Laser Schmaser ?

[IdahoMtnSpyder]

of course,if the bars are already straight,when the bike is underway, then you only need to shoot front and back to get the correct toe....no need to lock down the handlebars,as you will adjust both tie rods an equal amount

Hey Russ, it's good to see you're still around!

In reality though, how often are you going to find that the bike tracks straight ahead when the handlebars are in the center position? I believe the main reason for locking the handlebars in place is to prevent inadvertent movement of them from complicating the adjustment process.

After thinking about it some more I still contend toe-in can be correctly set without knowing what the track width is. What you have to end up with is both beams being an equal distance from the rear wheel when the process is finished. Once you know what the beam spread is at the front and the rear you can adjust the rear targets to set the distance between them to be the correct toe-in distance apart when compared to the front, which I think Lamont says is about 1 1/4" difference front target vs rear target? Then you move both targets sideways the same amount until they are an equal distance from the rear wheel.


View attachment 177934

 

[lindsayw148]

The key phrase in your comment is "good enough"!

Yes, it is. I have seen Spyders with NO camber on one side and DOUBLE camber on the other, so welding the frame (with its FIXED camber) must be fairly inaccurate, plus the five-times magnification effect solves most of the other problems. Even if the front wheel width measurement is out by the amount of the incoming toe-in/toe-out, that’s a VERY SMALL error, and the targets are placed to magnify that. Certainly it’s true that I have seen bikes with alignment so bad that the laser dot was right off the target (instead of within 20mm of center) but they were usually bikes with pronounced crabbing – handlebar was way off center – and re-measuring the front wheel width in those cases gave me a figure only a couple of mm different. Not enough to make a significant difference.

The enemy is VERY SLIGHT toe-out – that’s what causes the skittery, wandering steering as the wheels encounter bumps and irregularities on the road, causing one tyre or the other to carry more steering load briefly, spearing the bike off in whatever direction it’s pointing, until the other tyre hits the ground and changes that equation. All roads have camber, so the ‘downhill’ wheel (for me that’s the left one – for you it’s the right one), carries slightly more of the load, so it’s the one that usually shows the most tyre scrubbing effect from poor alignment.

 

[Jetfixer]

"This video by Shawn Smoak ido not see him measure track width. Possibly his video format omitted it, but if an alignment can be done without learning what true zero is, I would enjoy hearing how that is possible"


my understanding of true zero is handlebar position when bike is underway.....this explains why he dosent need track width(he knew the bars were straight)
if the bars point to the right,say,then you can adjust them back to centre by adjusting both wheels into the direction of the bars,until bars are straight when underway,then shoot front and back to set the toe,adjusting both track rods the same amount

this takes away the need for bringing the rear wheel into the equation(or making grids or finding the track width)...its only needed to set handlebar position(and greatly simplifies the alignment process).....but only if you can ride the bike,or ask the owner if bars are straight

of course,if the bars are already straight,when the bike is underway, then you only need to shoot front and back to get the correct toe....no need to lock down the handlebars,as you will adjust both tie rods an equal amount

there is only one adjustment for alignment purposes(tie rods)so how many things do we expect to influence?
ANSWER.....2 toe in/out and handlebar position when underway

russ

The point of locking down the handlebars after finding true center, is to zero out the steering angle using BUDS. This accomplishes a couple of things. It tells the DPS system where straight and true steering angle is, relaxes the current draw of the DPS system at true center, and also centers the turn signal cancelling. You want to adjust each front wheels' toe-in with the steering accurately centered. It is amazing how sensitive the DPS system is to handlebar input. The only way to see this is with BUDS.
Here's a partial screen shot of a BUDS DPS page. If you're not truly centered, your angle will always be off, which affects the VSS system, and the DPS system will always be supplying current to try to "center" you.

 

[merlot]

hi Idaho...yup,cant kill me with a stick

the bars dont need to be straight for the bike to track straight(just needs unworn tyres)

the bars have nothing to do with the tracking of the bike(ignoring shimmy and bump steer and power steering now activated due to offset)

the two front wheels will fall to the same angle about the thrust vector(push from the back wheel)

you can have perfect toe in/out but also have handlebar offset if the left and right tie rods are at different lengths

the best way to check handlebars is to ride the bike.....if the bars are straight,you cant adjust one tie rod differently from the other as you will offset the bars.....but due to the laws of physics(i call it the Plough Effect,im sure there is a correct term for this phenom but im not smart enough to know what it is)the bike will always track straight.....

it wont track straight if the tyres are already worn thru previous poor alignment or there are other mechanical faults evident

this is why i dont bother aligning anything to the back wheel....the bike will decide its own fate once it gets moving and physics take over

if you took a bike straight off the assembly line,however,then i would definately set the handlebars off the back wheel as the Big Boys do...then set the toe

i THINK that shimmy is the two front wheels trying to equalise their angle to the centreline of force(push vector) more noticeable when toe out is present, or zero toe

these are just my thoughts on the subject,as i didnt train at the "college of alignment"
come to think of it,neither did anyone else:roflblack:

russ

 

[PMK]

Yes, it is. I have seen Spyders with NO camber on one side and DOUBLE camber on the other, so welding the frame (with its FIXED camber) must be fairly inaccurate, plus the five-times magnification effect solves most of the other problems. Even if the front wheel width measurement is out by the amount of the incoming toe-in/toe-out, that’s a VERY SMALL error, and the targets are placed to magnify that. Certainly it’s true that I have seen bikes with alignment so bad that the laser dot was right off the target (instead of within 20mm of center) but they were usually bikes with pronounced crabbing – handlebar was way off center – and re-measuring the front wheel width in those cases gave me a figure only a couple of mm different. Not enough to make a significant difference.

The enemy is VERY SLIGHT toe-out – that’s what causes the skittery, wandering steering as the wheels encounter bumps and irregularities on the road, causing one tyre or the other to carry more steering load briefly, spearing the bike off in whatever direction it’s pointing, until the other tyre hits the ground and changes that equation. All roads have camber, so the ‘downhill’ wheel (for me that’s the left one – for you it’s the right one), carries slightly more of the load, so it’s the one that usually shows the most tyre scrubbing effect from poor alignment.

Simple chassis lean from unequal spring preloads can induce differences in camber.

So, if I understand your words correctly, you deem camber differences, or even simply camber alone, even if equal left and right, is a greater error in establishing the truly square box than incorrect toe setting?

As I understand the instructions, the point projected aft and downward to the floor is the base number of your targets span. From this dimension you have subtracted the width of the rim and divided by two in order to establish the zero points of the targets. Understood and fair enough, provided the incorrect toe setting prior to aligning, is inconsequential to the zero point of targets. Hypothetically, if the Spyder had even toe per side at 15mm per side on the targets, that translates to 3mm or slightly more at the aft edge of the tire. The point you project downward. Saying that, this would induce a 3mm per side error on the each target, 6mm total.

Is this correct?

 

[lindsayw148]

As I understand the instructions, the point projected aft and downward to the floor is the base number of your targets span. From this dimension you have subtracted the width of the rim and divided by two in order to establish the zero points of the targets. Understood and fair enough, provided the incorrect toe setting prior to aligning, is inconsequential to the zero point of targets. Hypothetically, if the Spyder had even toe per side at 15mm per side on the targets, that translates to 3mm or slightly more at the aft edge of the tire. The point you project downward. Saying that, this would induce a 3mm per side error on the each target, 6mm total.

No, not quite. The main issue is to avoid that camber error, so the laser should NEVER point anywhere except exactly parallel to the floor. When you point it down, it points outward; when you point it up, it points inward. Only a small amount but enough to make a difference because the error gets magnified over that distance. That's why the scale on the targets are at exactly 270mm height above the floor – the same height as the front wheel hubs. They could be a few mm higher or lower without causing a problem (try measuring the error in an extremely flat triangle that long and you'll suffer brain damage) but just keeping that laser beam parallel to the ground is what steps around the camber problem.

PS: (an afterthought from reading your quote again) camber doesn't make any difference to alignment between forward and aft edge of the wheel, so it doesn't affect the center-line of the targets. It's purely a top-bottom lean on the wheel, but pointing the laser up or down DOES make a sideways difference. So the combo of using a square on the floor to get a true vertical reading at the front wheels (not a camber-affected width) and keeping the laser beam parallel to the floor is what keeps it free of camber influence (plus the target scale at the correct height).

 

[UtahPete]

hi Idaho...yup,cant kill me with a stick

the bars dont need to be straight for the bike to track straight(just needs unworn tyres)

the bars have nothing to do with the tracking of the bike(ignoring shimmy and bump steer and power steering now activated due to offset)

the two front wheels will fall to the same angle about the thrust vector(push from the back wheel)

you can have perfect toe in/out but also have handlebar offset if the left and right tie rods are at different lengths

the best way to check handlebars is to ride the bike.....if the bars are straight,you cant adjust one tie rod differently from the other as you will offset the bars.....but due to the laws of physics(i call it the Plough Effect,im sure there is a correct term for this phenom but im not smart enough to know what it is)the bike will always track straight.....

it wont track straight if the tyres are already worn thru previous poor alignment or there are other mechanical faults evident

this is why i dont bother aligning anything to the back wheel....the bike will decide its own fate once it gets moving and physics take over

if you took a bike straight off the assembly line,however,then i would definately set the handlebars off the back wheel as the Big Boys do...then set the toe

i THINK that shimmy is the two front wheels trying to equalise their angle to the centreline of force(push vector) more noticeable when toe out is present, or zero toe

these are just my thoughts on the subject,as i didnt train at the "college of alignment"
come to think of it,neither did anyone else:roflblack:

russ

Oh, you Devil you!

 

[merlot]

hi Jetfixer

i agree with everything you say except this:and the DPS system will always be supplying current to try to "center" you

the DPS isnt there to bring the bike back to centre.......its only needed due to the forces required to overcome the bikes physics....ie its unwillingness to change front wheel angle to the push vector

as you know the dps assist increases as you turn the bars more

i dont know when it kicks in but i would be surprised if it were immediately off "centre"

also the bike is dynamic and jumping around a fair bit at centre so no matter how good you set it,it would always be changing its position

good explanation for locking down the bars,and the progression to the end,but it does mean that anyone without Buds cant be doing wheel alignments.......i never really saw the point of zeroing with Buds(i used to have Buds)but i now see the sense of it(you know its zero if you say it is) i work back to front and set zero dynamically

enjoying this topic and always learning
russ

 

[merlot]

Oh, you Devil you!

roflmao

 

[IdahoMtnSpyder]

the DPS isnt there to bring the bike back to centre.......its only needed due to the forces required to overcome the bikes physics....ie its unwillingness to change front wheel angle to the push vector

as you know the dps assist increases as you turn the bars more

Not quite right. The amount of DPS assist is a function of turning torque, not turning angle. The greater the resistance to turning, as measured by twisting of the steering column portion inside the DPS, the greater the assist. The net result is essentially the same since torque and angle are closely related. I don't know for sure but it makes sense to me that a long radius turn at high speed will prompt more assist than a short radius turn at slow speed.

 

[PMK]

these are just my thoughts on the subject,as i didnt train at the "college of alignment"
come to think of it,neither did anyone else:roflblack:
russ

Pretty Arrogant Statement.

 

[merlot]

Not quite right. The amount of DPS assist is a function of turning torque, not turning angle. The greater the resistance to turning, as measured by twisting of the steering column portion inside the DPS, the greater the assist. The net result is essentially the same since torque and angle are closely related. I don't know for sure but it makes sense to me that a long radius turn at high speed will prompt more assist than a short radius turn at slow speed.

yeah that makes a lot of sense
so the torque required to keep the bike straight under way would be negligible,so very little input from the power steering at zero steering angle

russ

 

[merlot]

Pretty Arrogant Statement.

how do you see arrogance when there is an imoji laughing?

russ

 

[PinkRosePetal]

.... I don't know for sure but it makes sense to me that a long radius turn at high speed will prompt more assist than a short radius turn at slow speed.

I would have thought it would be the opposite.

 

[PMK]

how do you see arrogance when there is an imoji laughing?

russ

The emoji selected, posted after the words you used, does not represent humor, but rather insulting laughter at others.

A laughter emoji never equates as a get out of jail free card.

As you do indicate though, there is certainly an amount of misinformation that has been posted. Time will tell how all of it sorts out.

 

[12tree]

Fight nice boys.

 

[ARtraveler]

Let's go back to being civil. It's only wheel alignment that is being discussed. :thumbup:

 

[jcthorne]

It is important to zero the steering angle sensor AND the DPS torque input sensor at the same point the toe vector is adjusted to. Otherwise the DPS will actually cause the bike to veer off straight ahead. Intentionally setting these two sensors wrong can actually make a Spyder track in a circle with zero rider input to the bars. IE all three items need to be zero at the same physical point for the bike to track well with little rider input. The bike will not track straight if the DPS is pushing it off center.

 

[IdahoMtnSpyder]

I don't know for sure but it makes sense to me that a long radius turn at high speed will prompt more assist than a short radius turn at slow speed.

I would have thought it would be the opposite.

Your comeback prompts me to either prove my point or prepare to eat crow. I get to do a little of both!
From the 2013 RT service manual.



I have to eat crow and admit I was wrong above when I said the steering assist depended on steering torque, not steering angle. Steering angle is one of the parameters that the DPS uses to calculate the assist, as is also speed. The service manual doesn't describe the degree to which each of the inputs has an effect, but the implication is that steering torque is the primary one. That's the parameter that stuck in my mind. So let's see why steering torque varies as I surmise above.

Centripetal force is the force exerted on a body to keep it turning toward the center of the curve. It is a function of the mass of the turning body, the square of the tangential velocity of that body, and the radius of the turn. If mass and radius stay constant the force quadruples when the speed doubles. F(centripetal) = m x V**2/r. Since we want to compare the force of the same mass at two different speeds at two different radii, F(long)/F(short), mass cancels out. The formula then becomes F(long)/F(short) = V(long)**2/V(short)**2 x r(short)/r(long). So let's put in 30 mph and 50 feet for the short turn and 60 mph and 100 feet for the long turn. It doesn't matter if we use imperial or metric numbers since the units cancel out.

F(long)/F(short) = 60**2/30**2 x 50/100 = 3600/900 x 1/2 = 4 x 1/2 = 2. You can see the centripetal force, which is supplied to the tires by steering torque, keeping them turned toward the inside of the curve, is twice as great at 60 mph and 100 ft than at 30 mph and 50 feet. What we don't know, since BRP doesn't tell us, is how much the short turn steering torque assist is increased because of the slower speed and sharper steering angle. If, in fact, there is greater steering assist at the tighter turn at slower speed, it's because of the algorithm BRP uses and not because of the dynamic forces on the bike. Interesting, isn't it?

 

[Jetfixer]

And to get trivial, the more the steering angle is wrong, the more you are trying to hold it straight with help from the DPS system. The more torque you apply to the handlebars, the higher the current draw of the DPS. That equates to more load on the alternator, which means more fuel consumption.