Front suspension

[portaz]

Hi guys,

I have come up with a slight issue with my 05 636.

I have been doing a couple track days lately, and I am finding under hard high speed breaking, the front end is shaking quite violently.

My last trackday was at broadford 2 weeks ago, and I actually got the suspension dude there to have a look at it, and set the bike up correctly, which did help it, however it still shakes sometimes.

From what we can see, it is the front fork bottoming out, meaning under breaks, it cannot compress any further...

When speaking to the suspension tech about it, he said that maybe the forks are too soft as standard.

Just wondering if there is anyone else out there with this kind of issue?

Daniel

[Strika]

I owned an 05 636 for 17,000klms with several track days on it including Phillip Island and Broadford. I ran around P.I. in the 46's and broadford in the 64's running BT014's and never had an issue! Provided you have the sag set properly and are not 100kg's+ yourself, then the issue isn't the bike, it's your braking technique. However, If you havn't set the sag, then it would benefit from that alone.

Give me some understanding of your weight and lap times and I may be able to suggest more.

[robracer]

when you say shaking you dont mean front wheel chatter do you?....as in really heavy braking causing the front to slightly vibrate

[Strika]

when you say shaking you dont mean front wheel chatter do you?....as in really heavy braking causing the front to slightly vibrate

I think what he is refering to is what he mentioned in his post. ie-the forks are reaching the end of there travel and are bottoming out causing as you say, front chatter/patter. But it only happens under brakes which suggests Sag or technique.

[robracer]

when you say shaking you dont mean front wheel chatter do you?....as in really heavy braking causing the front to slightly vibrate

I think what he is refering to is what he mentioned in his post. ie-the forks are reaching the end of there travel and are bottoming out causing as you say, front chatter/patter. But it only happens under brakes which suggests Sag or technique.

Reason I ask is that I get a chatter under heavy brakes but a cable tie on the fork leg tells me the travel is not totally used?
but sag has not been set on the crim yet
If it was bottoming out would you feel like a knock at the end of travel? arrr so many questions

[portaz]

I owned an 05 636 for 17,000klms with several track days on it including Phillip Island and Broadford. I ran around P.I. in the 46's and broadford in the 64's running BT014's and never had an issue! Provided you have the sag set properly and are not 100kg's+ yourself, then the issue isn't the bike, it's your braking technique. However, If you havn't set the sag, then it would benefit from that alone.

Give me some understanding of your weight and lap times and I may be able to suggest more.

Thanx Strika..

Im 87-88kg, and at broady i was doing 71's, and a bit over 2 min at PI, so way off your mark...

What is the sag? I cant say I have heard of it...

As mentioned, I got the bike set up properly for track and road at broadford by the suspension specialist, so im guessing he would of set this 'sag' you all speak of.

With regards to breaking techniques, how should I be breaking? At the moment, I hit the breaks at the breaking point, and blip the throttle when down gearing. Is there any other way?

Cheers,

Daniel

[2006zx10r]

Daniel next time your at broadford go find stewart fron SW racing, he is usally up there, he will sort you out... As to the breaking technique, compress the level slowly initally, allow the brakes to bite and apply more and more force, this should allow the front end to absorb the compression in a smooth fluid motion, and you let go of the brakes the same way...... remember slow in fast out !!

[Strika]

I owned an 05 636 for 17,000klms with several track days on it including Phillip Island and Broadford. I ran around P.I. in the 46's and broadford in the 64's running BT014's and never had an issue! Provided you have the sag set properly and are not 100kg's+ yourself, then the issue isn't the bike, it's your braking technique. However, If you havn't set the sag, then it would benefit from that alone.

Give me some understanding of your weight and lap times and I may be able to suggest more.

Thanx Strika..

Im 87-88kg, and at broady i was doing 71's, and a bit over 2 min at PI, so way off your mark...

What is the sag? I cant say I have heard of it...

As mentioned, I got the bike set up properly for track and road at broadford by the suspension specialist, so im guessing he would of set this 'sag' you all speak of.

With regards to breaking techniques, how should I be breaking? At the moment, I hit the breaks at the breaking point, and blip the throttle when down gearing. Is there any other way?

Cheers,

Daniel

Daniel, loads of guys will tell you they are a suspension expert. Sometimes these people are just good riders who offer some suggestions. I guess what I am getting at, is that the champions ride day suspension guru might not really be a guru at all, just a handy rider. I would highly recommend setting it up properly first including the sag (i'll explain in a moment) and the ride heights before spending money on spring and damper mods or changes.

Setting the sag:
Sag is the difference with the suspension totally unloaded (ie no weight on the springs, springs fully extended) and loaded. Here's how to set it.

Unload the suspension so the it is fully extended. Measure the length from a static point. Ie- lower triple clamp to the same point on the lower fork leg, or at the rear a static point on the subframe or ductail directly above the rear axle. Then repeat the measurement with you sitting on the bike in full riding position. (have someone hold the bike upright for you and another to measure.

What you are aiming for is a difference of around 30mm from fully extended to you sitting on it.

That's rider sag.

Once that's done we can start working on Compression and rebound adjustments. I might try and troll through my old posts to find what settings I ended up with on mine. I was around 80+kgs at the time so the settings should be close.

[portaz]

Daniel next time your at broadford go find stewart fron SW racing, he is usally up there, he will sort you out... As to the breaking technique, compress the level slowly initally, allow the brakes to bite and apply more and more force, this should allow the front end to absorb the compression in a smooth fluid motion, and you let go of the brakes the same way...... remember slow in fast out !!

Hi mate,

Yes Stewart was the person that set it up for me, so glad were on the same page there.

With regards to breaking, I will definitely take that on board. I do sometimes tend to smash the breaks on, so maybe smooth application will help.

Thankyou very much.

Daniel, loads of guys will tell you they are a suspension expert. Sometimes these people are just good riders who offer some suggestions. I guess what I am getting at, is that the champions ride day suspension guru might not really be a guru at all, just a handy rider. I would highly recommend setting it up properly first including the sag (i'll explain in a moment) and the ride heights before spending money on spring and damper mods or changes.

Setting the sag:
Sag is the difference with the suspension totally unloaded (ie no weight on the springs, springs fully extended) and loaded. Here's how to set it.

Unload the suspension so the it is fully extended. Measure the length from a static point. Ie- lower triple clamp to the same point on the lower fork leg, or at the rear a static point on the subframe or ductail directly above the rear axle. Then repeat the measurement with you sitting on the bike in full riding position. (have someone hold the bike upright for you and another to measure.

What you are aiming for is a difference of around 30mm from fully extended to you sitting on it.

That's rider sag.

Once that's done we can start working on Compression and rebound adjustments. I might try and troll through my old posts to find what settings I ended up with on mine. I was around 80+kgs at the time so the settings should be close.

Thanx Strika,

As mentioned, Stewart who is a suspension tech, was the person I got to set the suspension up, so im confident that he knows whats going on..

With regards to the sag, I though thats what it might of been, and yes, he did set it up properly. Previously, it was a fair bit out, especially the rear. im pretty sure he set it to be 28-29mm difference... which is on-par with what your saying...

I'm at PI tomorrow, so I will again look at the sag to make sure it is correct, then have a go at smoother breaking techniques to see if that helps. Just pray for me that it aint raining.

So I will report back on Friday to let you know guys know how it felt.

Thanx alot for your help guys, really appreciate it.

Daniel

[Strika]

Ok, if Stewart did it and he comes reccomended you prolly have a good base point to start from.

At the Island tomorrow, when you start playing with the damping settings don't move them one click and try them. Move them about 20% of the range then try them. The reason is, realistically, most humans won't pick the difference a click will make, but you will with thre or four. that way you know if you are heading in the right direction or not. Then if too far, back off half of what you went and try again. Make sure you try it on the same turn at the same speed and line each time to ensure a consistent base point.

As a rule if the sag is right (28-32 is fine) then start with compression damping to try and stop the bottoming out. You are more than likely to bottom at Honda and not really anywhere else at the Island, so use that as the static turn. Go a few extra clicks of compression and see what happens.

2006zx10r's advice re braking is spot on. Another method to try if you are confident you won't feck it up, is to pre-load the rear brake prior to squeezing the front one on. What this does is lower the rear a little and reduces the weight transfer to the front. It might just be enough combined with smooth progressive braking to fix the issue.

Good luck and have fun.

[portaz]

Ok, if Stewart did it and he comes reccomended you prolly have a good base point to start from.

At the Island tomorrow, when you start playing with the damping settings don't move them one click and try them. Move them about 20% of the range then try them. The reason is, realistically, most humans won't pick the difference a click will make, but you will with thre or four. that way you know if you are heading in the right direction or not. Then if too far, back off half of what you went and try again. Make sure you try it on the same turn at the same speed and line each time to ensure a consistent base point.

As a rule if the sag is right (28-32 is fine) then start with compression damping to try and stop the bottoming out. You are more than likely to bottom at Honda and not really anywhere else at the Island, so use that as the static turn. Go a few extra clicks of compression and see what happens.

2006zx10r's advice re braking is spot on. Another method to try if you are confident you won't feck it up, is to pre-load the rear brake prior to squeezing the front one on. What this does is lower the rear a little and reduces the weight transfer to the front. It might just be enough combined with smooth progressive braking to fix the issue.

Good luck and have fun.

Excellent, will do so.

And with regards to were im bottoming out at PI, it was only at the end of the straight pretty much, never at honda, which is surprising coz its another fast approaching corner... maybe i was breaking right at that corner..

Anyway, I will let you know how it goes...

Cheers,

Daniel

[robracer]

Dont forget the report Daniel

[Strika]

[

Excellent, will do so.

And with regards to were im bottoming out at PI, it was only at the end of the straight pretty much, never at honda, which is surprising coz its another fast approaching corner... maybe i was breaking right at that corner..

Anyway, I will let you know how it goes...

Cheers,

Daniel

Turn 1 should go something like this. top gear down the chute, sit up at first braking marker, in between first and second marker, grab enough front brake to make the nose dive to help turn it in, down two gears, lay it on it's side and balance out the throttle. Hard braking shouldn't be done at one mate, you'll end up spitting yrself off!!!

[Rossi]

Reading between the lines here and thinking outside of the box..........
Check your discs for run out could be a warped disc....... doesn't sound like it's "chatter" to me especially into turn 1 as Strika said maybe into Honda but not turn 1

[Strika]

Reading between the lines here and thinking outside of the box..........
Check your discs for run out could be a warped disc....... doesn't sound like it's "chatter" to me especially into turn 1 as Strika said maybe into Honda but not turn 1

I can understand you thinking this Rossi. If I hadn't owned one I would have asked the same question. Mine also did it till I sorted the set up. It's the forks reashing the end of their travel, and they sort of bind and shudder. It's weird and one of the only bikes I have owned which has done it??? Sort the pre-load and compressin and it won't do it anymore.