Brake juddering: THE SAGA CONTINUES.

[The Pastor]

Hi everyone,

I have an awesome gpz1000rx 1986, awesome except for the fact that under braking I get that bad juddering (real bad here, no slight pulsing BAD BAD BAD juddering.


Oh thats easy you say, new discs.

Done that. Problem still there.

Was suggested that the rim could be bent (hit a traffic island at speed) and to overhaul the brake calipers and get new bearings.

Done all that and still the problem is worse (I also fitted braied brake lines at this stage).

I thought maybe the "new" - read 2nd hand, discs were not true,so I sent them off to f1 in hammyton, and they confirmed that the discs are true and within tolerance. - they still re surfaced them to be sure.


F1 said to check out if the hub was out of true and to check theres no crap between the disc and the hub, I had a look and there was a very tiny ammount of stuff which I took off with a bit of sand paper.

so kb gurus, what on earth could be causing the juddering under braking? When slowly moving/pushing the bike and I apply light brake pressure I can feel the brake lever pulsing

I hope I have given out enough information.


Thanks for you help

Rm

[Ixion]

Worn forks (or fork bearings), worn steering head bearings, worn wheel bearings (front or rear), wheels out of line, bent triple tree, bent frame, bent swing arm, worn swing arm bearings, worn rear shocks, bad tyres, worn master cylinder, worn slave cylinder, old hydraulic fluid. Take your choice.

[slowpoke]

Just to confirm, has the problem only appeared since you hit the traffic island?

[The Stranger]

Do you have access to a dial indicator?
If not, lift the front and spin the wheel, do the disks move sideways within the caliper?
You should be able to get a fair idea by eye.

If you rotate the front axle when the wheel is still does it move the disks sideways within the caliper?

[The Pastor]

Thanks guys for your fast replies!


Worn forks (or fork bearings), worn steering head bearings, worn wheel bearings (front or rear), wheels out of line, bent triple tree, bent frame, bent swing arm, worn swing arm bearings, worn rear shocks, bad tyres, worn master cylinder, worn slave cylinder, old hydraulic fluid. Take your choice.

hmmmmm alot of those options sound very expensive. Wouldnt most of them have side effects that don't just happen under brakes?, Hydraulic fluid? You mean brake fuild? Obviously I put new stuff in when I got braided brake lines, and again when I over hauled the brakes. Put new wheel bearings in. The only one on that list that bothers me is wheel out of alinement, how would I check that?


Just to confirm, has the problem only appeared since you hit the traffic island?

No this has happened since I own the bike.


He has actually given quite a good description of the problem Ixion, i.e. can feel brake lever pulsing when only pushing the bike along, this discounts most of your "options". I dont have any help for RM, but I would suggest your post is not awefully helpful, perhaps you could refine your answer a little to be more specific.

Cheers speedie, hopefully somone will be able to sovle this mystery - It starting to sound like a scooby doo episode!

[The Pastor]

I should note, these brakes (and 1 speeding ticket, 2 licence tickets) have completely cleaned me out, no more $$ to buy anything.......




Do you have access to a dial indicator?
If not, lift the front and spin the wheel, do the disks move sideways within the caliper?
You should be able to get a fair idea by eye.

If you rotate the front axle when the wheel is still does it move the disks sideways within the caliper?


No dail indicator, Im just waitng for the discs to come back from f1, should be here by 3pm.

I'll give a go at spinning the wheel, if they move with in the caliper, what dose that mean?

[The Stranger]

No dail indicator, Im just waitng for the discs to come back from f1, should be here by 3pm.

I'll give a go at spinning the wheel, if they move with in the caliper, what dose that mean?

Given we know the disks are true.
If you rotate the axle but not the wheel and the disks move sideways within the caliper it would indicate a bent axle.

If you rotate the wheel but not the axle and the disks move sideways within the caliper it would indicate a bent wheel.

Quite simple tests really to test out the wheel and axle. You have already checked the disks. So then you have to look at the calipers themselves. I have not had experience of a caliper causing this, but was advised by a motorcycle mechanic that it can when I went through this problem with the GSXR.

They are pretty easy to strip and clean, so why not do that anyway.

[The Pastor]

Given we know the disks are true.
If you rotate the axle but not the wheel and the disks move sideways within the caliper it would indicate a bent axle.

If you rotate the wheel but not the axle and the disks move sideways within the caliper it would indicate a bent wheel.

Quite simple tests really to test out the wheel and axle. You have already checked the disks. So then you have to look at the calipers themselves. I have not had experience of a caliper causing this, but was advised by a motorcycle mechanic that it can when I went through this problem with the GSXR.

They are pretty easy to strip and clean, so why not do that anyway.


Ive cleaned the cailpers. And the wheel has been "unbent".


A bent axl, that could be it great snakes I might be able to fix it!\


Any way to check for a bent axle with out the discs?

[The Stranger]

Ive cleaned the cailpers. And the wheel has been "unbent".


A bent axl, that could be it great snakes I might be able to fix it!\


Any way to check for a bent axle with out the discs?

Yeah, with a couple of V blocks and a dial indicator.
I guess you could roll it along a known flat surface, but that would be the trick - getting a known flat surface.

[Ixion]

hmmmmm alot of those options sound very expensive. Wouldnt most of them have side effects that don't just happen under brakes?, Hydraulic fluid? You mean brake fuild? Obviously I put new stuff in when I got braided brake lines, and again when I over hauled the brakes. Put new wheel bearings in. The only one on that list that bothers me is wheel out of alinement, how would I check that?


Other side effects ? Possibly. You don't mention any , but every mechanic knows that doesn't mean much. The number of times I have heard something like "My xxx is doing yyy": " Hm well, we've checked a b and c. It could be d , but if it were you also be experiencing zzz " : "Oh , yeah , it does that, too" :brick:

Also, heavy braking puts more load on most supension components than almost anything else. So sometimes wear that causes minor effects the rest of the time , will show up markedly under braking. Especially if the bike is old and has been like that all the time you have had it - the "other effects" may be something that you simply take for granted.

Wheel alignment, check it with a ling straight edge along the axis of the bike. Check that with the forks dead in line ahead, both wheels are straight in line also, and in line with the swing arm. Check the wheels in several positions.

Perversely, wear or damage at the rear of the bike often shows up as a problem at the front. Did you check/replace the rear wheel bearings as well as the front?

Also, check your wheel for balance.



If you rotate the wheel but not the axle and the disks move sideways within the caliper it would indicate a bent wheel.

Quite simple tests really to test out the wheel and axle. You have already checked the disks. So then you have to look at the calipers themselves. I have not had experience of a caliper causing this, but was advised by a motorcycle mechanic that it can when I went through this problem with the GSXR.


OP does say



Was suggested that the rim could be bent (hit a traffic island at speed) and to overhaul the brake calipers and get new bearings.

Done all that and still the problem is worse (I also fitted braied brake lines at this stage).


though it would still be worth rechecking. A bent axle would definately be worth checking for .

Ultimately, judder occurs because something is causing the front wheel to try to head off along a different line to the rear wheel (and bike direction). The rotor/calipers try to force it back into line, then the "whatever" forces it out of line. Rinse lather repeat.Or , the reverse, the rotor/caliper is on a different plane to the bike so it forces the wheel out of line, and forward motion forces it back. Finding what is doing that is a mater of carefully inspecting everything for alignment.

[Crisis management]

Pulsing is usually caused by the disc pushing the brake pistons in and out, ie either warped or badly worn (high and low spots on the disc). If the discs are true, mounted square to the caliper (nothing bent) and the wheel assembly is straight then they should not pulse.
The Strangers advice is correct, check everything carefully, something ain't straight.

Just a stray thought tho, what are the condition of the brake pads? I'm not sure whether they could be causing pulsing but while you are reassembling the front clean and check the calipers and pads as well.

Good luck.

[The Pastor]

Thanks for the help, heaps of things to think about.

I put new pads in when I got new discs.

[The Stranger]

Thanks for the help, heaps of things to think about.

I put new pads in when I got new discs.

I did all of this stuff on the GSXR. It would shudder like hell under braking due to the rivets holding the disk to the carrier being way loose and it would go into a head shake under real heavy braking

Checked the wheel and axle.
Replaced the disks with larger diameter ones, replaced the calipers, master cylinder and fluid. Got some dual carbon pads.

I removed some of the oil from the forks and tightened the stearing head bearings. This got rid of the head shake, but it still fucken shudders under braking, though is way way better than it was. To be fair though, the disks have turned blue several times now so I suspect they are a little warped.

Point is, you can spend moon beams and still not have it 100%. It stops on a dime, so just realx and enjoy.

[The Pastor]

Point is, you can spend moon beams and still not have it 100%. It stops on a dime, so just realx and enjoy.

If I could get the juddering to 50% of normal i'd be well happy.

[pete376403]

IMHO, juddering (ie shaking the whole bike)will be something bent or loose, whereas worn disks are more likely to give a pulsing through the brake lever.
When you've had the wheel out, have you grasped the fork sliders and see if you can feel any back and forth/side to side movement? Loosen the triple clamp bolts a bit and try rotating the fork leg -if its bent you'd see the bottom of the slider moving around (can't explain it but I'm sure you know what I mean)
Are the surfaces where the caliper bolts to the fork leg good / flat? Caliper bolt holes or sliding pin holes not worn? (if the fault happens at pushing speed it would seem the caliper(s) grab the disk and are moving a bit, either on the bolts or slider pins)
Remove 1 caliper - put something between the pads so they don't pop out then try it with only one side active? Any change? (try to narrow it down to one side).
Mudguard bolts tight? Guard mounts can act as a cheap fork brace
Do you know anyone with a similar bike that you could swap the wheel with?

[The Pastor]

IMHO, juddering (ie shaking the whole bike)will be something bent or loose, whereas worn disks are more likely to give a pulsing through the brake lever.
When you've had the wheel out, have you grasped the fork sliders and see if you can feel any back and forth/side to side movement? Loosen the triple clamp bolts a bit and try rotating the fork leg -if its bent you'd see the bottom of the slider moving around (can't explain it but I'm sure you know what I mean)
Are the surfaces where the caliper bolts to the fork leg good / flat? Caliper bolt holes or sliding pin holes not worn? (if the fault happens at pushing speed it would seem the caliper(s) grab the disk and are moving a bit, either on the bolts or slider pins)
Remove 1 caliper - put something between the pads so they don't pop out then try it with only one side active? Any change? (try to narrow it down to one side).
Mudguard bolts tight? Guard mounts can act as a cheap fork brace
Do you know anyone with a similar bike that you could swap the wheel with?


whats a fork slider?

[pete376403]

the ally bit at the bottom that bounces up and down - the moving part of the fork leg - jeeze don't they teach ANYTHING in school anymore?

[The Pastor]

Nah its all picking up rubbish and patting your self on your back.

There doesnt seem to be any movement at all.


Disc's havnt arrived today, looks like it will come on saturday.

[Motu]

He has actually given quite a good description of the problem Ixion, i.e. can feel brake lever pulsing when only pushing the bike along, this discounts most of your "options". I dont have any help for RM, but I would suggest your post is not awefully helpful, perhaps you could refine your answer a little to be more specific.

Back to basics - the problem with people diagnosing problems is they leap from one possibility to another,dismiss suggestions as ''no,I've checked that'' and ignore other ideas as ''No,it can't be that''.It's practically impossible to diagnose over the internet,and not helped by the person in question asking ''what's a fork slider?'' Personally I'm not even going to bother.

[The Pastor]

Hey, im learning alright, I guessed that was a fork slider, but wasnt sure so I asked. Its fine with me if you don't want to share you knowledge.

[crazybigal]

its called a "stanchion" did they not teach you that at school?


the ally bit at the bottom that bounces up and down - the moving part of the fork leg - jeeze don't they teach ANYTHING in school anymore?

[crazybigal]

what state is your front tyre in? is it wearing un evenly?
ive had bad wheel alignments wear out tyres and under braking you can feel
it. just my 2 cents, you have changed the fluid havnt you?
make sure your alignment is good, dont go by the marks on your swing arm.
i run 2 steel bars down the bike clamped to the rear wheel and measure the distance between the bars, both front and back then the distance from the front wheel to the bar on either side.
id say its more a wheel problem since your discs are good and your brake pads and caliper are good (no stuck pistons) also make sure your pads dont have a glaze on them.
hope you figure it out!

[Ixion]

its called a "stanchion" did they not teach you that at school?

No, the staunchion is the fixed bit that is clamped in the yokes (USD forks are a bit anomalous). The movy up and downy bit, that the wheel is fixed to, is the slider. Cos it slides. The fixed tube is the staunchion. Cos it's staunch.

[The Pastor]

what state is your front tyre in? is it wearing un evenly?
ive had bad wheel alignments wear out tyres and under braking you can feel
it. just my 2 cents, you have changed the fluid havnt you?
make sure your alignment is good, dont go by the marks on your swing arm.
i run 2 steel bars down the bike clamped to the rear wheel and measure the distance between the bars, both front and back then the distance from the front wheel to the bar on either side.
id say its more a wheel problem since your discs are good and your brake pads and caliper are good (no stuck pistons) also make sure your pads dont have a glaze on them.
hope you figure it out!

Yeah When I get my discs back i'll try it out, my best guess at this stage is its wheel alignment or a bent axle, I didnt know wheel out of alignment could even do that!

[doc]

Back to basics - the problem with people diagnosing problems is they leap from one possibility to another,dismiss suggestions as ''no,I've checked that'' and ignore other ideas as ''No,it can't be that''.It's practically impossible to diagnose over the internet,and not helped by the person in question asking ''what's a fork slider?'' Personally I'm not even going to bother.
Motu you disappoint me. What about checkin the fuel level first. Back to basics. Never a truer word was said in jest stuff.

[Drum]

Sorry, couldn't be bothered reading it all.........did anyone suggest that the fork oil level could be too high?

[Brett]

I do believe you may have the issue that I do at present. Under hard braking every now and again I get a shuddering effect that is NOT the same as bent rotor pulsing. I think that I have got air bubbles in my hydraulic fluid, and will be replacing it tomorrow if I can be arsed. Will let you know how I get on and whether it works.

Can anyone confirm that DOT 5.1 Elf racing brake fluid is sweet in a gixxer?? I bought the stuff for my 200sx when i upgraded the brakes on that, but have since sold the car and now have enough to do the gsxr instead...

[riffer]

Hmmm. Brett - how long has your brake fluid been sitting? Is it unopened? If it isn't you might as well throw it away. Brake fluid is hygroscopic, which means it absorbs moisture from the air, degrading its performance.

[Brett]

Hmmm. Brett - how long has your brake fluid been sitting? Is it unopened? If it isn't you might as well throw it away. Brake fluid is hygroscopic, which means it absorbs moisture from the air, degrading its performance.

Was only a few months old, in an un-opened bottle so would still be perfect, however I just checked it, and it is silicon based and as such not suitable for my brake system. Will have to find some good dot 4 stuff...only no shops open tomorrow, may have to wait till Saturday.

[The Pastor]

I use shell dot 4, its cheap and works ok, and you can get it at shell.

[crazybigal]

egg or the chicken?
is the inside moving up and down or the outside moving up and down!
most people call the bottom part the fork leg.


No, the staunchion is the fixed bit that is clamped in the yokes (USD forks are a bit anomalous). The movy up and downy bit, that the wheel is fixed to, is the slider. Cos it slides. The fixed tube is the staunchion. Cos it's staunch.

[Max Preload]

All Kawasakis of this vintage had problems with warping disks. Throw a DTI on it, not that you'd need too - the runout was always obvious to the naked eye.

[Max Preload]

No, the staunchion is the fixed bit that is clamped in the yokes (USD forks are a bit anomalous). The movy up and downy bit, that the wheel is fixed to, is the slider. Cos it slides. The fixed tube is the staunchion. Cos it's staunch.

It's spelt stanchion - there's no "u". There goes your naming theory...

[Max Preload]

Yeah, with a couple of V blocks and a dial indicator.
I guess you could roll it along a known flat surface, but that would be the trick - getting a known flat surface.

Any decent precision engineering shop would have a surface plate and vee blocks and a DTI.

[Ixion]

Depends on whether you're a yank or not. Though the derivation was indeed bien trouve

[Max Preload]

Depends on whether you're a yank or not. Though the derivation was indeed bien trouve

Actually, unlike "colour" and "color" it's not one of those cases, but that's nitpicking.

[imdying]

It is how the French would say 'Le pwned'.

http://www.googlefight.com/index.php?lang=en_GB&word1=stanchion&word2=staunchion

[FROSTY]

A thought here dude--its been shuddering since day 1
theres a raft of things that "could be" the problem--as covered off here
But if you've blow ya bugget--why not sell the new disks --clearly they diddn't fix the problem

[The Pastor]

helleujah praise the lord I have a propper and working and not broken brake system.

[Squiggles]

so for those of us who cant read minds... what did you do that fixed it?

[The Pastor]

it was the brake discs that were warped, when I replaced them I did somthing wrong that im not going say.... But its working fine now (at least the first little test did, i'll go for a burn on friday for 80k or so and see hows it holding up (they always seem to take a good ride to get working consistantly)

[Max Preload]

it was the brake discs that were warped, when I replaced them I did somthing wrong that im not going say

That's a bit selfish. This is a forum for helping people, be it helping them split their sides laughing or simply for a How-not-to guide.

Spill the beans!

[The Pastor]

alright alright I may of








put the brake pads on upside down

When changing the brake rotors.


Even though Im sure I put them back on correctly as I made sure to see which way they came out and I checked with the manual.........

Thanks for your help everyone.

Rm

[riffer]

Um... there is a hole in the brake pads for the locating pin, isn't there? :mellow:

I still have no idea whatsoever how you did that?

Or do you mean the brake pads are the wrong way around so the metal on the back of the pad is hitting the rotor?

Glad to hear you got it sorted.

[The Pastor]

Um... there is a hole in the brake pads for the locating pin, isn't there? :mellow:


Not for my bike, its a 1986 gpz 1000rx, there is a lug at the top wich slides into a grove, but when I took them out they must of been around the wrong way as I put them back in the same way they came out! There was actually nothing holding them in! But they 'cliped' in so they looked ok to me.

[Crisis management]

Glad you sorted it RM, and I can't afford to laugh at your mistakes mate, I've made enough of my own!

There was the Commando head that I levered on for 3 hours before finding the 5th? head stud between the carbs, the "spare" circlips from the gearbox rebuild, etc, etc....

[puddy]

But a ZX10.End of story!

[The Pastor]

But a ZX10.End of story!

Mate that is my dream bike >_> one day when I get enough $$ I will buy one.... one day!


a little update, there still is judddering, but there is a massive improvement, so i'll be sorting the wheel alinment soon.

[Crisis management]

If it's juddering, not pulsing that indicates worn / lose head bearings or wheel bearings, not wheel misalignment.

Mind you, as Ixion was saying, check absolutely everything, it may be a combination of a lot of little things.