picked up an fj40, got some plans and some questions

ullose272 · 10-30-09, 11:46 AM

hey guys, new to the forum and new to fjs. i just picked up a 72 fj40 and im lookin at building a nice street/ mild offroad truck. i have a ~400hp 350 sbc sittin on an engine stand so im planning on using that. i want to do a spring over on it and throw on 35s or 37s. i will be probly driving this daily so i want it to have decent drivability. i want to use a th350 or th400 and a np205 t-case. will this case work with the stock diffs? the cruiser isnt here so i cant go look. would i be better off goin to chevy diffs? ive seen frame boxing kits, is this something that should be done? im a good mechanic with a few various builds under my belt, so the fabing shouldnt be a problem, just lookin for som advice.

John Smith · 10-30-09, 02:01 PM

Welcome to Mud! Start your journey here to learn about your new truck. http://forum.ih8mud.com/40-55-series...-jul-09-a.html Please post up some pictures once you receive your 40.

zrheard · 10-30-09, 02:05 PM

for a street rig i cant imagine needing to box the frame (but someone may correct me) most spring overs iv seen 37' tires are the minimum im running 33s w/only 3" lift and 35s would fit..... so i think 35s would look pretty small just my .02
welcome to mud!!

official welcome

idk what you mean by will the t-case work with your differentials... but im sure someone will be along shortly to let you know

but we do charge for our advice and experience here
we NEED pictures

lots and lots and LOTS of pictures

ullose272 · 10-30-09, 02:41 PM

i will put up some pics as soon as i get it home. im asking about the t-case because i know on some vehicles the diff is on the left, but after looking at some pics the diff is on the right? so using a normal np205 tcase should work with stock diffs?

Tankota · 10-31-09, 01:55 AM

np205 won't work too well with the offset rear differential that comes stock...especially with spring over there will likely be too much of a difference for the driveline to handle.

I run a dana 60 rear diff with my 205.

craptabulous · 10-31-09, 03:13 AM

for a daily driver or even a offroader i would forget the th400 or th350 and get a 700r4 , 4l60e , 4l80e or a nv4500 .

np205 and the rear offset diff sprung over is going to bind and vibrate . you can adapt those trannys to the stock landcruiser t-case or get an orion t-case or get a dana 60 or corporate 14 bolt , ford 9" , tacoma rear etc .

a 400hp sbc will probably throw a lot of heat , prepare to upgrade the stock cooling system .

Fryedaddy · 10-31-09, 02:44 PM

listen to crap you have a good build, the engine will require some cooling though. 150hp to 400hp is a big change. The engine will more than likely be lighter but heat quicker. Prob want to look at a power steering setup if you haven't stared as well. I'm not the worlds greatest but can help with a decent amount. Check my build and ask as you go. We all will help with our own expertise just ask. Haven't seen any pictures but most are rusted in the rear. If you are switching (Orange 45) will help you with the AA parts needed.

http://forum.ih8mud.com/40-55-series...-4-3-4spd.html

ullose272 · 10-31-09, 05:50 PM

i was planning on putting in a aluminum radiator, i know i can use the stock t-case but i was woried about durability and also the conversion kits are like $400, i could get a whole '70s chevy and use the stock axles, tranny, t-case, for that. im not really wanting to use a 700r4 because they are weak, and good lockup converters are $$$$$, the rpms dont really bother me as long as i can keep it around 3500 rpms around 65-70 mph. i think for tires im going to go with 35x13.50s.

Tankota · 10-31-09, 11:00 PM

35s and 4.10s work fine for the highway. I had them for several years and had no prob traveling ALOT on the freeway at 70mph. This was with a 1:1 final transmission ratio (no overdrive).

That's a TON of work to swap the entire drivetrain...lots of unintended projects pop up when swapping everything. There's enough info/people on here to help you out significanlty though.

GarageRat · 10-31-09, 11:31 PM

Quote:

Originally Posted by ullose272

i was planning on putting in a aluminum radiator, i know i can use the stock t-case but i was woried about durability and also the conversion kits are like $400, i could get a whole '70s chevy and use the stock axles, tranny, t-case, for that. im not really wanting to use a 700r4 because they are weak, and good lockup converters are $$$$$, the rpms dont really bother me as long as i can keep it around 3500 rpms around 65-70 mph. i think for tires im going to go with 35x13.50s.

The 700R4/4L60 (note: 4L60 and 4L60E are different, the E is electronically controlled while the 4L60 was the last generation 700R4) is TH350 based and in my experience one with the latest factory mechanical updates will survive if it's not flogged hard. If you're doing a ton of driving you might want the OD for milage however the deeper first is the main reason I prefer them. The one I'm building for my dad's cruiser has the good 5 pinion planetaries, aftermarket sunshell (The Beast), Alto Red Eagle clutches, 'vette servo, valvebody, and a bunch of other crap I can't remember all going into an 84 case. Have had the parts to eventually build the 700R4 to replace the TH350 in my T/A which has a warmed over Ram Air III headed 6.6 WS6 motor and the cruiser is getting a Dart headed 383 originally meant for my road racer that should be good for 550 hp so it's meant for some flogging. Parts total came to around $800 IIRC excluding converter and keeping in mind I pulled the 700R4 from my road racer for a WC T5 so I consider that free and I'm doing the build myself. Anymore they're not much worse to buy built than a TH350 or TH400 if you prefer to go that route. 400 hp will frag a stock TH350 (learned that the hard way with my T/A), TH400 will take that abuse if it's in decent condition but has more frictional loss.

As far as diffs, chevy's are a little wide in my opinion for 35's. I'm going to run an FJ60 front and a hybrid mini/LC centered rear, adds a few inches of width to where it's more stable and looks a little better (to me). A chevy 12 bolt rear is another possibility at 60" WMS with a wider front end to match but I would not wheel one a ton on rocks, sand or mud it'd probably survive fine. That's what we're doing with the build for my dad's.

Hope there's something worth while to you in that block of text,
Ryan

Lil'John · 10-31-09, 11:58 PM

From someone who daily drove a SOA with 35s and 4.11 gears, get an overdrive. The 35s are do-able especially with a V8 but in the long run, the engine will be happier with an od as will the mileage.

SOA with 35s looks okay as long as the springs you are using are stock and flat. That is what I ran on mine. Worked exceptionally well offroad and road pretty well onroad.

The stock tcase can survive... just depends upon YOUR driving habits. Mine survived behind the dreaded 5.0L TBI

I'm going to make one survive in my 6.0L Vortec FJ55 until I can get an orion.

On boxing the frame, it wouldn't hurt... especially at the REAR of an FJ40 and ESPECIALLY around the rear spring hanger and rear shackle hanger. On my FJ55, the frame got re-inforced all over the place and it is considered "stronger" than an FJ40 frame.

On the NP205, I personally would pass. Big, bulky and maxed out at 2 to 1 in an FJ40. If I HAD to have a centered tcase, I'd eye ball Dana 20s and Dana 300 tcases both of which have commonly available gearsets and strength upgrades. If I wanted to keep the offset of cruisers but didn't trust the cruiser tcase, I'd eye ball the Dana 18s.

FWIW, my FJ55 is being setup in my version of "ideal" big tire daily driver: 6.0L Vortec(~350-400hp), NV4500, NP203, LC tcase(to be upgraded to orion) with narrowed Dana 60s with 4.88 gearing and 35" tires.

Yes, I upgraded the cooling system in the FJ55.

ullose272 · 11-01-09, 04:43 PM

a stock th350 is decently strong in my opinion, i ran a basicly stock th350 in my high 11 second chevelle for a couple years with no problems. im going to use a 2-2500 stall converter i this so i want a 1:1 final drive so i stay above the stall cruising down the highway so the tranny will stay cool. i dont want to spend the money on a lockup converter for the 700r4 or the parts to strengthen the tranny, unless i can find a 4l80e ill tay away from the OD tranny. 8-10 mpg doesnt really bother me, my other vehicles get about the same lol. as for t-case, id really like something that will bolt up to a chevy tranny without an adapter but will work with stock diffs? anything fit that bill? how much wider are chevy axles over stock fj axles?

Lil'John · 11-01-09, 04:51 PM

Quote:

Originally Posted by ullose272

8-10 mpg doesnt really bother me

If you are lucky, you MIGHT get that mileage with that engine... but I doubt it.

My 5.0L was able to pull 13-15mpg if I kept the speed down to like 60mph. That was with a manual transmission. Older autos such as the th350 are known to get MUCH worse than manual. Add in the extra power, I don't see anything close.

Quote:

Originally Posted by ullose272

as for t-case, id really like something that will bolt up to a chevy tranny without an adapter but will work with stock diffs? anything fit that bill? how much wider are chevy axles over stock fj axles?

No offset tcases that I'm aware that will bolt to chevy trannys without an adapter.

MUCH wider... like 12"-14"(55" wide for stock cruiser 67-69" for chevy).

ullose272 · 11-01-09, 07:47 PM

i dont think 8 is out of the question, just because it makes power doesnt mean it cant be efficient. it looks like im going to need to get the adapter. what gear ratio usually came in fj diffs?

Tankota · 11-01-09, 09:20 PM

Almost all fj40s had 4.10s. Some of the last fj40s had 3.73s and so did most (all?) of the fj60s etc.

I recommend staying away from the jeep t-cases (dana 18, 20, 300). I've seen everyone of those have catastrophic failures on the trail. From ripping in half to breaking the output shaft clean off and even burning up while being towed to the trail. Surprisingly I haven't seen a broken cruiser t-case on the trail...seen em on the net though.

Downey · 11-01-09, 10:20 PM

I agree with GarageRat, a 700R4 will not require a 4L60E computor (that you don't have), will give you lower off road gearing, and will give you highway overdrive gearing---best of all worlds. Knowbody's been able to use a GM transfer-case with a Landcruiser off-set rear diff, the compound angle (angle on an angle) is just to great. The dog gone thing would buzz you out of the cab. I'd inject your V8 if not already injected, run 700R4 ,use one on my short 1" adapters (gives you a longer rear drive shaft, I have two left), use the stock transfer-case, and have no drivetrain trauma!!!

ullose272 · 11-02-09, 08:48 AM

how much are your adapters? the motor is built so it allready has an intake and carb, so thats what im gonna use. im going to use a th350 because i can get one for a good price, and i have a converter.

GarageRat · 11-02-09, 12:42 PM

Quote:

Originally Posted by ullose272

a stock th350 is decently strong in my opinion, i ran a basicly stock th350 in my high 11 second chevelle for a couple years with no problems. im going to use a 2-2500 stall converter i this so i want a 1:1 final drive so i stay above the stall cruising down the highway so the tranny will stay cool. i dont want to spend the money on a lockup converter for the 700r4 or the parts to strengthen the tranny, unless i can find a 4l80e ill tay away from the OD tranny.

It's your vehicle so do whatever makes you happy but I wouldn't bother with a 4L80E if that was the only OD tranny you'd want. When we were making decisions on what to do with my dad's chevelle to put behind a nasty vortech/nitrous/alcohol injected 535 we looked into using one to replace the TH400. Ended up going with a Richmond 6 speed instead given the price and all that was required to run one standalone for the 4L80E. If you've had good luck with close to stock TH350's then more power to you.