Jittery when braking

[shereen]

VFR400 NC30 When braking hard the bike 'jitters' through the handlebars. Took it to garage as I was concerned that the head bearings were knackered. Mechanic said it was the brake pads rattling inside the callipers and nothing I can do about it...... I'm not convince.

Thoughts?
____________________
"The Internet is the first thing that humanity has built that humanity doesn't understand, the largest experiment in anarchy that we have ever had"

[G]

Wouldn't expect that under hard braking.
Check the wheel bearings, which is the most likely cause of that sensation in my experience.

[Skudd]

I had the same thing and changed my pads which cured the problem.

if it is a pulse then it will be the disc.
____________________
Famous last words of Humpty Dumpty. " Stop pushing me "
Petty Anarchists look at "1984".............. The Visionary looks at "Animal Farm".

[shereen]

[G]

[P.]

Get your hands down there

See if the front wheel has any play at all, grab a friend to tilt the bike on its stand and lift the front wheel, check the play in the bearings. While you are there you can check the head bearings also

Possibly check your discs? mine doesnt do what you state, but I get odd knocking from tapping from the front one of the button looking things on my disc is moving.. the rest are solid

[shereen]

[P.]

disk or bearings, neither are too expensive.

[shereen]

[Kickstart]

Hi

Are the disks stock ones? Had a cast iron disk which caused a load of judder on the brakes without being warped (no pulsing through the lever) after the pads had stuck to the disk (put away wet). Point where the pads had stuck grabbed the pads.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[jimbothe]

The wavey discs on my Gixxer always gave the impression of judder and pulse when they were cold.

Are they waveys like these:

https://i22.photobucket.com/albums/b342/jgillard/Allmymotorslovelyandshiny004.jpg

or are they the knock off cheaper style ones?
____________________
Check out our tackle shop on Facebook:
https://www.facebook.com/#!/JklTackle

[shereen]

This is mine

https://i959.photobucket.com/albums/ae74/Clearancelines/190155_1897101268835_1280701830_2280141_1885277_n.jpg

It still does it after a 20 mile ride though. I assume it would have warmed up by then?

Im thinking to take it to another garage and see what they come up with. I dont know enough about bikes to check for the wheel bearings etc.

They did check for play in the front end but they said it was ok.
____________________
"The Internet is the first thing that humanity has built that humanity doesn't understand, the largest experiment in anarchy that we have ever had"

[jimbothe]

[Kickstart]

Hi

Mmm, those disks look like they have fairly major cutouts at the edge, both in how far they go round and how deep they are compared to the position of the pads.

Wonder if the pads are rocking off the disk as they outer edge goes over the cutouts.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[shereen]

[jimbothe]

I forgot to ask earlier. How long have they been jittery for? Recently or since you had the pads done?
As Keith says, your discs have very large 'wavy' sections. Did you put these on or were they already on there?

Just trying to establish a 'when' factor and to determine if it's something recent thats started it. For all we know it could have had the jitter from the day you purchased it
____________________
Check out our tackle shop on Facebook:
https://www.facebook.com/#!/JklTackle

[shereen]

[jimbothe]

[shereen]

[jimbothe]

Well it's hard to say without actually seeing the bike and feeling for movement but you said the mechanics checked for play and didn't find any. If they couldn't find any then it doesn't really leave much on the front end. You could remove the wheel and check the spindle for uneven wear but this is unlikely to cause a jitter.


Other than that, broken spring, worn internal bushes?
____________________
Check out our tackle shop on Facebook:
https://www.facebook.com/#!/JklTackle

[Drew]

[shereen]

Hmmm, thanks for all the replies.

I think I will pop it into another garage later and see what they think. If they don't know what they are talking about I will change pads/discs and see what happens. I'm keen to get it sorted before I got to France on bike at end of the month so I really should pull my finger out

Will update with what happens.

Thanks again for every ones advice
____________________
"The Internet is the first thing that humanity has built that humanity doesn't understand, the largest experiment in anarchy that we have ever had"

[shereen]

Well looks like France is cancelled.

Just got back from mechanic -

There is play in the forks, suggests replacing headstock bearing, seals. Fork bushes, seal + new oil. Also need anti rattle shims in the calipers

Total parts £150 Labour £105

And he's not even sure if any of that is the cause of the jitter ffs!


blaaaaaaaaaahhhh!! stupid bike

rant over
____________________
"The Internet is the first thing that humanity has built that humanity doesn't understand, the largest experiment in anarchy that we have ever had"

[P.]

Basically

"I dont know what it is so i'll replace every possible cause on the front end"

Sounds like a nice guy

Hes basically changing headstock bearings (you or boyfriend could possibly do that!)

Fork seals, are yours upside down forks? I dont think they are... they are EASY to do if they are right way up.

Im still not sure its that..unless your forks are so soft.

£255 for head bearings and fork seals.. This is your anus ( O )

I bought fork seals, dust seals, braided lines, pads all round and some other bits and bobs for £79... im sure headstock bearings arent overly expensive (probably a pig to do on your bike though)

[0l0dom0l0]

It's funny, I've got exactly the same problem with my 93 CBR 600. It jitters exactly as you describe under heavy braking only. Not a warped disc as there isn't a pulse through the lever.

I'm thinking it was because I was bottoming out the forks as they were shot. I'm in the process of changing them over so haven't had a chance to test them yet.

Mine wasn't wheel bearings or anything like that as it passed the MOT and I watched the guy check it all.

Possible it was my pads but not to sure.

Are you forks spongy? Could be that they need a referb or something.
____________________
CBT Passed: 30/08/2009, Theory Passed: 31/08/2010, Mod 1 Passed: 6/9/2010, Mod 2 Passed: 13/09/2010. Restriction ended 13/09/2012.

Bikes: 2007 Derbi GPR 50, 1998 Yamaha Fazer 600 (written off), 2002 Yamaha Fazer 600, 1994 CBR 600F, 2003 Triumph Daytona 600, Kawasaki ZX6R J1.....Current: 2006 Yamaha FZ6, 1998 Suzuki TL1000R and a Honda VFR 400 NC30.