Rear wags during hard braking

Most of the common fixes/issues have already been listed in this thread. Yes, the issue could be caused by anything, even a handful of uncommon out-of-range adjustments instead of just one. But thats less likely than the common ones. You probably need to change 1-2 common things to fix the issue well enough for you and your riding. Then as you get faster, you can fix it again along with 5 other things

 

if we made everyone starting a "setup" thread fill out a spreadsheet with all their setup parameters, the quality of service would definitely be a lot faster. but a lot fewer people would be helped, as some riders cant/wont get the info. im not bothered by having a conversation about their setup with incomplete info. if someone else is bothered, they dont have to post.

 

As stated previously, Mike is exactly right.

I mean this in a nice way but if your on here asking how to set up a motorcycles baseline then you have no idea on how to set up a motorcycle correctly. There is a ton of things to it.

Your best coarse of action IMO is to get someone who knows what they are doing to set you up at least with a baseline of proper settings and as you learn and progress tweek things as you see fit.

Baseline suspension set up is cheap. I can assure/ promise you that you will piss away way more money on less important things in this sport at some point.

 

Along the point Mike made, which is spot on as usual, do we even know this is suspension related? For example my 06 R6 used to tail wag all the time until I did the slipper clutch mod. Does this mystery bike even have a slipper clutch? Is there too much engine braking, and can it be flashed out? Etc, etc....

 

Your R6 wagged its tail even in the pits, you ham-fisted monster.

+1 for MDM.

 

Everything I ride lmao

 

Troof.

 

This stopped my rear wheel hop. Bleed some air into your rear brake so it is not so sensitive. And use your rear brake.. Worked for my Yamaha 1000

 

I had this issue with my r6 after we changed the oil weight to 10. It’s got 1.0 springs and 25mm valving.

upped the compression to 4 clicks from max dampening, three lines of preload. Took care of 70% of the problem. The other 30% I was ham fisting the brake far too hard from the get go. I applied the brake ever so slightly softer to start, before going HAM.

still a little floaty in the rear so I have to see what else is the culprit (the rear tire wear holes are showing raised leading edges which tells me I need to add rebound dampening) so chances are you need to play with a few settings.

edit: also as Jim said above, back brake. I’m making it a skill bit by bit. I was surprised how much stopping/stabilizing power it really had. So much so I’m working on machining a thumb brake.

 

Interesting thread. I have struggled with side to side wagging on my R6 and have slowly added some front preload to help.

.95 springs and 25mm valving. 38mm sag up front and 15 in rear. Rev matching better on downshifts also has helped this.

The one benefit is in a race, it makes your competitors question getting near you while your swaying back and forth on the brakes lol..

 

Damn Jon..

 

This! Lol... don’t pass an unstable bike on the outside unless you know the rider and for sure they will make the corner.

 

I'm going to agree with Metric Devil Mike here.

But ask the OP to think about a couple things.

What happens to the weight distribution and momentum type forces on a motorcycle under braking?

Think kind of like a see-saw....you apply brakes, front end dives under braking, and somewhere in the math
is a fulcrum point that leverages/pivots the bike on an axis...so the rear gets light and lifts....and your rear tire's contact
patch is so small it's either not contacting the pavement or hovering just a hair above....which is the "wag" you experience.
The front tire's contact patch expands under braking, and everthang compresses in front and shortens ALL the geometry at the nose of the bike.

Think about that for a second...

And you're adjusting the rear shock?????

Had a similar experience years ago with a GSXR750 I used for track days. I had put Ohlins on it front and rear, and went to VIR South for a NESBA day.
Back in those days, @lonewrench was track side tire and other support for that org. Asked him to help set it up...and before he took any money from me
he said, "Just go out and ride it." So, I went out, and had the same bike behavior you're describing. Went back to Chuck and told him what was happening
and that I just didn't like it. He had me bring the bike over, he took a few minutes, didn't measure anything that I recall, bounced the front and rear, and both
together, then made adjustments based on his years and years of experience.

Then he told me to go out and ride again....so I did....came back...told him some more about what it was doing and what I was feeling, a few more adjustments.
Went back out and the bike was perfect. Handling was spot on, almost telepathic, and the tire wear was magnificent the entire time I owned that bike.

I'm pretty sure there wasn't enough of everything in the front end of my bike that day, he fixed that, then re-balanced the whole thing with rear adjustments to account
for the changes. My guess is you're looking at this as a "front problem" or a "rear problem" when it's a whole bike is out of whack problem.

His services and expertise that day cost me $40. Worth every cent.

When and where is your next track day? Find yourself a @metricdevilmoto type person at that event and have them help you.