9** » Sat May 10, 2008 8:43 pm

Sounds to me like you may have a sticking piston or two. Have you cleaned and lubed them at all? although a seal may have failed if you can't get a smooth feeling at the lever. If it is a piston it's an easy job to do.

Remove the calipers and the pads then gently apply the brakes to squeeze out the pistons. Using a pice of wood (or similar) as a make shift disc (make it wider than the disc) will prevent the pistons from popping out, if any are sticking you'll be able to see, as they hit your makeshift disc the sticking pistons will be forced out. Clean them all with brake cleaner and make sure the pistons are thoroughly clean and not scored, a light smear with copper grease and push them back in. If their nice and clean you can do this easily by hand.

Apologies if I'm teaching my grandmother how to suck eggs. Maybe this will be useful for some-one who doesn't know how to do it maybe??

FYI most Brembo calipers (not radials) will fit the Falco, most of them have 62mm mounting points (at least I'm pretty sure it's 62mm) You can get a pair of Mille / Ducati brembo 4 pads monobloc calipers for about £100 off fleabay these days

F9

redfalco · #5 Post by **redfalco** » Sat May 10, 2008 8:53 pm

Me think's I shall be paying another visit to Halfords in the morning to purchase some more brake cleaner.

Hope all the grannies are busy sucking egg's or they may sell out.

Pierre · #6 Post by **Pierre** » Sat May 10, 2008 9:05 pm

Hasnt been in a bump has it? Reason i ask is if it was pulsing and you changed the discs (for new?) then maybe the wheel is twisted or the disc bolts arent clamping down evenly? or the forks are twisted so the calipers arent parallel?

Otherwise I would have said change the discs cos it worked for me . Btw, my warped discs had blue spots evenly around them where they hit then missed when braking

Nooj · #7 Post by **Nooj** » Sat May 10, 2008 9:09 pm

One thing there, do not use copperslip on brake pistons, the tiny copper bits will eventually grind your seals away, it's fine on the backs of the pads, but keep it away from the shiny silver bits. Use proper brake grease or silicon grease.

fastasfcuk · #8 Post by **fastasfcuk** » Sun May 11, 2008 8:13 am

it can only be warped disk's but if you've changed them and your sure there ok then as pierre says you've got a buckled wheel.the pulseing your getting is the disks pushing the pads back.

Falco9 · #9 Post by **Falco9** » Sun May 11, 2008 9:17 am

Nooj wrote:One thing there, do not use copperslip on brake pistons, the tiny copper bits will eventually grind your seals away, it's fine on the backs of the pads, but keep it away from the shiny silver bits. Use proper brake grease or silicon grease.

Very good point, Personally speaking I've always used copperslip because the cleaning is so infrequent and I do mean using a smear not a dollop. I've never had a problem over the 30yrs I've done this but technically though you are spot on!

Brembo do sell their own silicon grease for cylinder & piston re-assembly and that would be the correct grease to use on the pistons or I remember you can buy a "red" grease as well

F9

redfalco · #10 Post by **redfalco** » Sun May 11, 2008 4:34 pm

Had a go a the calipers again, this time making a mental note of how far each piston moved. Well the good news is they all move in and out, but the bad news is they all move a different amount.

Managed to get one caliper cleaned so that all the piston move pretty much the same distance, but I ran out of brake cleaner just in time to watch the world and british super bikes. So in all not to bad a day, and there is all ways tomorow after work.

D-Rider · #11 Post by **D-Rider** » Sun May 11, 2008 4:39 pm

Did you bed the discs and pads in properly when you fitted them? - if not it could be pad material deposition on the discs - which gives the same symptoms as warped discs.

See HERE

redfalco · #12 Post by **redfalco** » Sun May 11, 2008 4:55 pm

The feel in the brakes is pretty much the same now with new discs and pads as it was with the old one's, which the guy at the MOT reconed were warped. Not having a dail gauge took his word for it and fitted the new discs, but the slow speed pulsing at the brake lever was still there.

I could be the most unlucky person in the world to buy warped discs, or the fault could lay some where else. Just checking all the some where else's
before I have to spend any more money.

No Pierre the bike has not had a bump, it has done the usual look at me I'm an Aprilia watch me fall off my side stand.(not any gsxr more).

fastasfcuk · #13 Post by **fastasfcuk** » Sun May 11, 2008 5:07 pm

have you tried a hose clamp on one of the flexi's to see wich side is giveing you the problem to save you working on the side that is ok.im not telling you how to suck eggs but are the surfaces clean that the disc sits on.

redfalco · #14 Post by **redfalco** » Sun May 11, 2008 6:56 pm

I've got goodridge braided hoses, don't know how well they'd stand up to being clamped. Any who if one side is bad the other side wouldn't fair much better, they'll splash through the same puddles and collect the same road grime I would assume. Oh and I haven't got a brke hose clamp

Pierre · #15 Post by **Pierre** » Sun May 11, 2008 9:47 pm

You need a controled experiment , just like what grown ups have.

Where in the world are you? I have a spare front wheel and discs for my track bike you could try if near. If not, maybe a local rsv/tuono/capo? owner could lend you his for a quick blast