Suspension design for Locost with Vsusp

[cheapracer]

So, here is the above Lotus Elan simply rescaled in all dimensions to a Locost track in Vsusp..

http://tinyurl.com/9vyomhy


Notice how steady the RC is that seems so important to a lot of people, the RC even heads over to the outside wheel in bump allocating some of the bump load to the inside tyre as well as helping to prevent bump roll - not too shabby for a 1950's design but then again pyhsics don't change do they.

It also accomodates my own personal aim of 1 degree of pos camber gain for the first 2 degrees of roll and 1 degree of neg camber gain for the first 1" of bump bringing the sum camber total to no loss or gain at 2 degrees roll/1" bump.

[horizenjob]

Cheapracer where does the KPI of 3 degrees come from? I remember seeing the KPI for those uprights as 8 or 9 degrees on the blueprints.

Just curious....

[OptimusGlen]

It also accomodates my own personal aim of 1 degree of pos camber gain for the first 2 degrees of roll and 1 degree of neg camber gain for the first 1" of bump bringing the sum camber total to no loss or gain at 2 degrees roll/1" bump.

My latest design also fit's pretty close with your personal aim.

http://tinyurl.com/GlenGC7v07

(more info on previous page if anyone has interest)

[cheapracer]

Cheapracer where does the KPI of 3 degrees come from? I remember seeing the KPI for those uprights as 8 or 9 degrees on the blueprints.

Just curious....

Doh, caught out by the darn double pivot again, has happened to me before today too

Of course I was measuring straight through the LCA outer pivot (as one obviously does with a ball joint) totally ignoring that the steering pivot is seperate from the LCA lower pivot and is further outboard.

kpi lotus.jpg

I think you knew that Marcus and you were just being a Gentleman giving me a chance to redeem myself

But do note that Vsusp also can't recongnise that fact and incorrectly reads 2.5 degrees, not much can be done about that.

[cheapracer]

My latest design also fit's pretty close with your personal aim.

Indeed it does, even has just a touch of lateral scrub too which is a good thing with modern tyre tech (would have been frowned on not so many years ago) - if it was female you wouldn't kick it out of bed in the morning.

[Mach68]

i love this vsusp! heh i dont know what i'm doing with it but its cool! i'm starting from scratch. might use my maserati uprights, but might make new ones. probably going with an 18" tire (maybe a 235 up front,) roughy a 60" front track. lots of room for long a-arms. looks like i'm kinda stuck now till i get some dims for hubs and brakes.
keep up the good work!

[horizenjob]

i dont know what i'm doing with it but its cool!

I recommend bouncing up and down in your chair and making "vroom!" noises while using the ride height and roll buttons!

Cheapracer, do you have the dimensions for the Elan IRS too? It would be nice to compare the front and rear.

[cheapracer]

Cheapracer, do you have the dimensions for the Elan IRS too?

Yup, tomorrow.

[Posthumane]

Here is my latest iteration of my front suspension. It's not ideal, but I think it's getting close to the point of being good enough for a first shot on a car that will probably not see much track use.

http://tinyurl.com/atlhrde

This is using a modified upright from a 1984 Ford Ranger with a 4" extension to attach a heim joint as the upper pivot point, and a +002 chassis (book chassis made 2" taller at the front). Any feedback would be welcome.

[Brust]

Thought I'd throw mine up here and see if anyone has input.

MG Rear Suspension

[Brust]

Ok, I'v got a question- where is the "track" measured from? Center of tire on the ground? Outer edge of hub? The lines I see look like they're going through the center of the tire on the ground. Most helpful to me (says the beggar!) would be the upper outer part of the tire, or at least the outer part of tire as it hits the ground. I can do math from there to get the upper.

[erioshi]

Traditionally, I've always understood "track" to be a measure of distance from center to center. Of course you could just measure the entire width and subtract the width of one tire. I suspect that the idea of "track" had to do with the width of the suspension when it was common practice to use wheels that had zero offset.

[rx7locost]

Centerline to centerline is the definition. If 1/8" to 1/2" error is that critical to you measure at the point of contact. Camber and toe-in would affect the meaurements anywhere else.

Of course you could just measure the entire width and subtract the width of one tire.

I usually measure from the inside of one to the ouside of the other. No math required!

[Brust]

Thanks guys. I figured out that the program goes center to center (contact patch calculated). For some reason I thought it was outside to outside, which to me is easier for design if one of the inputs is wheel offset.

[Posthumane]

The outside to outside measurement would depend not only on wheel offset but also wheel (and tire) width, which is why I think it isn't used. If you change wheel offset at the same time as changing width so that either the outside or inside edge of the wheel stays in the same place then it is still a noticeable change since it would affect your scrub radius.