Wheel alignment specifications

[PMK]

Do you by chance know the range of toe change over the full suspension travel? And, is the Ackermann compensation correct or does it muck with the toe as well?

I never measured the toe change, bump steer over full travel of the suspension.

As for Akermann effect and associated changes, the Spyder uses a primitive design that may not optimize the Akermann and tire angles.

Considering the Spyder does not have true capability to adjust Camber, or Caster, and relies on toe setting only with a pinch of ride height as needed, Akermann changes would require redesigning the steering bellcrank and likely would never be optimized unless a wide steering rack were installed at the correct height or idler arms were added.

A vehicle that demonstrates bump steer in an amount such as the Spyder, will always struggle with finding alignment angles to be optimal at anything but straight ahead and laden. This demonstrates why those Spyders that run more toe in than others often have better cornering manners that involves chassis roll, while those with less toe in, will see better economy in straight line while sacrificing cornering performance, especially involving chassis roll.

All the best with it.

 

[DingerD]

As we change out the Crapendas, does anyone know what the proper torque setting is for the front lug nuts? Thanks all!

 

[ButterSmooth]

I never measured the toe change, bump steer over full travel of the suspension.

As for Akermann effect and associated changes, the Spyder uses a primitive design that may not optimize the Akermann and tire angles.

Considering the Spyder does not have true capability to adjust Camber, or Caster, and relies on toe setting only with a pinch of ride height as needed, Akermann changes would require redesigning the steering bellcrank and likely would never be optimized unless a wide steering rack were installed at the correct height or idler arms were added.

A vehicle that demonstrates bump steer in an amount such as the Spyder, will always struggle with finding alignment angles to be optimal at anything but straight ahead and laden. This demonstrates why those Spyders that run more toe in than others often have better cornering manners that involves chassis roll, while those with less toe in, will see better economy in straight line while sacrificing cornering performance, especially involving chassis roll.

All the best with it.

The toe settings seem to have been arrived at by experimental methods. Since a lot of folks have done the experimentation and confirmation of what works, there is no real reason to do a calculated confirmation of the settings as well. Thanks for the thoughtful response to a pedantic question.

 

[Possible]

As we change out the Crapendas, does anyone know what the proper torque setting is for the front lug nuts? Thanks all!

The service manual for Peggy's 2013 STS-SM5 shows 77 lb.ft. for the front wheels.

 

[PMK]

The toe settings seem to have been arrived at by experimental methods. Since a lot of folks have done the experimentation and confirmation of what works, there is no real reason to do a calculated confirmation of the settings as well. Thanks for the thoughtful response to a pedantic question.

Your welcome.

As for experimentation to determine settings, I doubt many owners have accomplished alignment changes on their own. Some have, but unlikely many. Most simply employ a dealer or alignment specialist to accomplish the task.

The unfortunate truth about front wheel alignment on a Spyder hinges around several factors. Rider or if two up rider(s) weight, ride height setting, spring rate, and even swaybar choice can influence best setup.

Regarding experimenting to obtain the settings, yes, this can be done, but requires an understanding of vehicle dynamics and the feedback the Spyder sends to the rider.

The other concerns, and why I made a few posts in this topic is simply clarification. Depending upon the method / equipment utilized, simply obtaining a "number" for the setting is in most cases meaningless, unless the same type tooling and method is used. Add to this, these specs shared, the reader must understand not only how to align, but also are the specs representing Total Toe or something else.

Again, all the best with how you proceed to align your Spyder. I would also not consider your questions pedantic, which I did need to research the definition. Safety is involved in understanding this topic, regardless of how primitive or inadequate from a performance standpoint the Spyder front suspension and steering may be.

 

[ButterSmooth]

Lots of things effect that. Load weight, spring rates to name two. We adjust to 3/4 to 1 1/4 toe in measured at 120" between targets. Which end of that range we shoot for depends on load and spring rate.

So that would be -.5°±.12°. BMW specifies that wheel alignment be done with the driver in his seat and 200# sandbag in the passenger seat, much like your "load and spring rate" adjustment range. I like it!

 

[redrazor]

Lots of things effect that. Load weight, spring rates to name two. We adjust to 3/4 to 1 1/4 toe in measured at 120" between targets. Which end of that range we shoot for depends on load and spring rate.

:shocked:wouldn't 3/4 inch of toe-in cause front tires to scuff outside edges pretty badly?? ..... and 1 1/4 inch toe-in would seem to slow you down and really scuff the tires.(??):yikes:

 

[PinkRosePetal]

:shocked:wouldn't 3/4 inch of toe-in cause front tires to scuff outside edges pretty badly?? ..... and 1 1/4 inch toe-in would seem to slow you down and really scuff the tires.(??):yikes:

Yep, I agree. That's seriously wrong.

Using the wheel rim as the datum (not the tyre) 2.5 - 3mm toe in is a good starting point. That's less than 1/8" for you USofA folks.

 

[DingerD]

Perfect! Thanks for digging.

 

[Cobwebs]

:shocked:wouldn't 3/4 inch of toe-in cause front tires to scuff outside edges pretty badly?? ..... and 1 1/4 inch toe-in would seem to slow you down and really scuff the tires.(??):yikes:

Yep, I agree. That's seriously wrong.

Using the wheel rim as the datum (not the tyre) 2.5 - 3mm toe in is a good starting point. That's less than 1/8" for you USofA folks.

Divide those numbers by ten is how you arrive at the actual toe in. The laser targets are spaced out ten foot apart to give accuracy.

 

[IdahoMtnSpyder]

:shocked:wouldn't 3/4 inch of toe-in cause front tires to scuff outside edges pretty badly?? ..... and 1 1/4 inch toe-in would seem to slow you down and really scuff the tires.(??):yikes:

Note that JC said 120" between targets. That would the toe-in over 120" which most likely is the targets spaced 60" in front and 60" behind the wheel center. That's about 0.6° for 1.25" toe-in.

 

[jcthorne]

deleted

 

[PinkRosePetal]

You did not read what I wrote. Toe in is set at 3/4 to 1 1/4 toe in MEASURED OVER A 120" TARGET DISTANCE.

That's not my quote but yep, I just clocked that, I obviously had my squint thinking cap on, apologies to you, JC.