Leaf Spring Public Service Announcement

[Malahki]

I also live in Southern Alberta and have experienced the trail closures. I however do not blame leaf springs, lol. For argument sake Behometh lets make a few comparisoms on whats better for the enviroment?

SUA on 37x15.5's VS SOA on 35x10.5's?

5 link coil on 37's VS SOA on 44's?

Or to simplify:

Skinny tire VS fat tire?

short tire VS tall tire?

Lets take it one step further:

solid axle VS IFS?

solid axle VS Portal axle?

Light vehicle VS Heavy vehicle?

So in my experience owning various 4x4's including 2 portal axle Unimogs and a portal axle independant suspension Pinzgauer. Portal axles obviously offer the best clearance.

So why not call an end to skinny tires because they dont float as well, short tires because they dont give enough clearance and all conventional solid axles because again they dont offer enough clearance...... oh and any heavy vehicles because well their heavy and they will sink faster and farther.

Again for argument sake but why arent you building a super lightweight vehicle with portal axles and super tall fat tires??

 

[NZCruisers]

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



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.

Yeah nah...

BJ71 makes some excellent points re tyre size and portal axles etc.

I would only like to add
That while you have kind of a point about links being a "better" suspension system to ride in and offroad with there are however downsides.

Like most Cruiser owners I don't have a bank in my inventory and as such opted to modify my Cruiser myself. For my needs SUA wasn't cutting it and links looked to be an expensive and complicated procedure to carry out properly by oneself in the shed hence I went with the simplicity of a spring over

To Spring over my 2 Cruisers, my time not counted was approx $2000 each and they took approx 2 months each spending weekends and the odd evening to do it all

I don't seem to have the issues you mentioned with yours , mine drives mint on the highway. I did 800km the other day and couldn't believe how comfy it was.

So yes while links are better offroad to an extent , the cost and time to set them up properly is a factor in making them a "better" system for someone like myself who drives too slowly offroad anyway to really notice the difference.
Just a factor I think you need to consider
Its kind of like , Well a Porsche 911 is a miles better car in terms of performance than a Toyota Corolla but it would be hardly practical for everyone to have one wouldn't it

 

[Delancy]

Just because this isn't Pirate, it doesn't mean people are going to bow down and blow you.

Bahahahaha.

Sig worthy.

Links FTW!

 

[Blade]

Do SOA on an european vehicle and be ready to go to jail for that! And let's see how it drives with 3.5-4tons load!

Also do those modifications (air bag etc.) on a 4 ton expedition vehicle like I have and drive down to south america and tell me again how reliable that is and how easy it was to get replacement parts!

my 2 cents
www.pawsontour.com

 

[Diesel Cruiserman]

This conversation still on the table...

Just kidding...

I have never owned a spring over vehicle however I had driven and been co pilot in said vehicles..

Not for me, but for other reasons, my age..time on the trails.... and lastly need to conquer that big climb or run through that big mud puddle are gone.. Mostly I do not like wrenching on the trail.. For a very short period I ran with a group that did said breakage every single time

I think it is more of a personal observation than what is right or wrong..


People with SUA with plenty of trimming can do as much damage to the trail as a SOA.

My rig of choice is a 1983 BJ42 with open axles on 33s, fairly collectable truck but I wheel it often and have not broke or bent anything yet...

After working next to NWFab, I would say a linked suspension is the only way to go but at a very high cost to build it right..which of course is not an option for some.


Rob

 

[bvissers]

So, I don't get it, forestry companies make thousands of miles of scars through our wild forests, many clear cut thousands of acres, our governments build 6 lane wide highways through pristine countrysides. Yet, the bottom of my four wheel drive touches the ground in some under used forestry trail ( possibly bogged up by its own capacity to stop the natural drainage of the land) and suddenly, because we haven't modified the bejesus out of an already very capable vehicle, we are scarring mother nature??. You took offence to some of the harsh comments people made, I took offence to the harsh comments towards anyone wheeling an SUA vehicle. I would think you may have stirred some feathers with those comments as the majority of the 4WD LC community with 6x's and 7x's are wheeling with SUA. And from a Highway safety perspective the potential danger to a roll over with an SOA far out ways any " scaring of mother earth" taking place. . I have countless people tell me that there SOA are as safe and as drivable on the Highway as any SUA, well simple physics dictates that is false. Any SOA doing an emergency maneuver at highway speed is far more at risk, not only to scarring the road as it rolls over, but to scarring families as lives are lost, only to get a few inches of ground clearance... ?? LAnd heals, people in rollovers don't always.

 

[JTarnow]

Maybe mine's broken but last time I looked underneath my SUA cruiser the diff was the low point, not the spring hangers.