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Learning how to build Lotus Seven replicas...together!
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PostPosted: October 29, 2020, 6:10 am 
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Hey all, Im planning on using Miata uprights/knuckles with custom arms.

Ive programmed Vsusp with the uprights, suspension points and arm lengths taken from the Vodou plans. also The tyres im thinking of using.

To be honest im not really sure what im doing and what I should be paying attention to. I believe you want the roll center to be reasonable close to center of gravity?

Anyone got any tips or suggestions on changes? im pretty much able to change anything except the knuckle dimensions, The wheel/tyre size is not set in stone yet either, I may go 235/40/17 or similar.

Hermits Miata Locost


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PostPosted: October 29, 2020, 9:45 am 
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post up your link in VSUSP and we'll have a look.

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PostPosted: October 29, 2020, 1:05 pm 
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With the roll centre near the CofG you'll be emulating VW or Corvair swing axles and get jacking and other classic joys ... :D

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PostPosted: October 29, 2020, 3:33 pm 
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post up your link in VSUSP and we'll have a look.



The link is at the bottom of the original post, click on "Hermits Miata Locost"


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PostPosted: October 29, 2020, 5:21 pm 
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https://www.locostusa.com/forums/viewtopic.php?f=35&t=20045&start=15

This is a set of near perfect numbers that Miatav8 worked out on my Series 5 chassis and the wheels I bought off Craigslist.

My actual setup is a little different and you can read through just a few posts following the one from MV8 to see pics

Yours really aren't terrible. Roll center moves around some. Unless your goal is a seriously competitive autocross car, that's good enough to build.

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PostPosted: November 2, 2020, 1:38 pm 
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On both ends the VSAL/IC are shorter, and RC lower, than I would design it...But you could certainly do worse, and sticking with an existing design significantly speeds up the process.

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PostPosted: November 2, 2020, 4:46 pm 
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Hey Driven5, how does the VSAL effect things?

Ive been researching and learning more but decided until I receive my components so I can measure them properly to worry about playing with the design anymore but my plan/goal is to have

Roll center 50mm/2" from ground level at ride height and move laterally less then 12mm (1/2") laterally up to 4degree's roll

Lower control arm level which I may use a extended lower ball joint to do so.

less then 19mm - 3/4" scrub radius

Likely going to move up to 17" rims for better Tyre availability in future.


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PostPosted: November 3, 2020, 4:01 pm 
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VSAL is largely going to determine the rate of camber gain, which is good for cornering but bad for braking and accelerating. The front needs less camber gain than the rear due to the camber gain from steering caster, which also aids braking performance. On the rear there is no appreciable caster effect, thus it's a more direct compromise between roll and accel/bump performance.

Your targets look pretty reasonable.

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PostPosted: September 6, 2022, 5:33 pm 
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Joined: August 29, 2007, 1:27 am
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Location: New Zealand
Hermit wrote:
Hey all, Im planning on using Miata uprights/knuckles with custom arms.

Ive programmed Vsusp with the uprights, suspension points and arm lengths taken from the Vodou plans. also The tyres im thinking of using.

To be honest im not really sure what im doing and what I should be paying attention to. I believe you want the roll center to be reasonable close to center of gravity?

Anyone got any tips or suggestions on changes? im pretty much able to change anything except the knuckle dimensions, The wheel/tyre size is not set in stone yet either, I may go 235/40/17 or similar.


Sorry for grave-digging but where did you get the control arm lengths? Perhaps I'm reading the plans wrong or there has been an update to the plans.
For example your front LCA has a length of 430 but i'm reading this as 404mm


You do not have the required permissions to view the files attached to this post.

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PostPosted: September 8, 2022, 5:26 pm 
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Location: Cntl Coast, CA
The wishbone print doesn't include the ball joints/TREs.


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PostPosted: September 8, 2022, 7:58 pm 
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Oh I see. Thanks!

It appears @Hermit hasn't been on for over a year and no build log.

Does anyone know if the numbers in his VSUSP link at the top is accurate for the Vodou plans as drawn?

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PostPosted: September 10, 2022, 5:29 am 
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https://www.facebook.com/HermitFab/

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Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12


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PostPosted: September 10, 2022, 6:17 am 
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Thanks. I've sent him an email.

If you don't mind, could you please look at the below setup.

I've looked at the 7SV link posted, but the arms appear to be sloping down at static which I though was bad.

I'mgoingtocrash]

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PostPosted: September 10, 2022, 9:40 am 
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I'd add the RC X&Y to the chart and try to reduce the movement through 3deg while reducing the static camber to about one or zero, then go back and forth to optimize camber gain before adding any static camber. Raise the frame rails in the chassis as appropriate to level the lcas.

Would you like me to try tweaking it a bit?

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Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12


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PostPosted: September 10, 2022, 10:34 am 
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I went ahead and tweaked it.

Here are your specs but with the chart adjusted to show six blocks/3 degree roll and the RC x&y and units switched to customary so it is easier to see:
I'mgoingtocrash

Compare to a front and rear tweak with same lca and uprights, with the front built around the capability of the rear, stable RCs, less static camber, matched gain:
I'mgoingtocrash tweaked 09102022

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Miata UBJ: ES-2074R('70s maz pickup)
Ford IFS viewtopic.php?f=5&t=13225&p=134742
Simple Spring select viewtopic.php?f=5&t=11815
LxWxHt
360LA 442E: 134.5x46x15
Lotus7:115x39x7.25
Tiger Avon:114x40x13.3-12.6
Champion/Book:114x42x11
Gibbs/Haynes:122x42x14
VoDou:113x44x14
McSorley 442:122x46x14
Collins 241:127x46x12


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