Triumphrat

dealsgapdragon · 09-30-2009, 11:03 PM

Right turns are more difficult then left turns. Setting alignment just made it worse. Rear wheel is 1/2 inch off centerline to the right.

youtube.com/watch?v=HcQW_u2AZM8

Many sportbikes and Harleys have this problem. Only fix is bending or machining swingarm and modifying front sprocket. How do racers fix this?

Agkistrodon · 10-01-2009, 04:26 AM

sounds like your bike got crashed and the swinger is bent. couldnt tell you how to fix it without seeing it myself.

Will · 10-02-2009, 12:30 AM

I never noticed this problem when I had a TT600. Have you put the spacers in the wrong place? If not, something is bent or adjusted wrong.

dealsgapdragon · 10-06-2009, 02:00 AM

Quote:

Originally Posted by Will

I never noticed this problem when I had a TT600. Have you put the spacers in the wrong place? If not, something is bent or adjusted wrong.

Spacers were correctly installed, according to the factory manual.

No crashes.

This is a common problem on many motorcycles, including sportbikes.

Quote:

"One of the problems with the CBR600 is that it isn't straight. Our ZX9R is the same. The front and rear wheels can be out of line by as much as 10mm."
-Performance Bikes magazine, The Setup, June 2000

"We typically find wheels are 3-4 mm out of adjustment, with one example of over 20 mm. Anything over 10 mm and the customer tends to come back simply unable to believe that we haven't rebuilt the whole bike, as it's been totally transformed back into the neutral handling bike the manufacturer intended. The system can also detect other issues like frame damage, that might otherwise go undiagnosed."
-Laser Track

My DIY plywood laser system "prototype" is based on this ally laser system and Laser Track, which requires changing spacers on Harleys.

Dealerships never check alignment of front and rear wheels, but occasionally check to see if the front and rear sprockets are in line if you pay extra.

I can buy extra-thin shims from an engineering supply company, but there's not enough room in the swingarm to move the rear wheel 1/2 inch back to center. Even then the sprockets would be out of alignment, without major surgery on the front sprocket mounting setup, or relocating the engine/transmission in the frame, or modifying the triple tree angles. Racers probably use custom swingarms to fix this.

This appears to be one of those problems nobody wants to talk about, because it's been a problem for so long, and only a factory (or race engineering genius) can fix it.

Hopefully this is something the factories are changing?

I first noticed it at lean angles over 45 degrees in a parking lot, with right turns being less confortable, with less lean angle visible on the rear tire. I checked the alignment 3 ways, thinking each way was unreliable in some manner, but they all got the same answer. Aligning the front and rear wheels (so the alignment marks on the swingarm don't line up) just made it handle worse, since it throws the front castor angle off center, and the sprockets are then out of line.

Right hand curves are harder for me anyway, due to countersteering affecting a steady throttle. Some racers say only steer with the inner arm, but that still affects the throttle position, since you have to countersteer twice in both directions in each turn.

I guarantee you, this is one of those Top Secrets that only the winning racers and factory lawyers guard with confidentiality agreements. Image how dangerous it would be for millions of cars to have defective alignment, with no way to adjust it (product-liability and wrongful-death lawyers would have a payday). I've never seen a magazine article telling how this problem is corrected, they just mention paying a fortune to a frame shop. But a frame shop won't modify a frame or swingarm, only straighten a bent frame, unless you pay a lot extra. This is probably why race prep shops charge so much for a fully blueprinted bike setup.

All I can say is measure the F/R wheel alignment on your bike, by whatever method you want, DIY or professional, and post the answer here. And be wary of right-hand curves.

Citizen Mike · 10-07-2009, 04:00 AM

Quote:

Originally Posted by dealsgapdragon

Spacers were correctly installed, according to the factory manual.

No crashes.

This is a common problem on many motorcycles, including sportbikes.

My DIY plywood laser system "prototype" is based on this ally laser system and Laser Track, which requires changing spacers on Harleys.

Dealerships never check alignment of front and rear wheels, but occasionally check to see if the front and rear sprockets are in line if you pay extra.

I can buy extra-thin shims from an engineering supply company, but there's not enough room in the swingarm to move the rear wheel 1/2 inch back to center. Even then the sprockets would be out of alignment, without major surgery on the front sprocket mounting setup, or relocating the engine/transmission in the frame, or modifying the triple tree angles. Racers probably use custom swingarms to fix this.

This appears to be one of those problems nobody wants to talk about, because it's been a problem for so long, and only a factory (or race engineering genius) can fix it.

Hopefully this is something the factories are changing?

I first noticed it at lean angles over 45 degrees in a parking lot, with right turns being less confortable, with less lean angle visible on the rear tire. I checked the alignment 3 ways, thinking each way was unreliable in some manner, but they all got the same answer. Aligning the front and rear wheels (so the alignment marks on the swingarm don't line up) just made it handle worse, since it throws the front castor angle off center, and the sprockets are then out of line.

Right hand curves are harder for me anyway, due to countersteering affecting a steady throttle. Some racers say only steer with the inner arm, but that still affects the throttle position, since you have to countersteer twice in both directions in each turn.

I guarantee you, this is one of those Top Secrets that only the winning racers and factory lawyers guard with confidentiality agreements. Image how dangerous it would be for millions of cars to have defective alignment, with no way to adjust it (product-liability and wrongful-death lawyers would have a payday). I've never seen a magazine article telling how this problem is corrected, they just mention paying a fortune to a frame shop. But a frame shop won't modify a frame or swingarm, only straighten a bent frame, unless you pay a lot extra. This is probably why race prep shops charge so much for a fully blueprinted bike setup.

All I can say is measure the F/R wheel alignment on your bike, by whatever method you want, DIY or professional, and post the answer here. And be wary of right-hand curves.

Thank you for posting your comments and those links on alignment, Dealsgapdragon.

Not being a sportbike pilot, I cannot comment on their alignment issues, but I have been going crazy trying to isolate and remedy alignment issues on my Honda Magna, which is how I found this thread in a Google search. My Magna behaves similarly: cornering left, it is remarkably stable and predictable, for a cruiser, anyway. To the right, it tends to fall into turns and even seems to show signs of headshake. And with limited cornering clearance from the get-go, that is a very unappealing set of handling characteristic.

I have had a small parade of well-meaning individuals -- some with good, working mechanical knowledge and some not -- whose responses ranged from dark pronouncements about the frame being bent (no sign of crinkled tubes or damaged paint) to it being a figment of my imagination, which it isn't either. Nor is the persistent ~1° bank to port necessary to track straight down the slab evidence of a livel;y imagination on my part. I found the only time "Eileen" (as I now call it) can maintain erect posture in motion is with the rear wheel deliberately misaligned, but I'm rather fond of sprockets and chains lasting more than a thousand miles, so I did not let that condition persist. Spacers are correct front and rear, swing arm bearings have no excess play in them, and there is no sign of impact damage anywhere on the bike. A few other people with the same model of bike have experienced the same thing, so I can only attribute it to tolerance stack up during manufacturing and assembly.

And what really gripes me is that I passed on a new Speed Four that my wife had given me permission to buy earlier the same day I came across my Magna. But noooooo, I decided to be responsible and to "save" a couple of thousand bucks...

BombFactory · 10-07-2009, 11:23 AM

I don't think there is enough evidence to suggest that all or even one particular motorcycle manufacturer has designed the rear wheel assembly to be half an inch out of alignment with the front. Out of the two TT600's and one Daytona 955i I've rebuilt from wrecked in which I did a careful and proper alignment check, none showed any offset. I would attribute any such offset to either damaged parts or random factory flaws (which is unlikely for something as structural as wheel alignment). To put it plainly: if the headstock is centered in the chassis, if both sides of the swingarm measure out evenly from the centerline of the chassis to the spacer mounting face, and if the wheel is centered in the swingarm, there can be no offset. I've yet to see anyone measure these independent parts to isolate the problem, but there instead seems to be a lot of speculation and no hard explanation. Furthermore, in the video, the sting line measurement and the measurement taken using a laser beam and piece of plywood against the front tire don't even match each other, so are the wheels truly offset in the first place?

Citizen Mike · 10-07-2009, 11:24 PM

Quote:

Originally Posted by BombFactory

<snip> I would attribute any such offset to either damaged parts or random factory flaws (which is unlikely for something as structural as wheel alignment). To put it plainly: if the headstock is centered in the chassis, if both sides of the swingarm measure out evenly from the centerline of the chassis to the spacer mounting face, and if the wheel is centered in the swingarm, there can be no offset. I've yet to see anyone measure these independent parts to isolate the problem, but there instead seems to be a lot of speculation and no hard explanation. <snip>

I honestly don't know enough to make an informed reply. One of the problems is securing a bike well enough to make measurements with the necessary accuracy and precision to determine just how well aligned the various components really are. The other is not knowing what kind of precision is really required.