|Posted on Tuesday, September 16, 2014 - 01:51 am: ||
In early August I was out at Heartland Park Topeka for a track day. I was having a blast, riding the hell out of my 1125R, I was running Michelin PP 2CT's with a couple thousand miles and a track day on them already, I played with fire and I got a little sassy with the throttle, and high sided at about 40-50mph. I saw it coming, the bike gave me all the normal warning signs. A wiser rider would have reigned it in and either toned it down for the rest of the day, or gotten new tires from the vendor, but apparently I am not a wise man.
The bike barrel rolled at least once (I was a bit preoccupied with my own rolling to count), It bent the subframe pretty hard, broke one of the threaded "nubs" where the subframe bolts to the frame, and it scraped more than a few places on the bike. I just got done rebuilding the damage I could find, and I took it for a little test drive yesterday, and the steering does not feel normal at all.
It drives straight, has no problem in a straight line and feels as stable as ever. If you lean into a moderate turn, the bike just fights and wants to be upright again. Initially I thought this was just an issue of fork height (which was completely thrown off during the rebuild), but I set it to the badweb recommended 10mm rather than factory 14mm, and it still feels weird.
I've worn tires down to cords before and never felt this kind of steering, so I really doubt it's worn out tires, I've "eyeballed" fork height before and never felt this drastic of a steering issue, I'm worried something is bent.
Any insight? Anything I should check immediately? How exactly could I inspect the swing arm for straightness? If forks are straight, how can I check the triple trees?
I'm on a tight budget, if it's forks or a swing arm, I doubt I'll be able to fix it until next year, I'm a student finishing my last semester at college.
Thanks for any help!
|Posted on Tuesday, September 16, 2014 - 06:47 am: ||
forks might not be straight in the triples. Take it to a dealer and have them make sure they are square. Hopefully a fork isn't slightly bent.
|Posted on Tuesday, September 16, 2014 - 08:06 am: ||
My guess is your forks are bent and your trail is out. Slight bends on conventional folks are easily straitened in a press, as they are mild steel. The upside down forks like these are a different story. Bends are usually in the upper casting and are not reliably straightened. This is easy to see. Just take the legs out of the triple clamps and chuck them up in lathe. Any run out will be easily seen. Further, once bent, I would not thrust them to be without cracks. I would be looking for forks off a wreck that are straight.
|Posted on Tuesday, September 16, 2014 - 09:40 am: ||
+1 on the above advice.
|Posted on Tuesday, September 16, 2014 - 09:44 am: ||
I've got an original set of forks from an 09 that were never crashed, pm me if interested.
|Posted on Tuesday, September 16, 2014 - 10:34 am: ||
from the old days....we used to take the 6ft florescent tubes out of the shop's light fixtures and with some rubber bands ( one in front and one behind) "clamp" them to the rear wheel/tire ...we could then see if there was and "offset" between the front and rear wheel by measuring the "gaps" on each side of the front wheel...the bike might track straight but fight you going into a turn...try and find two pieces of something (I would not recommend wood) that you can clamp to the rear wheel...aluminum angle, electrical conduit...the other tool you could use to check "angles" is an "angle finder"...the good ones are digital and are some times named digital protractors they are expensive...you could measure various reference points and compare the measurements.
here are some examples:
http://www.globalindustrial.com/p/tools/test-measu rement/Measuring-Protractors/pro-360-digital-protr actor-w-no-output?infoParam.campaignId=T9F&gclid=C jwKEAjwv9-gBRD5ofn2jd2N0UUSJACcdilsN0EUO2cSbrnGujw 4v_Ixy3aqaEqB6clzxwSBl5ajmxoC0mfw_wcB&gclsrc=aw.ds
I use the one like the mitutoyo for fabricating frames and roll cages...if you use it all the time it pays for itself.
re-assembly of the front end if done in the wrong sequence can cause "twist" or mis alignment...might want to support the bike in a way to get the front end off the ground and start over from the bottom ...up:
axle, pinch bolts on axle, lower triple clamps, upper triple clamps...sometimes the twist causes the axle not to align if we start from the top and go down... we force it and the front end is out of alignment.
|Posted on Tuesday, September 16, 2014 - 05:51 pm: ||
Thanks a bunch for everyone's advice. I'm slow to think it's bent forks because the forks don't show any signs of being smashed around. I'm really hoping it's twisted alignment in the front end, but we'll see.
Any other advice or input is greatly appreciated!
|Posted on Tuesday, September 16, 2014 - 09:55 pm: ||
You would be surprised how a very slightly bent fork will cause enough sticktion to effect handling. It's totally possible the sliders are bent and hidden in the upper tube.
|Posted on Wednesday, September 17, 2014 - 01:50 pm: ||
I destroyed my 1125cr at 90+ bending the forks, rim, triple clamps, swing arm, rear sprocket. I cracked the engine case where the frame bolt goes through at the V between the cylinders. i bent and twisted everything there is to twist and bend on the bike. I dismantled the bike and sent it to a guy in Napa California he straightened all of it and i replaced some parts and put the bike back together. If anyone can believe it or not i believe the bike rides more straight and true than it did new.
places to check:
1.) lower triple clamp, the rod that goes up through the frame at the head tube will bend first.
2.) The Rim, the rims do not have the structural integrity that most bikes do.
3.) Frame bolt between the cylinders. you can splinter the engine case if to much frame flex occurs.
4.) replace both front and rear axles, they bend easy.
5.) rear swing arm, loosen all the hard wear sometimes you can actually see the swing arm snap back to its original position when you go to remove the rear axle. when you pull the axle off the bike and set it on the floor you will know if it is straight and true.
I would loosen all the frame bolts and triple clamps rear swing arm and axles let the frame relax and let the bike settle and re torque everything per the manual then test ride it.
If the problem persists you have issues!
|Posted on Thursday, September 18, 2014 - 05:17 pm: ||
Thanks a ton for the help Buellishness! I just got done taking the front end apart and the rear wheel out, and problems have persisted.
The only thing I noted is that my front axle is bent... Which... Normally would look like the obvious culprit, but (let me explain), it's been bent for almost a year now with no issue. I got ran off the road a last summer and had to rebuild the front end of the bike and replace the frame. It was a great big party, and I bent the front axle, but didn't realize it until I was about to start riding it again, decided to give it a quick test, felt no issues and just decided to leave it. It doesn't seem to be damaged any further than I remember.
I did notice that the bike definitely has more trouble going left than going right, and my tire pressure was low (20psi), but that's not changing the equation.
It looks like I'm buying a new axle, because everything else looks fine.
|Posted on Thursday, September 18, 2014 - 05:21 pm: ||
broke one of the threaded "nubs" where the subframe bolts to the frame
I did the same and just got mine back together. I am just curious what your solution was?
|Posted on Thursday, September 18, 2014 - 08:13 pm: ||
Well... Given my previous offroading experiences... I had a my old frame laying around. I cut the "nub" off my old frame and cut the broken nub off the "good" frame, then bolted everything together so the nub was aligned on the frame and TIG welded the nub to the frame. It ended up working just fine.
In other news, I'm 99% sure my axle is the culprit, I noticed that this time, you can see the wheel tilt back and forth as you tighten the axle in. That wasn't a thing previously. I just snagged one off Ebay, and hopefully it'll solve my problem!