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Rear wheel lock-ups partially solved.

22K views 104 replies 35 participants last post by  Elijah 
#1 · (Edited)
Rear wheel lock-ups partially analyzed.

hi guys. i have experienced this rear wheel lock ups during downshifting after I adjusted my rear shock pre-load to "4" which means STIFFER. Remember that the motorcycle is subjected to a ROCKING MOTION during downshifting or sudden change of speed from high to LOW or LOW to high and vice versa. Now if the rear preload is too stiff then the effects of the tire patch touching the road is different from a soft PRE-LOAD during the rocking motion.

Normally all motorcyle is subjected to this rocking motion during sudden change of speed especially decelerating...

I would revert back to the STANDARD setting of the ninja 300 which is "2" and observe if the rear wheel lock ups and scratch would occur. but in my case I did not experience this rear wheel lock ups in the STANDARD "2" pre-load setting.

i will inform you guys soon in my "2" preload.

https://www.youtube.com/watch?v=-o-idvvdxKQ
 

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#2 · (Edited)
After watching your video and seeing you necro half the board, your issue like a bunch of other people have said and you seem to have ignored, is that you aren't matching engine speed to wheel speed. If the wheel is going faster than the engine is for that gear, the engine is going to drag the wheel as the wheel will try to drive the engine. The wheel wont be able to drive the engine up quick enough and the differential in speed between the wheel's initial speed and what it's immediately slowing down to causes a little chirp of the tires. A mini-lockup. Watching your video showed that you didn't give ANY throttle up at all before releasing the clutch and just dumped the clutch after a very slow and deliberate downshift. Even a slipper clutch wont save you from stupid ham-fisted moves like that. If you aren't going to use throttle to rev match the downshift, then you gotta let the clutch out much slower to give the engine and wheel time to sync up. It also doesn't help that you seem to have a small jungle on the roads itself as the picture of your tire there are completely covered in leaves and debris which means your available traction is MUCH lower than it probably should be.

Your rear shock pre-load is not at fault here. All that's going to do is set ride height. It doesn't stiffen the spring anymore because the spring is a standard, constant rate spring. K, the spring constant in this case, is truly a constant isn't variable along it's length. Setting the pre-load just sets the sag with the goal being to keep your rear suspension towards the middle of it's stroke so you hopefully don't top or bottom out the rear shock.
 
#7 ·
no! im sorry. you do not know what youre saying...you have no idea about compression and rebound. hehehe...before you fire your arrogant mouth first take a test on your ninja 300 by lowering the stiffness of the shocks.....and feel the real answer...hehehe...
 
#3 · (Edited)
He had a video?
LOL.... I tend to use the throttle for the brake first.
Throttle down medium hard, and as you slow down open the throttle up a little bit (no torque), downshift, rinse repeat... listen to the engine.
I have NEVER had the back wheel lock up during a downshift, even in the twisties on the dragon.....
You might need to practice the rpm vrs shifting.....
You sound like you might need a clutch replaced in the future.
 
#5 ·
It will have a tendancy to bark at you more if the spring is preloaded more, and the rear spring is fairly stiff on the 300 stock as they want you to be able to take a passenger safely... so don't over do it unless you're pretty heavy yourself, but I would guess that you're not.
 
#6 ·
guys i have really solved the problem. its a rear-shock preload setting. YOUR ARROGANCE WONT HELP YOU SOLVE THE PROBLEM. I am not arrogant but i CLEARLY solved the wheel hoping problem. In my analysis its very NORMAL since we make the rear shock preload to a more stiffer setting for better handling and cornering..but rear wheel hoping is really caused by a STIFF REAR SHOCK....
TRY Lowering your setting and the WHEEL HOP during downshifting will disappear...but if your VERY ARROGANT then theres nothing i can do about it....heres the final video::

https://www.youtube.com/watch?v=-o-idvvdxKQ
 
#8 ·
Awesome job! Glad you got the problem worked out. Awesome downshifting by the way. I loved how you were able to make the RPMs go from 9k to 2k back up to 9k in a matter of a second. Skills.

Freelancer may not know what he's talking about. Speed matching? Rev match? All that is useless if the preload is at 4.

Im so glad I left it at 2. Maybe that's why I haven't noticed any rear wheel lock up.
 
#9 ·
Does nobody rev match? I didn't even know this was a issue.
 
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#13 ·
The problem is you no matter what you have justified in your mind. If you are not matching engine RPM as you down shift you need to go back to school. All you are doing is masking your inability to down shift correctly and lashing out at people who are trying help you is ARROGANT!
 
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#19 ·
It just makes it much harder to do. The slipper clutch when it initially engages still produces some counter-torque on the spinning wheel before before the cams disengage the clutch. If your RPMs are far off enough, this counter-torque can be enough to give enough deceleration to the wheel that it causes a large speed differential where the deceleration is higher than the traction available on the tire. Think of it as an opposite burnout. Instead of very quickly providing more acceleration to cause the tire to break loose and burn out, you're instead supplying a huge deceleration to the wheel that starts out stronger than the traction available in the tire. Hence locked up tire. In reality the tire when you downshift and "lock" it up isn't actually locked up. It's still spinning but because of such high deceleration vs wheel speed, it looks and feels like it's completely locked. Then, because of inertia and momentum, the tire will tend to slow down a tad too much then it speeds back up again to match speed with the road again. This generally happens in the matter of less than a second or so though. Usually barking the rear from a botched downshift isn't too bad unless you're leaned over when you do it. Which is actually why the slipper clutch is really there to give a little aid for downshifting while trail braking.
 
#21 ·
No! Never been affected by your lenghtyfull arrogant words. Stiff suspension can lift the tires and delay the rebound in a downshift moment. Softer suspension can compensate for the sudden changes. Coz youre not an engineer i will not argue with you. Just try it for yourself and stop being so ignorant and arrogant.
 
#25 ·
You are so arrogant that you dont even understand the word "back torque limiter" ....kawasaki employed the term back torque limiter to limit the wheel hops coz wheel hops is very normal under stiff suspension. I am an engineer and i wont argue with you and your arrogant spirit. Kawasaki company would just laugh at your.explanation. Hehehe
If you're an engineer it would just mean that your country doesn't require any schooling or education. You're probably the same kind of engineer as the guys we saw while deployed who built a bridge that fell apart in 2 months. Please do the world a favor and don't touch anything until you've taken some basic physics, statics and dynamics. As of right now you probably couldn't find the center of mass of your ass with your head shoved so far up it.
 
#22 ·
You are so arrogant that you dont even understand the word "back torque limiter" ....kawasaki employed the term back torque limiter to limit the wheel hops coz wheel hops is very normal under stiff suspension. I am an engineer and i wont argue with you and your arrogant spirit. Kawasaki company would just laugh at your.explanation. Hehehe
 
#27 ·
Hey there buddy, just because you're an engineer (which is kind of broad to begin with) doesn't mean you know how to ride.. The only ignorance and arrogance that's been displayed is by you and the only evidence you've provided to support your claims is in the videos you posted.. Which explained everything to the rest of us.. Just quit while you think your ahead and go practice man. This place is filled with knowledge, don't let your ego get in the way of learning something new.
 
#32 ·
well aside the fact that the OP seems to be a 17 year old "engineer" - lets get past that. At first I was suspicious of the slipper clutch "feature" as well as the ABS. To my old fashioned brain they are good things but can have two down sides; that of expensive repairs down the road and that of making a less skilled rider stay that way longer, due to the fact that the bike usually wipes his ass successfully, but that one day, not well enough for him to become road kill.

First part - and this is a question for you all, I'm not sure of things - is the slipper clutch not supposed to cure this newbies lack of clutch control and rev-matching cluelessness? There are slipper clutches and there are slipper clutches. I imagine that at the price point that our bike comes in at that the slipper clutch is decent but not a miracle cure. Am I right? The clutch, under high torque, should just let the wheel slip rather than hop. I guess that with serious abuse the slipper clutch takes a moment to engage (disengage I guess) and in that second there could be a hop, since he may be near the limits of adhesion already. Or could he have a slipper clutch that is defective, not wiping his ass the way it should?

I have a similar dislike of ABS. I've always found the ABS of bikes I've ridden to be good, but not a stellar feature. After reading this thread I got to wondering about it and went out and used the brakes like a moron. Dang. The ABS kind of works, but I sure can make the tire squeal at the same time - which to me means that under some situations the ABS can misfire and put you down in a lowside (or whatever). I'm glad I got the ABS mind you, since it helps and it is for a complete newbie. Just the same I think that there is a lesson here - that technology is nice, but not a panacea. Beginers should still learn to ride as if they had no ass wipe mechanism. Are you listening, oh engineer OP?

The above posters are trying to help you out. :)
 
#34 ·
I imagine that at the price point that our bike comes in at that the slipper clutch is decent but not a miracle cure. Am I right?
Whenever I have made mistakes while downshifting/throttle blip, I have heard a somewhat loud "clack" from somewhere in the engine. Maybe that's the slipper clutch doing its job because I have never locked up the rear wheel. I once by mistake downshifted to 1st without blipping(I thought I would be in 2nd) & the revs shot up to 9k rpm, but the wheel did not lock. So I think the slipper clutch on the Ninja 300 works.

Regards,
Kaustav
 
#36 ·
The other downside of not properly rev-matching, even if it does not cause a hop or shoot the rpm stupidly abruptly high - is that it is more wear on the clutch plates and more shock to the springs. It also make a rider look like a ham-fisted goober. Everyone makes a mistake from time to time, sure. I judge a good rider by watching how they anticipate and how smooth they are. At the end of the day all we really have are two small contact points between tire and road. Best to not abuse it. :)
 
#37 ·
All I know is.... I watched his video....
He pulls in clutch doing about 40 mph,
he then drops his throttle to idle (you can hear it),
he then downshifts,
he then lets out the clutch fast....
the bike then chirps.... and hops....
he then twists the throttle back up...


I think he is an inexperienced rider.... the video does not lie.
 
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