Soild Axle Steering Movement (1 Viewer)

Joined
Apr 19, 2021
Messages
44
Location
Tasmania, Australia
Hi all,
Have had my HJ60 solid axle for about a year and love daily driving it. Its the first solid axle vehicle that I have driven a decent amount of times. I have rebuilt the swivel hubs and replaced steering joints and shocks and adjusted up the steering and it feels great, nice and tight
An interesting observation I have made is that when going over a bump or round a corner or the likes. The front axle moves independently from the rest of the car (as it should) but I can feel that then the axle moves away from the chassis it must pull on the steering linkage a little and essentially turn the wheels a tiny bit, because the steering box is staying put on the chassis but the axle moves away so therefore it pulls on the steering knuckle and pull steers the wheels a little.
It's sort of hard to explain, anyway.

Is this a thing, is is a solid axle thing?
I've never felt it on a ifs car.
Or is there Likley to be some other issue with the car.
The pull is not big, it is quite small but big enough to Warrant a correction.

Just wondering if anyone else has noticed this as a little soild axle nuance.

Thanks
 
Joined
Jan 4, 2011
Messages
4,391
Location
Vermont
All suspension types move and impact steering. Lots of angles and variation in linkages it’s pretty well unavoidable. There is one way to build a suspension so steering has zero change on movement but then the car would handle like crap.
 
Joined
Apr 14, 2008
Messages
5,794
Location
North of LA California
If you have a lift without caster correction then you are feeling and observing bump steer. The wheel shouldn't be turning when you go over a speed bump.

IF it is moving just a minute amount then that's normal. Hard to tell what setup you're running.
 
Joined
Apr 19, 2021
Messages
44
Location
Tasmania, Australia
If you have a lift without caster correction then you are feeling and observing bump steer. The wheel shouldn't be turning when you go over a speed bump.

IF it is moving just a minute amount then that's normal. Hard to tell what setup you're running.
Interested to know more about castor correction, setup up is by previous owner. As far as I am aware setup is stock springs and shocks with 2in extended shackles, will look at some threads about castor angle
 
Joined
Apr 19, 2021
Messages
44
Location
Tasmania, Australia
Bump steer sounds pretty right, I was quite intrigued myself after thinking about this last night. Imade a little mock up of a front axle set up to see clearly what it does. As you can see OSS is quite right, when the springs compress the distance between the axle and the chassis gets smaller but the drag link stays the same length, therefore it pushes the wheels sideways to make room for itself
received_256638749498797.jpeg
received_271456728029179.jpeg
 
Joined
Jan 4, 2011
Messages
4,391
Location
Vermont
Other topics to study:

steering Ackerman

thrust angle (in consideration of rear axle alignment)

toe, camber, castor

steering axis of inclination

Tire scrub radius
 
Joined
Jan 17, 2009
Messages
2,919
Location
In the membrane between heavy metal and gas
I put some 4 degree caster shims and the difference is pretty amazing. Way more stable.. tracks straight doesn’t “wander” This is on a 2” lift with stock length shackles. I don’t really understand how it works completely but it definitely does work. This is an interesting topic
 
Joined
Apr 14, 2008
Messages
5,794
Location
North of LA California
A shackle lift by itself is not good. The Shackle angle is important and will affect ridge quality. If your shackle is close to vertical you will have a seriously rough and bumpy ride. Consider that when installing your caster fix.

You have two options; add shims to your spring perch or cut and turn the axle housing. I chose the latter when I did my spring over axle (SOA) lift.
 

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