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3/4 ton Swap?

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k5blazinredneck

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I have been looking for a set of 3/4 ton axles for a while now and finally found some... i have a few questions about it though. The set i found is a 14 bolt (ff i think, idk how to tell a difference), and an 8 lug 10 bolt. the set costs $300. is it worth the money? i plan on running around 38s. i dont do very much wheeling so not much abuse. Is this really as effective as people say it is? And the only thing required is brake lines, conversion u joints, and new u bolts for the rear, right?
 
Depending on motor, Im assuming a 350, get some with 4.56s if possible. They can be found with a rear locker if your lucky. I would just spend the extra pennies and get front u bolts too. You will be amazed at the brakes too, much bigger and better. You can get away with 4.10s, but Iv always liked 4.56s because if you ever wana get a lower ratio, you dont have to find the carrier too. I think the front driveshaft will be fine, for the rear, you could probably just have one built for 200ish, with the same big joints, and not have to worry about which joint goes where. And 300 aint a bad price if all is well and good with them. The full floater has removable axles, I believe 8 bolts on the outside of the hub, big bolts, like 5/8in or so, the semi floater does not. That being said, I would really look for an axle with 4.56s over the 4.10s, I had 4.10s for a long time with a 350 and a th400, hated it, a dog for sure. Also, easy non dirty way of checking rear end ratio is instead of pulling the cover and counting teeth, you grab the yoke, and turn it over one full rotation and count how many times the tire rotates, if it goes over 3 and 3/4 times, its a 3.73, if it spins 5 and some change, its a 5.13. Its not exactly a fool proof way, but it gets you in the ballpark. the difference between 4.10s and 4.56s is not alot, but it is noticeable if you look closely
 
454Sub said:
Also, easy non dirty way of checking rear end ratio is instead of pulling the cover and counting teeth, you grab the yoke, and turn it over one full rotation and count how many times the tire rotates, if it goes over 3 and 3/4 times, its a 3.73, if it spins 5 and some change, its a 5.13. Its not exactly a fool proof way, but it gets you in the ballpark. the difference between 4.10s and 4.56s is not alot, but it is noticeable if you look closely
Click to expand...

i think you've got that backwards - but it could be the coffee talking. turn the yoke until the hubs/tires go one full rotation. count the yoke revs while you do this - that's your approximate gear ratio.
 
The axle retaining bolts on a 14bff are 1/2" bolts with a 3/4" head on them. The conversion u-joint works just fine.

Martin
 
If the front is a 10 bolt, chances are that the rear is a semifloat 14 bolt. Seems to me like the 3/4 ton 14bff only came in the older trucks, most of which had d44 fronts.
 
From 80 till ? had the FF rear and the 10bt, If memory served me pickups had the FF more often than the Sub, my brother bought a 3/4ton 91 and it had a 10bt and a SF 14bt, mine was an 80 3/4ton and it was a 10bt and FF 14bt
 
I am not positive, but I believe 1981 was the last year for the 3/4 ton 14 bolt full floater, and all 1982+ 3/4 ton Suburbans had 14 bolt semi floater rears.

The Dana 44/10 bolt front split is not nearly as well defined. Some late 70's models have a 10 bolt from the factory, and some 1980 models still have a factory Dana 44.

Martin
 
Can anyone tell from this picture if it is a ff or sf?
5La5Ha5M43L73I63Nac9c7d235cc13a6318e2.jpg
 
ok so i found another good deal. which is the better deal, the one posted above, or an eaton h072 rear with a dana 44 hd front. he doesnt know what gears are in it but he thinks it has 4:10s and a rear detroit. I found out that the first set has 3:73 gears. 300 for the 14bff and 10b. 350 for the eaton, d44.
 
The eaton is the 14ff's older brother. It won't be a bolt in. But a Detroit is a big plus. Be aware that there isn't much support for it. They are big, but Normally don't break. I would suggest making sure it has a Detroit. Otherwise I wouldn't bother with it. Not for that much $.

14b disc brake kits will also fit the eaton. You can also put 14ff shafts and Detroit in it.

If the Dana 44 is from the same vehicle as the eaton, its not a big deal either. External locking hubs are a turn off. I would also check the ball joints for play.

If it was me, I would buy it just for the locker. But it depends on if you really need it. Also if you want to go lower gears later, used 4.57s or 5.13s are hard to find.

Edit- 4.10s are the highest gears available for that axle. So you don't have to worry about it having 3.73s or higher
 
Detroit locker + flat top knuckle = way more than worth it to me. The Eaton is less common but basically equal in strength to the 14 bolt, parts are still available.

The Detroit, by itself, is in the upper $400's now-a-days. Add in a super stout rear axle, decent gears (you didn't mention what trans) and a front axle that is better suited for crossover and that's a winner in my book :pimp:
 
I think i have decided on the 14 bolt. what seals would you guys recommend that i replace before i put them on my blazer. and what seals for the front 10 bolt?
 
Whichever seals are leaking.

Rear hub seals
Diff covers.
Front inner axle seals ONLY if they are leaking.
 
Ok so I went and picked up the 10&14 bolt axles for 250$ today. I only found one thing wrong with them. On the 10 bolt, the pass. Side backing plate is bent. Where could I find one of these and how much would it cost? I'm going to use this thread to post all of my questions about this axle swap...
 
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