The IFS vs SFA Thread

[Fosters]

Yeah, I know I'm a tiny part of the market. But let's be honest, enthusiasts in general are a small fraction compared to the general public buying these things. Unfortunately for us Ford doesn't need to make all of us happy to have a very successful vehicle.

I disagree there... The enthusiasts are what drive the image - the mustang is popular because there was a cobra/mach1/boss/gt350, and so on, and because of that, the image, the v6/ecoboost sell like hotcakes. The wrangler sells like hotcakes because of the people who get the rubicon and do crazy shit with them... even if the majority of them are unlimited sports on soccer mom duty. Take any enthusiast car - remove the halo models, and analyze it on its merits (base model mustang/camaro/challenger/wrangler/etc) and they're just terrible cars, nothing spectacular about them; but yet those trims sell in the highest numbers for each of those models.

Oh, and side by sides are street legal here in freedom land

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[OX1]

I
5.0 v8,

I would buy one that had a V-8, no matter what else they did to it,
only because I know that non FI engines can be pushed way harder
than one with boost without the worry of high octane fuels, AIT, turbo lag,
etc............

 

[Jalisurr]

I disagree there... The enthusiasts are what drive the image - the mustang is popular because there was a cobra/mach1/boss/gt350, and so on, and because of that, the image, the v6/ecoboost sell like hotcakes. The wrangler sells like hotcakes because of the people who get the rubicon and do crazy shit with them... even if the majority of them are unlimited sports on soccer mom duty. Take any enthusiast car - remove the halo models, and analyze it on its merits (base model mustang/camaro/challenger/wrangler/etc) and they're just terrible cars, nothing spectacular about them; but yet those trims sell in the highest numbers for each of those models.

Oh, and side by sides are street legal here in freedom land

Yep, totally not disagreeing that they need to create a sufficient image of credibility and capability. I'm just disagreeing that the image needs to be that of a hard core SFA rock crawler rather than a tough high speed offroad machine. Either image will drive sales to the general public.

To work within your pony car example, the mustang uses (primarily) road course performance to sell, the challenger uses the drag strip. Both succeed in selling cars to the public using an image of performance. However, if you were a hard core drag racer, you might be cursing the Mustang's move from the solid rear axle as they double down on road course performance.

 

[Fosters]

I would buy one that had a V-8, no matter what else they did to it,
only because I know that non FI engines can be pushed way harder
than one with boost without the worry of high octane fuels, AIT, turbo lag,
etc............

I've had a 2.7 ecoboost, and still have my 5.0 coyote with a blower on it. An engine designed from the factory to have boost - especially the 2.7 - are tough as nails from the factory; I wish my 5.0 had the same size rods and pistons as that 2.7. And the same oiling system - the achilles heel of the coyote. turbo lag can be damn near tuned out - that reg cab F150 pissed off many cars off the line. The 4.6 cobra and the GT500s have been the same way... beefcake bottom end.

I won't be sad with any engine they put in... but the sound of the 5.0 is almost a requirement for a vehicle as iconic as this

 

[Fosters]

Yep, totally not disagreeing that they need to create a sufficient image of credibility and capability. I'm just disagreeing that the image needs to be that of a hard core SFA rock crawler rather than a tough high speed offroad machine. Either image will drive sales to the general public.

To work within your pony car example, the mustang uses (primarily) road course performance to sell, the challenger uses the drag strip. Both succeed in selling cars to the public using an image of performance. However, if you were a hard core drag racer, you might be cursing the Mustang's move from the solid rear axle as they double down on road course performance.

The weight and the size of the newer cars is a much bigger issue than the solid axle to irs swap in those. The IRS in the 99-04 cobras was junk because it was made to fit in the spot of a solid axle, which resulted in lots of binding and unnecessary weight because of the cradle holding everything in, but the 15+ is much better with regards to weight transfer and wheelhop.. it's not as huge of an issue on a mustang, or any handling car because the travel on that IRS is maybe 1"; and the camber, and with that minor of a change, you're losing a little bit of traction, but not as much as you'd think - you still have the full footprint of the tire on the ground, just a bit more pressure on the inside as opposed to the outside when the car is squatting to get off the line.

Now in an offroad situation, not only is the independent suspension going to be completely neutered compared to a solid axle in terms of travel, but also puts a lot of the ball joints, u joints, etc at much steeper angles as a solid axle, which puts a lot of extra stress on them.

I'd love to see an option for a solid axle up front, but I have the feeling bean counters would nix that kind of development for 2 different layouts... I do think it would be a much easier endeavor with a body on frame vehicle than it was in the unibody - stiff as a wet noodle - 79-04 mustang.

 

[Cybrrstarr]

If “FORD” gave us all the impression that the new “BRONCO” is going to be a direct competitor with the “JEEP WRANGLER” with IFS........


They are creating smoke and need to put down the Jim Jones juice.


The wrangler is popular for one reason.....

they’re all outfitted with 37 or bigger tires, they are all lifted to the sky, and can go anywhere on this earth we’re you want to be to get away from the crowds and overland. And yes that means that big A$$ rock just stopped 90% of you IFS from reaching the promise lands.

 

[OX1]

I've had a 2.7 ecoboost, and still have my 5.0 coyote with a blower on it. An engine designed from the factory to have boost - especially the 2.7 - are tough as nails from the factory; I wish my 5.0 had the same size rods and pistons as that 2.7. And the same oiling system - the achilles heel of the coyote. turbo lag can be damn near tuned out - that reg cab F150 pissed off many cars off the line. The 4.6 cobra and the GT500s have been the same way... beefcake bottom end.

I won't be sad with any engine they put in... but the sound of the 5.0 is almost a requirement for a vehicle as iconic as this

When you take really hard core engine usage, the FI engine is virtually always less reliable.
Guys who road race know, very few want to deal with FI. Heat kills everything, and even
a non FI V-8 can get real hot when you are sitting on that converter for 10 minutes on that impossible
rock obstacle or revving to the moon with mud halfway up your engine compartment.

The new 7.3 would be my first choice, but the coyote is still much simpler than any ecoboost
and would be the only one that might ever get in a bronco (yes, I know it isn't happening).
It would also get way better mileage once you put 37's on and make your new bronc about as
aero as a classic bronco. (EB motors are dismal for fuel on anything over moderate load).

"damned near" is not none. I have a 2.7 also. Great engine, but still laggy if you floor it out of
the hole. You need to brake boost it to really get it to launch. The 5.0 is much better, but even that
pales in comparison to an old BB with mechanical throttle. The 430 in my Bird, even with a 2.95 rear and
dismally geared 3 speed auto from the 50's, hits very hard with just minor throttle changes.

 

[Fosters]

"damned near" is not none. I have a 2.7 also. Great engine, but still laggy if you floor it out of
the hole. You need to brake boost it to really get it to launch. The 5.0 is much better, but even that
pales in comparison to an old BB with mechanical throttle. The 430 in my Bird, even with a 2.95 rear and
dismally geared 3 speed auto from the 50's, hits very hard with just minor throttle changes.

I dunno about that... the 5.0 is pretty peaky if you look at the torque curve. Granted, the numbers are higher overall, but the bulk of the torque is made much later in the RPM. peak torque is at 4500rpm, great for a mustang, and yeah, in truck version you can bring that down a bit... but like you said it's not gonna be an off-idle stump puller like older motors...

Now compare that to a 2.7 (esp one with the torque management and other junk turned off):

They make peak torque so low that it's hard to start a dyno that early... What you're experiencing is more the throttle response of a free revving v8 vs a turbocharged engine with every nanny on it. They are very neutered (as you can see from the stock dyno).... and if you think that's bad, my 965tq 6.7 with 4.30 gears can barely spin the tires - they really are that torque limited, esp in the lower gears...

 

[Fosters]

When you take really hard core engine usage, the FI engine is virtually always less reliable.
Guys who road race know, very few want to deal with FI. Heat kills everything, and even
a non FI V-8 can get real hot when you are sitting on that converter for 10 minutes on that impossible
rock obstacle or revving to the moon with mud halfway up your engine compartment.

Depends how you wanna look at it, again. Hardcore engine usage IMO would be an OTR truck... those see massive amounts of boost for over a million miles of hard work, and they're perfectly fine. Engines getting really hot is more of a function of the cooling system. Luckily Ford has been hitting it out of the park with cooling systems lately - everything from my mustang, to diesel trucks to v10s have been nothing short of insanely well cooled even when put through hell.

 

[TeocaliMG]

By what metric? Do we even know how many get built or sold? It's quite a small number I'm sure, and is theoretically going to get two internal competitors for that same small slice of the pie with Rangers and Broncos.

Being a popular marketing gimmick and being a popular product getting sales are quite different. I would guess Wrangler outsells F150 Raptors in the US by around 20:1, at least.

New to the thread, let me get up to speed but the Raptor moves like 30k units per year. It is well known that it blew Fords initial expectations out of the water, (or expectations for the lightning which they were actually originally planning to revive). Not Wrangler numbers but a far cry from 20:1 and not bad for 50-100% more expensive.

 

[TeocaliMG]

That is an absolutely horrendous article.
1) Wheel travel, SFA wins, hands down. The costs to build these 24" travel IFS suspensions is more than to build multiple SFA rigs. And requires suspensions mounted far ahead of the engine, or far under the chassis. I.E. MAJOR modifications to accomplish this, requires typically a completely custom rig.

2) Protection of steering components. Laughable, as the tie rods are in the same relative position. And they can be relocated (easier) on an SFA setup to higher or further back locations. Along with the fact that geometry stays consistent in the steering regardless of suspension compression at the time, there are significantly more steering setups/geometries available as binding at weird off-axis angles is not a concern. the only real exposure is the driveshaft and high centering. This is generally not MUCH of a concern.

This thread is going to be fun isnt it! hahaha.

At face value, yea you can get more wheel travel out of a solid axle than independent set up. But to what end? Wheel travel is more than just a number. The main advantage of a solid axle is the articulation, mainly given by downtravel of a single tire. The total downtravel of the axle is always less than the maximum downtravel of a single wheel. Things like the driveline and shocks drive this.

Independent suspension is independent so there is no inherent difference to either side with respect to travel. Something to keep in mind though is you will get more travel out of IFS for a given shock than SFA but who cares, you'll get whatever shocks you want. The wheel travel advantage for IFS is it can jounce way higher than a solid axle. Engine package is a b*tch and it bites both systems in one way or another. This is just one of the reasons IFS is so great at speed, those wheels have somewhere to go without having the whole rig skyjacked from the get go.

Comparing practicality, SFA will get more travel than IFS for a given useful track width, and IFS will get more travel for a given desirable axle path, which is incredibly important for steering/braking at speed.

All this aside, there is a lot more I can and will get into when I get to later posts but I just wanted to start by soiling the "wheel travel" bucket with some extra elements of complexity. In general when you get to 15-20+" of wheel travel you are doing something extreme, if that extreme thing is rocks, you know what you are building, if that extreme thing is high speed over unfriendly terrain, you know what your building. And unless you want to come up with a unique IFS rig that allows a single wheel down travel bias (what I am working on) then the 15-20"+ debate is settled. Therefore on stock to light modified applications from say 10-15" travel I think we can have a rather lively discussion about what the Bronco should/could have. Note for 10-15" travel the SFA will still have a single wheel down travel advantage and the IFS will still have a jounce travel advantage.

2) agreed silly point, I didn't even bother reading but it sounds like it has some silly stuff.

 

[TeocaliMG]

24 inches? That's cute.

Darn, I got my wheel travel asterisks in a little late I see lol.

The thing is they already have something that is really good for doing things at speed. It's the raptor. They don't need a second one. There are other SUVs that have an IFS. There are other trucks that have an IFS. There is one exactly suv/truck (non full size) that has a solid axle, and that's the wrangler. That's it.

Arguing that this one has to be IFS because it's what you want, when there are so many other options, is narrow minded. Either they compete with the wrangler, or they compete with the other mall crawlers and brodozers that are good at doing things at speed...

I already posted a big thing on this but just like you didn't read older posts, I am also too lazy to go back and dig it up.

Let me start by saying I don't think those of you who want SFA are wrong to want that. I like IFS, I have my reasons, and at a glance the market is saturated with lackluster IFS rigs (excepting the Raptor) and one really legit rig, which has SFA. I wouldn't go as far as to say correlation doesn't equal causation, but that's pretty darn close to the problem here. I don't doubt that the SFA plays a key role in the success of the Jeep, but there are a lot of unsung heros that if they didn't exist would doom the Wrangler regardless of the suspension. Those "heros" are particularly lacking in most of the competition, and certainly no competitor has the full rap sheet to match the Wrangler well before you get to the axle.

(Again, excepting the Raptor since it is a size and a half and 2 prices out of this fight)
1) wheel size:
Large wheel size offered stock, 33+
Large wheel size capable aftermarket 35+
Even Larger wheel capable with relatively low modification 37+

2) Maneuverability/ agility
Approach, breakover, departure
Turning radius (2door bonus XP)
sway bar disconnect

3) Drivetrain
Front, rear, center (where applicable) lockers
Ultra low lowrange

4) Modifications
Aftermarket support from inherently modular design (This is huge)

5) Image/Fun factor
Removable top (use it or not, this is a huge part of the image and therefore success)
Rugged styling (This alone can kill a vehicle. Most important thing for most buyers they will never admit. Nobody wants to drive an ugly car until its 20+years old and its cool )

6) Amazing Powertrain
hahaha just kidding on that one, well they at least just launched the diesel so we'll see how that goes.
This definitely helps, but it was apparently unnecessary for Wrangler success thus far.
As for Manual, this can be debated nowadays but I think its key for pleasing the true enthusiasts

7) The fun stuff this thread is for!
Wheel travel and articulation stock (no doubt incredible compared to current competition, again Raptor is not really competition in this segment)
Wheel travel/articulation with light modification (Competition left in the dust here, but as I have hinted, it doesn't have to be, at least in every facet)

Moral of the story, A LOT has gone into the success of the Wrangler (not 6), and unless Jeep were to experiment cutting out each of these one at a time no one may know exactly how key they all are. For now I will treat them all as very important. And my point by all this is that The Jeep is king right now because of these, and the go to "IFS" failures of the past did not come close to offering this rap sheet and IFS as an architecture is far from the smoking gun. ​

 

[Nickp]

I think you pretty much nailed it Teocali. It’s not so much that IFS is inherently bad, it’s just that no company has truly gone to create a wrangler fighter IFS rig. You could argue the FJ was in some ways but they definitely didn’t go all out. My buddy told me that Ford tested SFA and IFS and considered both options, so there must be reasons they went with IFS. Honestly one reason may be cost, which to me is fine because I’m definitely on a budget. Either way Ford only has 2 off-road focused vehicles, both are IFS, and both are unmatched and badass so I’m not concerned.

 

[JimmyDean]

I think you pretty much nailed it Teocali. It’s not so much that IFS is inherently bad, it’s just that no company has truly gone to create a wrangler fighter IFS rig. You could argue the FJ was in some ways but they definitely didn’t go all out. My buddy told me that Ford tested SFA and IFS and considered both options, so there must be reasons they went with IFS. Honestly one reason may be cost, which to me is fine because I’m definitely on a budget. Either way Ford only has 2 off-road focused vehicles, both are IFS, and both are unmatched and badass so I’m not concerned.

I don't think any sane person is saying that IFS is inherently bad, just that it is not the end all be all for all situations. And the most preferred use for the bronco, or most desired use for it for enthusiast, to rock crawl next to or ahead of the wrangler, is one of those spots that SFA excels over IFS for both strength and simplicity, as well as capability without having to spend outrageous wads of cash.

 

[Tslater1989]

What ever happened to the 4.3 v8 they were working on? It was essentially a scaled down version of the new 7.3 gasser. At one point, I know there was talk of it. That would be anperfect motor for something like this.

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