spongy front brake

hi guys,here in the u.k. all bikes need yearly bike certificate m.o.t.anyway mines FAILED garage tester said to much free play at front break.renew rotor,pads rebuilt m/c,thanks for supplying parts len. pretty sure lines are bled gonna take fitz;s advice renew s/s lines can anybody tell me how much pull on break lever b4 pads bite on rotor??any help or thoughts would be great,thanks in advance guys

 

There is a small adjustment bolt in the end of the brake lever that pushes against the piston. This can be adjusted to give the proper amount of free play in the lever. The exact spec can be found in your service manual.

The rebuilding, and upgrading of the front brake is considered a necessary maintenace issue. No money lost there.

Ghost

 

To (I think) answer your question, once the brakes have been properly rebuilt, there is very little lever travel before the pads bite the rotor; the brake should be like "grabbing a rock." You can use the aforementioned adjusting screw to introduce/reduce the amount of play.

 

You said they're bled, but how old are the lines?

NEW, stainless steel lines will make for a MUCH firmer, positive brake feel over the stock rubber hoses.

Check the date code on the lines, anything over 4 years old, REPLACE.

 

I could not see a date on mine when i looked but they feel solid to the point of grabby

 

Look harder. Slide the sheathing back (where there is sheathing) and look under it.

 

Check it out:

http://xjbikes.com/Forums/viewtopic/t=4 ... art=0.html

 

Yeah i just did they are the ones from 1981

 

yip original lines will replace these over the weekend and will get back to all with results ,thanks for the replies for now guys

 

Hey guys! It would be fine if you could cut and split some sections of your old brake lines, then take pictures on their condition inside the inner liner and post them on the forum.

 

yip their was still a lot of air, still in their!!!!!but will not be happy now till i replace these original line with s/s line notice the original line seems to be in two parts joined behind the yamaha badge on forks.can i cut all this away and relace with a single s/s line from m/c to caliper on wheel?if so what length of single line do i need,may sound a silly question??then i gotta split these long ways and post up a pic thanks for any thoughts guys

 

Now I'm putting on my flame-retardant underpants---

I still have all the original brake lines on ALL of my bikes. And the levers are ALL rock solid.

Dave F

 

Glad your old lines are still working, but as the rubber ages it will be more prone to cracking (failing) and then NOT working when you need them to. Like stopping for someone who makes a left turn and doesn't see you.

To answer Boldstar, yes you can use 1 or 2 long lines straight from the MC, you just need the proper Banjo bolt (the one from the splitter should work fine). It's alittle more annoying to route (zip-ties are handy) but in effect it's a better setup, less lines with less areas for air pockets to form.

I find when I bleed my brakes (or on my FZ750's the clutch as well) I have to REPEATEDLY bleed at each banjo. I've also had great success in after bleeding all the banjo's to bolt up the resevoir cover and move the bars and leave them at either side for a few minutes, trying to move around any bubbles. I've bled to what I though was a perfect system, moved the bars around abit and just for giggles bled again and still got tons of air out.

 

Dave, you're giving a very bad example, don't you know?

 

Changing-up to Stainless-wrapped Brake Lines is a great improvement.
But, if the Brakes are spongy AFTER you did a Bleeding; the problem is likely to be the Master Cylinder.

The Brake Lever should not be able to be pulled all the way to the Handlebars.
If the Lever is Spongy, ... the MAIN Hydraulic Seal might be "Leaking-by".
If so, the Secondary Seal applies System Pressure until the Pads contact the Rotor, ... then the Brake Fluid within the Master Cylinder Bore is FORCED out of the Cylinder's Replenishment Orifice.

This condition can be verified by observing the Brake Fluid in the Master Cylinder's Reservoir.
Level the Master.
Remove the Cover and Bellows Gasket.
(Take precautions to prevent Painted surfaces from a Brake Fluid spill.)
Extract Brake Fluid from the M/C Reservoir until the Reservoir is about 1/2 full.

Work the Brake Lever.
Observe the Reservoir.
If Brake Fluid shoots-up in a fountain-like fashion; the M/C's MAIN Seal needs replacement.

 

Just to add to Rick's post... wear saftey glasses. If it's blown it can shoot QUITE far and that stuff REALLY burns.
So does Carb Cleaner.
Don't ask how I know these things.
Also, WD40 tastes like chicken.

 

That last one made me laugh!

 

well guys been waiting for new lines to arrive,finally replaced with quote SEXY NEW S/S BRAIDED LINES had to get that in fitz :wink: and a big heads up for bringing the subject up.yep was original 81' lines actually split them long ways to check internals they [for what i could see] looked good no cracks or tiny rubber particals but bottom line is a BIG THANKS to all you guys who chimed in with replys and piece of mind that breaks are now replaced totally and rock solid

 

Now that you've split your old lines you could do what a really anal person like me would, and slip the old rubber over the new braided lines for an original look! :wink: Or not....... :lol:

 

OMG, ...

That's tantamount to having Leather Seats Vinyl Covered.

But, ... whatever floats your boat!!!

 

It's the Kawi Z (KZ in the US?) owners that take it to those lengths 8O

I'd just have the black PVC coating... possibly

 

The rubber sheaths only covered parts of the original lines, depending on the bike.

The new lines are only about 2/3 the diameter of the original, rubber and CLOTH lines. (Reminds me of the wiring in my '58 Bugeye Sprite among others.)

To reiterate:

THE PRIMARY REASON TO REPLACE BRAKE LINES IS THE AGE!!!!!

YAMAHA SAID FOUR YEARS. THIRTY IS BEYOND OLD in brake-line years.!!!!

Am I the only guy that's ever popped a brake line? Get serious, folks.

Let's see that sexy stainless... (black covers)





(I painted the fittings black on this bike. Talk about being careful with brake fluid...)

 

No, my mate has a range rover in the workshop now with 2 literally burst front brake hoses. Seen quite a lot fail in the sense that they lock on after hard braking due to loose flaps of rubber acting as a one-way valve, I'd say thet's more common here (less sun damage ) but no less dangerous.

And wow, if the devil's in the detail then Fitz's bike needs a 666 registration plate...

 

I'm happy with my current plate (it's the little details that count

 

Ahh yes, that does suit rather well BigFitz... Or is that OldNick? :twisted:

Tell you what, if this old 750 comes up half a tidy as that I'm on a winner... What proportion of NOS parts went into that versus proportion of plain hard graft on originals would you say?

EDIT- are those Dunlop Arrowmaxes on there?

RE-EDIT- oh no, can just see the Avon logo. similar tread pattern to the GT501's

 

The black bike was a no-holds barred, no expenses spared, build a bike to ride for the next 10 years project, so it doesn't count. It's NOT restored; it's resto-fied. It LOOKS stock; the running gear is essentially stock; but the rest of the bike has been brought up to 21st Century specs. I also powder coated and black-chromed a lot of parts, and added aftermarket bits, both current and period.

We're hijacking. My other 550 Seca was more of an original resto, with mild personalizations. Lots of work, not a lot in the way of parts except from other equally old bikes. I PM'ed you some pics.

 

I've been trying to check the hijacking a bit as I do get sidetracked very easily, but I figured here the o/p has resolved the brakes & they're rock hard now so it wouldn't do *too much* harm :wink:

restored/new built/resto-fied Whatever you call it, it looks pretty damn good. Subtle like, at a glance you'd only notice the radials & MZ-esque mirrors 8)