Knocking at the front

[RDly]

Hi all, I searched this problem on the forum and found a couple of topics where there is a front end knock.

What I want to know is this..... My knock is coming from the front brake calipers. I first thought it was the steering head bearings and checked them first. Of course they were fine and the bike has done less than 4000 miles.

My attention was drawn to the calipers and there's a slight amount of play. So the question is.... is this normal or a common failure?

It doesn't really bother me but would this be an issue for the UK MOT test? mine is going to be on Tuesday, or should it be ok?

 

[Shamus McFeeley]

Where exactly is the play in your calipers?

If they are "knocking" or "chattering", could be a few things. As I guess I would say your possibilities might be:

1. Loose hardware - either the caliper bracket bolts or caliper pin bolts have worked themselves loose.

2. Brake pad failure - The pad have failed in a way that they have worn unevenly, or part of the tangs on the end of the pad have broken off. This could cause the pads to engage the rotor at an odd angle.

3. Corrosion - the caliper pins might have become corroded to the point where they can't fully engage the rotor.

4. Rotor - your rotor is loose, or damaged in some way that is affecting how the calipers engage it.

These are just guesses, my advise would be to remove your calipers and inspect them. I would look over everything with a microscope: pads, caliper pins, every piece of hardware. Check the whole system, fluid level, line condition, everything.

 

[RDly]

Thanks for the reply Shamus. There is no corrosion, no wear to the pads, they are above service limits, everything is tight as it should be but when I apply the front brake I get a knock. This is only at slow or zero speed, at any other speed over 10mph it doesn't show itself.

I'm wondering if this is normal?

 

[Goop]

Did you remove the pads and check the surfaces to to see if there is any debris embedded in the pad material or if they are contaminated in any way?

 

[RDly]

Did you remove the pads and check the surfaces to to see if there is any debris embedded in the pad material or if they are contaminated in any way?

No, it's all bog standard and less than 4000 miles from new. The brakes work fine, so I just wanted to know if this is normal. Thanks for the responses so far!

 

[Goop]

I wouldn't say it's normal. My brakes do not knock and I've never heard others have this happen.

 

[Norbert]

It's likely that this is normal.

You have floating rotors, so they make this noise.
There is some free play so that the outer ring of the rotor (the part that contacts the brake pads) is able to expand and contract (from the heat exchange during braking) independently from the hub. This reduces warping, I think. Supposedly floating rotors are better than the conventional ones.

If you want, go to an empty parking lot. Brake. Hear the knock.
Zip tie your rotors and try again.

Don't forget to remove the zip ties once you head back home

 

[TownsendsFJR1300]

IMHO, the knocking is Not normal.

On both my FJR (same brake set up-dual 4 piston pots) and my FZ6, there is no knocking at slow speeds or any speed when braking.

Yes, the rotors do float but not enough to make an audible noise. Its possible the bolts that attach to the wheel hub itself may be not torqued down fully or there's a problem elsewhere. Its possible that you have a bad rotor (the connection between the rotor and mounting center was machined too loose from the factory)

If its under warranty, I'd be getting it checked..


If you raise the front wheel and have someone gently pull the brake lever while rotating the wheel, you may be able to narrow down EXACTLY where its coming from (listening for any knock/excessive play)...

 

[RDly]

Once again thanks for the replies.

I have the day off work tomorrow so I will check the torque settings etc.

When I first noticed this, my initial reaction was to check the head bearings, they were fine. Then I put the bike on the centrestand and pushed and pulled the forks but no slack anywhere.

Then I grabbed each caliper in turn and found they both had movement on their mounting bolts of maybe a millimetre. This is what is being transferred to the bars. It's not an audible knock, just one I can feel.

I'll update this thread once I've had a closer look.

I originally thought this may be within tolerance, and for such a low mileage bike, but reading your replies so far I'm not so sure.

Cheers!

 

[Humperdinkel]

Floating rotors do make funny clunking sounds sometimes & its normal , my guess is go straight back to where you started at teh steering heads bearings , rip the crappy ball bearing out & replace them roller bearings :thumbup: I think you be suprised..

 

[Norbert]

If your calipers have some free play, take them off, inspect and clean the bolts and threads, and torque (see service manual for specs) them back on with a dab of thread locker.
Check for free play again.

I still think it's the rotors. My f800gs has a clacking sound cause by the floating rotors. It's very loud, but normal.

I'm sure you'll figure it out, whatever the problem is. :thumbup:

 

[RDly]

Ok, a quick update.

Had both calipers off and checked everything. The 12mm threaded pins that hold the caliper to the hanger have a small amount of play where they enter the bushes in the caliper. There's slightly more movement on the left than the right.
Also, where the fingers at each end of the pads fit over the shims on the hangers there's about 1/2 a mm free play but no signs of wear, I think this is where the main knock is coming from but it's exactly the same on each side.

I rechecked the head bearings and found the top race spacer was locked to the stem, I released it, removed the bearing and inspected it and the races for wear (there was none) then re-greased it and re-fitted it, still knocks!!

I never checked the lower bearing as I didn't want to do a full strip!

The rotors are fine, no excess play and all the bolts are tight.

After all the above I have concluded the 'knock' is where the pads have a small amount of movement between the shims (1/2 a mm) and when I push and pull on the bars with the brake applied the calipers are actually moving with the rotors due to the pads gripping them, and knocking against the hangers.

I would appreciate if anyone can confirm the same with their bikes.

Just to say again, this isn't an audible 'knock', just one I can feel through the bars.

Cheers!

 

[ThatsRicci]

I had a knock once... couldn't figure it out, happened when i hit bumps in the road. turned out my fuel tank bolts were loose.... just a thought!

 

[RDly]

I had a knock once... couldn't figure it out, happened when i hit bumps in the road. turned out my fuel tank bolts were loose.... just a thought!

Definately not that but thanks anyway

 

[grommit]

Have you checked the floaters...



http://www.600riders.com/forum/fz6-general-discussion/4467-shudder-low-speed-turn-front-brake.html

 

[RDly]

Have you checked the floaters...



http://www.600riders.com/forum/fz6-general-discussion/4467-shudder-low-speed-turn-front-brake.html

Yes and it's not that, I still wish to hear from anyone who had this symptom.

 

[PhotoAl]

Had a problem like that. The front would clunk or bump going over bumps but generally felt OK. The clunks or bumps were felt thru the bars. I checked the front end and could not get any play in the strearing head when the bike was on the stand. Finally replaced the steering head bearings and the problem went away!

Currently I have some shudder when breaking at low speed and also at 40MPH or less the front feels too quick as it wants to turn too much. I have a PR2 front tire with 14,000 miles on it and the sides have worn more than the center so that there is a slight scalloped shape and the blocks are un-even. I attribute the shuddering under braking to the unevenly worn blocks and the too easy tip in to the scalloping. By the unevenly worn blocks I mean that the front of the blocks are worn more than the rear of the block -probably due to braking. Will replace it with another PR2 very soon.

 

[RDly]

Well I've decided to stop fannying around with the brakes until one thing is ok for certain, and that's the head bearings.
I've ordered some AllBalls taper bearings and will ditch the standard rubbish once they arrive.

I'm wondering if my lower bearing has gone the same way as many others (Rusty)

Anyhow, will update here when I get the replacements fitted. probably at the weekend.

 

[RDly]

Well sorry for the delay in replying, I've been a bit busy!

Anyway, I ordered a set of 'Allballs' head bearings from ebay for £20 delivered and set about stripping out the original races and fitting the new tapers.

I was concerned about keeping the front end supported so I put the bike on its mainstand and laid a plastic crate beneath the downpipes as the bike was front heavy.

Next was to remove the inner fairing panels, the calipers were unbolted and suspended on wires to prevent the hoses from being damaged, then I removed the front mudguard and wheel.

At this point the balance of the bike went neutral, I thought WTF? Then I removed the forks and the bike slumped on the rear wheel. The front end is really heavy!!

Next was to get the old bearings out so it was a simple task to undo the upper yoke nut and lift the top yoke clear and shove it forwards so I could get to the stem locknuts.

Once the locknuts were removed it was an easy job to lower the bottom yoke from the frame. At this point I found the bearings were perfect, well greased and not rusty.

Now I had to get the outer bearing shells removed from the frame. Yamaha have thought of this and provided two recesses for each shell so you can get a suitable tool in there to remove them, I used a heavy duty 14" screwdriver and they popped out without any trouble.

Fitting the new outer shells was also a doddle, using the old outers as drifts to get the new ones in using a hammer and a little care.

The lower race was a bit more of a problem. The original race was well stuck, after using a blowtorch it decided to move and with a little fettling (Hammer) it came off cleanly.

My Allballs kit was supplied with 2 seals, however the upper one was too small so I couldn't use it??? The original lower rubber seal was fine but would snag the taper inner so the Allballs one had to be used. After fitting the lower seal I used the old inner race to drift in the new inner taper to the bottom yoke.

Next was the upper race. This was surprisingly difficult and might be best done by releasing the Torx bolts holding the frame halves together, however I never had a suitable Torx bit so I repeated the same process as I did for the lower shell and it went in ok with a bit of effort.

I won't bore you all with the rest of the rebuild as it's pretty much 'bread and butter' stuff.

I booked my MOT and waited for the day to ride the bike. I hadn't test rode it as getting out of my rear garden is a pain and FZ6's are heavy so I didn't want to do my back in!!

Come the day of the MOT I had to negotiate several roundabouts en-route. Well what can I say? I nearly **** myself!! The taper bearings had completely changed the handling. No longer was it dull and uninteresting, it was a new riding experience. The turn in to corners was now very sharp, perhaps too sharp. The effort to corner had gone and I found myself having to countersteer away to prevent oversteering. This new found ease of handling has also resulted in less fatigue, since changing the head bearings I have done around 200 miles and every mile has been a dream, why Yamaha had to dumb down a bikes handling by fitting cheapo components is beyond me!

Anyway, the bike passed its MOT with flying colours. The knock I felt which was the original reason for this topic was the floating calipers, no cause for concern.

Finally, I was surprised to find my Allballs kit contained a bearing cover/seal which was of no use to me, plus the bearings were cheap chinese ones available from ebay for a couple of quid each. I'm not saying the bearings are inferior but they are certainly cheap to buy, the only advantage I got by buying the Allballs kit was the lower bearing seal, since the original Yamaha seal can't be used with a Tapered bearing.

Apologies for the long post but I feel it may have valuable information for anyone finding themselves in the same predicament :thumbup:

 

[macem29]

thanks for the detail....