Ifs 101

[arse_sidewards]

x2 on the alunimun cases being junk. Nobody at the OEMs cares because they figure you'll only do a few low range clutch dumps during the warranty period and it'll survive a few just fine. But if you dish out enough abuse you're gonna get a silver surprise in the diff fluid. From the differential's perspective a rock bouncer climbing a hill looks a lot like low range clutch dumps but with a much higher duty cycle. Nobody's figured out how to make something that isn't based off a Ford 9, D60 or better survive that kind of for an extended amount of time yet.

I don't want to digress too much with regard to specific differentials but they bring up another set of issues. Anyone who isn't running a transaxle buggy has the front diff and the engine oil pan trying to occupy the same space and high pinion only makes it worse. And then there's the width you have to deal with. Because you can't have the ring gear and the crank shaft occupying the same space nor can you have the drive shaft making a line through the bellhousing the whole shitshow needs to be offset to one side. So then you've got a package that's probablty 24" or more from joint center to joint center. And then that means your lower control arms can't be much closer than that (because doing so would cause stupid amounts of plunge). Trying to cram IFS into a narrow vehicle (say a Ranger with a WMS to WMS in the 60" ballpark) and come out with decent travel at the end is incredibly frustrating because you wind up stuck having to work around stupid short control arms and big angles on the axle shafts.

IIRC someone awhile back ran the 3rd member integrated into the LCA of an IRC. It seemed like a great "best of both worlds" of the TTB and traditional IFS/IRS. You give up a lot of unsprung weight doing that and create some minor drive-line inconvenience (the drive shaft now moves and you therefore need room for it) but you don't have the stupid center joint angle and plunge issues of the TTB and you don't have the diff acting like a mandatory spacer between your LCAs like you do in a traditional IFS.

You do see the GM IFS snap their CVs and Tripod(t) joints, especially in the pulling circles, most of the time in lifted trucks, that are already running their halfshafts at sharp angles, then the extra droop....bind....snap.

with the amount of steering failures on those trucks, it’s not surprising

I considered making a joke about pulling trucks pretzeling a tie rod and the knuckle going to the stop at nearly full droop when I wrote that post. Glad to see we're all on the same page.

 

[Aisin]

x2 on the alunimun cases being junk. Nobody at the OEMs cares because they figure you'll only do a few low range clutch dumps during the warranty period and it'll survive a few just fine. But if you dish out enough abuse you're gonna get a silver surprise in the diff fluid. From the differential's perspective a rock bouncer climbing a hill looks a lot like low range clutch dumps but with a much higher duty cycle. Nobody's figured out how to make something that isn't based off a Ford 9, D60 or better survive that kind of for an extended amount of time yet.

I don't want to digress too much with regard to specific differentials but they bring up another set of issues. Anyone who isn't running a transaxle buggy has the front diff and the engine oil pan trying to occupy the same space and high pinion only makes it worse. And then there's the width you have to deal with. Because you can't have the ring gear and the crank shaft occupying the same space nor can you have the drive shaft making a line through the bellhousing the whole shitshow needs to be offset to one side. So then you've got a package that's probablty 24" or more from joint center to joint center. And then that means your lower control arms can't be much closer than that (because doing so would cause stupid amounts of plunge). Trying to cram IFS into a narrow vehicle (say a Ranger with a WMS to WMS in the 60" ballpark) and come out with decent travel at the end is incredibly frustrating because you wind up stuck having to work around stupid short control arms and big angles on the axle shafts.

IIRC someone awhile back ran the 3rd member integrated into the LCA of an IRC. It seemed like a great "best of both worlds" of the TTB and traditional IFS/IRS. You give up a lot of unsprung weight doing that and create some minor drive-line inconvenience (the drive shaft now moves and you therefore need room for it) but you don't have the stupid center joint angle and plunge issues of the TTB and you don't have the diff acting like a mandatory spacer between your LCAs like you do in a traditional IFS.







I considered making a joke about pulling trucks pretzeling a tie rod and the knuckle going to the stop at nearly full droop when I wrote that post. Glad to see we're all on the same page.

It wouldn’t be so bad if GM didn’t use leftover Cavalier steering parts in the trucks.

 

[Stephen Wilson]

If you have big bucks, they do make custom diff's with the CV's back-to-back to maximize axle length. Of course that doesn't help with a front engine competing for the same space. https://www.proformance.com.au/ifs-irs-diff

 

[Treefrog]

x2 on the alunimun cases being junk. Nobody at the OEMs cares because they figure you'll only do a few low range clutch dumps during the warranty period and it'll survive a few just fine. But if you dish out enough abuse you're gonna get a silver surprise in the diff fluid. From the differential's perspective a rock bouncer climbing a hill looks a lot like low range clutch dumps but with a much higher duty cycle. Nobody's figured out how to make something that isn't based off a Ford 9, D60 or better survive that kind of for an extended amount of time yet.

I don't want to digress too much with regard to specific differentials but they bring up another set of issues. Anyone who isn't running a transaxle buggy has the front diff and the engine oil pan trying to occupy the same space and high pinion only makes it worse. And then there's the width you have to deal with. Because you can't have the ring gear and the crank shaft occupying the same space nor can you have the drive shaft making a line through the bellhousing the whole shitshow needs to be offset to one side. So then you've got a package that's probablty 24" or more from joint center to joint center. And then that means your lower control arms can't be much closer than that (because doing so would cause stupid amounts of plunge). Trying to cram IFS into a narrow vehicle (say a Ranger with a WMS to WMS in the 60" ballpark) and come out with decent travel at the end is incredibly frustrating because you wind up stuck having to work around stupid short control arms and big angles on the axle shafts.

IIRC someone awhile back ran the 3rd member integrated into the LCA of an IRC. It seemed like a great "best of both worlds" of the TTB and traditional IFS/IRS. You give up a lot of unsprung weight doing that and create some minor drive-line inconvenience (the drive shaft now moves and you therefore need room for it) but you don't have the stupid center joint angle and plunge issues of the TTB and you don't have the diff acting like a mandatory spacer between your LCAs like you do in a traditional IFS.







I considered making a joke about pulling trucks pretzeling a tie rod and the knuckle going to the stop at nearly full droop when I wrote that post. Glad to see we're all on the same page.

Wasn't it one of the ufo cars that put the diff in the rear lower control arm? I think Madram11 has a walk around of it.

 

[Isdtbower]

If you have big bucks, they do make custom diff's with the CV's back-to-back to maximize axle length. Of course that doesn't help with a front engine competing for the same space. https://www.proformance.com.au/ifs-irs-diff

Several years ago, Tim and I queried Weismann Transmissions about making a new diff for front engine IFS cars. (My preference) One day I saw one sitting on their shop table and was mad it wasn't mine. They were made for Pro4 and in the $30k range. The idea was back-to-back CV's or wherever and an offset pinion to your liking. I wanted 8". Later, the diff was not up to real KOH style abuse, but live quite well in a portal arrangement. Cody Wagoners IFS/IRS car. I also noticed that back to back CV's made the lower control arms go under the diff and making ground clearance worse. The bull gear diff was already 7" deep. When I came up with another option, I kind of passed on that diff but really appreciated the effort they made...and continue to make in the high end offroad market.

The "standard" 9/10" IFS diff is about 14.5" flange to flange. By cutting off about 1.75" from one side of the drop-out you can drop that distance to 12.75" . Summit Machine in Draper, Utah offers a billet case with that design. I went with that...polished. Spidertrax is now offering the same in a fabricated steel case. This allows for longer arms/half shafts, etc and the need or opportunity to change your geometry. Thelow pinion other good news of cutting the side was moving the pinion further to driver and a chance to sneak a driveshaft to it with minimal engine offset...if any. I will know soon.

For the rear IRS, I had a quick change built with billet outside bells that are almost flat. The flange to flange width is 7", which easily gets you "24" of suspension," But because of the diff thickness of 7" that number is really in the range of 18" because of the diff grounding out on stuff. I am presently reworking some of the geometry there to regain some. The IRS design took awhile to figure out as I had a long list of requirements that I THOUGHT could be met with the experience we had in IFS design. I have covered this elsewhere. But unique and hopefully works in real life. There are definitely great IRS systems with all the wants except strength. I hope it is not overkill! And in retrospect, I wouldn't go IRS again. Mainly because of advances in 4 bar and the grounding issues.

 

[arse_sidewards]

...talks about shit that costs more than my house...

Were you the guy who was forming the oil pan around the diff and was shooting for some insane tight clearance between the main journals/crank pulley and diff housing?

What do you mean by "the grounding issue" in relation to IRS?

Wasn't it one of the ufo cars that put the diff in the rear lower control arm? I think Madram11 has a walk around of it.

Found it.

I don't see why this sort of packaging wouldn't be even more beneficial in the front

 

[YotaAtieToo]

Man that's a trip, I thought they were just using ttb rear ​​​​​​

So basically the diff replaces the shaft section ov cv, then has some type of carrier bearing in the middle. Seems like the only downside would be a little less ground clearance on that side and a little more unsprung weight.

 

[Wilson]

Man that's a trip, I thought they were just using ttb rear ​​​​​​

So basically the diff replaces the shaft section ov cv, then has some type of carrier bearing in the middle. Seems like the only downside would be a little less ground clearance on that side and a little more unsprung weight.

it’s a giant custom cv bell that Joe designed, not your typical carrier bearing setup.

the “housings” serve as the lower radius rods as well. It’s a trailing arm setup.

 

[YotaAtieToo]

it’s a giant custom cv bell that Joe designed, not your typical carrier bearing setup.

the “housings” serve as the lower radius rods as well. It’s a trailing arm setup.

Well, yes. I was the term loosely.

I can see that now as well. Definitely looks interesting. I'm trying to figure out what the diagonal bar that goes forward and toward the middle is doing

 

[arse_sidewards]

Well, yes. I was the term loosely.

I can see that now as well. Definitely looks interesting. I'm trying to figure out what the diagonal bar that goes forward and toward the middle is doing

No reason you couldn't replace the custom bell with a short shaft, bearings and a couple normal plunging CV joints.

 

[Treefrog]

I'm trying to figure out what the diagonal bar that goes forward and toward the middle is doing

Trailing arm of sorts.

I don't see why this sort of packaging wouldn't be even more beneficial in the front

It still has trailing arms. You might run into clearance issues.

 

[arse_sidewards]

It still has trailing arms. You might run into clearance issues.

Yeah, kind of goes without saying. I was thinking that integrating the diff into a more traditional traingle-ish lower control arm might be the hot ticket. But I was hoping to get some input from the people who actually race as to why they don't do this since it would seem to solve so many packaging issues that everyone deals with.

 

[YotaAtieToo]

Yeah, kind of goes without saying. I was thinking that integrating the diff into a more traditional traingle-ish lower control arm might be the hot ticket. But I was hoping to get some input from the people who actually race as to why they don't do this since it would seem to solve so many packaging issues that everyone deals with.

Seems that for ifs you either run rear engine, or front passenger engine ​​​​​​

There may be more downsides to the diff arm thing that we realize.

 

[Tech Tim]

Yeah, kind of goes without saying. I was thinking that integrating the diff into a more traditional traingle-ish lower control arm might be the hot ticket. But I was hoping to get some input from the people who actually race as to why they don't do this since it would seem to solve so many packaging issues that everyone deals with.

I don't race, but I did sleep at a Holiday Inn Express once.

It works in a trailing arm set-up because the way a trailing arm travels and the overall size. An A-arm set up would be huge and completely too complicated. You can do so much more with a center mounted diff.

 

[arse_sidewards]

It works in a trailing arm set-up because the way a trailing arm travels and the overall size. An A-arm set up would be huge and completely too complicated. You can do so much more with a center mounted diff.

So basically the driver's side of a TTB

Not trying to have an answer to everything, I just want people to convince me I should keep building a TTB for my Ranger "proper" IFS. Because that would save me a hell of a lot of money and frustration.

 

[Wilson]

So basically the driver's side of a TTB

Not trying to have an answer to everything, I just want people to convince me I should keep building a TTB for my Ranger "proper" IFS. Because that would save me a hell of a lot of money and frustration.

it was either on Instagram or FB, but Joe Thompson laid out why it was “not like ttb” when the Gomez cars were debuted. It is center-pivot, not opposing. The goal for those cars was a sxs on steroids, kind of like patooyee mentioned early on.

 

[Wilson]

But.... do the ttb! I think that there is more universal trail potential with that design. The camber swing is the biggest drawback, but if you want to do some serious Boulder-wheeling and haul ass in between, it’s hard to beat.

 

[arse_sidewards]

it was either on Instagram or FB, but Joe Thompson laid out why it was “not like ttb” when the Gomez cars were debuted. It is center-pivot, not opposing. The goal for those cars was a sxs on steroids, kind of like patooyee mentioned early on.

I'm just saying if the TTB can fit in a truck so can a fuckhuge control arm that happens to hold a diff.

 

[Wilson]

I'm just saying if the TTB can fit in a truck so can a fuckhuge control arm that happens to hold a diff.

Gotcha, and with that being a rear engine car; steering was the only thing missing in that pic!

 

[YotaAtieToo]

it was either on Instagram or FB, but Joe Thompson laid out why it was “not like ttb” when the Gomez cars were debuted. It is center-pivot, not opposing. The goal for those cars was a sxs on steroids, kind of like patooyee mentioned early on.

I never really spoke with them about their 4400 rigs, but one guy I worked with also went to high school with them. Supposedly the full independent rigs will get through the rocks easier and faster than the solid rear rig. Everyone thinks solid axle will always win in the rocks, but getting through a trail as fast as possible and crawling obstacles for fun are really not even close. Sxs's will get through trails on 32s that challenge rigs on 37s, but it's a totally different experience. The sxs and it's occupants are probably going to be in much worse shape at the end of the trail.

Take the same idea of high center clearance and a smooth belly, but make it full size on 40s and I can definitely see how they could move through rock trails.



Hopefully this isn't too far off what the thread was started for. It seems like it's just turned into "bs about the 1 or 2 things you think you know about ifs"

 

[Wilson]

YotaAtieToo I think most here (watching) are in that dream realm. Hopefully enough guys with the real knowledge stay engaged. I dug deep a while back and had everything drawn up for a 4600 class Tacoma before finally coming to grips that I had neither the time to build it myself or the funds to pay someone else to.

 

[YotaAtieToo]

YotaAtieToo I think most here (watching) are in that dream realm. Hopefully enough guys with the real knowledge stay engaged. I dug deep a while back and had everything drawn up for a 4600 class Tacoma before finally coming to grips that I had neither the time to build it myself or the funds to pay someone else to.

Ya, oh well, it's like any other large tech thread.

Although it would be a blast, I wonder if ifs would really be a huge advantage in 4600? I mean the last few years it's been won by low power leaf sprung rigs

A single cab Tacoma or 4runner 3rz would be a fun 4600 though. I've looked at mild mods for our 4runner. The rack being in the back and tie rods having a slight forward angle prevented me from really doing anything, since my first priority was to move the tire forward. The 2nd gen tacoma/4th gen 4runner/fj cruiser is a much better platform.

The river city whatever guy had something neat going, but just missed the mark. It's almost like he wanted to get a bunch of sponsors to build his dream overlander rig, "race" a bit, then put the shinny doors back on.

Is that the only independent rig to run 4600?

 

[Wilson]

Ya, oh well, it's like any other large tech thread.

Although it would be a blast, I wonder if ifs would really be a huge advantage in 4600? I mean the last few years it's been won by low power leaf sprung rigs

A single cab Tacoma or 4runner 3rz would be a fun 4600 though. I've looked at mild mods for our 4runner. The rack being in the back and tie rods having a slight forward angle prevented me from really doing anything, since my first priority was to move the tire forward. The 2nd gen tacoma/4th gen 4runner/fj cruiser is a much better platform.

The river city whatever guy had something neat going, but just missed the mark. It's almost like he wanted to get a bunch of sponsors to build his dream overlander rig, "race" a bit, then put the shinny doors back on.

Is that the only independent rig to run 4600?

Things evolved and I think the v8 runner would be the best platform. Rustynailjustin really wanted to build one, and I know that he helped steelcityracing with race support on his (which I agree with your synopsis).

there have been other independent 4600 builds. Bailey cole started out in a torsion bar 1st gen runner. I was looking at Tacoma’s early on because Dave gave me the go-ahead on coil overs.

 

[YotaAtieToo]

Things evolved and I think the v8 runner would be the best platform. Rustynailjustin really wanted to build one, and I know that he helped steelcityracing with race support on his (which I agree with your synopsis).

there have been other independent 4600 builds. Bailey cole started out in a torsion bar 1st gen runner. I was looking at Tacoma’s early on because Dave gave me the go-ahead on coil overs.

I was one of the ones who suggested the V8 4th gen to steel city guy early on. Hindsight, it's a larger rig and I'm not sure if the V8 is really an advantage in the class? He also went 4.88s and 1:1 high, which I think was a mistake. Even most of the 600+hp 4400 guys are running some sort of reduction for better acceleration. Heck I'm. Pretty sure the 1200 hp trophy trucks are geared down. 4spd atlas in 2:1 is definitely the way to go for the desert.

​​​​​I just wonder if the size and weight of the V8 4runner kill the V8 advantage. A healthy 3rz in a gutted taco would probably move pretty well on 35s. I wonder is sxs 35x10s are allowed? Many are dot approved and would be way lighter.

I guess that's the beauty of 4600, it's still a little up in the air on what can take the win. Realistically, a well built 2 door jk/jl would be hard to beat, but also boring.

 

[Provience]

Ya, oh well, it's like any other large tech thread.

Although it would be a blast, I wonder if ifs would really be a huge advantage in 4600? I mean the last few years it's been won by low power leaf sprung rigs

A single cab Tacoma or 4runner 3rz would be a fun 4600 though. I've looked at mild mods for our 4runner. The rack being in the back and tie rods having a slight forward angle prevented me from really doing anything, since my first priority was to move the tire forward. The 2nd gen tacoma/4th gen 4runner/fj cruiser is a much better platform.

The river city whatever guy had something neat going, but just missed the mark. It's almost like he wanted to get a bunch of sponsors to build his dream overlander rig, "race" a bit, then put the shinny doors back on.

Is that the only independent rig to run 4600?

steal city racing is going to be running again and most of the "problems" that missed the mark were from marlin, the guy isn't the engineering brains behind design, and marlin has used it to wail on and honestly still seem to be working towards a better product.

for staying in the class rules, it is a pretty solid effort for high clearance IFS to bash on.

there've been other IFS 4600 rigs, but nobody that went as "full custom" as him, or at least that was willing to share it all online.

 

[YotaAtieToo]

steal city racing is going to be running again and most of the "problems" that missed the mark were from marlin, the guy isn't the engineering brains behind design, and marlin has used it to wail on and honestly still seem to be working towards a better product.

for staying in the class rules, it is a pretty solid effort for high clearance IFS to bash on.

there've been other IFS 4600 rigs, but nobody that went as "full custom" as him, or at least that was willing to share it all online.

I was more talking about the build overall, he didn't seem to make much effort to save weight. Big heavy bumpers, ect. I tried explaining the gearing thing, but no, cause V8, ect. Then the first year they go out with some cheese ball mockup steering arm deal. Which I get, they ran out of time, but weld some extra material on.

I think it's hard to spend all that time, money, and effort then really go out and push as hard as you need to. A local guy told me that he had a hard time racing his first full build (4500? Iirc) because after put everything he had into it, he basically went out and destroyed it every race.




So if the class leaves axles "open" wouldn't a full proam ifs under a Tacoma be legal? Dual a arm, check, coilovers, check, rack and pinion, check?

 

[Provience]

So if the class leaves axles "open" wouldn't a full proam ifs under a Tacoma be legal? Dual a arm, check, coilovers, check, rack and pinion, check?

yeah it would, and many people have talked about doing it.........but our overlanding friend is on the very short list of people actually doing something about it

 

[Wilson]

yeah it would, and many people have talked about doing it.........but our overlanding friend is on the very short list of people actually doing something about it

He’s hardly custom. Not knocking what “marlin” is trying to do, but it’s goal is production and comes with flaws, if you’re racing.

 

[Provience]

He’s hardly custom. Not knocking what “marlin” is trying to do, but it’s goal is production and comes with flaws, if you’re racing.

it's custom until it is production, and they still aren't available to the public yet

 

[Wilson]

Good