If you feel slippage coming from the rear when switching from right to left in a chicane even after the tires have come to their correct operating temp, what would you check for? I had this happen last weekend and I put an extra psi in the rear and it got better but it didn't go away.
Too much Rebound Damping in the Rear?
Too soft a spring?
Tire Pressure? Higher or Lower?
Too much compression damping?
Can you be more specific on when you feel it slide? In the middle of the transition? As it starts to take a set when going into the second half of the chicane? When its fully loaded after completing the transition?
My first thought is to say too much rebound. What solutions have you tried so far?
Last edited by BC999S; 09-20-2009 at 05:42 AM.
Reason: typo
I'm no pro, and a little info can be harmful. What's the tire look like? Rebound issues will show up in the tire wear. I recall that too much preload will do that also. Man, there's so many variables. I'd start with checking the sag first. Then work the bike up and down, seeing how it rebounds. Is it too fast? Too slow? Are both ends balancing out?
Too much rebound....and smooth throttle inputs in the transition. I asked Jeff Wood the same question during a Penguin school a few years back @ Homestead...
Can you be more specific on when you feel it slide? In the middle of the transition? As it starts to take a set when going into the secind half of the chicane? When its fully loaded after completing the transition?
My first thought is to say too much rebound. What solutions have you tried so far?
Exactly!!! I feel it right in the middle of the transition right before I tip it over to the other side!!!! That's right.
I'm no pro, and a little info can be harmful. What's the tire look like? Rebound issues will show up in the tire wear. I recall that too much preload will do that also. Man, there's so many variables. I'd start with checking the sag first. Then work the bike up and down, seeing how it rebounds. Is it too fast? Too slow? Are both ends balancing out?
Pics of the tire are helpful
Too much preload??? hmmmmm. My spring is soft so I do have my rear preload max-ed out to get close to my correct sag.
I can take pictures of the tires tomorrow and post up but to me it was unconclusive.
Too much rebound....and smooth throttle inputs in the transition. I asked Jeff Wood the same question during a Penguin school a few years back @ Homestead...
My next track day I will loosen up the rear rebound by 1 or 2 clicks and see how it responds.
I do remember reading that too much rebound will prevent the wheel from remaining in contact with the ground when the road is uneven causing slippage.
But, since I ran Metzeler M3 tires, I read a few reviews and a lot of the testers all complained about carcass flex coming from the rear. That could be another factor too.
Like BC, rob and jay said, I am thinking rebound damping and sag as well.
You´re actually compressing the bike with your weight in a corner, then you lift it up and throw it to the other side, which will unload the suspension.
The rear is losing grip, because the shock doesn´t let the tyre/swingarm loose quick enough. In a good video I saw, Max @ Traxxion.com said the tyre is "looking for tarmac" or sth similar. He mentioned correct sag is important. Maybe your shock spring is way too soft and in addition to that, you have rebound set too slow?
Loosening rear preload by clicks? Usually damping is adjusted by clicks and preload is adjusted with a spanner using these little collars. The metal rings that sit on top of the spring:
Rebound is at the bottom, vice versa to the front forks.
Like BC, rob and jay said, I am thinking rebound damping and sag as well.
You´re actually compressing the bike with your weight in a corner, then you lift it up and throw it to the other side, which will unload the suspension.
The rear is losing grip, because the shock doesn´t let the tyre/swingarm loose quick enough. In a good video I saw, Max @ Traxxion.com said the tyre is "looking for tarmac" or sth similar. He mentioned correct sag is important. Maybe your shock spring is way too soft and in addition to that, you have rebound set too slow?
Loosening rear preload by clicks? Usually damping is adjusted by clicks and preload is adjusted with a spanner using these little collars. The metal rings that sit on top of the spring:
Rebound is at the bottom, vice versa to the front forks.
Thanks. I actually made type-Os. I meant to say rebound. I edited my post. My preload is maxed (it's hydraulic adjusted which requires an allen key to set) out to get the correct sag but I'm not sure where my rebound is. I'm going to start loosening the rebound by 1-2 clicks at a time to see if it gets better.
Thanks.
The problem was definitely noticeable and that is the reason I could not go fast. Losing rear traction in transitions is an easy recipe for a high side when you get back on the power.
You may need to get that thing sprung to your weight. The valving may not be set up to work within the "range" of your weight either. Maybe off to Kyle or someone?
I had a spring that wasn't stiff enough, no matter what I did it was never right. The preload was maxed. It had a few handling quirks.
You might, just might be able to cover it up a little with a tire with a stiffer sidewall, check your rebound and dial in a touch of compression damp....just think of ways to mask that spring. Again, I'm no pro. I know when I've switched tire brands, some were stiffer and I had to dial back some of the settings.
sounds like you have too little rebound damping, making the rear return too fast. Try slowing it down a little by adding a couple clicks of damping. How is the bike finshing corners? Holding a line, or running wide? As far as preload goes... sounds like too much, if anything; or too much rear ride height.
Re-read through the thread...I had a similar issue on my 749 with the rear returning too fast and upsetting the chassis and not getting grip when cranked over. In your case where it's not hooking up as the bike comes up does sound like too much rebound damping, or too soft in the rear. Makes sense why you're running wide on corner exit. What bike is this on, and what are your sag numbers?
Re-read through the thread...I had a similar issue on my 749 with the rear returning too fast and upsetting the chassis and not getting grip when cranked over. In your case where it's not hooking up as the bike comes up does sound like too much rebound damping, or too soft in the rear. Makes sense why you're running wide on corner exit. What bike is this on, and what are your sag numbers?
It's on my MV and my rear sag is about 32mm last time I checked, I think.
Rear Suspension tuning question
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