Yamaha TRX850 Enthusiasts Forum

ARGH! couple of seasons ago my front brakes started to judder when stopping bike, it was quite annoiying in just few last meters before bike stopped. So first I cleaned rivets and it seemed to help but after a while juddering came back. Last winter I ordered EBC discs and i have been happy until now. These discs have started to judder in higher speeds, above 60 kmh, but under that they work nicely and no judder can be felt. Brake pads have been all time genuine Y's
Whatta hell, any ideas ?

edit. now with EBC's I can feel that pads are moving away from discs in higher speeds since in first braking lever goes much deeper than with next ones

Either discs are warped (or even marginally out of true) or the discs are 'floating' too much

The judder seems to be a re-occuring problem , coming back even after a new set of discs, have you checked the calipers at all for a drag on the wheel?, it should spin fairly freely, whilst doing this check, take note of where the wheel stops it might give a clue to a warped disc if it stops in the same place every time.
The other thing to check is head/steering bearings, pull the front brake firmly and rock the bike back and forth, you will need to give it some. and feel around the steering bearing at the same time (might be a two man job!)

The discs might also be slightly dished

I wonder why these discs behave so differently, original judders in low speed, ebs in high speeds.
I havent had time to check those thoroughly, but long and cold winter will be here soon so I will dismantle brake calibers, maybe reason can be found there

Rane850 wrote:I wonder why these discs behave so differently, original judders in low speed, ebs in high speeds.
I havent had time to check those thoroughly, but long and cold winter will be here soon so I will dismantle brake calibers, maybe reason can be found there

you might have a leaking seal in one of your calipers dropping a spit of oil onto the disc, and make sure that the disc rotors are torqued up evenly....and a leaking SEAL isnt what you would want...seeing you.r from Finland

are your wheels plastic coated ? ......... sometimes if the coating is beneath the discs they bed in and go out of true

have you checked your headstem bearings?

Had the exact same problem a few months ago, culprit was the LHS front wheel bearing. Felt fine above 10 km/h but on the brakes pulling up would go shudder and goto shit. Lucky I found it before it collapsed on me at 100 km/h! Take the wheel off and have a good look at them, if its bad enough you might be able to just pull the wheel side to side while the handlebars are locked and see the wheel move independent of the forks / calipers.

Good luck!

I took calibers off and dismantled them. Pistons are not moving very nicely. I used compressed air for pushing them out and those inner pistons were quite hard to get out, I had to really push air there!
Dust lips ( outer narrower seals) looks like they are glued to calibers, I doubt that. I think they have oxide and road grit in seals groove which has pushed seals tighter towards pistons.
I will give them thorough clean and new seal kits. Lets see how they work then. But I think those brake discs are ruined

I just got seal kit from my parts man. 1NL-W0047-00 has seals only for two pistons! so I have to order two kits more and it doubles my budget.