The IFS vs SFA Thread

[TeocaliMG]

If you’re changing everything shouldn’t you want the option with the lowest up front costs?

Yes, see there's a good point! I have no way to prove or quantify that. Its no secret that doing slight upgrades to SFA is cheap but from the OEM perspective I am not convinced (from what I have seen and worked on) that SFA is a big cost save offered stock. But again, I have no hard data to compare there, i'm sure the bean counters know.

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[JimmyDean]

Also OX1, if I may ask, why are you considering a Bronco over say a Super duty Tremor? Other than the fact that the Bronco is just plain cool, and probably cheaper, than a good spec Tremor. If you aren't into the articulation as much as the huge tires the Superduty offers quite literally a superduty driveline/steering/chassis. Spec it with the powerstroke and you can spin those swampers through anything you want!

I have a 250 on 37s w/ power stroke.
She is quick, and strong.

and heavy.
And can’t fit in a lot of trails, just too wide and too large a turn radius.

also, expensive.

 

[TeocaliMG]

I have a 250 on 37s w/ power stroke.
She is quick, and strong.

and heavy.
And can’t fit in a lot of trails, just too wide and too large a turn radius.

also, expensive.

Yea, i'm wondering about the use case, among other things. But it is still a pretty sick offering

 

[JimmyDean]

Yes, see there's a good point! I have no way to prove or quantify that. Its no secret that doing slight upgrades to SFA is cheap but from the OEM perspective I am not convinced (from what I have seen and worked on) that SFA is a big cost save offered stock. But again, I have no hard data to compare there, i'm sure the bean counters know.

And when a diesel breaks, she breaks. My 250s been parked since Christmas with a HP oil leak I’m working on.

 

[TeocaliMG]

And when a diesel breaks, she breaks. My 250s been parked since Christmas with a HP oil leak I’m working on.

This is true, though you have a 6.0 right? Granted the woes of the 6.0 are generally overblown, its still not legendary for robustness.

 

[JimmyDean]

This is true, though you have a 6.0 right? Granted the woes of the 6.0 are generally overblown, its still not legendary for robustness.

Yeah. The 6.breaking my bank.

 

[TeocaliMG]

Yeah. The 6.breaking my bank.

I gotta get around to doing some actual work, but sometime i'll sketch up my idea for an SFA conversion that would play well with IFS in terms of retaining some components for cost.

 

[OX1]

So if i'll play devils advocate a bit:

Again, if it is going to be IFS (lets assume solid axles don't even exist), Why is it
not a more extreme design, by a significant amount, vs what every explorer comes with?
And if it is, please point out where?

IE, are tie rod ends fully sleeved with high angle joints at rack?

Getting better than the std range adjustment cams on control arms?

As I've mentioned, how about upgraded urethane boots?

High clearance upper knuckle for wide tires without them sticking way out?

More diff clearance from factory angle of CV already aimed downward

and/or lower control arm clearance..

We getting above average bump steer (meaning less) and how? Something better than this?

Better than typical IFS (Edit, meant ball) roller hub bearings??

Obviously, many of these things we don't know yet, but the obvious from external pics
is not leading me in this direction so far.

 

[OX1]

Also OX1, if I may ask, why are you considering a Bronco over say a Superduty Tremor? Other than the fact that the Bronco is just plain cool, and probably cheaper than a good spec Tremor. If you aren't into the articulation as much as the huge tires the Superduty offers quite literally a super-duty driveline/steering/chassis. Spec it with the powerstroke and you can spin those swampers through anything you want!

What I meant is it is not nearly as important on moss, mud, and wet leave covered terrain, as it would be to dry areas with
sandpaper covered rocks. Who cares how many tires are on the ground when they are all spinning no matter what you do.
Cheap, robust drivetrains matter more than anything else at this point.

Just one example. Crappy quality old vid, best watched about 1/4 or less screen size

http://luxjo.supermotors.net/RAUSCH CREEK/20 MAR 2010 MEB/MOV02356.MPG
http://luxjo.supermotors.net/RAUSCH CREEK/20 MAR 2010 MEB/MOV02357.MPG

I'm already campaigning a wide, 6000+ lb rig, and that just makes everything worse when you have no traction.
I get away with it with 43 stickies and ridiculous amounts of clearance (and full EXO), meaning I don't have to take
any line that makes sense (and on jeep size cut trails, usually can't) for mere mortal rigs...........

 

[BAUS67]

…………….

To bring this around to my initial question though I want to keep these comparisons a little closer to stock because as I said, when we start talking about built rigs, you can do whatever you want.

Thanks for the added input guys, I love talking about this and i'll add more when I get the chance. I will say that in general I like the offroad enthusiasm of the pro SFA guys!

So I would say that being totally stock, the biggest advantage to SFA is being able to take abuse better (don't get the chairs). What I am getting at is I have seen IFS stuff not built for the off-road even though it is on a 4WD vehicle. If you think you are gonna clear that rock in the trail and you misjudge a SFA may take the shot and keep going, I have seen inferior IFS A-arms rip out of its mounts. Now did I say all the time, NO, but I feel a stock SFA can take more abuse than stock IFS. SFA is easier to maintain. rip a cv boot, from a large stick buried in the mud hole you just bored through and yourbustin' out the wrenches. A wheel joint in a SFA will chew it up and spit it out. This stuff may sound silly or overblownbut I am just trying to give examples of things that have happened to me and for these reasons I don't take an IFS rig wheeling much.

I think the point you are trying to make about IFS travel vs SFA travel is (I'm no engineer but ….) a Link style suspension (SFA) cannot do as good of a job, through the range of travel, with caster and camber changes like an IFS can. Did I say that correct. It's not that I don't like IFS I just think it needs some improvement if it wants to deal with the harsh environment that is encountered in certain off-road situations. I'm sure Ford will put a quality product out there in the end, I thought we might see some of the those high clearance arms or something different than the norm.

 

[Stampede.Offroad]

... I thought we might see some of the those high clearance arms or something different than the norm.

The jist would seem to be where's the beefy truck version of this?

.

 

[BAUS67]

The jist would seem to be where's the beefy truck version of this?

.

Yes, that is my point. Now don't get me wrong the one posted here is a lot beefier than the first 4DR camo with low pro car tires on it. Those arms look like the ones on my Explorer, but these arms look much beefier. I thought maybe we would see something unconventional because they are bragging up its off road prowess. Then seeing it had a "normal" looking IFS it didn't blow me away. It does appear to work ok but I haven't seen it in the hard stuff yet. Some 4LO, instead of 4HI, action would be nice. Lockers and a real transfer case go along way in helping the suspension do it's job.

One question all of this brings to my mind …… Since IFS is so great then why still the SRA why not IRS also ??????

 

[TeocaliMG]

Yes, that is my point. Now don't get me wrong the one posted here is a lot beefier than the first 4DR camo with low pro car tires on it. Those arms look like the ones on my Explorer, but these arms look much beefier. I thought maybe we would see something unconventional because they are bragging up its off road prowess. Then seeing it had a "normal" looking IFS it didn't blow me away. It does appear to work ok but I haven't seen it in the hard stuff yet. Some 4LO, instead of 4HI, action would be nice.

One question all of this brings to my mind …… Since IFS is so great then why still the SRA why not IRS also ??????

I know we all like to tease the explorer, I was going to respond to OX1 but if you get a chance take a peek under a Kia Telluride and then the Ford Explorer, you will see why the Kia is steeling our thunder right now, and you will also see which one you want to take in a demolition derby in 20 years (hint, not the kia). The explorer also has over 8" front wheel travel. It is a wayyyy overbuilt IFS system for any road going SUV, and that is partly why we are arguably uncompetitive from a cost/value standpoint to the customer. Now, all that said I would expect the Bronco IFS to be a whole other level above the explorer, and it is. Would I also like to see beefier hubs and high clearance arms? heck yea! but that costs money too, if it didn't, then things like the JL would launch with full floaters for example.

 

[BAUS67]

I know we all like to tease the explorer, I was going to respond to OX1 but if you get a chance take a peek under a Kia Telluride and then the Ford Explorer, you will see why the Kia is steeling our thunder right now, and you will also see which one you want to take in a demolition derby in 20 years (hint, not the kia). The explorer also has over 8" front wheel travel. It is a wayyyy overbuilt IFS system for any road going SUV, and that is partly why we are arguably uncompetitive from a cost/value standpoint to the customer. Now, all that said I would expect the Bronco IFS to be a whole other level above the explorer, and it is. Would I also like to see beefier hubs and high clearance arms? heck yea! but that costs money too, if it didn't, then things like the JL would launch with full floaters for example.

I didn't know what it had for wheel travel but I do know it has absolute shit for approach and departure angles not to mention no ground clearance. Did I read the word cost in there. though it was about appealing to the masses "we want a nice ride" . Make it ride nice and perform off-road, we want our cake and eat it too, and not spill my coffee while trail riding. Just joking, but back to cost. that is another SFA over IFS attribute is its cost to maintain and/or repair much less with SFA. So would it be fair to say then that no IRS because of cost ???

 

[TeocaliMG]

I didn't know what it had for wheel travel but I do know it has absolute shit for approach and departure angles not to mention no ground clearance. Did I read the word cost in there. though it was about appealing to the masses "we want a nice ride" . Make it ride nice and perform off-road, we want our cake and eat it too, and not spill my coffee while trail riding. Just joking, but back to cost. that is another SFA over IFS attribute is its cost to maintain and/or repair much less with SFA. So would it be fair to say then that no IRS because of cost ???

Cost is very complicated, in my experience with Superduty SFA can still be VERY expensive to fix/maintain, at least when you do it according to OEM standards. Granted it is cheaper to do most common modifications, I am not convinced it is much cheaper from the OEM, if it is, it is easily outweighed by other attributes both on and off road.

As much as I rave about IFS over SFA in general, the comparison is a lot murkier when comparing IRS and SRA. A lot of the vehicle dynamics that make SFA nearly hot garbage at anything over crawling speed become beneficial on the rear, mainly the huge arcing axle path, (and anti-squat and a host of other things). IRS can also achieve this but it is a harder sell from a wheel travel/arc path quality standpoint. Hence the only real benefit of IRS over SRA is high level vehicle handling.

For example I am not entirely sold on IRS for my dream off-road build. I have two competing ideas, a design for IFS/IRS which allows crazy articulation via some creative changes to the driveline/subframe or a linkage geometry for SRA which has more inherent anti'roll at speed without compromising articulation at low speed (without the need for sway bar or sway bar disconnect)

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