4400 IFS Rear Engine Ultra4 Build

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I guess there is a weight/money calculation with part choices. But some people do a 203/205 doubler. You can have 2:1 and 4:1.

Yea, my buddy is actually selling a 203/205, the issue is length and that thing is huge and I'm sure weighs like 200lbs, plus for not much more than the 203/205 setup you can just get a single speed atlas that is geared lower.
 
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So plans are changing again. Talked to lots of people, started a thread on pirate and got screamed out for my poor decisions, etc. TL;Dr -- the LC axles are leaving. I knew they were gonna be a weak point, and if I'm gonna have a big engine and a tube chassis and all this shit, may as well do the last step of the axles correct. I am not a fan of tons, they weigh a lot and you still need to spend a lot of money to make them actually good (locker, gears, truss, shafts, etc.) so I'm thinking I'll run a 609s. That shit is a lot of money, so what I'm thinking is in the near future buy the housings so I can mock things up once the chassis gets to that point, and then piece the rest of the axles together after that (probably have the 3rds be the last part since that's like the single most expensive piece). Need to do more research, so far I'm leaning between Spidertrax and Ruffstuff, though the issue with spidertrax is I'd have to run their smallest housing which is 3.5"x0.25" since it's their only mild steel one. However it also weighs a lot less than like a ruffstuff which is 3/8" tubes and I still want to try and stay as light as possible.

Also talking to one of my 4400 buddies, he thinks a 2:1 from a np205 won't be low enough for crawling with a 4l80 and the tranny will get too hot. There's not really any gearing options for a 205, that means an atlas essentially if I don't want to have a huge and heavy crawlbox setup. Second he says that most Ultra4s have 40-50% drivetrain losses, which regardless the lq4 will make 2x the power the 80 series made before but knowing that much loss might mean I'm more inclined to deck the motor a bit more.... But at least with everything else built up, I can upgrade the motor at any point and not really worry about upgrading everything else down the line if I build the axles and tcase and tranny strong from the get go.

http://offroaddesign.com/catalog/Magnum Box.htm
 
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@stumbles is a Classifieds Whore, one of the best for sure.

I didn't even know where the classifieds was to be honest, I saw the vendor marketplace but never scrolled far enough down the forum to see the normal classifieds until today when I couldn't find the atlas in the vendor tcase section haha
 
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You're the man! Sent him a message. I have a buddy who lives right near him too
No troubles. I look at classifieds everywhere when I get some downtime at work, lol. I have found some decent deals for my truck that way.
 
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I didn't even know where the classifieds was to be honest, I saw the vendor marketplace but never scrolled far enough down the forum to see the normal classifieds until today when I couldn't find the atlas in the vendor tcase section haha
Sorry I should have put up the link.
 
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Time to get to work! Until I visit my folks for Thanksgiving.... Got my buddy's 4600 rolled out of the shop and moving on, so time for my own project.

Cleaned up the shop a bunch and made some room, I thought maybe I had made too much room for it until I started laying it out and realized maybe I don't have enough room.

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Had a buddy come over and we cleaned the tubes with acetone and then marked all the tube junctions and tube numbers with sharpie since they're etched in normally and a bitch to see easily. It also took a lot of second guessing and moving stuff around and looking at pictures and figuring shit out to get the tubes setup right. There's no instructions with the chassis and the tube names were confusing for a few parts (like the front V brace isn't called a V brace, but the rear V brace is called a V brace, so took forever to figure out what exactly was the front V brace). But we got it laid out!

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The cage on the 4600 I just did was 90% 2", and the cage I did on my 4500 last year was all 2", so this 1.75" chassis feels TINY. Very glad I got the DIY kit too, my reasoning was for safety since I wanted to make sure I could fit in the chassis before welding it up and if need be change it so I have plenty of helmet and body room. It didn't even cross my mind to just straight up measure my seats, my 4500 wasn't THAT far off from the 48" wide rock lizard so sure it will probably be fine! Yea no, the seats are each 24" wide, so the seats side by side right off the bat are wider than the entire chassis.

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It shouldn't be a big deal to fix, all the lateral tubes will need to be stretched. Potentially I can just widen the roof too and be fine, but right now I'm leaning towards widening the entire chassis since I don't want my elbows being tight with the codriver and the door bars. Luckily all the lateral tubes are straight with the exception of the roof windshield bar, and I already bought a 1.75" die a few weeks ago. Tomorrow I'll order some steel and hopefully have it when I get back from Thanksgiving.

Tomorrow I'll hopefully start tacking it from the bottom up. I might tack a lot of it together and swing the LQ4 in just to see if the engine width or the occupant width is the driving factor for the chassis dimensions. Right now I'd like to still run this chassis, I think it'd be immensely cheaper to modify it than get a different chassis or build my own, and I like to make stuff so modifying it isn't a big deal. However it is really tiny, and the 1.75" tube makes me nervous. I plan to brace the shit out of it, but the last two cages I did were all 2" and this thing looks so small by comparison. I even took some calipers to the tubes to verify they were 1.75" since they looked so small. I still like my overall concept and idea, but I need to seriously weigh the options before I start cutting and welding on this kit.
 

AssBurns

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With your weight goals, the 1.75" tube will be plenty strong. Sucks you gotta make the chassis wider than initially planned. Are those seats really wide or is the chassis THAT narrow?

How much wider do you plan to go?
 
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With your weight goals, the 1.75" tube will be plenty strong. Sucks you gotta make the chassis wider than initially planned. Are those seats really wide or is the chassis THAT narrow?

How much wider do you plan to go?

Yea I'm sure you're right, just not used to tube this size haha. The seats are exactly 2ft wide, and the chassis is exactly 4ft wide on the outside. It's a combination, my seats really flare out far on the shoulders which is part of the reason I think they're really comfortable. I know Matt's PRPs don't have nearly the shoulder/back support mine do, though I'm not sure how mine compare to like a stock seat. The inside of the land cruiser's cage was slightly over 4ft wide, which is why I thought 4ft would be plenty. I think if I widened it by even as little as 4" total it would make a ton of difference. The shoulder's flare out so far you could fit a shifter between the actual bottom part of the seat, so really it's just room on the side and maybe a little extra in the middle that's needed. Right now I'm thinking if the engine fits fine, which from my quick measuring of the "hood" and bottom of the chassis I think it'll be tight but actually fit in the stock area without modification, so then probably widen it in total like 6-8" just to make it roomy and since I'll probably have like a 72" WMS there's not a lot of point to skimp on comfort inside the cage, plus more room would make it easier to get out in the event shit hits the fan.
 

AssBurns

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Yea I'm sure you're right, just not used to tube this size haha. The seats are exactly 2ft wide, and the chassis is exactly 4ft wide on the outside. It's a combination, my seats really flare out far on the shoulders which is part of the reason I think they're really comfortable. I know Matt's PRPs don't have nearly the shoulder/back support mine do, though I'm not sure how mine compare to like a stock seat. The inside of the land cruiser's cage was slightly over 4ft wide, which is why I thought 4ft would be plenty. I think if I widened it by even as little as 4" total it would make a ton of difference. The shoulder's flare out so far you could fit a shifter between the actual bottom part of the seat, so really it's just room on the side and maybe a little extra in the middle that's needed. Right now I'm thinking if the engine fits fine, which from my quick measuring of the "hood" and bottom of the chassis I think it'll be tight but actually fit in the stock area without modification, so then probably widen it in total like 6-8" just to make it roomy and since I'll probably have like a 72" WMS there's not a lot of point to skimp on comfort inside the cage, plus more room would make it easier to get out in the event shit hits the fan.
I was thinking about 6" would give you a ton of room for comfort and the added safety of keeping the cage further from your head/body would be a bonus in a major crash. Sounds like those wide seats are already gonna keep you pretty secured and comfortable anyways, so might as well give a little extra wiggle room in there since you are gonna have some wide ass axles under it.
Going with fully fabricated 609's, huh? Any idea what housing, hubs, 3rd, etc you plan on using?
 
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Going with fully fabricated 609's, huh? Any idea what housing, hubs, 3rd, etc you plan on using?

Well spidertrax mild steel housings are $800.... and weigh like 55lbs apparently since they're 1/4" vs 3/8" and I figure with a truss on top the tube doesn't matter all that much...... And their fully fabbed knuckles are only $1800..... So kind of debating that, no idea on a 3rd, probably just some cheap shit with a spool in the back and a detroit up front or something. Maybe run their 35 spline unit bearings. I'm thinking buy housings in the near future and then just deck them out from the outside in over time so I can mock up with housings, then onto rollers, then add thirds, etc.

I was also looking at stroker kits from Skat, a 6.7L stroker rotating assembly is like $2700 and doesn't really require any modification of the block and dynos with an okay cam at 600hp...... Lots of ideas are being thrown around in my head right now :D
 
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Got the steel in from Midnight4x4 today so finally got to make a little progress. I read everyone's comments probably 100 times, then researched more, then talked to a buddy who races 4400 and coincidentally has the same seats as me. I decided to widen it 6" everywhere, that will bring the interior room to ~53" and the outside to ~56". The lower dash bar is actually ~50.5" on the Rock Lizard, so the interior stock is around 47" (I originally thought the outside of the chassis was 48").

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Everything so far is pretty straightforward. I was going to mock up the roof too but one of the roof bars (A/roof line/C) is bent out of wack by a few inches so stopped at the lower half of the cab. Based on the one good A/C pillar, I think I might end up raising the roof anyways for helmet clearance. With the lower cab tacked up I slid it over to the LQ4 and throw some wood under it so everything was generally at the height it would actually be and then threw the seats in a pseudo random spot to see how they'd fit around the tranny.

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Width wise everything looks amazing, height wise it's hard to tell and I was too lazy to throw the A/C pillar bar to see where it lined up. If the truck was 2WD it'd be fine, the tranny clears the seats decently, but I think with an atlas thrown on there it'll interfere with one of the seats. The engine can come back around 8" from where it is in the photos too. So I see it as two potential options, assuming the Atlas won't seem to fit--either bend/lower the bottom subframe bars so the whole drivetrain will sit lower or raise the seats and the roof assuming the roof is too low). The latter seems to be the obvious choice, but maybe everything will fit fine.
 
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I'm super excited with some ideas, and figured I'd throw them up on here instead of posting on instagram or something so I can get some thoughts before I go further insane.

So my thinking prior to yesterday was build the lizard for 4800, then build my 4runner and LT it (again), then use what I learn from the runner and build a 4400 IFS car. Well, why not just turn the lizard into an IFS build? At the end of the day the cost is about the same, IFS 9" setups are insanely expensive but the axles I wanted to run were already insanely expensive---and in some ways IFS would be cheaper since I would fabricate the arms and spindles and stuff myself so wouldn't need to spend $1800 on spidertrax knuckles. So if SA vs IFS costs the same, why even go SA? I like IFS, and nothing against SA but they just don't turn me on. I like to go fast, and occasionally crawl, not vice versa.

So I started thinking about it and talking to some friends, and then there was kind of this flurry of thoughts of oh well the front diff might be hard to package and stuff but what if the engine was just rear mounted for the hell of it... So I was like fuck it, and flipped the chassis around so the engine was in the back, and that bitch fits GOOD. Like at first glance it fits better in the back than in the front. The seat fits nicer since the engine and bellhousing isn't getting shoved into the passenger area as much, it fits easily within the constraints of the current rear chassis "outline". If I had a front diff, well now the front driveshaft is short and straight, then the transfer case offset output would help clear the engine and tranny for the rear axle and run an offset rear diff. Then the IFS I can mount anywhere and pull the axle line way closer to the seats to sit more forward. With the 48" trailing arms and 40s I would be looking at a minimum ~112" wheel base, but pull it back to like 116" probably.

So obviously with it being a tube chassis IFS car it would fall into the unlimited class, but let's be honest, most of the races would be desert races (BOR, SNORE, short course, etc.) where IFS makes sense. And then for the rare Ultra4 race, well I would be rolling with the big dogs and it'd cost a lot but there's not even that many U4 races I planned on doing anyways since they're so far away. For a rig that will be used 90% in the desert where I like to play, and occasionally racing, and since I'd rather build an IFS car, it seems like this is the more fun path to go down. Not to mention I can build the whole thing and do the front diff and axles last and run it as 2WD and test it out before spending the $5k on a front diff, hell I might want to even remove all that shit for strictly desert races anyways to lose weight.

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Pros and Cons that I see:

Cons:
-Biggest is the transfer case setup, which I'll give Advance Adapters a call today, but seems like what is normally the front driveshaft is just the rear and the rear is now the front. Unless there's an issue with that, which I would assume they can just flip the gears or something and make it so normal 2WD is just what normal front dig is and vice versa.
-Fuel cell placement, I could put it up front but that's maybe a little sketchy? Not sure.... I was also thinking I could run twin fuel cells under the seats (I don't want to make a custom one) and that would keep the weight balanced out and keep the CG low. In the back would add a lot more rear weight plus you have exhaust and stuff going on.
-Front drive stuff? The IFS 9" housings are really expensive, but everything seems straight forward. Spidertrax even sells like hub "bungs" that you can build a spindle around and that a unit bearing bolts to, it's chromoly though so I would have to ask for mild steel or just make one myself for my spindles. So little questionable with all that, but not much crazier than normal.
-Steering would need to be like a TT rack or something, which sounds scary but I don't think would be that big a deal. I've also seen creative IFS steering setups with gear boxes and normal hydro rams, so probably not that big a deal with some research.

Pros:
-I like IFS and building it
-I would bump to unlimited/Ultra4 for racing, so I could run any size tire (probably 40s)
-I could run a coilover + bypass, and for my trailing arms I can actually reuse my 14" coilovers and then they mate up perfectly with a 18" bypass behind it so could save a little money
-Maybe/hopefully the same overall end of the day cost between IFS and SA
-More room with the engine behind the seats
-Transfercase easier to package arguably
-Rear mount radiator has less plumbing
-I like IFS :D


Other thoughts? I have awhile to make up my mind but just trying to think of everything. I haven't touched the chassis in 2 weeks, and hoping to order an Atlas race case by the end of the year, then I'll have everything for the drivetrain so can lay it all out and keep chugging with the chassis.

EDIT: Just talked to AA, they said there's no issues or additional cost to build the tcase for a rear engine setup.
 
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Put this together in the past couple hours, just to get an idea of what I want to do and help with the chassis layout and suspension geometries. The chassis is identical to what I have tacked up so far, then grabbed the closest CAD models I could find online. So shown is a LS3 with a turbo 350 and an atlas 2, then some dynapro MTs that I scaled up to 40" and put them on some 17" procomp beadlocks. The seats are twisted stitch. The trailing arms and rear axle I threw together really fast. I'll flush it out more (obviously), but like how it's looking already.

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AssBurns

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So stoked for this thing to turn into an IFS rig! Any idea which front diff you are gonna go with at this point?
Currie seems like the most popular but spydertrax has a narrow diff that would be cool to add a little more travel. That’s what’s cool about a rear engine, you can make your front geometry however you please without worrying about packaging.
 
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So stoked for this thing to turn into an IFS rig! Any idea which front diff you are gonna go with at this point?
Currie seems like the most popular but spydertrax has a narrow diff that would be cool to add a little more travel. That’s what’s cool about a rear engine, you can make your front geometry however you please without worrying about packaging.

Right now thinking Currie, their whole 9" IFS setup ready to rock is like $5k and that's including 3rd member, where as spidertrax is more than that for just the IFS housing and inner stub shafts. I was reading up on Shannon Cambell's car and he only pulls 18" of front travel which seems really low to me, I'll have to talk to RCV and see what their max deflection is, but I'm guessing something else will limit it since you'd think with 30" arms you could easily pull more than 18" of 4WD travel.... Also, I figure I'll get the front diff and axles last probably, because I should be able to drive the car totally fine without the front drive components. So if I'm working faster than the money can flow, then I'll be able to start testing it in 2WD and just be waiting for the front diff and axles to bolt up which would be nice.

The rear engine makes packaging everything really nice, it'd be so hard to fit a 9" diff under/next to the engine if it was in the front. Now it's a straight shot from the atlas into the diff, and then the rear I can offset a lot so theoretically shouldn't get caught on rocks as much since it'll be closer to the tire, plus this will allow the rear driveshaft to be longer too. And now I can run the pair of 2.5x14 coilovers I have, and that will match up perfectly with a pair of 18" bypasses on the trailing arms and both will top out at ~25" of rear travel which is pretty good, and will be a cheaper setup than running IBPs like I was planning on before.
 
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