e mare libertas
Yup, that swot it is. Didn't take me more than about 10 seconds after I first noticed it riding the bike back to get a very strong impression that a warped rotor would be the only thing that could make the brakes feel that way.Originally Posted by F5 Dave
Yup, I'll do the brakes (and maybe get brave and attack its innards with a can of carb cleaner) this weekend, all going well.
Anyone got a Zeal manual, by the way?
kiwibiker is full of love, an disrespect.
- mikey
No8 Wire Extraordinaire
Yeah if you do pull the pistons out, carefully take the seals out before getting near with any cleaner. Anything like this will swell the seals. Once they are out then go for it. Spectro metal cleaner is king.
Then you will likely notice some white powder under where the seals were which can be cleaned out. If the pistons need more cleaning some fine scotchbrite (plastic kitchen pad) is good to remove minor corrosion without stripping off the plating hopefully.
You can use a small sash clamp (~$4 from you know where) to push the pistons back in, but obviously they need to be straight in the bore to start with using finger pressure.
Sadly this won’t cure the disc issue, but brakes that drag may help cause the problem in the first place.
Don't you look at my accountant.
He's the only one I've got.
parting of the sensory
If the pistons are really unhappy (pitted and corroded), then they'll need some polishing with Autosol metal polish or similar. If you can, a buffing wheel is best to use for this.
When you put the seals / pistons back in, lubricate them with brake fluid. And don't get this stuff on your skin - it makes it nice and shiny, but takes days to clean off, and while it's soaked into your skin, its hygroscopic nature will wrinkle your skin like an old prune.
Or so I believe....
Incidentally - the brakes on the VifFerrari also pulse, but I took the bike back to the dealers and asked them to check them for runout (warpage) and they said they were fine, so it's just corrosion on the disk surface which should wear off. Unless they're lying, to avoid replacing the disk(s), which is not out of the question...
This weekend (if chores allow) I'll be checking the runout myself, and pulling the disks off to scrub them (seeing hard braking hasn't done it).
... and that's what I think.
Or summat.
Or maybe not...
Dunno really....
No8 Wire Extraordinaire
If it’s really bad you will feel it at the lever.
Corrosion on the disc? Oh please! My Iron PFMs would go orange if wet & left. They scrubbed it off in about 4 rotations.
However some pad materials apparently bite & let go, something about gassing & heat.
The big question is whether you feel it braking at high speed. This is a safety issue & can only be the discs.
Discs can warp in several ways. As you would imagine a crinkle or wave warp. Or they can ‘cone’. Or if badly machined they could vary in width. This being the worst scenario.
Don't you look at my accountant.
He's the only one I've got.
e mare libertas
That's probably the ABS going off, you creaky old Honda rider. Or the linked braking system, or the ActiveSuspensionReticulation (tm), or the RetroTorquedStabilityEnhancer (tm), or summat...
Anyway, mine doesn't pulse. It shudders. And with the currently way-mushy forks, there are narsty effects at high speed when braking hard over bumpy bits. Viz, to wit, I don't do it, because it will make me fall off.
kiwibiker is full of love, an disrespect.
- mikey
No8 Wire Extraordinaire
Yams often have soft forks. Fire in a bucks of 20 cent pieces & another 15mm of fork oil per side should help.
Failing that some stiffer springs. This can be free, If they have enough fee coils not to bind then removing a few coils will stiffen the rate. The top coil needs to be bent flat using heat & ground. Then the preload spacer needs to be made longer to accommodate the lost length.
Let me know if you want to try this I’ve done a few now. Um as recently as last night as it happens.
Don't you look at my accountant.
He's the only one I've got.
parting of the sensory
Well, the right-hand disk did have visible corrosion on the disk in patches, including one patch the shape of a brake pad. If it was even (and just rust), then it wouldn't have been an issue.
The left and right disks don't match - they have different drilled patterns and the carriers are different colours. So one of them has been replaced.
It's only apparent when braking gently at low speed (when tootling along in heavy traffic), and it's of the "bite 'n' let go" variety. Bloody annoying it is too...
I've had bad disks before - when I replaced the VF500's front disks with NSR(?)250 ones I couldn't get a straight right-hand one, so I fitted the straightest left-hand one they had, reversed. It had a slight wave warp.
I got rid of most of the warp by fitting different numbers of paper washers under the mounting points.
Judicial bending with a big shifting spanner can also work, or pounding on a hard, flat surface with a large blunt object, like an auto transmission or one's head...
... and that's what I think.
Or summat.
Or maybe not...
Dunno really....
e mare libertas
Yams warp their discs. Yams have soft forks. Yams rape your grandmother and leave dirty dishes in the sink. Boiled Yams taste bad.
Remind me why I bought a Yamahahaha, someone?
kiwibiker is full of love, an disrespect.
- mikey
parting of the sensory
More likely to be the OverabundanceOfTrendyAcronymicalFairingDecals...
And it doesn't have ABS (there wasn't room for another decal on the fairing). Only the VTEC VFRs have ABS as an option (wonder how they fit VTEC, DCBS, HECS, EFI and ABS on the fairing?) And because we're a QuietBackwater, we don't get the ABS version anyway.
I'd shudder too, if I were your bike...
Anyway, as Dave said, that'll be summat to do with gassing and heat. Stop eating chilli beans.
... and that's what I think.
Or summat.
Or maybe not...
Dunno really....
No8 Wire Extraordinaire
Forks are easy to stiffen. The Discs are a problem, but so are many bikes when they get old. Just put new discs on my Suzuki.
As a brand they have very few issues.
Don't you look at my accountant.
He's the only one I've got.
parting of the sensory
It was an excuse for a Motorcycling Adventure, to whit (to woo...) riding from Wellietown to D'Auckland.Yams warp their discs. Yams have soft forks. Yams rape your grandmother and leave dirty dishes in the sink. Boiled Yams taste bad.
Remind me why I bought a Yamahahaha, someone?
... and that's what I think.
Or summat.
Or maybe not...
Dunno really....
No8 Wire Extraordinaire
um I was going to suggest just using the back brake in traffic, but ah, ah, somebody done connected them.
Maybe it's the back disc that is bent.
Don't you look at my accountant.
He's the only one I've got.
parting of the sensory
Nah, it's definitely the front end.
When braking with the front brake, it operates two pistons on each front disk, and the centre one in the rear. The brake pedal operates the other two pistons in the back, and the centre pistons on the front disks. The feel is quite different when using the brake pedal as there's less front braking going on (and hence very little pulsing).
It actually works quite well, eliminating a lot of dive (the bike sort of squats down, rather than the front dipping), and means using the pedal when in traffic offers a little more finesse than the lever, but they bite hard when using both.
The worst thing about them is the complexity when bleeding them, and the initially weird feeling after other bikes (lack of absolute control over how much of each brake you're using).
The newer generation of DCBS is a lot more subtle, and very good indeed.
... and that's what I think.
Or summat.
Or maybe not...
Dunno really....
There are currently 1 users browsing this thread. (0 members and 1 guests)
Posting Permissions
Reply With Quote
Bookmarks