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3/4 ton swap

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k5blazinredneck

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So my plan is to do a 3/4 ton swap for my 1990 blazer. I'm relatively new to all of this mechanical stuff so what all is required. Also, is the 14b(ff or sf) and Dana 44 the best option? What all would have to be modified to do this swap. What would be the best gearing option for either 35x13.50r15 Toyo open country M/Ts or 35x14.50r15 Nitto Mud Grapplers?
 
I did the 3/4 ton swap. Are you doing a lift at the same time or already lifted?

3/4 ton swap consists of a front Dana 44 8 lug or GM corp 10 bolt 8 lug. The rear 14b semi float is also considered 3/4 ton. A Dana 60 front and 14b full float rear would be a 1 ton swap. Although some 3/4 ton trucks came with the 14b ff rear. And to confuse you even more, it is not uncommon to find a 1 ton truck that has had 3/4 ton axles swapped under it. So, you need to know what you are looking at when you go out looking for axles or a donor truck.

My donor truck had the 10b front and 14bsf rear with 4.10 gears. I have no problem running 35" tires with the 4.10s but the optimal gear ratio for 35s behind a 700R4 would be 4.56s (some say 4.88s or 5.13s).

If you have to buy tires, forget about 15s. You will at the least need 16s but you may be better off going straight to 17s. The 3/4 tons have huge front brakes and need a 16" wheel for clearance. Unless you want to grind the brakes to clear 15s or use a heavily offset wheel for clearance. I found a set of used 17" H2 wheels for my swap.

I'll link a pic for your viewing pleasure....
gallery_195_54_3375985.jpg
 
There isn't much of a difference between an 8 lug Dana 44 and an 8 lug 10 bolt. The older, external hub Dana 44's are a little weaker at the hubs though. The 14 bolt full floater is a better axle than the semi floater. Although a 14 bolt semi floater is a small upgrade over a rear 10 bolt.

As for wheels, 15" wheels fit with a small amount of grinding, but you will need 8 lug, 15" wheels.

What transmission do you have? That we'll determine what gearing you need. I have 4.10's with my SM465 in my Suburban, and I wouldn't want any deeper.

Martin
 
82355 said:
The 14 bolt full floater is a better axle than the semi floater. Although a 14 bolt semi floater is a small upgrade over a rear 10 bolt.

Martin
Click to expand...

Martin, can you clarify this statement? How is a 14bsf just a "small" upgrade over a tiny 10 bolt? I am kinda new to the game but find it hard to believe a 14bsf is a small upgrade.

Ben
 
82355 said:
There isn't much of a difference between an 8 lug Dana 44 and an 8 lug 10 bolt. The older, external hub Dana 44's are a little weaker at the hubs though. The 14 bolt full floater is a better axle than the semi floater. Although a 14 bolt semi floater is a small upgrade over a rear 10 bolt.

As for wheels, 15" wheels fit with a small amount of grinding, but you will need 8 lug, 15" wheels.

What transmission do you have? That we'll determine what gearing you need. I have 4.10's with my SM465 in my Suburban, and I wouldn't want any deeper.

Martin
Click to expand...
i have the 700r4 transmission
 
496truck said:
I did the 3/4 ton swap. Are you doing a lift at the same time or already lifted?

3/4 ton swap consists of a front Dana 44 8 lug or GM corp 10 bolt 8 lug. The rear 14b semi float is also considered 3/4 ton. A Dana 60 front and 14b full float rear would be a 1 ton swap. Although some 3/4 ton trucks came with the 14b ff rear. And to confuse you even more, it is not uncommon to find a 1 ton truck that has had 3/4 ton axles swapped under it. So, you need to know what you are looking at when you go out looking for axles or a donor truck.

My donor truck had the 10b front and 14bsf rear with 4.10 gears. I have no problem running 35" tires with the 4.10s but the optimal gear ratio for 35s behind a 700R4 would be 4.56s (some say 4.88s or 5.13s).

If you have to buy tires, forget about 15s. You will at the least need 16s but you may be better off going straight to 17s. The 3/4 tons have huge front brakes and need a 16" wheel for clearance. Unless you want to grind the brakes to clear 15s or use a heavily offset wheel for clearance. I found a set of used 17" H2 wheels for my swap.

I'll link a pic for your viewing pleasure....
gallery_195_54_3375985.jpg
Click to expand...
its already lifted.
 
bensk5 said:
Martin, can you clarify this statement? How is a 14bsf just a "small" upgrade over a tiny 10 bolt? I am kinda new to the game but find it hard to believe a 14bsf is a small upgrade.

Ben
Click to expand...

Because it is still a semi floating rear end. Light duty junk. Find a Medium, or Heavy Duty truck running a semi floater . . . . . .

Martin
 
k5blazinredneck said:
its already lifted.
Click to expand...

Then plan on getting some new u-bolts, front and rear. Mainly because it's not a good idea to reuse old u-bolts, especially on the front. And you'll need new ones for the rear because the axle tubes are larger.

Whatever shocks you have now can be reused if they are in good condition, front and rear.

The raised steering arm can be transferred from your old front 10b to the new front 10b or D44 (whichever you find). A 10b is essentially a D44 from the knuckles out. The 10b front axle isn't really better or worse than a front D44. I like the 10b because there are plenty of them out there, parts seem to be cheap and plentiful. Some people will say that once you put the word Dana in the description the parts double in price for no apparent reason.

Rear driveshaft is a crapshoot. You will need a conversion joint at the rear joint or what I did was swap the pinion yoke from the old rear 10b over to the 14b sf. That way I have all the same joints instead of one oddball. The yoke is a direct swap but I suggest a new pinion seal while you have it apart. The biggest problem you may have though is the spring perches on the 14b sf. Mine came out of a reg cab long bed K20 and once installed it pointed the pinion almost directly at the t-case. That required me to have a new rear CV driveshaft made after the lift/axle swap. May not be your case but plan for that expense.

Some will, and have, said the 14b sf isn't worth the upgrade. The fact is that it's a huge improvement over the 10b rear, even if it is still a semi floating axle. All depends on how you want to use it. The axle shafts are huge in comparison, the gears are larger, bearings are bigger, carrier is bigger. It's a good axle upgrade for up to 35" tires and mild/moderate wheeling. Would I suggest it for 35s (or larger) and hard core wheeling? No, I would not. But for most users it is a good rear axle.

How do you plan to use the truck? That's the deciding factor for your axle choice.
 
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