who said independent suspension was not good offroad?

 

Many.

For example Toyota marketed the 105 live axle version of the 100 Series Land Cruiser for this proclaimed reason.

And why do so many people do SAS's on lot of different IFS/IRS equipped trucks?

I'm not personally saying independent suspension isn't as good. I'm asking why do people say so, what are the real world off road limitations or even enhancements over live axles.

 

One of the major limitations is flex. Then the CV joint's aren't all that strong. CV strength can be taken care of, at a cost though. With the amount of cost it's just cheaper to just go SAS.

Shhh don't tell Shannon Campbell though, he spanks many solid axle trucks.

 

What kind of offroading are you talking about? Solid and independent both have advantages and disadvantages.

For the sand crowd and go fast desert stuff, independent certainly gets the nod. But the main issue is that travel is still the limiting factor for independent. Which is pretty much the only reason in an unlimited budget vehicle why you would still see a solid rear axle - they can still offer more travel. CV's can't quite keep up with the travel. I know there is some top secret mega dollar CV's out there that are getting some big angle numbers but this is for a very select few people.

For the high performance trail crowd, solid axles still work the best. Dollar for dollar, you can have a much longer travel suspension that is more durable. When speeds start slowing down, the benefits of IFS diminish quickly. You aren't likely to see a competitive cone dodger with independent suspension any time soon. It has been tried a few times. The solid axle allows for a degree of forced articulation from the left and right tire and ground clearance at the axle does not diminish when a wheel compresses. Higher unsprung weights also offer increased stability when the vehicle is at severe operating angles.

 

The solid axle allows for a degree of forced articulation from the left and right tire and ground clearance at the axle does not diminish when a wheel compresses. Higher unsprung weights also offer increased stability when the vehicle is at severe operating angles.

At this point, these are the only downsides to IFS/IRS with the exception of cost.

Cost will come down soon too, but you can't beat the physics. Strength is a non issue anymore.

 

http://www.pirate4x4.com/forum/showthread.php?t=930660&highlight=

 

:laughing:
But Good for him!

 

Im not even sure he is referring to KOH/go fast IFS. I think he means OEM IFS....

 

That's six letters that should not be used together

 

Im no expert here by any means, however, SA setups have been done and are readily available and have been for years and years. Even today alot of the really heavy duty vehicles out there are still using 1960's technology because it works. IFS and IRS have not been around as long and is just now getting popular with the offroad crowd in general. With that being said i think if you look at the broad spectrum of the "OFFROAD" world you will see that it really depends on 1 or 2 things.
1. if you wanna go fast, (desert, baja style etc.) go with IFS and IRS.
2. if you wanna go slower and are into rocks, mud or southern rock bouncing styles go with a SA.

3 THE EXCEPTION is KOH..... build what ever you want cause 9x out of 10 its gonna break before you get back to camp anyway and thats the fun part.

Again Im no expert. don't hate me cause im opinionated.

 

takin this to JV for some "testing" this weekend...

 

Stoked to see that rig finally ready for testing.....please update your build thread with some pics of both the finished rig and testing pics

 

I believe an affordable, competitive, IFS assembly is possible. Yea the IFS parts can get expensive but is the whole front end really that much more than the solid parts? where are the differences?

IFS
you need
-8 heims and 4 uniballs. dont need the best stuff
-2000 for a pair of nice outer RCV's
-$700 for pair of 35sp 935's
(or spend about same price for 4 series 30 cv's)
-1500-$2000 for a 9' center with drive plates/bearing ($2500 for dutchman)
-pair of axle shafts
-ram would work fine for steering. dont need a rack

Unlike a solid axle you dont need ujoints. solids run bling outer joints too. (like rcv). solids still have links and need a total of 8 heims to run all the links.

in all reality the only price diff in hardware ammounts to the price of an extra set of cv's, and the 4 uniballs. a little more for the basic housing because the ifs housing has its own set of bearing and you need to buy those stub shafts. 2-3 thousand is the only difference. Thats chump change if one is building a competitive racer. And that is not a deal breaker if you are building a play toy for the weekends.

But the parts list doesn't show the whole picture. You can drop 10K in your fabricators wallet real fast. (worth every penny) The IFS front end is going to require a lot more cash because all these parts to date are one-offs and require a lot of pre-thought design and most of the ifs cars to date are spending money on fabrication. Unless someone has the time and skills to put it together right its going to get pricey. It doesn't have to be this way. Production jigged upright assemblies shouldn't cost more than $300-$400 a Pair. look at it. if you get rid of all the sexy weld washers and overkill gusseting the upright is nothing more than a cheap builder cup and 6 tabs. The Aarms would work fine if you built them from tube. there doesn't need to be any plate construction in any of the assembly. Its only a matter of time before we see a complete $8000 ifs assembly hit the market. you just weld it in and go fast with 15+ inches of travel


And campbell's car is not expensive. His engineering is not the best either. He uses good parts but doesn't throw money away on bling fabrication that doesn't make the car any faster. And he keeps the weight down. the guy is kicking everyones ass with a trackbar in back.

 

And campbell's car is not expensive.

i believe that there is a huge difference on this board on what is considered expensive. 8k for a front end used to be crazy loot. a car like campbells, even just the front end setup, seems kinda expensive to me. definitely can't wait to see all the ifs v2.0 rigs hit the dirt..

 

(and maybee he can drive)

 

Not running a rack would be a poor idea. The rack is one of the huge gains in performance that a ifs has over a sas in the desert.

Fullhydro steering is sketchy at best at desert race speed.

 

absolutely. One thing that makes IFS cool is that it allows one to use a rack. cant run the rack on the solid axle.

but the gains to having IFS are still worth it even if you have to use full hydro. IFS with Full hydro is still faster than Solid with full hydro

look at deremos's rig
http://www.pirate4x4.com/forum/showthread.php?t=761183&highlight=

 

and nobody has done a standard saginaw box with IFS. look at all the desert cars doing that. and all the crawlers that are doing it.

 

no rack on these..steering box it is.. driving it right now outside!

 

ill say it again as in some other threads on here.....

for some reason the thinking in this "sport" has gone down the same road desert racin did....

THIS SPORT DOESNT HAVE TO BE AS EXPENSIVE AS YALL ARE MAKIN IT

somewhere we have forgotten that there are some cheaper tryed and true methods of doin stuff around here....

the sginaw steerin box for example instead of a stupid unubtainium rack:shaking:

if u have that coin, so be it......but dont forget.....it can be done for a real world price........
and believe me ....ive seen some 10 and 15 thousand dollar streight axles....

 

Just because you can't afford it doesn't make it stupid. :laughing:

There will always be a cheaper way of accomplishing a task, but just because it is cheaper doesn't make it better , like wise being expensive doesn't make it the best.

If the Saginaw box was a better way of steering a go fast desert racer then the majority of racers would still be using them. Back in the day that is what everybody used and guess what , the rack was developed and proved to be a better mousetrap for the task.

Yes you can use a traditional steering box and it will get the job done, but the Howe rack is a superior method of steering a long travel high speed desert racer.

 

amen
good geometry and a strong build goes a long way. But you cant fake HP and there is no such thing as cheap suspension.

They will give a trophy to every child on my kids soccer team this year.

 

^ well said and to the point. :smokin:

 

:smokin:..leavin tomorrow!..need to update my thread!

 

How did your trip go Mosebilt?

 

Nice buggy. Flexin that bitch in a handicapped spot. I like your style dude.

 

Saginaw-type steering box with an idler-arm, swing set linkage and hydro-assist is the way to go. Not only is it a hell of a lot cheaper, but bump steer can be reduced further than possible with a rack. Mostly talking about bump steer while turning, and how it's possible to design the steering linkage to move with the suspension linkage.

 

Mostly talking about bump steer while turning, and how it's possible to design the steering linkage to move with the suspension linkage.

Jesse,

To my reckoning, the best way to do that would be to run the swingset arms in the same arc as the spindles, yes?

Any change in frame mounted steering arm to spindle steering arm would cause bump steer. So take a '86-95 Toyota IFS set-up for instance, you would need to move the steering box and the idler back to the same plane as the spindle steering arms, BUT with the drag link and idler arm pointed forward on the same plane as the spindle steer arms and the arms are the same length.

Now it would all travel in the same arc in the same plane throughout the travel with little to no bumpsteer.

What are you thoughts Jesse?

 

Yup. You can mount the steering box and/or idler-arms to complement the spindle inclination and make the geometry such that the steering linkage will move with the spindles in a manner that reduces bumpsteer as the suspension cycles while steering. That's the biggest potential advantage as I see it. Additionally, there's the relatively low cost associated with building a steering system that has the potential to be strong/durable and easy-to-service using readily available off-the-shelf parts. But this isn't anything new. Think I first saw or heard about it on an SPD truck? Been a while though, don't remember. Know there was some discussion about this type of steering in a thread on RDC about Camburg's new trophy truck a while ago if you want to dig for some tech on the subject. Think they've ended up using racks in the trucks they've built, but remember asking some questions about how to design/model that type of steering linkage. Remember thinking it would be an interesting design exercise, but haven't had an opportunity to apply it to anything yet.

 

Found that thread on RDC that I was looking for. Here's a link.

 

The Camburg Kinetic thread was the first place I saw it and it made sense, though as you mentioned, they ended up going with a steering rack for simplicity

Both the Kinetic thread and the Roll Center thread had good info on it:

Well for one thing it appears that the idler arms are placed at the same angle as the respective king pin axis for that side. This would help the Inner TRE follow a more similar three dimensional path as the outer TRE, as the tires were turned. Consequently, this would reduce bump steer in turn. The orientation of the arms about their respective axis plays a part here too. Basically, the more similar the movement of each arm, the better the ends of the "links" follow each other. In any case, it's nice to see this level of detail being considered. As always thanks for sharing.

Draw up the suspension in 3 different spots, drooped, ride height and full bump. I then draw circles with the tie rod end on the spindle as the center at all three locations. Adjust the length of the radius till they make a nice intersection. That is a good point to put your inner pivot.......

If you have camber gain, there will be a little more work involved.

You want to mimic with the steering swing what the spindle (steering arm) is doing.

So an expensive rack can be gotten around low-buck by doing some planning with a steering box and idler arm placement.

 

I've seen a non power assisted rack mounted to a solid axle on a flatfender a few decades ago. A universally jointed, slip jointed column driveshaft to the rack would appear no different in its affect on bumpsteer as a transmission driveshaft would have.
AG.

 

read this

 

The answer is in this book.

http://www.amazon.com/Race-Car-Vehicle-Dynamics-R146/dp/1560915269

Pitch and roll axis are in different places on IFS vs solid generally speaking. That's not to say you couldn't make the same in independent vs solid. Weigh transfer is typically different too.

These go-fast rigs you're seeing won't push the weight around the same way on an RTI ramp as a solid axle vehicle would. There's typically a lot more front-> back weight jacking on IFS compared to solid where there more side<->side.

 

thats funny...i have that book, good read..over, and over, and over...:smokin:

 

Thanks John-Mosebilt for showing me your builds before the Expo. You are definitely a world of knowledge and making new things happen. You are on my target list when the time comes for action!!!