Front brake question

[texas-ss-tornado]

OK, new project 94 has a "sticky" front brake, although that's probably not a good term for what it's doing. Hard to describe, but the action of the lever is not smooth, you can pull it in slowly and nothing happens, then all of a sudden, about halfway through it's lever travel, it will grab, and then the brake seems to work OK. I'm wondering what could cause this, maybe air in the line? I'm going to give it a good bleed tomorrow but wondered if anyone else had experience with this symptom?

 

[KJShover]

It could be air in the line, or possibly a sticky caliper.
But I'm leaning more to a fluid swap and bleeding.

 

[MaxMidnight]

Whilst it never hurts to bleed the brakes and change the brake fluid I don't think that is your problem.
Air in the line would give the lever a soft feel and you would need to exert extra pressure to get the brakes to work.

Start by removing the lever, clean and re-grease the pivot.

Remove the callipers, one at a time, then the brake pads and inspect the area around the pistons for a build-up of crud and/ or corrosion.
It will help if you ease the pistons out a little, but be careful as you pull the lever as you don't want to pop them out.

A piece of wood about the same thickness as both pads inserted into the calliper will prevent this.
As you pull the lever look to see if one or more piston is seized or slow in coming out.

Carefully scrape away the detritus and then clean around them using (say) an old toothbrush (as using that belonging to your nearest or dearest tends to annoy) with brake fluid.

Once clean you should, with a bit of effort, be able to push the pistons back into the bore and they should all come out at the same rate when the brake is applied.
If a piston is badly corroded then rather than try to clean it up it may be easier to get another calliper (an excuse to upgrade?) depending on the degrees of rust.

 

[donnelly317]

Mines the same way.. I bought FZR1000 6 pots and I can even feel it worse because of the increase brake feel. Im getting a Nissin master. I could almost garentee its the master seeing how I changed fluid and calipers and it's still there! Ill let u know if it goes away.. either a new master or a rebuild kit might need to be in hand for you

 

[tugla]

a rebuilt on the master may be in order or change it out,lots of choices or not that expensive to get a factory one.

 

[texas-ss-tornado]

Thanks the insights fellas, will let you know what I find out! unk:

 

[bazwell]

I'm in a bit late... but I'd look at the m.cyl as it sounds like it might be mechanically binding.

 

[mild83]

I'm having the same problem. Just tonight I was able to finally put some miles on in mixed riding. I noticed that from 20 mph, I could pull the front brake lever all the way in (to the point that it hit the accelerator) and the bike would only slow down. Certainly not bite down from what I'm accustomed to on my 929 (I do expect there to be a major difference b/w the two).

The bike had just had a brake service in march 2012, had the front and rear brake fluid, clutch fluid, rear hub fluid. Then noted that the previous owner brought the bike in for what seems to be the issue mentined above, and the notes state "tech did not feel anything wrong with the front brakes. they are old an old style brake system so they don't grab as hard as a newer bike will" WTF? that seems really odd.

Thoughts?

 

[gamorg02]

100% not normal. do u have 4pot or 2pot calipers? what year vmax?

sounds like air in the line. could need a master rebuild.

 

[MaxMidnight]

++1

That sounds dangerous!

 

[mild83]

100% not normal. do u have 4pot or 2pot calipers? what year vmax?

sounds like air in the line. could need a master rebuild.

I'm sorry, it's a 91 (I just realized I never updated my profile), it's 100% stock, I'm not sure if it's 2 0r 4 pot calipers.

++1

That sounds dangerous!

Yeah, when I test rode it, it didn't seem this pronounced when I test rode it. Then I reviewed the service paperwork that was completed (it was at a very reputable dealer) and figured that it was just typical. My previous 2 bikes haven't really ever had any issues. Both are sportbikes, so again, I just expected it to be normal.

 

[one2dmax]

It will normally lock up the brakes but just take more effort. They will be 2 piston calipers. If you really want a brake upgrade you should do some checking on our 6 piston hayabusa conversion. This will get you brakes like you are used to on the sportbike.

 

[gamorg02]

seans upgrade options are great, definitely something to keep in mind

have you bleed the system? if a shop did the work i would promptly take it back.

altho a lot of us don't trust shops and i'm sure we can walk you thru bleeding.

 

[mild83]

It will normally lock up the brakes but just take more effort. They will be 2 piston calipers. If you really want a brake upgrade you should do some checking on our 6 piston hayabusa conversion. This will get you brakes like you are used to on the sportbike.

I'd prefer not to upgrade, as this is kind of a cheap option for me as a purchase, trying to keep it in good, running (safe!) condition.

seans upgrade options are great, definitely something to keep in mind

have you bleed the system? if a shop did the work i would promptly take it back.

altho a lot of us don't trust shops and i'm sure we can walk you thru bleeding.

Well, the work was completed in march 2012, roughly 2k miles have been put on since then. I'm thinking the dealer will tell me to pound sand, but I"m going to call them.

 

[one2dmax]

The adapters are $60. With the right scores on ebay you can get the rest of the stuff for a couple of hundred (or less). Can't put a price on safety.

 

[kiwi JK]

Sorry to break in on this thread but I have a question about the front discs fitted to my 89,they are obviously not standard but I dont know what the hell they are .
They are cast iron material (read rust like buggery if they get wet) 320mm OD 220mm ID they are floating on 10 pucks but are only 3.8mm thick which means that I have problems every time I have to get my 6 monthly warrent of fitness check (safety check). The calipers are post 93 4 pots mounted on what are obviously fabricated extension brackets.
Dont get me wrong these brakes work awesome but the thin discs are a source of some concern so I would like to upgrade to something that will be more acceptable to our local inspection authorities unless someone can shed some light on what these discs are and what minimum thickness should be.
Thanks in anticipation for any help
JK

 

[Fire-medic]

A pic for the lads to help i.d. would help. Thinking maybe some Ducati replacement part as the dia. is right, # of buttons, & thinness sounds like a weight-shaving spec. Smells like a Ducati part. Try searching in here under replacement rotors or some such.

 

[mild83]

Talked w/ my dad and brother, both seem to think it just needs to be bled. Is there a how-to video/write-up on the site?