Fj40 axles swap. School me

Joined
Feb 13, 2018
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41
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Southern Illinois
Looking for some feedback on my little bobbed ‘86 4Runner project. Scored some fj40 axles for the right price with 5.29 gears and was thinking of using them for my SAS. I know the gas tank will have to be moved to clear the driveshaft but has anyone else done this swap? Any issues id probably run into?
28AFC0C3-46F2-4F1B-9F31-85E8FB5062FE.jpeg
 

Gumby

Supamod
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Knee deep in hookers and gin
 
 
 
 
Centering a 40 rear isn’t that hard. The inner diameter of the tube is the same as the OD of a mini housing. Use mini outer tubes and axles.

Woody has a write up that’s prolly 20 years old.
 
Joined
Feb 9, 2004
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3,035
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Cool Comfy AZ
 
 
 
I guess you could, but I also have to ask why? That 40 front axle is way early, drum brakes, likely coarse spline birfs, etc.

Keep the wider rear axle on the 4runner, obtain a 84-85 front axle (disc brakes, fine spline birfs, later locking hubs), do the SAS, steering is gonna be crossover any way and your box is already there.

To each his own, just throwing it out there.
 
Joined
Feb 13, 2018
Messages
41
Location
Southern Illinois
I guess you could, but I also have to ask why? That 40 front axle is way early, drum brakes, likely coarse spline birfs, etc.

Keep the wider rear axle on the 4runner, obtain a 84-85 front axle (disc brakes, fine spline birfs, later locking hubs), do the SAS, steering is gonna be crossover any way and your box is already there.

To each his own, just throwing it out there.
the axles were free and bigger housing and already have the gears I was planning on. I also have wide offset wheels to keep the stance wide
 
Joined
Dec 19, 2007
Messages
481
Location
Harrisonburg, VA
 
 
Looking for some feedback on my little bobbed ‘86 4Runner project. Scored some fj40 axles for the right price with 5.29 gears and was thinking of using them for my SAS. I know the gas tank will have to be moved to clear the driveshaft but has anyone else done this swap? Any issues id probably run into? View attachment 2316797
you’d be way better off finding a mini axle and use your ifs rear. That 40 axle has drum brakes, coarse spline axles and is spring under.You’d be way farther ahead buying 5.29’s for 8” diffs than all the fab work it will take to make those work. Your deep dish wheels won’t overcome the width differences. You can use your ifs hubs on a mini front axle and the width will match your ifs rear.
 
Joined
Feb 9, 2004
Messages
3,035
Location
Cool Comfy AZ
 
 
 
you’d be way better off finding a mini axle and use your ifs rear. That 40 axle has drum brakes, coarse spline axles and is spring under.You’d be way farther ahead buying 5.29’s for 8” diffs than all the fab work it will take to make those work. Your deep dish wheels won’t overcome the width differences. You can use your ifs hubs on a mini front axle and the width will match your ifs rear.
What he said. You're going to eventually put disc brakes on that coarse spline 40 axle and you won't like it doing it. Oh and you'll need to center the rear diff. Sure it can be done but again, why?

The ring gear is larger, but so what? Unless you plan on running sticky 42s and hydro steering and will be fully locked, you're fine. I've run 35s with stock original ring gears and original birfs for almost 3 decades with this rig.

Good luck with the build regardless of what you do. It's your rig, feel free to ignore us. Have fun.
 
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