LocostUSA.com

I have tried the Vodou numbers, but I'm not planning to use them.
The arms length will be after my calculations, I'm using only the design form Vodou, since it is design with the Miata NA spindles in mind.
The side view mounting points should be OK to use, right?
I'm trying to get a proper suspension movement, that is the main goal. The mounting points I can change, modify, add tubes if I have to.
vsusp has metric setting in the Preferences tab(under Redraw during drag).
I'm wondering, others which front suspension design/mounting locations they went with, with the 442E chassis?
I have went through many build threads, watched videos on Youtube, and many, if not most of them, don't really talk about this part.
Really like his video, but I don't think his numbers are correct, am I wrong?
https://www.youtube.com/watch?v=KApfoaNBYsE

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Tibor


'20 Alfa Romeo Stelvio daily
Locost/442E in progress

If you have the front end of the 442E chassis already built, I'd stick with that. There's nothing magical about the Miata spindles as far as I know. Are they set up for double wishbone suspension or for a strut type suspension?

If it's setup for struts from the factory, then is there an adapter for using an upper ball joint in the VoDou plans? If you have the Miata spindles already, and there is an adapter involved, I'd build the adapter, get the correct ball joints (upper and lower) and then you can determine all the spindle measurements yourself accurately.

You know your tires and wheels, hence rolling radius, offset, tire width, etc. You have all the data you need to model the situation. It's just doing careful measurements and documenting everything graphically for use in the design.

There is a solution out there. There are some simplifying assumptions you can make to get a design started. For example, assume the lower control arms will be horizontal, See where the chassis side brackets need to be in that case given your ride height choice (remember, you can alter ride height if you want). If that location is workable, use it, then start altering the angle of the upper control arm starting with a 10 degree down angle and see if the brackets will work on the chassis side in that case.

See what the above gets you in Vsup and if it's not satisfactory start altering the chassis side bracket locations to improve the design behaviour. Unless you change the wheels, tires or ball joint adapter(s) the spindle side figures are cast in concrete, so to speak.

Cheers,

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Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886

Tibor,

If you get all your parts together, you can do things like the following:


This takes the mystery out of things. You can visualize in real time and get good ideas and approximate measurements and locations using the colored tapes and the real parts.

You have to set your chassis at ride height (wood blocks work great) and be able to set the track (notice tape on tire) from a good chassis centerline. When you get a setup that looks workable, put the approximate locations in Vsup and see what you get performance wise.

Most likely you can alter the locations in Vsup to improve things. You can also turn immediately to the real world build to see if those changes will work there. This is how I started out.

Cheers,

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Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886

All the info about the spindle is already in vsusp, Miata suspension is a double wishbone, though the lower one is not an A arm style shape.
I'm using the ES2074R like everybody else(mostly everybody) for the upper ball joint and the Miata lower ball joint.
Planning to make the lower arms fixed, with Energy poli bushings and 1" DOM tube w/0.95" wall thickness and the 1/8th sheet metal pieces from the Vodou drawings(these are already done on laser machine at work).
For the upper control arms the plan is, to use the forged threaded rod ends on the chassis side(personally not a fan of the look, but I want to have strength and adjustability, and a bit of comfort), and I machined the adjusters at the ball joint side w/locking nuts.
My biggest issue is, that I don't have a sample of a good suspension, to see the end result that I should achieve.
I'm shooting for 3" bump and 2" droop, right?
With the 3" bump, what is the maximum angle(camber gain) that I should shoot for? I know that the lower the better, but it is very hard to achieve anything below -1.6 degree. That is enough?
If I have that -1.6 degree, then the 3" roll angle gives me a +1.7 camber. I see now that everything is a compromise, but which one should be my main goal over the other here?
I would prefer to see something in the software that is nearly there, before I cut metal. I have already waisted material for the jig.
MiataV8 OKed one of my first vsusp, but me the idiot, I did not measure the chassis accurately enough, because I did not have any brackets done yet, and I was off quite a bit after I had all the components
I was watching the video that I have posted today, and another Youtubers video Leftfootfirst, and they had the virtual swing arms much shorter, in the 70s.

_________________
Tibor


'20 Alfa Romeo Stelvio daily
Locost/442E in progress

<YOU:> My biggest issue is, that I don't have a sample of a good suspension, to see the end result that I should achieve.

That's why I though it might be useful to run the VoDou design. You have the data for the chassis and spindle side now. See if it's worth using as a starting point. The geometry and the lines of action are what really count. If moving a chassis bracket a little, but preserving those two relationships, you'll get pretty much the same result except for possibly the steering rack location, which you might have to change (bump steer).

<YOU:> I'm shooting for 3" bump and 2" droop, right?

Nope, it's just the opposite; 2" bump and 3" droop.

<YOU:> With the 3" bump, what is the maximum angle(camber gain) that I should shoot for? I know that the lower the better, but it is very hard to achieve anything below -1.6 degree. That is enough? If I have that -1.6 degree, then the 3" roll angle gives me a +1.7 camber. I see now that everything is a compromise, but which one should be my main goal over the other here?

If you get a positive (or negative) camper change of 1.6 degrees at 3" of bump (or droop), that's pretty good. Assuming the change is linear for the sake of conversation (it's probably close to that) you'd get 1.6 divided by 3 = ~0.5 degrees per inch, which is pretty good for a street car.

Further, let's say your camber change is positive with the maneuver. If you start out with 1 degree negative camber static, you'd get +1.6 added to -1.0 = +0.6 degrees positive in the maneuver. Not bad. One degree of negative static camber is common on Caterhams.

<YOU:> I would prefer to see something in the software that is nearly there, before I cut metal. I have already wasted material for the jig.

Understandable.


<YOU:> MiataV8 OKed one of my first vsusp, but me the idiot, I did not measure the chassis accurately enough, because I did not have any brackets done yet, and I was off quite a bit after I had all the components

If you make a few brackets, clamp them to the chassis where you want to try things out and put a bolt through them, you can measure accurately to or from them using the hook on a measuring tape. Just subtract half the bolt diameter when you're measuring from the bolt and add half the diameter when you measuring to the bolt (hook pushed against the outside of bolt) and it's like measuring from the center of the bolt & bracket.

<YOU:> I was watching the video that I have posted today, and another Youtubers video Leftfootfirst, and they had the virtual swing arms much shorter, in the 70s.

I can't make any comment without seeing how his suspension behaves. Does he know?

Keep at it. Take a break if you need to. Sometimes coming back to a problem with "fresh eyes" will make a situation become considerably clearer.

Cheers,

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Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886

Thank you Lonnie, for your patience.
I can imagine, that it is not easy to help somebody that is so beginner.
I had engineers at work, doing safety training in the machine shop, and they ask me how do you use a chip hook.
By the way I'm a machine shop supervisor/machinist, at Honeybee Robotics in Altadena. Blue Origin is our parent company. They have acquired us last year.
0.5 camber, 59.375 track(same as rear), tires are narrower at front(215/50) than the rears(245/45), wheel width is 8" all around.
There are spots, where you can input bump and roll angle. So at the bump, I should go only +2", do I care about -3" droop number?
Camber gain with a +2" bump is -1.685(-)-0.498= -1.187 degree
Left camber is 1.652 degree, with a +3 degree roll angle.
Virtual swing arm is 127.886
Ok, I have input all the Vodou chassis numbers into vsusp and this is what I have got:

7 Duratec-Vodou-w/13mm wheel spacer(offset 27)

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Tibor


'20 Alfa Romeo Stelvio daily
Locost/442E in progress

I feel like this version is the best, it is not the Vodou, they are my pickup points.


7 Duratec-Maybe the best?-w/10mm wheel spacer

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Tibor


'20 Alfa Romeo Stelvio daily
Locost/442E in progress

Any opinions?


I made another one in two versions, one w/0.5 camber and another one w/1 degree camber.

7 Duratec-Book numbers-w/13mm spacers-0.5 degree

7 Duratec-Book numbers-w/13 mm spacer/1 degree

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Tibor


'20 Alfa Romeo Stelvio daily
Locost/442E in progress

@tibimakai

I don't like the second one, 1 degree negative camber static, at all. Things move around too much and the camber change with dive worries me.

The 0.5 degree negative camber one is better, but I hesitate to endorse it. I do favor swing arm lengths longer than what you're using and I think camber changes can be reduced from what it gives you in that configuration.

I don't have enough experience with Vsup to have a lot of confidence in what I'm seeing. I'm not saying there's anything wrong with Vsup. I just don't know it well enough, so I don't want to say, "Hey, great, go with that." I'm used to seeing a lot more data in an interactive and animated way with my 3D program.

Which chassis side locations are you using for the control arm brackets in the above versions? Is it the VoDou ones, or something else? Are you confident the McSorely chassis will support the actual locations you're entered?

Cheers,

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Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886

There’s nothing wrong with -1 degree camber. Nothing wrong with -2 degrees, either. There are factory cars that come with that much static camber.

No one is going to tell you what to chose because everything is a tradeoff and what’s ideal for you may not be ideal for someone else. Aggressive suspensions are typically challenging to tame so keep things within reason (no high roll centers, overly short swing-arms, high scrub, etc) make it adjustable, and you’ll likely find a happy spot. My take is that you’re building a street car, so don’t fret too much. Go into it knowing everything is a compromise and chances are you’ll want to make adjustments after the fact and that’s okay.

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Regards, Ron

Those two are done after the "book", with tiny modifications.
Lonnie, no worries I understand that you can't help me with vsusp. Thank you very much for all your help until now.
I would prefer a 0.5 degree camber.
I would like others opinion, who used vsusp in their build.
How about the previous single one? It is McSorley 442E.
MiataV8 mentioned earlier, to keep the yellow and blue line in the graph leveled to each other and under 3 degrees.

7 Duratec-Maybe the best?-w/10mm wheel spacer

_________________
Tibor


'20 Alfa Romeo Stelvio daily
Locost/442E in progress

@tibimakai

The above looks like the best of the recent series you've done. The camber changers are much better. At least visually, the location of the tie rod ends on both the chassis side and the spindle side look really good, which is a positive indicator in terms of any potential bump steer (toe-in/toe-out).

I didn't do an exhaustive set of manipulations, but the ones I did do looked better in all respects.

Cheers,

_________________
Damn! That front slip angle is way too large and the Ackerman is just a muddle.

Build Log: viewtopic.php?f=35&t=5886

"Which chassis side locations are you using for the control arm brackets in the above versions? Is it the VoDou ones, or something else? Are you confident the McSorely chassis will support the actual locations you're entered?"
Vsusp does not show side locations, so I haven't done anything regarding side locations. I will use mostly the Vodou numbers.
I think that the last version should be "good enough" for a street car, and I will try locating those side mounting points this weekend. I know for sure that the bottom bracket will be in the air, not by much though. I will have to add some material there for sure.
In vsusp, under Steering tab, it shows the steering rack length and height, anybody knows, if those numbers are OK, they can be trusted?
Thank you Lonnie,

Tibor

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Tibor


'20 Alfa Romeo Stelvio daily
Locost/442E in progress