Radius arm plates and panhard mounts... (1 Viewer)

[MikePL]

I would like to know what I don't know.

We all know that lifted cruisers need to have their suspension adjusted and...

1. It seems to me that the radius arm plates made by eimkeith are much better than the caster correction plates or eccentric bushings because they retain the same caster angle and physical angle of the radius arms and also move the wheel a bit to the front. Much much better than other stuff, so why are people installing caster plates and they usually pop up as the go-to solution, while they are more of a band air and are harder to install than the eimkeith brackets.

2. Why are adustable panhards also the go-to solution, while they are heavier, are a non-stock part in case they need replacement far away from home and the panhard is at a higher angle anyway, it's only longer. Again, a panhard bracket which lifts the panhard mounting hole as much as your lift, seems like the perfect solution but still the adustable panhards seem to be the most popular way of dealing with the problem (partially dealing with it).

I want to modify my cruiser right and this is why it puzzles me that people use things I wouldn't use...

 

[NeverFinis]

1. 3rd option: New radius arms. Require no welding, and fixes the caster issue.

Originally, I went with caster bushings due to cost, and then switched to new radius arms when funds allowed. I don't think caster plates, or radius arm plates were even a thing when I first used caster bushings.

2. Are you referring to the front or rear axle or both? You should only use a panhard bracket on the rear. Using on the front will create steering geometry issues as it will no longer be parallel with the drag link.

Adjustable panhard bars allow centering of the axles. This could help with tire clearance and puts the pitman back at its centered position when the wheels are pointing straight.

In my case, they also allowed me to center the front axle, and move the diff further away from the LS oil pan sump for more clearance.

 

[MikePL]

But regarding the steering, do you think it would be an issue in practice? Some people install high steer arms which already throw the pivot points and angles a few inches off (see attached pic link). I assume that extreme suspension travel might create some movement in the steering wheel but probably not noticeable 90% of the time: flat roads.

I am really interested if someone has some real-life experience as I want to build a lightweight overlanding rig and I am chasing grams as they easily add up.

https://sleeoffroad.com/wp-content/uploads/2022/12/HiSteer02.jpg

 

[NeverFinis]

no idea about in practice. People generally don't like bump steer.

They raised the panhard mount point on that axle on that image you provided, keeping it and the drag link parallel.

I mean, they thought it was important enough to raise the axle panhard mount...

 

[mudgudgeon]

But regarding the steering, do you think it would be an issue in practice?

Any change from stock Toyota geometry is likely to have negative consequences.
Toyota doesn't millions over years/decades developing suspension and steering design and geometry. Toyota design strikes a solid balance of performance, comfort, safety, predictability, and flexibility

Every design change away from stock is a compromise to stock performance

You lift your truck because it looks good or gives you more ground clearance, it changes the design parameters on every part of the suspension system.
Does that result in a practical change in performance? Absolutely.
Some changes in performance are more critical and more obvious than others.

Some changes will absolutely have a negative effect on on-road handling, comfort and safety in a trade off for some improved performance offroad, or "better" looks.

How much time & money etc you want to put into correcting loss of performance, or bringing stuff back to ideal geometry is a personal choice.

 

[Broski]

High steer arms are not an issue with leaf springs.
I only see High steer arms on 80s that are three linked in that case panhard is modified so it matches the angle of the drag link to avoid bump steer.
Frame side drop brackets are in great solution for low lifts.
They do cut down on ground clarence which shouldn’t be an issue on an overland rig.
If you’re building an overland rig IMO there’s no reason to lift it.
All the questions you ask have been covered many times.

 

[OrangeCrusher]

@MikePL my rig has a front axle panhard mount that's moved up about 3 inches. I didn't do this myself, it was done as part of a radius arm flip mod by one of the previous owners. The steering has not been modified as far as I know. Some description of it here - I actually ended up shortening the panhard bar despite a 3" lift, to center the axle.
As a result, the panhard bar is now sitting on somewhat less of an angle than the steering link.

I don't have any other lifted 80s series to compare the driving behavior to so can't exactly say how this impacts driving behavior. The only thing I can say is that the rig used to have significant bump steer due to the rear panhard mount not being corrected. I recently welded in the Eimkeith bracket in the rear and this has led to a significant improvement. I was only able to weld in the axle bracket in the rear as the frame side appeared to be hitting parts of the parking brake mechanism at full compression. So the rear panhard bar is also not perfectly horizontal, just sitting at a much better angle now.
There is some small amount of bump steer remaining now but I cannot say if it's caused by the front or the rear or both.

It's also hard to separate it from what I would describe as generally poor handling in onroad corners due to the absence of sway bars, soft springs and the high center of gravity. As was said above, if you primarily plan to drive the rig onroad or on light terrain like gravel roads, any lift is a negative driving manner wise. E.g. I'm mostly driving my rig offroad, and putting it on the trailer for everything farther than say 50 miles. This may sound utterly ridiculous, but I can take corners faster with the rig in tow on the trailer than driving it by itself So worth thinking about how much lift, if any, you really want.

I don't know if this helps you but the guidance I would give is: If moving the front panhard mount gives you a really important benefit and you can live with a potential minor bump steer impact, go ahead and do it.

 

[Njck22]

I would like to know what I don't know.

We all know that lifted cruisers need to have their suspension adjusted and...

1. It seems to me that the radius arm plates made by eimkeith are much better than the caster correction plates or eccentric bushings because they retain the same caster angle and physical angle of the radius arms and also move the wheel a bit to the front. Much much better than other stuff, so why are people installing caster plates and they usually pop up as the go-to solution, while they are more of a band air and are harder to install than the eimkeith brackets.

2. Why are adustable panhards also the go-to solution, while they are heavier, are a non-stock part in case they need replacement far away from home and the panhard is at a higher angle anyway, it's only longer. Again, a panhard bracket which lifts the panhard mounting hole as much as your lift, seems like the perfect solution but still the adustable panhards seem to be the most popular way of dealing with the problem (partially dealing with it).

I want to modify my cruiser right and this is why it puzzles me that people use things I wouldn't use...

The argument against drop brackets is that the brackets hang down, and would result in less improvement in breakover angle than a lift using new radius arms or other caster correction would grant. There is still some improvement.
From an engineering standpoint, these drop brackets for both the panhard and the radius arm change the forces that are applied at the frame/axle at the mounting points. These frames are tough and I doubt they would lead to problems, but you are essential adding a torque moment to a frame section that was meant to take a axial or radial load, adjustable panhards or new radius arms do not change that. They may direct forces at a different angle to the point.

All this from someone that has iron man drop brackets to run 35s

 

[Broski]

Moving the front Panhard with out moving the drag link is a bad idea!!
Drop brackets won’t hurt break over angle, they can get hung up on big rock when back up.
If you want it to drive nice leave it alone.
Replace all bushings & spring with stock height springs this should net you about a one inch lift. Add nice shocks.
You will be amazed at the difference!