Leaf Spring Public Service Announcement

[Behemoth60]

I started this response, but decided not to hijack that thread....

so why exactly were these trucks ever engineered to have the springs under the axle?

is this true?
More control with SUA.
More expensive to lift SUA.
More chance of axle wrap with SOA.?

A sprung under axle passenger vehicle has not been sold by a manufacturer in North America for almost 20 years. Toyota, Isuzu, Suzuki... I think when the 90's arrived, they had all stopped that horrific period of engineering.

SUA is EASIER on the manufacturer. Plain and simple. There is geometry to making suspensions work... as torque is applied to the suspension, either braking or acceleration or turning, the suspension will react based on some complex geometry. Based on that geometry, the vehicle will experience different responses, such as 'dive' while braking, or 'Squat' or 'anti-squat' under acceleration. Even Roll when cornering is effected by the critical geometry.

In order to get good geometry with SOA, the location of the shackles in the rear must by very high in relation to the axle. Look at the rear of an an American pick-up truck... The springs are outboard of the frame, and the shackles point upwards to the spring. In order for Toyota to have done this, they would have had to redesign the frames or something.... Expensive. Rather then get all the BENEFIT of SOA, their engineers burden us with their cheaper designed suspension.

I have also built and driven some SOA Cruisers. I now feel, it's time for me to make a public statement about SOA Cruisers.

Everyone, please stop doing Spring Over Axle modifications.

Allow me to explain.

First of all, please do not mistake this declaration as an endorsement for SUA suspensions. I will not take a SUA vehicle off the highway. I will generally avoid wheeling with people who insist on driving SUA vehicles off-road. The dangly axles are very damaging to the trails as spring plates and u-bolts scar the face of mother earth. If you wheel SUA... you should be ashamed of yourself. This is inexcusable behavior. Just sit there stuck in the ruts and think about what you've done. Shame.

SOA is excellent off-road. If your vehicle is a dedicated trailer queen and only ever wheeled on the trails, then I do believe that SOA is an acceptable modification. There are things you can do to alleviate axle wrap, but they are stop gap measures. And frankly, by the time you've set-up a SOA correctly, you could have installed a proper suspension already.

The problem with SOA is the on-road manners. Remember that geometry I was speaking of? You've messed with it. SOA is divvy when braking, very squaty when accelerating, and has a very high roll axis making it rolly when turning. All in all, innocuous when wheeling, terribly annoying when driving.

I just put 8000 km on my SOA BJ74 this summer. On the trail... absolutely kick ass. There's not to many rigs that can keep up. The problem was the on-road portion of those 8000 km. I was driving at highway speed perfectly straight, and drove over a dip in the road. As the front suspension compressed, the inevitable bump-steer engaged. It was all exacerbated by the dive, squat, and roll as the suspension worked its way through the dip with the induced bump steer. It's an exaggeration to say, but I almost rolled the truck going straight and level down the highway. Nay, SOA has too many on-road foibles to be a proper suspension for upstanding Cruiser heads.

Solution.

No More Leaf Springs!

5 link front. Ensure your pan-hard link is parallel to your drag link, and you've avoided bump steer. The 5 link (unlike the cheap-out 3 link solution that Toyota put in the front of the 80 series) will maintain proper caster angles throughout the suspension travel for a stable and safe on-road ride at any height. Some nice coil-overs are compact and easy to mount.

4 link Rear. I like air bags in the rear for 2 reasons... coils require a fairly tall towers, whereas airbags are can generally fit in a lessy-tall area. Secondly, in a expedition style rig, you can adjust air pressure to maintain desired ride height as you load up the kitchen sink.

So, fellow Cruiser brethren. I make this call to one and all. Cast of you leaf springs. Embrace links.

 

[Josie'sLandCruiser]

 

[tlcruiserman]

What The...

I am not a fan of the SOA myself, been their done that back in the day to my 40 series in the 80's BUT...

Just because I am not a fan, I really think whatever you want to do and works for you, as long as it is still safe, knock yourself out

B What is up with the post???

Michael

 

[Clint79]

hmmm
hiluxs soa seem to work okay

 

[BJ-44]

A properly set-up (good geometry) SOA has decent road manners. If you have bumpsteer yours it not set-up right. My 44 doesn't exhibit any bumpsteer on the road. Like Clint79 said what about the Hiluxs they have SOA from the factory and no bumpsteer?

 

[Gib009]

your spring over was done wrong.

Your statement about SUA not being able to wheel is like saying nobody should be able to wheel if they dont have 44inch tyres because there diffs might touch the precious mother earth

pretty much the biggest FAIL public service annoucement i have heard

 

[Behemoth60]

First of all... Wow. The venomous personal attacks in response to my admittedly staunch opinions are not expected from the Mud community. I must confess, I was expecting a rebuttal, but I was expecting things like 'Well, leaves aren't perfect but they're inexpensive and simple' or something similar.

I will rise above the personal slander, and engage in a brief debate on the topic of leaf springs, which I will now attempt.

You have very little understanding of suspension geometry and how to build it properly.

I dont' think that's true.

A properly set-up (good geometry) SOA has decent road manners. If you have bumpsteer yours it not set-up right. My 44 doesn't exhibit any bumpsteer on the road. Like Clint79 said what about the Hiluxs they have SOA from the factory and no bumpsteer?

Decent road manners, I agree. But not great road manners like a properly linked truck. First of all, bump-steer is the least of my complaints about SOA rigs. The dive, squat, and roll are my major complaints. But since you've isolated the bump-steer issue, let's talk about bump steer...

All leaf sprung vehicles have bump steer. There's no way to make the distance between the pitman arm and steering arm travel travel in a concentric arc with the hub/axle/leaf spring. On a SOA, the best practice (am I wrong about this?) is to limit this effect by making your pitman arm as flat as possible. For the record, on my recent build, the total drop from pitman arm to steering arm is 0mm... Yep, it's perfectly parallel to the axle (this SOA uses 4x4 labs high steer arms). The problem is that the arm is above the axle, instead of on a plane with the center of the axle. With SUA, they mitigate the bump steer by getting the steering arm roughly on the center plane of the axle. Impossible with SOA on a Cruiser where high-steer arms are pretty much the only option.

Now, my SOA has great road manners in all except a scenario when my Left front wheel (RHD BJ74) compresses a lot, specifically a big 'whoop' in the road (such as I described in my first post), or making a hard right hand corner where there is a 'whoop' mid-corner (I know, very rare, but there is just such a corner between my house and the hardware store, so I go through it a lot and it's really annoying". In those two, admittedly rare, scenarios, the bump steering is very noticeable. The rest of the time I drive, it's straight and true. On my 8000km expedition this summer, there were maybe 3 situations where I noticed the bump steer, specifically.

I am not convinced that any leaf spring vehicle with a mechanical steering set-up can be 100% bump steer free. certainly, it can be mitigated and minimized to the point where it is rarely noticed, but never eliminated.

But like I said, bump steer is the least of my complaints about leaves. Wont' someone please refute my dive, squat and roll arguments, which are annoying every single time I drive rather than pick on bump steer, which was an annoyance for about 20 dramatic seconds of the 100 hours I spent behind the wheel on this summer's expo.

your spring over was done wrong.

Possibly. I've posted all the pics of my SOA. There's a link embedded in my original post. What did I do wrong? Details. Educate me.

Your statement about SUA not being able to wheel is like saying nobody should be able to wheel if they dont have 44inch tyres because there diffs might touch the precious mother earth

You have mis-quoted me. I said I wouldn't wheel SUA, and avoid wheeling with SUA trucks due to trail damage. Not that 'SUA is not able to wheel'.

Here in Alberta, there is significant rutting and trail damage, and massive trail closures in the past 3 years, due, in part, to rutting. I am on a government advisory committee on trails in one of our local areas, where I chair the trail committee for that group, and conduct training for local volunteers to conduct trail inventory and actually design sustainable trails. My mission is to return trails for us to use, but vehicular impact is a significant barrier to overcome.

My concern is that all vehicles have impact on the trail, and when axles and springs and u-bolts contact the ground, there is a very large soil displacement due to the mainly clay-base of the trails in our specific area. I've driven through ruts without touching the dirt, and had SUA vehicles follow me in and get stuck on their springs, then get dragged through, displacing disappointing amounts of dirt.

So, yeah, I am concerned about axles touching mother earth, because in my backyard, at least, the trails get damaged, then closed, as a result. People, even in this very community, are not responsible enough to say "hey, maybe I SHOULDN'T wheel on this trail due to the impact it might have." Instead, there seems to be a self-righteous and entitled opinion that "if he can drive through that rut without spinning his tires or displacing the soil, then I have the right to winch through and displace 200 kg's of dirt in the process" SHAME, I say. I have done that, felt that shame, and decided to do something about it. One such action is to encourage people to get their leaves out from under their axles. Or, more specifically in this thread, get rid of leaves entirely.

 

[Ratpuke]

How time changes... well, pretty much everything.

Such a shame, Peter. I will miss seeing you out there...

BTW, If you're referring to any of the roads N of FSJ, they're definitely rutted to hell and neither straight nor level.

 

[Z()LTAN]

My SOA cruiser is more stable than a coily with an equivalent lift

My SOA cruiser can travel at speeds in excess of 140kmph

My SOA cruiser has just as good if not better handling than the factory SUA setup

My SOA cruiser has no bump steer

My SOA cruiser performs flawlessly under breaking

MY SOA cruiser does not suffer from squat

and lastly

My SOA cruiser has more flex than a coily setup... and still drives like a champion.

My SOA cruiser's suspension cost me $2000 all up... try and get a coily suspension set up and working as good as mine does for that price...

 

[Clint79]

Maybe your 5 link's are more sorted to the tracks and trails you use but
Not every one with a cruisers wheeles on the exact terrain you do , so leafs or coils SOA or Sua different set ups or types of suspenion to suit the different owners needs So i dont think any type of sus is better than another i think the better is what better suits your needs and wants out off the 4x4

 

[pradocruzer]

I do apologize Behemoth60. I should have not stated that you were unable to properly build a SOA set up. I do not know you nor your abilities. I was rather upset to be told what I should or should not do.
In my opinion, and mine only, any modification of lift (or drop for that matter) will affect the handling characteristics of any vehicle. There are many different ways to help the handling characteristics on 3,4,5 link, leaf sprung and torsion bar set ups. I do not think I have been in or built a vehicle being modified that works as good on road as off road, street, drag high speed ect...
It is very difficult to build a linked suspension set up and have the mounting points above the bottom of the axle tube. You need a fair amount of lift to have the right separation between the upper and lower link and I find that the center section hits the most dirt of all. They only way to lift your center section is bigger tires which raises your center of gravity and in my opinion hurts on road handling.
In my opinion the more lift you have the bigger gap you get between on and off road handling.
I think the comments that bothered me the most were " The dangly axles are very damaging to the trails as spring plates and u-bolts scar the face of mother earth".
Start your cruiser up and rev it a few times and stand behind the tail pipe.

PRACTICE WHAT YOU PREACH.

 

[Behemoth60]

My SOA cruiser's suspension cost me $2000 all up... try and get a coily suspension set up and working as good as mine does for that price...

Thank-you Z()LTAN for a slightly more intelligent response than your first post. I had certainly admired your work on your 75, and was quite shocked by your vitriol.

 

[Behemoth60]

I think the comments that bothered me the most were " The dangly axles are very damaging to the trails as spring plates and u-bolts scar the face of mother earth".
Start your cruiser up and rev it a few times and stand behind the tail pipe.
PRACTICE WHAT YOU PREACH.

I appreciate the apology. Thank-you.

I am personally involved with the politics of OHV trails in Southern Alberta (Past President RMLCA, Past Vice President Alberta United Recreationist Society, Board member and Advisor to the Alberta 4WD Association, Four Wheel Drive Representative on the Ghost Stewardship and Monitoring Committee, and chair of the Trails-Subcommittee advising Alberta Sustainable Resource Development on trail designation designations for trails in the Ghost Forest Land Use Zone NW of Calgary.) Ergo trails are my passion.

The attitude of wheelers feeling entitled to winch their trucks through soft muddy terrain of their favorite trails is why those trails get closed. I realize I have a life-long battle to change this attitude of entitlement.

The RMLCA chose not to run a trail this summer... not because it was too hard or no one wanted to or it wasn't legal or anything... but because we just 'shouldn't' due to our impact.

After 3.5 days and 2000 km and 5K in mods and prep to get there, I aborted my expedition this summer after 4 hours on the trail, because the trail couldn't sustain what my truck was about to do to it. It was legal for me to be there, and my rig was capable enough to gouge through the trail. Instead I/we went on camping/road trip for 8000 km.

My description of SUA rigs scaring the face of mother earth was poetic license, admittedly. I am sick of watching both extremes of wheelers damage trails... the small trucks winching like belly scrapers excavating a trench because they insist they're entitled to be there, and big HP a-holes shooting rooster tails. For the past 3 years I've preached 'Build you truck for minimum trail impact' No spinning. No 'excavating trenches' . High clearance, low ground pressure. And that means, to me... get the leaves out from under the axles. The web is littered with pictures of me doing exactly those activities I now preach against. But I never felt good about it, started to feel really bad about it, watched the trails get closed, and have started to do something about it. And that's what I practice.

But I won't stop telling you, and everyone, the following. "Stop scraping your rig's scratchy dangly bits on our trails. You're wrecking the trails, and the government is closing them. I am sorry if this offends you, but you need to realize what you're doing, feel a bit of shame for what you've done, and take some responsibility to do things different.

I am not involved in air quality issues, and don't preach anything in particular, except that gassers suck. And leaf springs suck too.

 

[EWheeler]

Just because this isn't Pirate, it doesn't mean people are going to bow down and blow you. Your rant seriously makes you come across as a lunatic and I doubt you will find many here with views aligned with yours. About the only argument in that verbal diarrhea that I agree with is that we as a community need to continue to embrace the action of Treading Lightly. There are a few idiots out there that ruin it for the rest of us by leaving behind trash, venturing off designated trails, or other ignorant actions. Contrary to your beliefs, dragging u-bolts are not the reason why our trails are getting shut down.

My CliffNotes for this thread is that you suggest we all link our rigs, and then stick to the paved backroads or logging roads. That is seriously what you are asking us to do. You are no longer one of us, you are one of them. Oh, and GFY

 

[BJ-44]

If you have too much dive, roll, and squat...My fix for you is the same thing I teach the Army here in MRAP drivers training "slow down because you going too fast for conditions/design of the truck" These trucks are extremely top heavy and have stiff SOA suspensions but experienced drivers that drive safe speeds for the conditions have no roll, rollover, or dive issues. Now new or agressive drivers on the other hand can be scary.

Tearing up a trail with a rut plow SUA...sounds like somebody needs a hug from a tree. Did GreenPeace hijack your MUD account? Low SUA trucks usually smooth out a trail when they Rut Plow it.

 

[Behemoth60]

Profane responses continue instead of debate.
Thread locked

 

[pumba]

My good you talking about Alberta canada give me a break mother earth lol your a joke

 

[rick_d]

my 2 cents

I think many SOA have been done subpar over the years. Deferred maintenance on SUA (on 40’s especially) lead to sloppy steering and control. For me I have searched for a suspension system for 90%+ highway travel and simple SOLO offroad travel that limits parts and failures. I tend to drive 350-450 miles and drive 35 miles of dodgy road to get where I am going, then turn around two days later and make it home for work Monday AM at 0630. A sound leaf sprung system has worked for me for about two decades even though I started with the IFS system in the 1980’s. In my advanced age I am branching out in the next month to the dreaded “3 link” toyota system but coil travel and longevity have been tried and tested with the 80 series and later the 105 and 78/79 series trucks and I hope will provide a smooth but sound ride for the next decade. I will still use the SUA rear as 32/33” tires fit my needs on a 102” wheelbase vehicle.
That all being said, I think it is dangerous to run a 90% offroad system on highway’s especially at 75mph- yet I see this done all the time with bullshiat lifts and 5 links etc that someone paid through the nose to install.
Be careful and run the fewest failure points possible and please folks replace the bushings on a regular basis not every 30 years.

 

[yotahed]

Deleted: pointless

 

[brownbear]

Please lets keep a topic on course and without personal attacks. Thread re-opened.