Rebuild or replace?

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Bubbajones69

Joined
Aug 12, 2017
Threads
6
Messages
25
Location
Annapolis,MD
Hi everyone - working on my restoration of my 1969 fj40. I’ve torn into the axles and found quite the surprises. No fluid in front dif, mystery rear axle (centered rear dif) 11 spline? and lots of worn out bearings. It is currently drum brakes all around but bought disc conversion kit from b&m. I probably should have waited on buying those till torn down but oh well. Here is rear dif - doesn’t look bad but not sure about 11 spline axles

Rear dif

Rear dif


New engine....
New engine

New engine


Rebuilding th350
Scary transmission

Scary transmission



The big questions now is do I rebuild the existing axles or go try to find axles from another vehicle and do a transplant? I’ve got a new stroker 350 to put in and considering an atlas 2 transfer case... what would you do? Welcome thoughts and opinions - I am happily ignorant trying to restore this soon to hopefully be awesome fj! But should probably start calling it the money pit :)
Welded yokes

Welded yokes

Steering knuckle

Steering knuckle

Steering knuckle

Steering knuckle

 
Last edited:
Since the centered rear axle last was used in 1963, what you’re REALLY asking is opinions on putting a FIFTY FIVE year old axle designed for a 100hp motor behind a torque monster SBC.

Kind of a loaded question put that way.
 
There are no upgrades for the centered axle. Only less-used used parts.
 
OK - do you have any recommendations for replacement axle? The previous owner had a np241c transfer case but it is really long which made driveshaft really short - if I have to replace axle - would you go with something centered and atlas 2 or offset with something else? I have a working th350 so was going to use that with the new 350 - engine is over 500 hp
 
OK - do you have any recommendations for replacement axle? The previous owner had a np241c transfer case but it is really long which made driveshaft really short - if I have to replace axle - would you go with something centered and atlas 2 or offset with something else? I have a working th350 so was going to use that with the new 350 - engine is over 500 hp
 
What are you going to use it for?
How deep is your wallet?

Based on the drivetrain you're planning, I would suggest Corp 14 Bolt rear and Dana 60 front. You could stay Toyota with FJ80 axles front and rear. Both of these axle set choices mean more suspension fab. They are not bolt in.

You could swap in newer FJ40 axles with front disc brakes (76+ or mini truck conversion) and upgrade the axle shafts, but that could get pricey. They would be direct bolt in though. You would need an offset rear transfer case.

Which all leads back to the first two questions...

Welcome btw :flipoff2:
 
Thanks! This is all new to me and learning as I go- we hope we can use it as a daily driver with some fire road type off-roading weekend fun. I can put some money in it but trying not to go too crazy
 
With 500 ponies under the hood you are the owner of a chain looking for its weak link. Pick your poison. There are a lot of rear end choices out there. The only one I wouldn’t use is the one you have.
 
For DD use and mild wheeling, you can rebuild your axle with newer shafts and run it (with rebuilt diff) and bolt it in. For the front, find a complete set of Toyota mini-truck front knuckles with brakes and swap them onto your front housing. Rebuild the diff and buy new axle shafts and and birfields (outer axle shaft/joint). The new shafts for fr & rr can be an upgraded strength.

Replace the transfer case with a stock FJ40 t-case, or replace both the transmission and t-case with stock FJ40 4sp units.

However, with a 500+ HP engine, you will have to be mindful of the skinny pedal ;)
 
Or you could do a mini truck-LC hybrid centered rear end. You'll need a later 40 rearend and 85 or earlier Toyota pick up rearend. It's a relatively cheap mod. You can do an advanced search to find info on it. I also think there's a write up in faq. I've been running one for yrs with center rear output t/case. Imo, Offset rear output t/cases suck.
 
Can I rebuild or replace the third member in the rear to upgrade from the 10 spline axles to 30? Anyone make the axles anymore?
 
Bubbajones69 said:
Can I rebuild or replace the third member in the rear to upgrade from the 10 spline axles to 30? Anyone make the axles anymore?
Click to expand...

Never had 30 spline for the Cruiser centered rearend.
 
What about the 27 spline? Since it is a 9.5 housing wouldn’t a pinion upgrade do the trick? Looking at my front and rear thirds - the look the same - except front has fine splines and rear is only 10. This is definitely not my area of expertise, trying to learn as I go... my rear centered housing is in good shape (so is the third) I suppose I could always just clean it up rmayve replace the bearings and seals and run it till it breaks-

The front is a different story- the third for the front is going to need some major TLC - there was no fluid in the dif(it was only 2wd when I got it) lots of surface rust on the birfields and axle shafts and 50 years of crud.... I could really use a parts washer!
 
500hp in a truck in which every system is antiquated means you are going to replace just about EVERY Toyota part with 1 ton GM stuff before you are likely to be happy with it. And when I say that I mean the entire braking system, steering, suspension, electrical and so forth.

If you're set on it, it can certainly be done certainly not cheaply. Hopefully you are your own fabricator. For axles I'd probably go with Currie units that you can have made into any width. Or Dynatrac. You can narrow stock Dana 60's but you better know what you're doing to get it right the first time.

Just my $.02 but I've been down this road before...
 
That is pretty sweet - soo many choices! I really wanted to do the new Cummins but couldn’t come to terms with the crazy price. Got a great deal on the 383 stroker with full serpentine and efi - now just need a drivetrain that will be good... hp probably more around 400 - fat fingers earlier
 
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