front brake low speed judder

[Johny w]

My gs r1150gs 2003 (no ABS) has a low speed brake judder, I've replaced the pads and sanded the discs, believing that it may be contamination, but they're still the same. I've spun the wheel and eyeballed the discs against the pads and there does'nt seem to be any significant side to side movement that would cause such an issue.
Im snookered!! ..... shall i just replace the discs? I feel i might be throwing my money away as it may be a simple fix.
Any others had this issue and fixed it?

 

[Greg Masters]

Oil contamination?

Disc runout (ie disc moves side to side when wheel rotated)?

Disc warping or uneven thickness?

Check all!

 

[Aidan1150]

Maybe more unlikely, but I'd be taking a good close look at the wheel bearings too whilst following Greg's suggestion.

HTH

 

[SBD]

Check the discs are running concentrically, when spinning the wheel.
Caliper fixings tight?
No play in forks?

 

[twizzle]

Warped discs…always show at low speed and you will never see the run out with the naked eye

 

[Johny w]

Warped discs…always show at low speed and you will never see the run out with the naked eye

Oh I thought it would have to be quite visible to make a judder......I've taken the discs off today, I'll measure them with a vernier.....they may have been replaced as there was no markings on them, and they look very worn.
If I don't replace the ABS ring, would I have to fit washers of the same thickness in its place behind the disc?
And there was 10 wavey washers, but with new Galfer discs they supply 20 waves washers!! It makes .e wonder if something has been omitted in the past.

 

[Johny w]

Check the discs are running concentrically, when spinning the wheel.
Caliper fixings tight?
No play in forks?

Yes all good, ill measure the discs at work. thanks

 

[Johny w]

Maybe more unlikely, but I'd be taking a good close look at the wheel bearings too whilst following Greg's suggestion.

HTH

Thanks, they seem very good, no play.

 

[Johny w]

Oil contamination?

Disc runout (ie disc moves side to side when wheel rotated)?

Disc warping or uneven thickness?

Check all!

 

[Johny w]

Thanks.....Ill check thicknesses at work

 

[Steptoe]

Warped discs…always show at low speed and you will never see the run out with the naked eye

This

Thanks.....Ill check thicknesses at work

A warped disc has nothing to do with the thickness of the disc.

 

[Wrigsby1]

Warped discs…always show at low speed and you will never see the run out with the naked eye

Absolutely... It's only a miniscule amount for a slight judder and if you spin the wheel on the centre stand you'll probably find the slightest of tight spots ... You can ride for a time with very slightly untrue discs but they are likely to get worse pretty quickly if your using it regularly...

 

[theoneandonly]

warped you say ?
go lube all the bobbins , hit it radially with a mallet , spin the bobbins with a drill . ride and drag the brakes , get them HOT , then use them hard ! get a big bang as they suddenly release , problem solved. ...or not.
judder ? or pulsing ...2 different things.
judder ....what pads you using ? Ferodo or some other crap ?

 

[Johny w]

This


A warped disc has nothing to do with the thickness of the disc.

Uneven thickness is what I measured and they're fine and no warping!!

 

[sproggy]

Warping isn't uneven thickness though. To measure warping you need a dial test indicator against the face of the disk, then spin the wheel to measure deviation.

 

[albatross]

Before checking all thie above mentioned have a look at your brake pad’s ..
Last judder I came across was due to pads down to metal and started engraving the disc…
New pads , all solved…so start on simple stuff first…

 

[Steptoe]

Warping isn't uneven thickness though. To measure warping you need a dial test indicator against the face of the disk, then spin the wheel to measure deviation.

I said the same. Not sure if it was fully understood

 

[Johny w]

warped you say ?
go lube all the bobbins , hit it radially with a mallet , spin the bobbins with a drill . ride and drag the brakes , get them HOT , then use them hard ! get a big bang as they suddenly release , problem solved. ...or not.
judder ? or pulsing ...2 different things.
judder ....what pads you using ? Ferodo or some other crap ?

More of a pulsing ad you describe, put new brembo pads on and it's still the same.
Discs are evenly worn at 4.9mm so they must be quite new. Might be cheap Chinese crap as there's no markings.
Bearings seem good but I'm going to replace them with premium ones.

 

[Steptoe]

Discs are evenly worn at 4.9mm so they must be quite new. Might be cheap Chinese crap as there's no markings.
Bearings seem good but I'm going to replace them with premium ones.

FFS, how many more posts are going to say the thickness of a disc has nothing to do with measuring the run out of a warped disc.

 

[Johny w]

FFS, how many more posts are going to say the thickness of a disc has nothing to do with measuring the run out of a warped disc.

I never said that!! ...... greg masters said check for warping or UNEVEN THICKNESS.....which is a good point, uneven thickness would cause a similar symtom.....that's why I said i would measure the thickness, i think you've missunderstood me. I know warping has nothing to do with thickness.