Outer Limits 4x4 Board

I just wanted to know ( i have searched with no diffinative answer), what a 1/2 and 3/4 ellyptic suspension setup is? From what i can tell it appears the bottom leaf in the spring lies flat, not curved. Is this correct? What are the advantages, and what is the cost to perform the modifications?

normal leaf spring set up is considered 1/2 elliptical as it's half of an oval.

3/4 elliptical is when the shackle is attached to an upside down leaf that is mounted to the chassis. there are 3 quarters of an oval visible.
http://www.outerlimits4x4.com/PHP_Modul ... elliptical

1/4 elliptical is when there is no bottom leaf altogether. there is an upside down leaf pack attached to the chassis and diff. this set up also requires control arms to locate the axle.
http://images.google.com.au/images?svnu ... tnG=Search

If you want to see examples of these both, Screwy's rear suspension on his MQ is 3/4 elliptical, so is grimbo's rear and Rocbox's rear. A example of 1/4 eliptical is the aztec buggy (shorty40's rig) or Sam kecks really old sierra from tough truck 2.
Layto....

As to cost, you are in the realm of custom work, so the performance/cost thing can get pretty out of hand.

a 3/4 elliptic suspension can be done pretty easily on a narrow track suzuki (up to 88) but post 88, it is harder as the springs are outboard of the chassis, so there is more fabrication.

You have to also consider that your shocks will need to be replaced and custom mounts made, the fuel tank and possibly the exhaust will have to be moved, and unless a lot of work is done to make the front flex properly, the car will be forever throwing front wheels in the air when climbing off camber obstacles. (looks cool but makes the car a bitch to drive)

I built my own car 3/4 eliptic, and have built 2 others. It does work but I feel that on a SWB with a predominantly stock front end, you would loose more than you would gain.

1/4 elliptic involves fabricating a complete link suspension. At this point, the spring choice is the cheapest part of the job. Once you have built the links, airshocks, coils, airbags or leaves, there are advantages and disadvantages with them all.

I guess that 3/4 could be done for a few hundred dollars if you had a friendly mechanical workshop and with very little welding. It can be done to drive well on road. Grimbo, Mine, and Critta (Mock - OZRock) drive/drove fine on road with rear 3/4, even with long, soft shocks. They are all SPUA LWB cars though.

1/4 elliptic will be a couple of grand, all up. You will face the problem of the imbalance from front to rear travel even more, and if you exploit the travel that can be built into a link suspension, you will find that your axle is too narrow to allow serious travel without jamming th tyres into the chassis. On road drivability ususally suffers too, depending on how it is set up. It is not very easy to hide a linked car, so you would be looking for an engineers too.

On the cars I build, I put faar more work into the front than the rear. IMHO, this adds far more off road capability than a rear axle that will flop all over the place- that's why I inboard the front springs, go to RUF, bumpstop under the chassis and add longer shackles and shocks. this makes for a very "planted" and predictable car. Cars that are soft rear 3/4 and have standardish front ends can be pretty spooky.


Steve.

My 1/4 elliptic setup

I've posted this before but here goes....Weld a 50x6 mm. bedplate between the bumpstop plate and the original fixed shackle bush ring. Get your buggyleafs made from 5mm stock. Secure with Grade 8 bolts AND nuts. Shackle angle at rest is crucial. If not right it will invert. No need to move fuel filler pipe on the other side...just weld an extra gusset between bedplate and frame to prevent any tendency to pinch the rubber pipe. With these and Climax fronts I ramp 800+ on a 23 degree ramp. Not bad for SPUA!