Independent REAR suspension

**Psychlone** · 12-07-2008, 05:24 PM

Replacing the rear solid axle with an independent suspension would greatly improve ride quality and handling, especially when there is a lift on the vehicle.

As regards offroading qualities, the most winning vehicles in the Dakar rallye have independent suspension in all four corners (double wishbones like the FJ has in the front).

Where independent suspension looses out to solid axles is when the wishbones are too short and too weak for offroad use. That limits articulation and durability. So what I would like to see in a future uber-cool FJ would be super durable and long A arms front and rear.

The only area where solid axles still have some advantage over independent suspension is with rock crawling, but the FJ with it's limited 360 degree visibility is probably not a good choice for that activity anyway. For that kind of offroading its most likely better with purpose-built vehicles or open jeeps with solid axles.

**jeshua** · 12-07-2008, 05:40 PM

IRS would be sweet but it is looked down on from the hard core wheelers and seen as just for mall crawlers and grocery getters. It would be difficult and time consuming to do while still having the strength, durability and travel of a SA. There are some guy in the desert racing world that do it and it is much more costly to do right then to toss a trussed 9" back there. That said it wont happen as it would take a lot of R&D on Toyota's part to get something designed that could hold up to the weight, power and abuse and then it would be made fun of by all the jeep guys and seen as moving away from the off road design philosophy, epically since the FJ works well as is.

I'm sure you were doing this more to stir the pot then anything but I like it.

Sean K. · 12-07-2008, 06:10 PM

That's b/c it IS for mall crawlers and grocery getters. It's inherently weak and has very limited towing/hauling capability as the geometry changes significantly when adding weight.

If IRS was so great, Toyota (with it's millions of R&D dollars) would be implementing it on their 4x4 designs. They aren't b/c it's not economically feasible, it's weaker and it offers little to no extra value and is actually a liability in many instances.

Factory IFS has never been and will never be what Psychlone is suggesting. Factor in the cost....do you have any idea what a trophy truck's suspension costs (which btw, most still run live axle rear ends)....It's upwards of $125K. Read that number again. It's worth repeating....$125K!

What about track width....do you know what a Predator Series IFS track width is? 94"! In order to get a measly 24" of wheel travel, the a-arms have to be that long. It's impractical for a street driven vehicle in America....not to mention one used in Europe where the roadways are narrower to begin with. (I mention this b/c Psychlone is from Europe).

By contrast, a standard 1/2T solid axle is about 65 1/8-67.5" wide and can easily achieve 32" of wheel travel with leaf springs and a 14" travel shock mounted appropriately. You simply cannot do that with IFS. The geometry will not allow it.

Sean

Sean

**Psychlone** · 12-07-2008, 06:11 PM

Thanks for your comments. It's not to stir the pot at all, thus what I perceive to be a reasonably balanced and carefully phrased suggestion. (Of course there's one guy that is sure to chip in at some point, as a rock crawler buggy that has taken a wrong turn and ended on an FJ Cruiser forum, but that's moot and irrelevant when it comes to what the FJ is and is being used for)

Not having IRS might very well be one of the reasons the FJ is not marketed in Europe. If it were to be sold in Europe my guess is that it would need to have:

independent rear suspension to ensure a decent ride especially for back-seat passengers
a drastically improved mpg but with similar torque (better V6 engine)
diesel engine as only choice of at least an option
full-time 4WD in the automatic

I know the trade-offs between solid axle and independent rear suspension. But I think the fun in life comes from trying to remove what other's perceive as trade-offs. That has always been where great engineering progress wins out.

DominicG · 12-07-2008, 06:16 PM

If the FJ had F & RIS, i would have not bought it

But i would without a doubt take 4 wheel long travel anyday over solid axles.. (i can dream, right?)

mmmm...

Sean K. · 12-07-2008, 06:20 PM

Quote:

Psychlone previously said:

Thanks for your comments. It's not to stir the pot at all, thus what I perceive to be a reasonably balanced and carefully phrased suggestion. (Of course there's one guy that is sure to chip in at some point, as a rock crawler buggy that has taken a wrong turn and ended on an FJ Cruiser forum, but that's moot and irrelevant when it comes to what the FJ is and is being used for)

Not having IRS might very well be one of the reasons the FJ is not marketed in Europe. If it were to be sold in Europe my guess is that it would need to have:

independent rear suspension to ensure a decent ride especially for back-seat passengers
a drastically improved mpg but with similar torque (better V6 engine)
diesel engine as only choice of at least an option
full-time 4WD in the automatic

I know the trade-offs between solid axle and independent rear suspension. But I think the fun in life comes from trying to remove what other's perceive as trade-offs. That has always been where great engineering progress wins out.

Dude, that's bull**** and you know it. This thread was in specific response to my comments in the thread about SAS.

You've got an agenda.....just admit it. There's nothing wrong with having one.

I have one. I'll admit it. It's to keep more manufacturers from building completely un-trail worthy ****wagons that couldn't wheel their way out of a paper bag.

Let's think of some factory IRS examples shall we?....CRV. Ya, that's bad ass.

I see them on trails all the time.

LR3....oops, seen one on the DIRT road to Martinez Canyon once. They turned around at the rocky section that I've seen stock Suburbans go through.

Ridgeline....yep, on the Rubicon all the time.

Newer Ford Exploder.....yes, a trail eating machine!

What exactly is the FJ "being used for"? From what I see, they are being used as trail/expedition rigs.....by far more people here than those that are even pre-running. If IRS was so hot....why wouldn't have these people bought a Ridgeline or LR3 instead?

Sean

Sean K. · 12-07-2008, 06:21 PM

Quote:

DominicG previously said:

If the FJ had F & RIS, i would have not bought it

But i would without a doubt take 4 wheel long travel anyday over solid axles.. (i can dream, right?)

mmmm...

And I'd agree with you there....that would be cat's ass....but it ain't ever going to come from a factory that way.

Sean

**toytaco** · 12-07-2008, 06:23 PM

Doesn't the Nissan Armada have IRS? And tow alot too?

DominicG · 12-07-2008, 06:23 PM

Quote:

Sean K. previously said:

And I'd agree with you there....that would be cat's ass....but it ain't ever going to come from a factory that way.

Sean

When i win the lotto.. i will have some nutso 150mph desert flying speed monster like that

**jeshua** · 12-07-2008, 06:24 PM

Quote:

Sean K. previously said:

That's b/c it IS for mall crawlers and grocery getters. It's inherently weak and has very limited towing/hauling capability as the geometry changes significantly when adding weight.

If IRS was so great, Toyota (with it's millions of R&D dollars) would be implementing it on their 4x4 designs. They aren't b/c it's not economically feasible, it's weaker and it offers little to no extra value and is actually a liability in many instances.

Factory IFS has never been and will never be what Psychlone is suggesting. Factor in the cost....do you have any idea what a trophy truck's suspension costs (which btw, most still run live axle rear ends)....It's upwards of $125K. Read that number again. It's worth repeating....$125K!

What about track width....do you know what a Predator Series IFS track width is? 94"! In order to get a measly 24" of wheel travel, the a-arms have to be that long. It's impractical for a street driven vehicle in America....not to mention one used in Europe where the roadways are narrower to begin with. (I mention this b/c Psychlone is from Europe).

By contrast, a standard 1/2T solid axle is about 65 1/8-67.5" wide and can easily achieve 32" of wheel travel with leaf springs and a 14" travel shock mounted appropriately. You simply cannot do that with IFS. The geometry will not allow it.

Sean

Sean

I know what its cost and thats why it will never happen. Pflueger's new TT is IRS and from what i heard that truck cost him around the 2 million mark, $2,000,000.00 thats a lot of coin.

And like you mention to get it strong enough and the geometry to work right would cost to much. It could work but the cost would out way the benefits 100:1. thats why it will stay on the CRV's and Rav 4's were you don't need the strength or travel/articulation. Also a good point on what the width would look like once you got everything else to work right. And for they guys like you that play in the rocks there really isn't any benefits even if you could get it to work right and be affordable.