Wishbone suspension on a11?

[aek]

I have looking around the internet and found out that wishbone suspension its used on race track cars. Have any done that on a mr2? I see on La Bala kit car they use the aw11 spindel with a adapter to creat wishbone suspension, but i dont like the rear suspension set up. Here are some input:
http://www.racingaspirations.com/index.php
http://www.racefabinc.com/mid-engine_suspension.htm
http://www.modified.com/tech/0508_sc...t_3/index.html
http://images.google.no/imgres?imgur...a%3DX%26um%3D1
http://www.grabercars.com/phpbb2/vie...f7e96798aa9525
I want my mk1.8 lower and make its go faster round the race track...its this the way to go?

[biteme]

Oh my ... as if that thing needed to be lower!

Hope you're ok mate :)

[jayray]

I wouldn't have thought you could make double wishbones work in any mr2, due to the room they take up across the engine bay.
You would have to widen the track a fair bit more to accommodate it, and with its current width what it is, your car would be wider than it is long :icon_eek:

Lots of things you can do to make it quicker while retaining struts.

[Jim-SR]

you can do it properly on the front. on the rear youd have to compromise for something similar to the front setup on FWD Civic/Integras. they run super short top arms with the damper vertically up the middle like a MacPherson, but without taking the side loadings. its really compact, but heavily compromised, unfortunately on the rear there just isnt the space to do it any other way. and with the space a V8 is already taking up...

youre talking some pretty full on fabrication work though. youd have to semi-space frame the car around the suspension mounting areas to create the wishbone mounts. im not sure youve got enough benefits to be had to make it worthwhile with a compromised setup. you could spend the same money on better dampers for the MacPherson setup and find way more performance. double wishbone is ultimately the best setup, but on proper race cars they use long wishbones and build the car around the suspension. if youve got to compromise with short top arms then youre getting very few of the benefits. the Honda setup is no better than a MacPherson.

[aek]

Jhonny Q: I am Ok..I live in Norway with the black gold:D Now the cold season starts, so I need something to do rather than look at tv:thumbsup:
Jayray and SR-Jim: I have to make a new front end on my car because its needs to be 17cm wider to be the same with as the back. On the front I use 10cm spacers that make it act a bit nervous. So the front will be made new in this winter and I am playing with the wishbone suspension idea...

With all that work you are doing would it take much to create a Wishbone Suspension for the rear?

..and this person ask this when I made the rear suspension on my mk1.8 and some friends telling me this is the best suspension setup...I need to search and learn more about suspension setup.
Here a person that have done something the same...
http://www.home.earthlink.net/~roethler/front.html

[jayray]

If you do need to redo the front end, then wishbones are probably the best for a clean sheet design.
Jim would know better than me just what is required to make and design the suspension pickups and what type of design might work best in the space available.

For a traditional double wishbone design, there simply isn't enough room with a transverse engine.
And if you'd have to use a similar design to the hondas you're not really gaining anything from by going away from macphersons.
I would guess the best thing to do for the rear suspension is to do it after the front is finished, then play with you pickup points and geometry to get it handling well.

[Jim-SR]

you could even do something odd and run wishbone front and macpherson rear. avoid pushrods if you can, it over complicates everything. just run the damper in between the arms.

heres a picture of the Lotus Elise setup...
http://www.sandsmuseum.com/cars/elis...suspension.jpg

theyve also got the transverse engine issue, so the rear top arms are very small and the dampers are mounted very vertically, essentially like a macpherson strut.

you could actually implement this fairly easily on an MR2 (albeit in quite a crude way) provided you were willing to modify bodywork to fit around it. youve essentially got the lower wishbone sorted, the control arm and strut bar take care of that, forming a triangle. you need to fabricate an upper arm that will attach to the AW11 upright (using a bracket that uses the existing macpherson strut holes) and then attach the damper to the lower "wishbone". thats the hardest part, youve got a driveshaft in the way. id suggest using a forked bracket like on a Honda in some way.

get me some detailed pictures of your current rear setup and il see if i can offer some advice. i know that youve already framed a lot of it and removed the chassis in those areas so it may be easier in your case!

[Gary Symons]

That pic wont show (on my machine anyway)

I guess it has been taken from here:
http://www.sandsmuseum.com/cars/elis...echnology.html

[jayray]

What is it exactly that makes wishbones so much better than macpherson struts?
And how is that compromised by the honda or elise suspension (but still superior to struts)?

[Jim-SR]

What is it exactly that makes wishbones so much better than macpherson struts?
And how is that compromised by the honda or elise suspension (but still superior to struts)?

geometry change and load paths primarily.

the 2 simplest issues are with camber change - macpherson struts gain positive camber (e.g. the wheels stands up more) through their bump travel. in other words, the car leans to the outside wheel, which you then want to gain negative camber, but it does the exact opposite and rolls onto the outside edge. its not quite that simple, but thats the general point of it.

and then lateral loadings - the strut has to take the majority of the lateral load and it is applied laterally to it. so youve got a damper with a shaft sticking out of a cylinder, the lateral load is applied and pushes against it and the weak point is the shaft poking out of the cylinder. in normal useage there is deflection at the shaft (which is again bad for geometry changes) and there is also a resultant friction, which can contribute more than double the force that the damper is contributing in some scenarios!! inverted insert macpherson struts go some way to resolving this issue, they reduce deflection and friction, but there is still some there.

wishbones, if designed correctly, will gain negative camber in bump, and the damper has loads applied longitudinally, e.g. the loads push the shaft into the body, with minimal lateral loading. wishbone setups can also be substantially lighter for the same strength. macpherson struts are very heavy, but only because the strut itself has to be strong enough to withstand lateral loading in its weakest plane. wishbones have load applied mainly in their strongest directions so can be smaller and lighter.