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PostPosted: August 9, 2014, 2:45 pm 
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Mid-Engined Maniac

Joined: April 23, 2006, 8:26 pm
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Yes, figure about 1/2" compression, or 1"smaller OD.

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PostPosted: April 4, 2015, 12:36 pm 
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Joined: August 11, 2012, 10:56 pm
Posts: 187
Location: Arizona
Vsusp update
- added tire sidewall compression input (Wheels/tires setting) - suggested by Horizenjob
- added rolling radius output: takes into account sidewall compression
- tire circumference still does NOT take into account sidewall compression

- updated test for internet explorer (still highly unrecommended) so it will detect all IE browsers
- changed Front/Rear suspension toggle from a link to a button
- changed Reset Trim toggle from a link to a button
- fixed some issues with displaying units
- updated window title, now starts with 'VSusp:'
- minor styling update for select/dropdown boxes and output boxes
- added tire section widths: 125, 135
- added /82 profile/series tires
- added 10 and 11 inch wheel diameters
- added max length for string controls
- fixed min/max check for number inputs
- fixed dimension highlighter/mouseover for explicit tire width
- internal code cleanup and performance fixes

As always, thanks, everyone, for your interest and patience :)

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PostPosted: December 18, 2015, 6:39 pm 
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I appreciate all the work you've put in to this Rob. I think it is a great educational tool and a lot of fun.

If you are still making improvements, I have a suggestion.

By adding an outer tie rod joint location point, a point can be determined where a line drawn to the instant center crosses a line between the lca and uca inner pivots. The distance between the point on the left and the right would provide the rack length between inner pivots. The frame and control arm lengths could then be adjusted to work with any particular rack we want to use. Another measure could provide the vertical mounting height.

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PostPosted: December 22, 2015, 8:47 am 
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Miatav8,MstrASE,A&P,F wrote:
I appreciate all the work you've put in to this Rob. I think it is a great educational tool and a lot of fun.

If you are still making improvements, I have a suggestion.

By adding an outer tie rod joint location point, a point can be determined where a line drawn to the instant center crosses a line between the lca and uca inner pivots. The distance between the point on the left and the right would provide the rack length between inner pivots. The frame and control arm lengths could then be adjusted to work with any particular rack we want to use. Another measure could provide the vertical mounting height.


I'll start looking today or tomorrow at how I can implement this feature. It's seems feasible at this point to add to the tool.

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PostPosted: January 4, 2016, 12:53 pm 
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Updates for calculating the steering rack position are almost done. I'm finishing the dimension highlighters and should be able to update in the next few days tops.

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PostPosted: January 10, 2016, 3:09 pm 
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A few days turned into almost a week :?

Vsusp update
- steering rack calculation: rack height/width (suggested by Miatav8,MstrASE,A&P,F)
- increased diagram width to accommodate new Steering panel
- added most of the steering dimension highlighters
- added setting for showing/hiding IC/RC/steering lines while still showing the IC and RC dots

There are still some tooltip and mouseover updates, but the ability to calculate the steering rack is there.

- Make sure to enable steering in the Steering panel
- Set the outer tie rod center location relative to the wheel mounting hub
- Tie rods should stay pointed at the instant centers, for the most part
- Tie rod lengths shouldn't change much on roll/bump. This indicates little to no bump steer (good)
- Should work fine with MacPherson strut

Please let me know if you see any bugs

:cheers:

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PostPosted: January 10, 2016, 6:09 pm 
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That's great Rob, I'm glad you're still putting effort into this.
:cheers:

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PostPosted: January 14, 2016, 12:51 pm 
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Glad to help when I can :) I wish I had more time so I could do more

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PostPosted: January 29, 2016, 5:57 pm 
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Joined: December 16, 2012, 12:06 pm
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Location: Portland Maine
I really appreciate the steering rack calculation. Thanks Rob!


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PostPosted: January 29, 2016, 7:23 pm 
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Joined: April 23, 2006, 8:26 pm
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Way back when I asked if when increasing caster (leaning the upright aft in side view) the program take into account the outboard steering pivot rising? I just bring it up because I got bit by this with the Mitchell sw, which instead thought I was redesigning the upright's pick up points... no, no, no. As a result there was some bumpsteer right out of the box :(

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PostPosted: February 3, 2016, 8:57 am 
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I don't think Rob gets notified when there are responses to this topic. Try a pm.

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PostPosted: February 16, 2016, 6:30 pm 
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KB58 wrote:
Way back when I asked if when increasing caster (leaning the upright aft in side view) the program take into account the outboard steering pivot rising? I just bring it up because I got bit by this with the Mitchell sw, which instead thought I was redesigning the upright's pick up points... no, no, no. As a result there was some bumpsteer right out of the box :(

Hi KB58 - sorry I just saw your post now. Answering your question, vsusp doesn't take caster in account. So, yes this would cause a bump steer issue unless it is taken into account. :(

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PostPosted: February 16, 2016, 7:39 pm 
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I guess I misunderstood the question before.

Bumpsteer is only tweaked with the wheels parallel. Any change to caster should throw it off. Any change from the tweak for parallel to compensate would also throw off the parallel setting, but I suppose there would be a compromising solution.

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PostPosted: February 17, 2016, 12:34 pm 
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If one measures the vertical height of the knuckle's steering arm while ignoring caster (car is setup and aligned), then vsusp's steering calculation will work ok. In other words, treat all measurements on the vehicle as if you're looking flat/two-dimensional picture.

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PostPosted: July 31, 2016, 7:42 pm 
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Location: Arizona
I found out the other day that Vsusp is calculating SAI/KPI incorrectly. It's using the angle between the line formed by the upper and lower ball joints and the wheel centerline. It should be using the angle between the UBJ/LBJ (a.k.a steering axis) and a line perpendicular to the ground.

I'll try to get a fix in soon, but I wanted to give you guys a heads up. :oops:

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