Outer Limits 4x4 Board

hey all, just a quick Question , debating this with my old man, i got a SWB GQ that ive just lifted 4", on max travel, the rear diff has axle steer, is this normal ? ive got standard control arms and panhards (soon to have ajustable upper control arms) the axle steer isnt major but is still bad(ish)

Cheers

Ryan

More info on what you term 'axle steer'

Yes the more wheel travel you get with any link set-up then it will get more axle steer! Simply due to the set-up!

i think u will find that it is normal if u r still using your standard control arms and that. y dont u lengthen them so u will get more travel and less axle steer

ok, hard to explain but ill try lol... at full travel the rear wheels look like they are turned but i dont kno how to explain so ill try and draw a pic...try not to laugh as its the best i can do lol

| | (front and rear diffs sitting on level ground)

| \ (front diff level, rear diff at full flex)


make sence?

hypolux wrote:i think u will find that it is normal if u r still using your standard control arms and that. y dont u lengthen them so u will get more travel and less axle steer

yeah thats the plan and also the next question, how much work is involved in lengthening the lower links?
upper links are ok cause im getting ajustable

rear axle steer is pretty much unavoidable due to the configiration of the control arms, when one side travels up and the other side travels down the the arc of the arms causes axle steer. It's just more pronounced on rigs with more articulation than normal.

Ryan wrote:

hypolux wrote:i think u will find that it is normal if u r still using your standard control arms and that. y dont u lengthen them so u will get more travel and less axle steer

yeah thats the plan and also the next question, how much work is involved in lengthening the lower links?
upper links are ok cause im getting ajustable

dunno how hard it is i have leaves

Depending what size tyres you are going to run, but I would leave the lower links the same length as standard, otherwise on full compression the tyre will rub the rear of the wheel arch, but you might want to shorten your upper links to match up the uni angles (best to go adjustable links).
of course if you were going to hack the guards, then a bit of rubbing doesn't matter.

i have a GQ LWB, i have axle steer and at the moment it doesnt bother me, but im gettin custom lower control arms made up to give me more clearance, them may even be a little bit longer but ill wait and see.

Axle steer is firly common in a coily with big lift. Try not let it bother you much, i cant see it doing any damage. THe axle steer gets pretty bad as mine did the other day, when i bent a lower control arm then flexed it, it felt like 4 wheel steer but the opposite, it crept a fair bit.

To help it out a bit, you could try getting adjustable lower control arms, or lengthen your own. having adjustables will make it easier to find the right length mind you it will not completely rid you of it.

Shawn

Depends Wendle from the board runs a tri 4 link and has lengthen lower arms by a decent amount duz not rub on full stuff even with 37"s but he also has no rear quartrs but this setup also has alot less axle steer

Mad truck

Iwill be makin my lowers bout 40mm longer to aid in keepin similair wheel base due to lift

well the 33 MTRs on full compression rub the back of the rear wheel arches, but i will be doing the same as A1MAV and cutting the guards off anyway

i thought id have to lengthen the upper links to bring the pinion angle up? cause most of the angle is at the gearbox end and only a little at the diff end, so i thought i would have to point the diff up more??
all part of learning i spose

Cheers

Ryan

The pinion of the diff has to come down to match up the drive flange angles, ie parallel, to prevent eventual driveshaft vibes. can also lower gearbox via packers to help angles. can be tricky to get this right with the shorties... can even raise the engine if you have a body lift.

ok thanks heaps for your help much appreciated

Cheers

Ryan

from what i can gather, you can reduce axle steer by moving the frame side brackets for the lower links closer to the centre of the frame. they will be more like / \ than | |. also, axle steer is usually not that big a deal if most of the steer effect occurs towards the last part of the articulation cycle. essentially, it is unavoidable; but you can reduce it with inboarded frame mounts for the lower links, and using longer links so that you have a larger arc of travel.

Area54 wrote:The pinion of the diff has to come down to match up the drive flange angles, ie parallel, to prevent eventual driveshaft vibes.

Depends on which style of shaft he is using.

N*A*M wrote:from what i can gather, you can reduce axle steer by moving the frame side brackets for the lower links closer to the centre of the frame. they will be more like / \ than | |.

I'm pretty sure that will bind up bad when there is a panhard rod involved as well.

if you had enough triangulation, you would not need a panhard. what i'm describing will make a 4 link look like X X from above, as opposed to |\/|. would a watt's link solve the binding problem?

Double triangulated 4-link is a good solution, but I dare say a bit more involved than what Ryan is trying to get away with???

Is the watts linkage the one with two half-length panhard type links coming from either side onto a central pivot??

Sounds like Ryan doesn't really plan to do anything about his axle steer. Most of the steer effect will occur towards the end of the travel cycle anyway. It's no big deal, especially if it's just a trail rig.

Yeah the Watts link is the one with the central pivot.

Some of the time roll steer will help you, some times it will work against you and the rest of the time it wont matter. Roll steer at front almost never matters - because you naturally compensate with the steering

It results from the roll axis not being level with the ground. Most link set-ups on 4bys have some roll steer.

The roll axis is determined by the contol arm (link) geometry. The roll centre is the point where the roll axis passes through a vertical plane at the axle. There are 2 control points that prevent transverse movement of the axle, which determine the roll axis (axis passes through both points).

Point 1 near the axle:
a) For parallel upper contol arms (looking from above) with a panhard rod the roll centre is the point where the panhard rod intersects the centreline of the vehicle.
b) For upper contol arms converging near axle, or an A-frame it is located at the intersection of the upper control arms or the ball joint of the A-frame.

Point 2:
a) For parallel lower contol arms (looking from above) the point is at infinity in the plane of the links.
b) For lower control arms converging at the chassis it is located at the intersection of the lower control arms.

In elevation draw a line through these 2 point to determine the roll axis.

From memory, with a Nissan both the upper and lower control arms are parallel (looking from above). So find the point where the panhard crosses the centreline and draw the roll axis through this point parallel to the lower control arms.

With a link set-up, you can only reduce roll steer by changing the location of these 2 points to make the roll axis closer to parallel with the ground.

yea was just checking to make sure that it was normal and not something thats about to go snap lol, i will end up changing the link setup on front/rear soonish anyway, just gotta save the $$ but thanks everyone for your help,
the steer hasnt caused any problems yet (but i havent been wheeling much yet either)


Cheers

Ryan