Ultimate IFS

KidVermicious

New member
So, I'm daydreaming. Work with me here.

Take a solid front axle housing. Cut off the ends and move them inboard, to roughly match the width of the 7.5 diff and longside tube. Now get a pair of custom axle shafts machined to match those lengths, a custom length front driveshaft, and weld up some fittings to the housing so that it bolts up in place of the 7.5 diff. With me so far? Good.

Now, the strength of the IFS system is the fact that it's independant, leading to better high speed handling. The two biggest weaknesses are the outer CV joint and it's aversion to high angles caused by lifting. So lets take away those weaknesses. A birfield, or better yet a Longfield, can handle angles better than a CV joint, right? Lets take a pair of Longfields and set them up back to back, so one bolts up to the axle flange and the other goes through the IFS spindle, just like the factory CV joints. We'll reuse the factory spindle, nothing wrong with it. Add a solid axle hub, and bob's your uncle. Might as well extend the factory a-arms, since we're creating a custom outer shaft anyway. And ditch the damned torsion bars, lets go with a tunable coilover setup instead.

Now we've got an 8 inch axle housing that gives us the flexibility of a removable 3rd just like a solid axle, we've got solid 31-spline ends all over just like a solid axle, we've got the ability to lift to the limit the front DS will allow just like a solid axle... it's an IFS system with all the strength and almost all the flex of a pre-IFS front end.



Yes, it would cost $50,000 and your first-born child to fabricate. That's not the point. Is it mechanically feasible?
 
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The rear end of some early model Supras had an 8" IRS diff with an LSD. Ive seen (on the internet) people putting them under the front of an IFS truck, but they need the 4" drop bracket to get it to clear the oil pan.

Combined with a some sort of LT and some RCV shafts...id say you could do it for way under budget.

Toyota 4WD Surf Owners :: View topic - 8" Front diff upgrade - It Is Here!!!

Supralux_Installed1.jpg


Happy dreaming!

Edit: Info on the shafts: http://www.pirate4x4.com/forum/showthread.php?t=908156
 
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Hmm, neat. Looks like the drop bracket is required to clear the DS because the IRS diff is centered. On the other hand, he gets better halfshaft angles because it's centered.

eta - yeah, he's running basically stock CVs, Supra inners to Surf/4Runner outers and gets his strength because his angles aren't as extreme. Awesome idea, but he has to add the drop bracket lift to clear the DS, run the Supra diff backwards/upside down (not ideal), and doesn't have the gearing/locker choices available for a front 8" diff.

I think I need to read up on Longfields, and see if they really would make a good substitute for CV shafts.

eta again - exactly like that Pirate link, Hyde, I didn't even know those existed. Thanks!
 
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Hmm, neat. Looks like the drop bracket is required to clear the DS because the IRS diff is centered. On the other hand, he gets better halfshaft angles because it's centered.

eta - yeah, he's running basically stock CVs, Supra inners to Surf/4Runner outers and gets his strength because his angles aren't as extreme. Awesome idea, but he has to add the drop bracket lift to clear the DS, run the Supra diff backwards/upside down (not ideal), and doesn't have the gearing/locker choices available for a front 8" diff.

I think I need to read up on Longfields, and see if they really would make a good substitute for CV shafts.

eta again - exactly like that Pirate link, Hyde, I didn't even know those existed. Thanks!

RCV used to make longfields until they started selling direct. I had them on my old 4runner with a V8 and 40's and i never broke one. If you do ever break one, its free replacement forever. SAS w/longs! Do it.
 
May be a stupid reply, and I may be missing the point, but if keeping the IFS front (not "the", but "a"), is the point...why not go with something proven?
So far I understand the durability factor, and you will widen the front as a residual effect...why not go with what some of the desert trucks use. Ford IFS with longer travel, less bind due to geometry, and back it with a 9 inch in the rear? Tons of gear selection, less fabrication, better travel, so on.?
 
KidV, durability isn't the only major reason for dumping the IFS--there's also ground clearance. The primary reason people switch to the solid axle is so when you put your tire on an obstacle, the whole axle raises up, not just the wheel. And with leafs, the wheels have MUCH greater articulation, better than even the most extreme IFS (short of million-dollar Baja rigs, anyway). No matter what you may come up with, you will always be compromising your clearance if you have IFS.
 
Going to disagree with ya there bob. Youll get more clearence with the IFS because the diff isn't hanging down. And the factory ifs has around 7" of travel...which is just less than the stock SA truck and the same as a factory Jeep Cherokee. I do agree though, its easier to get more travel for cheaper out of leafs than ifs.

And putting a supra diff in the front is no different than putting a rear solid axle 8"3rd in the front. Also, I believe they use the same bearing/gears as the 4cyl 8"3rds used in our years, so gearing and locker options are the same.

And csrobb...you taking about the Ford TTB? GTFO with that schit man. There is a reason you dont see TTB ifs anymore or on any of the KOH ifs cars. Ive never seen a set of tires on a TTB that were worn evenly....But the 9" is a schweeet axle...Haha.

Toyotas IFS is a pretty capeable platform that can take a pretty good beating. If there was a cheaper solution for stronger shafts, it keep it over a SA.

Just my .02
 
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the ttb IFS is just flat out crap. i had a ford ranger for my first rig and that set up gave me more problems than the V6 out of it did. that almost jaded me so i was really hesitant before buying an IFS toyota.

i read through a few builds with long travel and the centered Supra diff and i think if i ever when to long travel i would take a little extra time to do that. i think thats so sweet! i wonder if a body lift and a lift to the drive train would be cheaper than a bracket lift. you would just need enough on the drive train to clear the oil pan.... or i wonder if someone could custom make an oil pan if you would even need to bother with a bracket or body lift.

i love day dreaming!
 
KidV, durability isn't the only major reason for dumping the IFS--there's also ground clearance. The primary reason people switch to the solid axle is so when you put your tire on an obstacle, the whole axle raises up, not just the wheel. And with leafs, the wheels have MUCH greater articulation, better than even the most extreme IFS (short of million-dollar Baja rigs, anyway). No matter what you may come up with, you will always be compromising your clearance if you have IFS.

IFS definitely has it's pluses and minuses when it comes to crawling, but not all offroading is crawling. I do a fair amount of desert bombing and fireroading, and I log lots and lots of freeway miles getting to and from fun places, and those are things that a straight axle is never going to be as good as an IFS at doing.

Those shafts linked upthread would be ideal, if it weren't that they still use the weak outer CV. If you're not replacing the weakest link in the system, I just don't see the point.

If I had a machine shop, or access to one, I'd totally do this. Just to see if I could. I think it's got potential, but probably not enough potential to make it worth paying somebody else to set it up.
 
And putting a supra diff in the front is no different than putting a rear solid axle 8"3rd in the front. Also, I believe they use the same bearing/gears as the 4cyl 8"3rds used in our years, so gearing and locker options are the same.

Well, I'm talking about using a front 8 inch axle, though, not a rear. It's got two advantages over the Supra IRS diff - it's not running backwards, and it wouldn't require a bracket lift.

The big disadvantage is that you have to cut it down. But that just means fewer people jumping on my bandwagon. :D
 
IFS definitely has it's pluses and minuses when it comes to crawling, but not all offroading is crawling. I do a fair amount of desert bombing and fireroading, and I log lots and lots of freeway miles getting to and from fun places, and those are things that a straight axle is never going to be as good as an IFS at doing.

Those shafts linked upthread would be ideal, if it weren't that they still use the weak outer CV. If you're not replacing the weakest link in the system, I just don't see the point.

If I had a machine shop, or access to one, I'd totally do this. Just to see if I could. I think it's got potential, but probably not enough potential to make it worth paying somebody else to set it up.
true on the ifs riding better prob much better than a solid axle .my 85 4runner rides on the ruff side , it gets tiring at times
 
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Not that I take it as an attack...but the fact remains, other than a complete tube chassis setting the engine back over a foot or two, to narrow the frame enough to set the pivot points of an A-Arm front end together close enough to increase travel over the 12 to 15 inch range...you WILL NOT find a stronger, easier system, with less breakage because of geometric issues, with a broader selection of gearing...and the most travel than this...if tire wear is a concern at this level of modification(s)...you will probably ask how many miles to the gallon a Corvette gets too.
 

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.if tire wear is a concern at this level of modification(s)...

I do a fair amount of desert bombing and fireroading, and I log lots and lots of freeway miles getting to and from fun places,

For the ammount of highway miles he drives, Id say tire wear is something to consider here.

I do agree again with you that there is TON of aftermarket support for the TTB.. I just done like it. Haha! But if your going to go through that much work, a solid axle on coilovers would be just as smooth and comfy.
 
Well, it is really. I need another moneywasting project like I need a hole in the head.

But it's fun to chew it over and discuss pro's and con's, no?

I can give you that hole in your head. I have a new rifle that i need to dial in a bit more. Then you can leave your money wasting to me.
 
I've been watching that YT thread - dude keeps breaking stuff. I'll be more impressed when he comes back from the desert without any carnage. :)
 

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