Front Fork Issue (Gen4 owners)
- Thread starter noxx
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Just to add to thread - I am having front for problems too with an odd clunking noise noticeable at slow speed. On top of that I had the battery going flat in 48 hours. By chance I was in the garage and the bike turned on the dash all by itself no key and lit up like a Christmas tree.. back to the dealer now - will post if I get a fix or any news.
I think my bike is developing this issue. Picked my bike up Oct 2019 and the 500 miles i got on it last year were OK. Its got 1300 miles on it now. Now I've noticed, at slow speed, a rattle or knock on the front end. You can feel it through the bars (I can't say as i can hear it with plugs and helmet on though). It definitely feels like something rattling but disappears once you get above 30 mph. Its most noticeable when you ride through a bumpy car park with out any brakes applied. The other thing I've noticed, and I'm not sure if the two are connected, when pushing on it feels like the front wheel is pattering on corner entry. At first I put it down to a cold front tyre. Checking the front tyre its scrubbed down to the wear indicators on the edges but the back is fine. That's the first time in my life I've worn a front out before the rear. I've checked everything I can and nothing feels lose. No play in the forks or headstock.
Coyotegsxr
Active member
re 84 - I know you're experienced so hesitate to ask, have you checked the front brakes? Also, if active suspension fitted, run the engine whilst checking front fork action (bouncing the forks) as the electronic damping will need to be active whilst you do it.
Excessive front tyre wear may be down to a number of things. You may be "good on the brakes", or the brakes may be dragging, or the forks may be running out of travel during braking, hitting bumps, or under compression through corners. Damping failure won't cause it - that brings a whole load of other unpleasantness to the fore.
Fit a zip tie around one of the fork stanchions snug to the fork seal to check travel. That will show you if you're hitting bottom of travel, which would also cause a clunk. Walk the bike forward and hit the brakes. When the forks drop and rebound is there a clunk?. How hard is it to push the bike? Go for a ride and then check the zip tie position. Has it been pushed to the bottom of travel?
The other thing to note is that the bike is set-up for a rider weighing 85kg booted and spurred. If you are much heavier than this, front pre-load will have to be increased to set sag at the right amount. I think fork travel is about 120mm if I remember right. Aim for about 30mm of front sag with rider onboard, and work on from there. But best look up the suspension threads for this.
Don't forget to check the rear suspension set-up to match the front.
If after all that, the problem persists, then explain what you have done/investigated to your dealer, and ask them to check.
Excessive front tyre wear may be down to a number of things. You may be "good on the brakes", or the brakes may be dragging, or the forks may be running out of travel during braking, hitting bumps, or under compression through corners. Damping failure won't cause it - that brings a whole load of other unpleasantness to the fore.
Fit a zip tie around one of the fork stanchions snug to the fork seal to check travel. That will show you if you're hitting bottom of travel, which would also cause a clunk. Walk the bike forward and hit the brakes. When the forks drop and rebound is there a clunk?. How hard is it to push the bike? Go for a ride and then check the zip tie position. Has it been pushed to the bottom of travel?
The other thing to note is that the bike is set-up for a rider weighing 85kg booted and spurred. If you are much heavier than this, front pre-load will have to be increased to set sag at the right amount. I think fork travel is about 120mm if I remember right. Aim for about 30mm of front sag with rider onboard, and work on from there. But best look up the suspension threads for this.
Don't forget to check the rear suspension set-up to match the front.
If after all that, the problem persists, then explain what you have done/investigated to your dealer, and ask them to check.
Coyotegsxr
Active member
Further to my post above - handbook page 108 - 109 refers to front preload. It should be 40mm of travel from no load (fully extended) to bike plus rider. A lot more than this, and you could be bottoming out on fork travel.
Thanks Coyotegsxr, all good points. Its not the brakes, bike is easy to push around and the brakes go on and release no problem just pushing the bike. Forks are not bottoming out, you can see the tell tail mark the wiper seal is leaving on the fork stantion. Plus I'm light for the bike if anything, and I'm no demon breaker! The front tyre is worn on the edges from cornering not braking. Yes it's a Racetech so soft but so is the back. It strikes me as odd I've worn the front out before the back just with road miles. Combined with the 2 separate things I'm feeling from the front something does not stack up. I'll need to get it into the dealer to have a look.
At the start of this thread 2 guys had the same problem. Unfortunately one of them is no longer with us, and I'm sure he could have described what his issue felt like.
Coyotegsxr
Active member
Just one more thing that I experienced with my Fireblade that was almost impossible to diagnose and was discovered by accident - Wheel bearing failure.
Bear with me (no pun intended). My Fireblade, a '97 RRV (so when they were bullet proof) had about 5k on the clock and was 8 months old. I was a slow road rider, still finding his feet with his super-fast road riding pals. One day I applied gentle braking in a village and it felt like I'd bottom out. There was an audible clunk that I also felt through the clipons. It then clunked a few more times until I released the brakes. It did it again, at low speeds (<30mph) on the brakes. Riding normally, it felt fine.
I discussed with my friends (one of whom owns a milling and turning business). I was convinced it was warped discs. They were doubtful I had experienced anything and dismissed my diagnosis. I remained adamant, so my friend offered to put a dial gauge on the discs to prove I was 'full of it'. The discs weren't warped, but the bearings were shot.
The weird thing was the front wheel felt fine on the bike, with no evidence of shot bearings (checked by the standard wiggling of wheel test). So the only symptoms were clunking during braking and a feeling that I'd bottomed out the forks.
New bearings stopped the clunking and feeling of bottoming out.
Bear with me (no pun intended). My Fireblade, a '97 RRV (so when they were bullet proof) had about 5k on the clock and was 8 months old. I was a slow road rider, still finding his feet with his super-fast road riding pals. One day I applied gentle braking in a village and it felt like I'd bottom out. There was an audible clunk that I also felt through the clipons. It then clunked a few more times until I released the brakes. It did it again, at low speeds (<30mph) on the brakes. Riding normally, it felt fine.
I discussed with my friends (one of whom owns a milling and turning business). I was convinced it was warped discs. They were doubtful I had experienced anything and dismissed my diagnosis. I remained adamant, so my friend offered to put a dial gauge on the discs to prove I was 'full of it'. The discs weren't warped, but the bearings were shot.
The weird thing was the front wheel felt fine on the bike, with no evidence of shot bearings (checked by the standard wiggling of wheel test). So the only symptoms were clunking during braking and a feeling that I'd bottomed out the forks.
New bearings stopped the clunking and feeling of bottoming out.
How have you measured the forks fully extended? And what was the measurement?
Coyotegsxr
Active member
Hi Soof - it's a two man job. bike on side stand. 1st Man stand on left of bike and turn the handlebars hard right, put right foot on side stand base, grip both bars and lean back till front comes off the ground. 2nd man measure distance from axle casting to fork seal (a vernier gauge is best for this). Then repeat with fully kitted rider onboard, having bounced the suspension a couple of times.
I don't have any concerns at the mo' so just haven't got round to it. The 40mm is straight from the handbook.
I don't have any concerns at the mo' so just haven't got round to it. The 40mm is straight from the handbook.
Coyotegsxr
Active member
OK - stung into action, I got the much better looking half of me to help. With me onboard fully booted and spurred front fork sag was 40.5mm
Coyotegsxr
Active member
Hi Soof - standard 2020 M-Sport with all settings as factory. Front forks 119.79mm fully extended. So call it 120mm.
excellent! Thanks for the info.
Coyotegsxr
Active member
I've just come off the S1000RRforum.com site and can give you all an update on the front fork "knock" The link below refers, but in short, BMW USA states:
"[FONT="]Early production bikes have manufacturing tolerances which cause the problem. The issue will be corrected in the future production. [/FONT]
[FONT="]The noise comes from the bottom valve of the closed Cartridge (left fork).
At the change from pressure stage to rebound stage the Checkvalve-Shim compresses the spring and the nut gets in contact with the shim packet."
[/FONT]
The link below refers:
https://www.s1000rrforum.com/thread...ing-front-end-on-a-2020-s1000rr.241244/page-2
"[FONT="]Early production bikes have manufacturing tolerances which cause the problem. The issue will be corrected in the future production. [/FONT]
[FONT="]The noise comes from the bottom valve of the closed Cartridge (left fork).
At the change from pressure stage to rebound stage the Checkvalve-Shim compresses the spring and the nut gets in contact with the shim packet."
[/FONT]
The link below refers:
https://www.s1000rrforum.com/thread...ing-front-end-on-a-2020-s1000rr.241244/page-2
Reading the US posts they are describing the same feeling. I'll get it to the dealer but I'm loathed to lose it for any time following lockdown.
Got to love some of the dealer advice "the knocking front end can be eliminated if you ride in race pro mode and turn the front damping up to 14 (max)"!!
Got to love some of the dealer advice "the knocking front end can be eliminated if you ride in race pro mode and turn the front damping up to 14 (max)"!!
Hi my dealer was happy to progress a replacement but I was fine with the fork replacement. So far so good. Still a bit of noise from the carbon front mudguard though. Cluncking definitely fixed. Will post again should I have any problems. I have done 1k miles on the new forks and a track day.
What's the normal amount of oil residue on the fork stanchions? I swear this bike has more than my previous bikes. Is it something to worry about? Think I've seen other people complain about it too, those who did, was anything done about it or did you just learn to live with it?
Both my forks seem to always have a tiny amount covering them. I had it checked at the RIS and the mechanic said they are all like that
