Gears, axles and lockers, seeking input? (1 Viewer)

[houstonfj40]

Guys/Girls,

I am beginning a project on my 40. Run around town truck with my boys, baseball and things. Going to pull it to CO this summer (3-4 weeks) where I will take it on some light wheeling, one step I know of around the Snowmass/Crested Butte area I may need to clear above tree line. Can I get feedback on my questions here, thank you!

Early 1972 FST with SBC 350, TH350 trans

1. Upgrade to hwy gears. I think this is a no brainer due to how we use it most. (Sits on 32's)

2. This truck has the older axles, corse spline I believe. I have read about them being "weaker". Do I change out to stronger axles? Is easy wheeling going to be that hard on them?

3. If I go that far, and thru those changes, do I also do lockers. Again, seems like overkill, but would be easier to do while in there. ( also doing a Saginaw PS conversion so a front locker won't be as bad)

Or just wait until things break!

Thanks for your thoughts!

 

[jakek2525]

3.73 gears won't drop your rpm a whole lot. 2800 cruising rpm in a 350 really isn't that bad. It used to be the norm till everyone god spoiled by O.D.

 

[jakek2525]

Got ,lol

 

[GHalll]

Nice rig.. If it were mine and I wanted to put different birfields, I would do a FJ60 front disk conversion. If you wanted to cruise highway a lot then you may want to buy a set of late model FJ40 complete axles front and rear with 3:73 gears. Then maybe put Detroit Lockers in. ALL of which pretty much requires a full rebuild of the front and rears. So price it all, rebuilding your current axles with gears, rebuild kit, 60s knuckle/disk parts and lockers or buying and rebuilding late axles that come with disks, gears and installing lockers.

A locker in the front axle won't affect the handling at all with the vehicle in 2wd and the hubs unlocked which is good. Lock the hubs and put in 4wd and you'll have LOTS of traction up front. I personally like Detroit lockers. Put lockers in both axles if you have the cash.

 

[jakek2525]

You got a winch yet?

 

[40Wanted]

Lockers are fun, but good limited slip diffs can get you a lot of places and won't have the negative characteristics that go with a locker, especially since you say this is mainly an around town rig. Like GHalll said, a locker up front would be good, no negatives in 2wd and full traction when you lock in the hubs.

Don't know what part of Houston you're in, I'm on the Northeast side. If you decide to upgrade to the later model axles, I am going to be pulling my stock '76 axles (still 4.10 gears but fine spline and front disc brakes) & swapping in 1 tons on my project. If you're interested let me know and I'll get with you before posting them on the classifieds or Craigslist.

 

[Pin_Head]

I would just run it for a while as is.

 

[houstonfj40]

You got a winch yet?

Going on during the project. Some of the CO stuff is above tree line.

 

[houstonfj40]

I would just run it for a while as is.

Is current thought, see what I can/can't do. She will get FI and winch though.

 

[White Stripe]

I would do a winch, fuel injection, and disc brakes at least up front, preferably front and rear. If u have time power steering but not a big deal. If u have more than one rig on the trail(highly recommended) winch isn't as important. Sounds like u don't need a locker.

 

[shawnfj40]

^ ? Everybody needs a locker. Thats kind of like saying "You don't really need, four wheel drive". Lockers will get you into places, a winch will get you out of.

 

[Rock40]

Gears, lockers, disc brakes, axles upgrades.....kind of a ball of yarn and once it starts to unravel it can be hard to stop.

With the kind of wheeling you're describing, your factory axles are going to be just fine on 32" tires. Have a light foot, my more or less stock axles survived 37"s and a Vortec 5.7 engine.

Disc brakes and fuel injection would probably be the first two mods I'd do. The drum brakes are not great off road and a smooth running engine is vital.

Swapping out to FJ60 3.7 ratio differentials will help you some on the highway but will not much of a difference between the 4.11's you currently have.

If you're set on lockers (which is not a bad idea) I'd go ARB and be done with it. There's LOTS of debate on which lockers are best so make your own choice though. I had a Detroit in the rear of my 40 for rears and it drove me nuts making turns at low speed. The 40 is a short rig and the locker would really jerk the truck around as it locked/unlocked. It was absolutely HORRIBLE in the snow/ice also.

The ARB's are expensive but you'll do them once and forget it. Selectable lockers are exactly what Toyota put into some of the 80 series trucks and for good reason. You get 100% traction when in use and when off, you have a truck that drives like a stock vehicle.

Bottom line is what you really want to spend and these mods get expensive. My guess is your 40 would wheel pretty admirably just the way it is now.

 

[Living in the Past]

Didn't see number 2 addressed. The pinion changed to fine spline during the 78 model I believe. The axles you have should be fine spline if original. Those changed sometime in 68 from coarse to fine spline.

 

[terrx]

I would just run it for a while as is.

x2

 

[houstonfj40]

Gears, lockers, disc brakes, axles upgrades.....kind of a ball of yarn and once it starts to unravel it can be hard to stop.

With the kind of wheeling you're describing, your factory axles are going to be just fine on 32" tires. Have a light foot, my more or less stock axles survived 37"s and a Vortec 5.7 engine.

Disc brakes and fuel injection would probably be the first two mods I'd do. The drum brakes are not great off road and a smooth running engine is vital.

Swapping out to FJ60 3.7 ratio differentials will help you some on the highway but will not much of a difference between the 4.11's you currently have.

If you're set on lockers (which is not a bad idea) I'd go ARB and be done with it. There's LOTS of debate on which lockers are best so make your own choice though. I had a Detroit in the rear of my 40 for rears and it drove me nuts making turns at low speed. The 40 is a short rig and the locker would really jerk the truck around as it locked/unlocked. It was absolutely HORRIBLE in the snow/ice also.

The ARB's are expensive but you'll do them once and forget it. Selectable lockers are exactly what Toyota put into some of the 80 series trucks and for good reason. You get 100% traction when in use and when off, you have a truck that drives like a stock vehicle.

Bottom line is what you really want to spend and these mods get expensive. My guess is your 40 would wheel pretty admirably just the way it is now.

Rock40

Thanks! FI and PS in next couple weeks. I think I will stick with current set up. If I did lockers, I think ARB only make air lockers for this setup. Would you do one or both axles? If one done, which?

Marc

 

[Rock40]

When I've done ARB installs, I've always done both front and rear at the same. However, if I was starting with a truck (like yours) with open differentials both front and rear and I only had one ARB, it would go in the rear axle. Upgrading to one ARB in the rear will get you in/up a lot of places your truck was stuck on before but you'll still be able to steer easily and the truck will drive/feel pretty "normal" offroad. Many times, I run around in the dirt with the rear ARB locked all the time. It does put some extra strain/wear on stuff but I've never broken anything yet. Nor do I expect anything to break under use like that.

Keep in the mind that with ARB's, you'll need to source some sort of compressor and the ARB one's are the easiest as they contain the electrical harness and are fairly plug-and-play. Once you have that and the rear ARB installed, it'll be very easy to add a front ARB later on.

You may check with Marlin Crawler about prices. Although expensive, I purchased Marlin's fully built 3rds for my 84' truck. By the time you source out all the individual parts (gears, install kit, bearings, ARB, etc) the price was more or less a wash and Marlin guarantees the gear set up if you break the gears in correctly (not hard). He has some pretty good sales throughout the year and will offer free or 1/2 price shipping too. If you do it yourself, please stay away from the cheap Chinese or sub-par parts. You NEED to have the differential and ARB set up absolutely correctly with high quality components.