what would i have to do to run 37 on a stock(ish) 1970 fj40 (1 Viewer)

[pb4ugo]

Id do your 4" lift and tires and buy the appropriate size winch and recovery gear, along with a nylon snatch strap. A winch will drag you over or thru just about any obstacle in front of you. Next join a local offroad club and gain some seat time and see what other folks have done. Most folks wheel with at least 1 other vehicle so they can help each other thru the trails. Later you'll probably want at a minimum a locker in the rear. If you decide to go with something other than a lunchbox locker, you should consider installing lower gears at that time. ,4.56's are a waist of money, theres not enuff difference from 4.11's. 4.88's are not much better, but id install that ratio into my 40 again. Anything taller will effect road driving rpms considerably. After these changes and you want more gearing, then look at major driveline changes and try to build lower gearing thru the trans and transfer cases to spread out the reductions thru out the drive line. Try to keep blacktop drivabilty with lower gearing off road. There are many combinations to achieve these goals. Do your research, and try to make wise desicisions so you dont have to go back and make major changes again.

 

[mattcamp]

For reference: 4" sua springs, Downey articulating shackles which give a but of lift as well, and 35" bfg km3's (measure 34.5) it does have longfields front axles though. I had 4.88's but went back to 4:10's and thinkin will switch back again, lol. Disc front and rear, stopping is important!!! It is a 5.3 and 4L65e however. This has been years of changes and adaptation, it had front and rear aussie lockers, I pulled the rear out because it started disengaging roughly. Next mod is selectable lockers. Lunchbox lockers are fine for what they are but they are not very smooth. Do lots of reading, let others experiences influence you, trial and error can get expensive.

 

[mattcamp]

For reference: 4" sua springs, Downey articulating shackles which give a but of lift as well, and 35" bfg km3's (measure 34.5) it does have longfields front axles though. I had 4.88's but went back to 4:10's and thinkin will switch back again, lol. Disc front and rear, stopping is important!!! It is a 5.3 and 4L65e however. This has been years of changes and adaptation, it had front and rear aussie lockers, I pulled the rear out because it started disengaging roughly. Next mod is selectable lockers. Lunchbox lockers are fine for what they are but they are not very smooth. Do lots of reading, let others experiences influence you, trial and error can get expensive. View attachment 2374695View attachment 2374698

Oh yeah, one more little note, once you modify an fj40, it will feel different. They are pretty well balanced machines stock and lifting and changing engines changes how they drive and feel so make sure that's what you want. Do quality work and it will pay off, crappy mods really destroy the fun. Spoken from experience, haha!

 

[Pighead]

What would you have to do to run 37s? Drive it for 20 or so years.
It took me 24 years to get to 37s.
I did 31s, 32s, 33s. wheeled plenty and wore them down, lots of mods along the way. Lunchbox locker then a Detroit.
Big jump was the SOA and then 35s. Power steering, front discs and a doubler at the same time.
100 other mods. extended stainless brakelines, bigger alternator, winch, spare tire carrier (is your stocker gonna carry a 37?)
There are 100 things that will make a better wheeler than jumping to 37s.
A locked 40 on 33s can get through the Rubicon, with body damage of course. But you get body damage on 37s.
More important than tire size is driver experience and vehicle sturdiness.
a sturdy 40 on 33s beats a half-assed rig on 37s.
Build the core of your 40 to someday support 37s, do not slap 37s on a minimally modified 40 and expect to wheel it, you'll kill somebody.

 

[declan mcgrath]

What would you have to do to run 37s? Drive it for 20 or so years.
It took me 24 years to get to 37s.
I did 31s, 32s, 33s. wheeled plenty and wore them down, lots of mods along the way. Lunchbox locker then a Detroit.
Big jump was the SOA and then 35s. Power steering, front discs and a doubler at the same time.
100 other mods. extended stainless brakelines, bigger alternator, winch, spare tire carrier (is your stocker gonna carry a 37?)
There are 100 things that will make a better wheeler than jumping to 37s.
A locked 40 on 33s can get through the Rubicon, with body damage of course. But you get body damage on 37s.
More important than tire size is driver experience and vehicle sturdiness.
a sturdy 40 on 33s beats a half-assed rig on 37s.
Build the core of your 40 to someday support 37s, do not slap 37s on a minimally modified 40 and expect to wheel it, you'll kill somebody.View attachment 2375339

very well put thanks I’ll take it slow go up as times go on and take it one mod at a time

 

[declan mcgrath]

so iv been looking at some rear disk break conversion kits how does this one look also how would i tell if i have full float axles or semi float

Page 292 Land Cruiser Rear Disc Brake Conversion Kit

www.sor.com

 

[navydivedoc]

You almost certainly have a semi float. If you have a bolt on rear cover on the axle, it's a semi float.

 

[FJBen]

so iv been looking at some rear disk break conversion kits how does this one look also how would i tell if i have full float axles or semi float

Page 292 Land Cruiser Rear Disc Brake Conversion Kit

www.sor.com

you don't NEED a rear disc conversion. Plenty of good stopping with good drum brakes. A good setup disc/drum setup works good. Yeah they are a pain, but there are A TON of other things to spend you money on with this cruiser rather than rear discs. I'd venture less than 25% of the FJ40s on here have rear disc conversions...but I could be off on that.

 

[bhsdriller]

Yeah i'm not running 37's but with a fresh master cylinder and pads/rotors up front it stops just as good if not better than my newer 4runner

 

[declan mcgrath]

Yeah i'm not running 37's but with a fresh master cylinder and pads/rotors up front it stops just as good if not better than my newer 4runner

Hell ya good to hear cause my fj came with the front already converted

 

[subzali]

Suggestion: drive your 40 (not FJ) the way it is and find out what it “needs” as you go. I drove mine unlocked with bald tires for about a year in college before having money to throw at it. First step was a good set of tires and i got a deal on a lock right auto locker for the rear. That’s it. Gone tons of places. Added power steering and a winch. That’s what I felt I needed. Tranny and tcase swaps are complicated and can get expensive. Gears can be expensive.

you just don’t need all this flash bang stuff to get out and have fun. Do that and come back and tell us what you think it needs. Don’t just web wheel. Where have you taken it so far and what did you come back feeling you need to get through that “next” obstacle?

 

[bikersmurf]

I’ve owned mine since ‘91. I’m still running open diffs. I’d recommend narrower 33s. I ran 33x12.50s for years, but am much happier now that I switched to 33x10.50s.

One thing to watch for is tires often differ from their theoretical size. My 33x10.5r15 BFG ATs are about 32” tall. In comparison my 255/85R16 BFG MT which should be about a 1/2” taller is about 34”... go figure. If I were starting over I’d seriously consider 255/85R16s which are a touch narrower and gain 1” under the differentials. They’d fit with a similar lift and be easier to steer.