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PostPosted: November 26, 2013, 7:24 pm 
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I see what you guys mean about loosing some of the data when using the link.

This is parallel unequal length, default spindles, 205-50-15 adjusted for near zero scrub, rc just below ground and stays below but shifts side to side within track. Aimed for 1:1 camber gain per degree roll with little camber gain in bump.

Any idea what the default spindles are supposed to be?


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PostPosted: November 26, 2013, 11:16 pm 
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No idea on the default spindles. Chet's were Miata, I think.

How do you get camber gain in roll and not bump? I'm missing something here…

I don't understand the x displacement of the roll center thing. We look at roll center as a way to calculate the dynamic weight transfer when cornering. It's the vertical height here that defines that and the horizontal displacement is not important. So I ignore those numbers.

People seem to aim for less then 1:1 camber correction so that they don't lose so much traction in braking. Single wheel bumps may be an issue too. I've read 25% - 50% as a common range and so now I aim for less then I once did. I'm also making my suspension attachments with bolt on tabs so I can try changing some of this stuff to see how much difference some things make. I sort of expect to find out the same things others found out before me though and land up with numbers like I mentioned…

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PostPosted: November 27, 2013, 11:49 am 
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I was talking about striking a balance with conflicting goals. Do you have a link to your dims? I'm trying the Champion and Gibbs dims also. I found I can approximate a spindle that will work with their control arm lengths and pivot points.

I can appreciate those who measured their spindles now since it is more complicated than just knowing the kpi.

When I type vsusp in the address and click my last vsusp address, I still have to re-enter a few things like wheel offset and lca inner pivot distance to the lower frame corner.


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PostPosted: November 27, 2013, 1:56 pm 
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Miatav8,MstrASE,A&P,F wrote:
I was talking about striking a balance with conflicting goals. Do you have a link to your dims? I'm trying the Champion and Gibbs dims also. I found I can approximate a spindle that will work with their control arm lengths and pivot points.

I can appreciate those who measured their spindles now since it is more complicated than just knowing the kpi.

When I type vsusp in the address and click my last vsusp address, I still have to re-enter a few things like wheel offset and lca inner pivot distance to the lower frame corner.

Hi MV8, would you mind pasting in an example link and also what the expected wheel offset, for example, should be? Thanks -

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PostPosted: November 27, 2013, 2:08 pm 
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Trying something different. Need to work on the rc height, though it doesn't move more than 7" to the side in 5 degrees roll. Dreamed up spindle with kpi close to desired caster.
Uca sloped down 14 degrees and twice the length of lca.
Camber gain is .425 degree per degree roll.

I'll find an example link Rob. The offset is defaulting to 1.575.


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PostPosted: November 27, 2013, 2:17 pm 
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default values

If I click the link, it doesn't stay highlighted, so I drag across the entire length to highlight, then right click copy. I tried control c but I've never used clipboard before. Offset should be 3.5. I just used my link above and it changed quite a lot.


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PostPosted: November 27, 2013, 3:47 pm 
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In the console (<ctrl-shift-j> on firefox and chrome), I do see VSusp complaining about the Y-distance between the frame bottom and the lower control arm mount. The minimum value allowed is 1mm, and it was coercing the number. But I don't see why it can't be zero, so I'll fix that and check out the rest of the min/max while I'm at it

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PostPosted: November 27, 2013, 4:19 pm 
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Vsusp update
- updated various control min/max values (thanks MV8)

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PostPosted: November 27, 2013, 8:12 pm 
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Here is Gibbs book front dims with the same 5 degree kpi spindle and tire assembly and with an 11.3 kpi assembly no offset change to rim to zero scrub created by kpi change. 11.3 required shortening uca. Adjusted gc to level lcas.

link to 11.3:

default values


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vsusp gibbs 5 kpi.JPG
vsusp gibbs 5 kpi.JPG [ 111.55 KiB | Viewed 3111 times ]
vsusp gibbs 11.3 kpi shorter uca .JPG
vsusp gibbs 11.3 kpi shorter uca .JPG [ 110.31 KiB | Viewed 3111 times ]
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PostPosted: November 27, 2013, 8:53 pm 
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Champion with same spindle assys and gc set to level lcas.

5 degree:
default values

11.3 degree:
default values


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vsusp champion 5 kpi.JPG
vsusp champion 5 kpi.JPG [ 109.49 KiB | Viewed 3109 times ]
vsusp champion 11.3 kpi.JPG
vsusp champion 11.3 kpi.JPG [ 97.23 KiB | Viewed 3109 times ]
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PostPosted: November 28, 2013, 6:39 am 
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UCAP (upper control arm pivot)
LCAP (lower control arm pivot)
GC (ground clearance)

Left off the dims on the champion pics so I am reposting those. Check file names on attached images for description.

Found a much lower rc and .75 degree camber gain per degree roll by raising the ucap along the 67 degree slope from 8.962” from the lcap to 11.064”. This required a shorter uca. The ½ degree gain per degree roll should be slightly less than that. I also found the rc shifts from side to side much less, only about 2 inches at 5 degree roll, if you care about sideways shift of the rc. This is still with the 5 degree kpi spindle I dreamed up.
Based on Chets measurements, the miata spindle is about 7 degree kpi, not 11.3 as published for a miata. I came up with the 11.3 kpi based on the dreamed up 5 degree by moving the ubj attachment up and inboard.
The arm lengths described are pivot center to pivot center. The arm framing lengths are described in the book. I added 2 inches initially. End result arm lengths should be middle adjustment range of the arm.
default values

Swapped 5 kpi for 11.3 kpi spindles and adjusted uca length as required. Result is a higher rc that moved about 4 inches to the side compared to 2 inches with the 5 kpi spindles and slightly less camber gain.
default values


Attachments:
vsusp champion 5 kpi.JPG
vsusp champion 5 kpi.JPG [ 113.82 KiB | Viewed 3090 times ]
vsusp champion 11.3 kpi.JPG
vsusp champion 11.3 kpi.JPG [ 107 KiB | Viewed 3090 times ]
vsusp champion 5 kpi higher wider ucap shorter uca same slope.JPG
vsusp champion 5 kpi higher wider ucap shorter uca same slope.JPG [ 116.6 KiB | Viewed 3090 times ]
vsusp champion 11.3 kpi higher wider ucap shorter uca same slope.JPG
vsusp champion 11.3 kpi higher wider ucap shorter uca same slope.JPG [ 116.96 KiB | Viewed 3090 times ]
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PostPosted: November 28, 2013, 9:22 am 
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Gibbs looks way better with the right (merkur/sierra) spindles. Nice, imho. Camber is just a bit too aggressive for the reasons HorizonJob stated.

default values


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vsusp gibbs sierra spindles .JPG
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PostPosted: November 28, 2013, 10:02 am 
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Mustang II/ pinto on Gibbs. Lowered lcap on frame and adjusted lca length. Incomplete dims on MII spindle. Played with numbers until I had 11 degree kpi with 10.15 distance between joints and 5.30 from hub cl to lbj cl. Not bad imho, but actual spindle dims should be confirmed. Also, it looks like the slope changed when I lowered the lcap because I didn't pull it inboard at the same time.

default values


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vsusp gibbs Mustang2 lwr lcap .JPG
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PostPosted: December 15, 2013, 9:10 pm 
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Vsusp has been a huge help in sorting out my suspension tradeoffs. It has literally saved me hours of work. It’s proved a little addictive though, so not all the savings are net.:lol: Thanks, Rob, for putting Vsusp together and continuing to add improvements. :cheers:

Here are a couple of add-on tools that helped me with my VSUSP efforts. They do pre-processing for specific knuckle/spindle configurations. Some of the calculations, like control arm length, may eventually find their way into Vsusp. Others that are more hardware specific are less likely to.

In exploring rear suspension alternatives using T-Bird knuckles on Vsusp, I was playing with a number of design elements (tire size, ride height, pivot points, etc.) This in turn was causing a lot of hand calculation to create Vsusp inputs (Xs, Ys, and control arm lengths.) As my T-Bird knuckle dimensions were known and fixed, a little spreadsheet app was created to do the work. I can now feed the spreadsheet my parameters (page 1) and have it calculate and/or copy them into Vsusp inputs (page 2). This saved me a lot of time playing with the many possible variables. The spreadsheet (Vsusp Input Generator) in the attached zipped file includes measurements of my T-Bird knuckles. Your dimensions might vary, but these should be close for most T-Bird knuckles. I haven’t tested it, but with a different set of fixed knuckle dimensions, the spreadsheet might also work for Miata or other rear uprights.
Attachment:

Similar problem with my front suspension; I was trading off a large number of variables. Some months ago I posted a spreadsheet which takes the Wilwood Mustang II dimensions and geometry (from Wilwood’s engineering drawings), along with (for Car9 at least) a set of chassis design inputs (page 1) and creates the X,Y,Z inputs needed for Wishbone’s 3D suspension calcs (page 2.) But as Vsusp’s graphical user interface is so much easier to use, a third page has been added which maps the Wishbone 3D inputs into Vsusp 2D inputs. (Note: Vsusp's X’s and Y’s are defined differently from Wishbone’s X,Y,Z’s which can cause confusion.) The updated Wishbone Input Generator spreadsheet is also attached below. This spreadsheet has allowed me to rapidly make multiple Vsusp runs while exploring a number of front suspension parameters including monoball pin lengths, ball joint stud lengths, etc. without a lot of foreplay required :shock:
Attachment:
Wishbone Input Generator V4.0.zip [16.78 KiB]
Downloaded 79 times

So, I’m not done with the suspension work yet. Still fine tuning my RC heights, camber correction curves and Roll Axis inclination with Horizonjob. But here's the current Vsusp Project Link for the front and rear as defined in the two spreadsheets:
Car9_Tom1

And here are the current roll charts:
Attachment:
front roll chart 2013-12-15.jpg
front roll chart 2013-12-15.jpg [ 45.21 KiB | Viewed 2990 times ]
Attachment:
rear roll chart 2013-12-15.jpg
rear roll chart 2013-12-15.jpg [ 42.53 KiB | Viewed 2990 times ]


Advice, comments and suggestions are always appreciated. Hope some of this is useful to other Locosters.

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My Car9 build: viewtopic.php?f=35&t=14613
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PostPosted: December 17, 2013, 10:04 am 
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Hey Tom,

Not sure what you mean by input generator. It appears to be a list of specs that have to be entered one at a time into vsusp. There is no need for a separate attachment to show your specs. In Vsusp, each setting is basically a different page on the site. You only need to provide a link to the address. Just turn the address blue (at the top or bottom of the page) then right click to copy. It will show "default" when you paste it into your post but every address is default, since every address is a different combination of settings.

I showed my specs photos by selecting the spindles tab then moving the cursor to where the dims of the arms were overlayed, selected "PrtScn" on the keyboard, then pasted that into paint and cropped.


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