Outer Limits 4x4 Board

Hey Bluesuzy I had to highjack your pics because I couldn't find the others I was looking at a few days ago sorry. But I have to say you are doing a remarkable job on your build up.
I have been looking through a few build threads as of late and this front end set up is becoming more and more popular. I understand that it is for engine clearance. But what are its advantages and disadvantages? I have a mate looking to start linking a luxy and just starting to think of how to do it and what to get.

is it just a radius arm?????

uninformed wrote:is it just a radius arm?????

its a radius arm that does not bind up like a normal radius arm.

what shadow said, does the same job just with a lot less binding.. a 3 link with a panhard will offer a similar solution wouldnt it? (also offers engine clearance)

im guessing it still needs a panhard?

I would have thought if not going a radius arm a 3 link the better option...and while RA's do bind they can be made well and can be tuned to help roll stiffnes, maybe not great for a crawler but more appropirate for speed events????

cheers,
Serg

Zuri92 wrote:what shadow said, does the same job just with a lot less binding.. a 3 link with a panhard will offer a similar solution wouldnt it? (also offers engine clearance)

The advantage of this over a normal radius is the obvious extra pivot point to the rear of the upper short arm attaching to the lower control arm. This design isn't anything new as it has been used on Jeeps for some time now.
3 link is not ideal for onroad due to the steer that a 3 link introduces on flex as for onroad you have to have a panhard (effectively the 4th link). Panhard values become important when considered with bump steer etc at speed when cornering engineers tend to frown on it.



brooksy

brooksy wrote:

Zuri92 wrote:what shadow said, does the same job just with a lot less binding.. a 3 link with a panhard will offer a similar solution wouldnt it? (also offers engine clearance)

The advantage of this over a normal radius is the obvious extra pivot point to the rear of the upper short arm attaching to the lower control arm. This design isn't anything new as it has been used on Jeeps for some time now.
3 link is not ideal for onroad due to the steer that a 3 link introduces on flex as for onroad you have to have a panhard (effectively the 4th link). Panhard values become important when considered with bump steer etc at speed when cornering engineers tend to frown on it.



brooksy

you can build a 3 link with out flex steer quite easily?

Yes but many won't have the panhard set-up properly with roll centre & is required for onroad.



brooksy

brooksy wrote:Yes but many won't have the panhard set-up properly with roll centre & is required for onroad.



brooksy

What aspect of the roll centre are you referring to?

Hey thats mine! (zook lwb)

I went this way because of room. Keeping it all low within 150mm rule if it comes in. Y link + panhard, still to be mounted(last minute thing to suit draglink angle)

No room for low tri 4 link+panhard, not much room for a 3link+panhard with high pinion front.

I like the 2 points of contact for torque control. A 3 link+panhard will be flexxy, but diff will be able to 'wrap' more and all it takes is 1 bolt to snap, and your diff rolls under your car.. I guess its similar as the top chassis mounts of my arms though..Jeeps flex quite good, so it was just a make it and see thing. Pootrol bushes and 3/4" heims


There is more room in a lux!!

I like it. Seen this done on a V8 Suz/Bundy. Seem to work. Great for clearance problems.

I can see this being handy for off road on the front axle, but would having it on the rear axle mean that it would have an infinite instant centre giving it similar lack of antisquat issues like rear radius arm setups? Would it hop like a mofo on hill climbs?

rockcrawler31 wrote:but would having it on the rear axle mean that it would have an infinite instant centre giving it similar lack of antisquat issues like rear radius arm setups? Would it hop like a mofo on hill climbs?

Short answer to your questions is 'Yes'.

Longer answer is No.
This type of suspension does not have an infinite instant center. The instant center is in the frame side bolt.
This suspension geometry does have what I would consider to be 'above average' Anti-Squat. It does not guarantee wheel hop on hill climbs.

Luke.

That answer makes no sense.

Firstly, i´m led to believe that radius arms have an infinite instant centre just like parallel four links. The result being that the torque from the diff is able to apply a leverage to the chassis directly at the mounting point instead of a point above or below the centre of gravity leading to drive/launch torque pulling down the rear end and loading up the springs to the point where the springs over come the torque force and rebound.

Unless my limited grasp of this stuff is way off - which isn´t entirely out of the question.

I am not sure why you say my answer makes 'no sense'.

The instant center is the theoretical (or actual) point at which the upper and lower control arms intersect. To find this point you must run a straight line between the axle and chassis side mounts.

Run a piece of string from the upper axle mount to the chassis mount, then from the lower axle mount to the chassis mount.
In the case of a radius-arm type suspension as shown in the first post/picture of this thread, The point at which they intersect is the center of the chassis side control arm mount (or center of the bolt)

With the 5-link (or parallel four link) the instant center is ONLY infinate if both the upper and lower control arms are the same angle.

I hope this clears things up.
Luke.