3/4 elliptical flex

[mrRocky]

G'day guys, i did a Buggy leaf type setup on my lwb a while ago and finally got around to sorting out the shock length so its not restricting the setup. Tested it out on the w/end and have now found something is stopping the buggy leaf from flexing to its max. I have extended the brake line by 6" and inverted the shocks which measure about 890
Could the handbrake cable be the culprit, or perhaps i need a softer leaf.
What have you guys running similar setups had to overcome ?

[just cruizin']

got any better pics because that show us nothing really

[grimbo]

the biggest problem is the lack of weight in the Sierra Diffs I recon. Mine gave pretty good flex but it was never fully flexed up. Also I ran into problems with the tyre fouling on my tray

[alien]

try the skinniest top leaf you can find... maybe a shagged zuk front main leaf??? needs to be like rubber to flex well as the lower leaves need to stretch it down before they start unloading.

[mrRocky]

nah there the only pics i have at the moment. I have put a secondary stop after the bolt holding the leaf so the bolt doesnt have to take all the downward force but it only gets about halfway to this stop.
There is a fair bit of weight, im running 32x11.5 tyres with steel rims and 2" solid steel wheel spacers that weigh about 8kgs ea.
I will flex it up during the week and see if i can find the prob, hopefully its not the handbrake cable as i really cant be assed trying to extend/move that.

[just cruizin']

With the handbrake you should be able to remove the bracket holding it to the body and use a spring instead thus restraining it normally but allowing it to flex.

[grimbo]

I was running 34" Swampers on steel rims and they still weren't heavy enough.

Are you tyres fouling on the chassis at full flex?

3/4 eliptic isn't a way to get masses of flex, especially SPUA what it does offer is a more progressive flex and it also tends to help the ride quality over obstacles as it is effectively a longer spring, so it does it's flex in a nice smooth motion compared to a drop shackle.

[mrRocky]

Yeah i have found that it makes a big difference over obstacles and flexes alot easier. I dont know what i was expecting really, i think ive been looking at too many U.S. sites.
Flexed it up today and the little bastard spring just wont bend any more.
I spose it might get a bit softer with more use. If i use a longer leaf i think i may start to invert the shackles.

[zook4fun]

what spring did you use for it?.

you might need to find a spring with more of a ark in it. spring will only want to bend so far.

[grimbo]

the spring isn't going to bend any more than that, if it did you would just end up snapping the spring.

Also an arched spring bends less than a flat spring

[VR Rodeo]

Alot of the guys in the states may be running YJ's too which will help. It also appears your stock pack isnt opening up yet either.

[just cruizin']

Some observations:

1. Your 3/4 leaf is flexing fine.
2. Your standard packs aren't
3. Your shackle angle is too upright at normal ride height
4. Shackles may be too long.

[mrRocky]

Yeah shackles are a 3" booty fab special, i do have some decent 2" boomerang ones to go on but didnt want to risk tyres hitting on the tray till i knew how much it would flex.
Originally i used standard shackles with much the same result.
I also tried mounting the 3/4 spring further towards the front but found the shackles kept inverting. I looked at how the guys in the U.S. set them up in regards to shackle angle and they all seem to be quite straight.
The leafs are 2" efs but they are still pretty new so the dont move much at all.
I will try it with a 2" shackle and see what i can do about the leafpack.

[just cruizin']

Are you bump stops touching on compression? tack some 50x50 rhs onto the chassis, this will limit up travel and push the drop side down a bit.

[mrRocky]

haha whats a bump stop. I know they are deemed as necessary but my springs are pretty stiff and my shocks dont bottom out so i didnt really think they would make much difference. The last thing i want to do is limit up travel.

[grimbo]

bump stops help the leverage on the opposite side of the diff, helps with flex. Well only if they are the right height

[mrRocky]

so if i put them just before the spring reaches max compression it shouldnt restrict uptravel too much and help leverage downtravel on the opposite side. Well thats something i never would have thought of.

[GRPABT1]

Bump stops are a key ingredient in a 3/4 IMO I have mine setup so there is very little up travel but alot of droop. This stops the shackles from inverting too as I have them setup at a nice 35-45 degrees sitting on flat ground.

Without the big, wide, heavy diffs and tyres of the americans you won't get fully sick ramp flex. What you will get with a decent setup is progressive flex that can be tuneable to match the front and more flex when crossed up in real world situations.

I agree with the observations that Just Cruzin made.

Check out my members thread if you want some ideas.

[ljxtreem]

so if i put them just before the spring reaches max compression it shouldnt restrict uptravel too much and help leverage downtravel on the opposite side. Well thats something i never would have thought of.

Bump stops will restrict vertical up travel, but not up travel caused by flex.
The bump stops will force flex, and will cause the compressed tyre to tip in towards the chassis and force the drooping wheel down.


Mock

[ljxtreem]

Im also thinking you would have to disturb your vertical up travel quite a bit to get any forced droop effect.

Mock

[GRPABT1]

You need to remove the pins on your normal spring clamps also.

[Guy]

Stop stuffing about with it and go out and drive it for a while.
Get some weight over the rear, an alloy tray backed sierra will have sweet FA weight over the back wheels .. does not need to be alot.

[just cruizin']

Full size spare tyre right at the back of the tray should do it

[mrRocky]

Cheers guys i will try some bumpstops and a few other things
I'am not really keen on adding too much weight to the car as it goes well offroad with the 6:5's but getting there is a struggle with 30kw of 1ltr power as it is.

[JrZook]

Some observations:

1. Your 3/4 leaf is flexing fine.
2. Your standard packs aren't
3. Your shackle angle is too upright at normal ride height
4. Shackles may be too long.

Id agree with the above statement. The compression on your leaf packs don't look to crash hot. Id try removing the bottom most leaf as well as adding bump stops as suggested.

Dan

[zookprojectfnq]

This is the flex achieved with standard bump stops on a swb with efs light duty rears and a standard suzuki main leaf for the top

[mrRocky]

Ok finally changed the shackle angle to about 30 degrees when sitting flat
and removed the pins on leaf packs so they now open up when flexing, i havent addressed the bumpstop issue yet but i have run into a snag with the tyre hitting the half leaf on top so i will look at some bumpstops and spacers to sort it out.
I have gotten more flex out of it but i reckon theres another few inches left in it so i will put up my results.