LocostUSA.com

Looking for tips or hazards to avoid as I start on a multilink setup. Original link length is where I'll start, but welcome any pointers.

I would think that you'd need some 3D modelling software to have the best luck with calculating the camber gain and roll centre movement.

I've reused the entire multilink rear subframe from my donor car so I'm not much more help unfortunately. I think starting with the OEM lengths/locations is a very good idea

Good luck!

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Scratch built turbo V8 hot-rod in progress
http://locostusa.com/forums/viewtopic.php?f=18&t=19549

You'd have been much better off buying a complete subframe then make rear fenders as needed for the track. This would have saved a lot of work.

There isn't much room to make it narrower than the original sub and still use the original geo.

Without a sub to map, I'd start with the bottom arm as long as practical or original length, hub vertical, at ride height and zero toe, then fit the top link for desired characteristics in a 2d program like vsusp as lca and uca not on actual length (since they are not perpendicular to the wheelbase) but distance between pivots as viewed from the front/rear of the car.

Next, the toe link to maintain zero through normal travel.
Next, torque reaction struts that don't bind through normal travel.
Make toe and the uca or lca adjustable.

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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

Thank you guys, this is helpful. I do have the benefit of access to a Model 3 so I'll be taking dimensions from it. But I might reconsider buying a subframe if I get stuck. The OEM subframe is way too wide for the 7, but I see your point about ease of build. One of the fortunate side effects of going with a front motor is its elevated position which I think will help with LCA positioning. What is interesting are 2 of the 5 mounting points are ball joints, the rest are not. I would like to build a quick-adjust toe system to accommodate track conditions. MV8 - you refer to torque reaction struts - is that the purpose of the 3 angled arms?

The upright looks like an RX8 one, so you might look at the aftermarket stuff for those units.
You could also just use the upper and lower pickups to attach A-arms, use the mid pickup for toe control and not use the angled ones.

While precisely analyzing it would need a proper 3D suspension program, you can probably get 'close enough' by still treating it as essentially a glorified double wishbone. The upper two links and lower two links each pair up to create both an upper and lower 'virtual wishbone', with the middle link being your toe control link.

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-Justin

"Orville Wright did not have a pilots license." - Gordon MacKenzie

Thanks guys. Your comments are really helpful. I'd love to get fired into this but a plumbing job needs done on the house this weekend!

Yes. That way the upright can be lighter/weaker by spreading the load evenly across all the bushings under various conditions. Best to use all the attachments or risk upright failure under peak loads at a critical moment.

_________________
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