IFS v's live axle

[Den]

Hi everyone,
please settle a debate for me, between myself and a mate of mine.....

We both agree that live axles are better....

We both agree that live axles articulate better....

however we disagree as to what lets IFS down physically.

I say because Cv's blow and cant handle the pace

my mate says because lower control arm gets in the way.......

Please confirm for us what it is that contributes most to IFS failing when 4 wheeling....

[WICKED]

you forget the piss weak streeing

[me3@neuralfibre.com]

Arms are too short resulting in excessive arcs and angles. (CV counts as arm)

Live axle pivot is effectively the opposite side suspension mount resulting in an arm length equivalent to roughyl 2/3 the track width of the vehicle.
IFS arm lenth is generally 1/3 track width or less. Can't be more than 1/2 track width unless arms are assymetrical.

[Madmac]

main thing that lets IFS down is lack of flex

[grimbo]

main thing that lets IFS down is lack of flex

main thing that lets down a live axle is ride quality and handling that an IFS excels at. But then neither of those things are what he is asking.

It actually comes down to the type of 4wheeling, most mild to medium stuff the ifs will handle fine without any negative results. It is usually when the going gets a lot tougher and combined with larger wheels and lockers that things can break.

[Madmac]

it really depends on the given vehicle, IFS hiluxs are notorious for busting crown wheels, i broke 4 or 5 when i had mine, i also broke 1 CV and a tierod too. as grimbo said IFS is fine for touring and mild wheeling, but not suitable for the hard stuff

[shakes]

the biggest thing I saw wheeling with a mate in an IFS is that when faced with a step up etc. One wheel lifted, the other done its job and stayed on the ground but it lost all ground clearance between the wheels and just bellied up on the log/rock whatever the obstacle was

But with a Live axle ground clearance stays vitually the same no matter what the angle.

my brain is fried from too much trade school, someone else might be able to explain that better.

Simon

[Coatesy]

From what I've experienced with my current model Grand Vitara (I know, I know ... not a real 4WD ... I keep getting reminded of that everyday by my mates) ... The real issue with IFS (and IRS in my case) is the articulation.

I have a lot of clearance when all 4 wheels are on the ground, but when coming up to a significant rock step, there just isn't enough travel or flex to keep the car from getting crossed up.

I'm having a Dobinsons kit installed which should give me more travel, so I'll see how it goes then ... but coming back to the question that Den asked, during my wheeling, I've pushed the GV to it's absolute limit in it's current form, and it's probably been to places no other GV has seen ... and during that time, I've given my control arms some pretty big whacks on rocks ... and they've been great ... no sign at all of any damage.

I have heard of others with IFS with smashed CV's though ... on more than a few occasions ... So my vote goes to CV's for the weak point .

[Bitsamissin]

Always excepting Tojo's (C&P) the CV has to be the week point especially at full lock under load with a front locker.
The steering assembly would be next.
Paj's have a problem with the idler arm bending - they don't break just bend.
This ultimately kinks the steering arm and results in busted tie rods especially running 33"+ tyres. This doesn't happen suddenly but over time from constant hard offroading.
Also the CV boots are vulnerable especially with auto disconnect front diffs like Paj's with super select and the Tojo's CAD system but a manual hub conversion can fix that.
Honestly I can say in 4 years of hard abuse in my Paj I broke 2 tie rods, bent one steering arm and 2 idler arms (before the SAS).
I never broke anything else on the IFS even running a Detroit locker and 35"s but did replace a couple of CV boots (had to replace one CV joint because of contamination) until I put on manual hubs.
I totally agree that a live axle is better when the going gets really tough and is a lot more comfortable offroad and stable.
However a twin locked IFS with 35"s will go a lot of places.
A particular Surf and Prado I know spring to mind they go anywhere our live axle rigs go and do it nicely I might add.

[playdoh]

I learnt to drive in a Paj, first car was an IFS 4Runner, now I have a Prado, every vehicle has it's weak links. My Prado currently has only about 6" difference at the wheel between front and rear travel, so the main issue remains that IFS ground clearance is not constant as mentioned above, depending on how much it is crossed up, it can go from having better under-diff clearance than a live-axle with same tyre size, to having much worse, because when fully crossed, the control arm mounting brace under the diff is much more obtrusive than a diff pumpkin.

These pics are coming in very handy, lol

[HG]

Yeah but I bet the Prado owner drives like a Sissy Girl

[HG]

Cool bar Playdoh what type is it.

[playdoh]

Yeah but I bet the Prado owner drives like a Sissy Girl

I'll bet my panel beater wishes I did, that gold is hard to match, lol (as you can see on the bottom shot with the rear bumper)

The bar is a Formula Offroad winch bar with the uprights cut off.

As long as you remember that IFS needs the wheels kept on high ground, they'll go a lot further than most people expect, with front and rear difflocks they should have no trouble keeping up with a locked live-axle (modded to a similar level)

[leehamescort]

CV blowing is the usual problem on an IFS, Crownwheels are a hilux problem but easily fixed wiith the right lokka.

You can't tell me that Solid axle cars arn't let down by their CV's.

Do something silly in any car it will break, do it right and IFS or Solid will get through (similar spec)

[playdoh]

I sheared the splines of a stub axle in my 4Runner ( i blame the difflock, couldn't be my driving ), but i,ve never broken a CV

[me3@neuralfibre.com]

I think I can answer your question a little differently.

Why are they less capable?
Because they have less travel. This is due to the short arms and excessive arc angles.

What lets them down offroad?
The short travel limits their ability to gain traction. The designers assume they are only "moderate" offroad vehicles and build them to suit. The owner tries to keep up with live axle vehicles and pushes it harder to compensate. They then either get stuck with lost traction or break.
You could beef up all the weak parts, but then you launch into all the other side effects.

Alternately you drive it within it's limitations and do mild mods.

Paul

[leehamescort]

Why are they less capable?
Because they have less travel.
What lets them down offroad?
The short travel limits their ability to gain traction.

I disagree - the short travel only limits their traction if they don't have lockers, with lockers, the fact a wheel is in the air does not prevent forward progress.

In some instances less travel is an advantage as the vehicle is not hindered by a wheel dropping 3 feet down a hole, then having to climb back out of the hole, the IFS will cruise over the top of the hole and lose no time or momentum getting caught up in the hole.

Descending down large dropoffs at an angle can be very "interesting" in an IFS but you have to take the good with the bad and drive accordingly, as with any vehicle - long vs short, wide 'vs' skinny, light 'vs' heavy, IFS 'vs' Solid.

IFS vehicles if setup right can do the hardcore stuff.
All vehicle doing the hardcore stuff break, CV's, axles, diffs, hubs - I have broken them all in my IFS, but all the other blokes on the same trips with solid axles are breaking the same things. If you abuse it, it will break.

Patrols/Cruisers are only indestructable if they are poser trucks, anyone who really uses them, breaks them.

Flame suit on.

Catcha
Leeham

[sloshy]

ifs for on road and maybe beach
solid for off road
simple no contest when the right kind of work is done
yet to see an ifs comp rig

[+dj_hansen+]

ifs for on road and maybe beach
solid for off road
simple no contest when the right kind of work is done
yet to see an ifs comp rig

One IFS comp rig....
http://carl.outerlimits4x4.com/viewtopi ... highlight=

[PajeroSRV]

simple no contest when the right kind of work is done

You're dead right sloshy. Its all about the right kind of work.

Take a look at the cars Leehamescort is talking about and you'll see where he is coming from.

[RaceRunner]

We compared the Suburban in stock trim with the 6-inch IFS lift from RCD and the ORU 6-inch live-axle conversion. In stock trim the Suburban would easily drag its rocker panels on bumps in the trail. The RCD IFS lift improved this, but the real clearance gains were seen with the live-axle conversion.

Approach and departure angles are always improved when you lift a vehicle. Stock, the Suburban couldn’t get its front bumper over much more than a street curb. The IFS lift allowed the truck to actually get its tires onto this test ramp, while the live-axle conversion enabled the truck to drive to the top of this obstacle.

The stock suspension is balanced and offers a moderate amount of travel. The RCD lift offers more space for tires and some additional clearance under the vehicle, but the amount of suspension travel remains about the same as stock. With the live-axle conversion, we got not only a lot of lift, but also a huge increase in suspension travel. This equates to better articulation when on the trail.

While the RCD IFS lift and the ORU live-axle conversion are marketed as 6-inch lift systems, the live-axle system provides more clearance between the body and tires. The actual measurements, taken at the transmission crossmember, indicate that the IFS kit provided about 5.5 inches of lift, while the live-axle conversion came in with 10.74 inches of lift. The actual lift after installing larger tires was even more for each kit. As for tire size, 35-inch tires were the maximum recommended with the IFS lift while 37-inch tires worked well with the live-axle kit.


Have you ever wondered about the real, practical differences between a stock IFS truck, one that is lifted using qualify aftermarket components, and one that has been given a straight-axle conversion? Yes, we know about the difference in price. That’s important. But equally important are these questions: How do they handle on the street? And how do they work on the trail? We here at Four Wheeler wanted to know, and so did the folks at Off Road Unlimited (ORU) in Burbank, California. To that end, ORU obtained a ¾-ton ’01 Chevy Suburban. We drove it and subjected it to our usual course of vehicular torture. Then the guys at ORU installed an RCD 6-inch IFS lift. We drove the truck again. Finally, the ORU technicians installed one of their own 8-inch live-axle conversions, which adds 2 inches of lift via brackets and can be used with lift springs of your choice to gain 4 to 10 inches of lift. After the conversion, we flogged the truck for a final time.

The first issue to consider when looking at a lift—once you get past the cost of this modification—involves on-pavement ride and handling. Our test loop consisted of a 100-mile drive over all kinds of surface-street and freeway conditions. As expected, the Suburban exhibited the most stable feel on pavement, and the best ride quality, when it was in stock form. The RCD IFS lift felt slightly less stable on corners due to the higher center of gravity (CG) of the truck, but overall the ride was only a little harsher. This was due to the fact that the stock Autoride shocks no longer were in use and that the front torsion bars were cranked up a little tighter. Overall this lift was nice to drive on the street.

The real surprises came from the ORU live-axle conversion. With this system the on-road handling and ride were surprisingly good. While the CG of the truck was much higher than stock, the body roll in corners was minimal. The custom springs ORU had built by National Spring were amazingly soft and provided a nice ride on the pavement. In addition, the King shocks were perfectly tuned, and absorbed the small bumps on the highway almost as well as the stock Autoride suspension did. Don’t get us wrong, the on-pavement ride and handling of the live-axle lift wasn’t as nice as that provided by the stock suspension. But it was pleasant enough that we would be willing to drive the truck to work on a daily basis.

The off-pavement behaviors of these three suspensions, though, really is what this story is all about. For this, our test loop consisted of the trails and controlled obstacles at the Hungry Valley SVRA area near Gorman, California. These include a frame twister, a mini-Rubicon, and other challenges.

In stock form, the Suburban had trouble just getting its front bumper over a tall curb on the street. When off pavement, it seemed to make contact with almost every rock on the trail. Handling on washboard roads at speed was nice, but whoops would cause the suspension to bottom out. Installing the RCD IFS lift provided more clearance for rocks and improved the approach and departure angles. This allowed the Suburban to tackle trails that we previously never would have considered. While there was greater clearance under the truck, the suspension’s articulation was only slightly improved. On washboard surfaces the truck still handled well, but it was a little more top-heavy, thanks to the lift. The ride was a little stiffer, but this helped to keep the truck from bottoming out on small whoops.

By contrast, the live-axle conversion really shined off-pavement. The lift and suspension changes provided even more approach and departure angle than the IFS lift did. We also found that there was a lot more clearance under the vehicle as well. Not only did the live-axle swap increase the distance between the rocks and the truck, it also vastly improved the suspension articulation compared to either IFS system. In our testing, the live-axle-equipped Suburban was able to climb all the way to the top of our test obstacle with ease. The stock truck couldn’t even make it to the first step and the IFS lift truck only went about half the way up. In our high-speed trail tests, the Suburban, in its live-axle configuration, rode like a dream. It was less harsh at speed than either of the other two systems, and it handled whoops like a thoroughbred horse handles hurdles. On the durability side, the new front suspension and Dana 60 axle are much stronger than the stock IFS pieces they replace. In addition, there is much greater availability of lockers and limited slips for the Dana 60.

Our evaluations show that the stock Suburban is great for hauling kids and gear around town and even on graded Forest Service roads. For running moderate trails, an IFS lift is a better choice than a stock suspension, but expect to have some small trade-offs in on-pavement ride quality and expect durability of the stock differential and CV joints to become an issue, especially with tires larger than 35 inches tall. The live-axle conversion was truly at home off the pavement and we’re confident that it can handle tough trails and come back for more. As a bonus, the live-axle conversion was civilized enough to drive daily on the pavement. While this kit is quite costly, it’s worth every penny if you want to do some serious four-wheeling, and still drive your truck daily on the street.

Hope its answered your debate??

Cheers,

MarkJ

[playdoh]

Just to keep the debate alive

That IFS kit is a straight lift kit, designed to gain height, all other considerations are secondary. To be fair in that comparison, the live axle swap should have had heavy duty standard height coils with six inch spacers, as that is effectively what was done with the IFS.

There are many kits out there, like mine, that improve travel as well as gaining height, admittedly the higher end kits do require a substantial increase in track, and they will never be able to go quite as far as a live axle, but with the right components, IFS can definitely hold it's own against a live axle with the same level of mods.

[leehamescort]

Racerunner was the test vehicle twin locked?? An IFS vehicle must be twin locked to overcome the lack of travel. An unlocked IFS vehicle will never perform well in a difficult offroad situation.

As for IFS comp cars, they will come.

The main gripe with IFS is the lack of travel, enormous amounts of travel is not always the best thing.
Other than slow rock crawling work, many Comp vehciels run fairly stiff suspension for better high speed handling thus reducing their travel.

If you drive with twin locked IFS vehicles (i dare say most people havn't as they are not that common) you will be amazed where they go and how easily they do it.

I am not pushing my own barrow here, my vehicle is nowhere near the most capable but just wanting people to reallise their is more than one way to do things. Variaty is the spice of life!!

catcha
Leeham

[cj]

I run twin locked IFS and although there are times solid could be better I tend to get most places, some that solid axles don't go either but there are so many variables including type of IFS, gearing, vehicle, weight, driver etc. that generalisations are just that, generalisations. There are a lot of people who seem to parrot information collected from other sources(not always reliable) without their own practical experience. Is IFS the be all and end all no, but it is not always as bad as it is made out to be either.

[brown hornet]

ifs for on road and maybe beach
solid for off road
simple no contest when the right kind of work is done
yet to see an ifs comp rig

One IFS comp rig....
http://carl.outerlimits4x4.com/viewtopi ... highlight=

i notice that the ifs comp rig you put the link to is upgrading to a solid axle !!!

wonder why ?? cause they are stronger and are better for offroad, can't think of any other reason.

[grimbo]

ifs for on road and maybe beach
solid for off road
simple no contest when the right kind of work is done
yet to see an ifs comp rig

most offroad racing trucks in the Baja and the like are IFS I believe.Also a Hilux with IFS competed in the US Top Truck a few years back.