full size dana 44 questions

[papy]

i have a spare dana 44 from a 79 bronco. just wondering what the main differences are between an early bronco dana 44 and the 78/79 bronco/f150 dana 44 are? i know the width is different what else?

if adapting to an early bronco other than the length of the passenger's side are they the same?

JP

 

[Rustytruck]

The differential is a high pinion and the early bronco is a low pinion. you need a higher lift to use a high pinion. I believe the axle tube in the later Bronco is thicker. the axle wedges are castings so the tube isnt continuous on the drivers side. the high pinion turns in reverse rotation and is stronger because the gears are not driving on the coast side of the gears. the later Bronco has disc brakes. Its allot of work to make a later bronco cut down to early bronco width.

 

[papy]

Great info!
Thank you

 

[jamesroney]

The differential is a high pinion and the early bronco is a low pinion. you need a higher lift to use a high pinion. I believe the axle tube in the later Bronco is thicker. the axle wedges are castings so the tube isnt continuous on the drivers side. the high pinion turns in reverse rotation and is stronger because the gears are not driving on the coast side of the gears. the later Bronco has disc brakes. Its allot of work to make a later bronco cut down to early bronco width.

The differential is a high pinion, and the EB is low pinion. You do not need a higher lift to use a full width high pinion, but if you narrow a high pinion to use EB length shafts, you will need 3.5 inches of suspension lift. The axle tube in the 78-79 Bronco (3.0 x 1/4 wall) is thinner and stronger than the Early Bronco, (2.75 x 5/16wall) The 76-77 F150 Dana 44 is Thicker than the early Bronco at 2.75 x 1/2 wall. The 78-79 axle wedges are cast into the inner C, so the tube isn't continuous on either side. The high pinion turns exactly the same rotation as the low pinion, (otherwise it would drive backwards) but the gears are machined to be stronger in the reverse direction and are not driving on the coast side of the gears. Reverse rotation gears rotate the same direction as normal gears. The 78-79 Bronco has the exact same disc brakes as the 76-77 Bronco. It is a lot of work to cut down a 76-77 F100 housing. It is even more work to cut down a 78-79 housing to early bronco width. You cannot independently change the caster from the radius arm wedge angle on a 78-79 housing. 75-79 F100 knuckles have a different ackerman angle, and tie rod end taper, and use bigger and stronger axle shaft u-joints. 78-79 housings use different inner axle seals.

Passenger side is ~6 inches longer, Drivers side is 5/8 longer.

 

[Madgyver]

we did a full width high pinion D44 swap.

 

[Nothing Special]

.... The high pinion turns exactly the same rotation as the low pinion, (otherwise it would drive backwards) but the gears are machined to be stronger in the reverse direction and are not driving on the coast side of the gears. Reverse rotation gears rotate the same direction as normal gears....

You can flip a low pinion axle so the right end is on the left and the left end is on the right. If you do that it will have a high pinion, but if you tried to use it the axle would rotate the wrong direction. "Reverse rotation" gears correct that. So yes, in a high pinion axle with reverse rotation gears everything will rotate the same direction as it does in a low pinion axle that's installed correctly. But reverse rotation gears are needed in a high pinion axle to reverse the rotation you would otherwise get.

 

[bax]

The differential is a high pinion, and the EB is low pinion. You do not need a higher lift to use a full width high pinion, but if you narrow a high pinion to use EB length shafts, you will need 3.5 inches of suspension lift. The axle tube in the 78-79 Bronco (3.0 x 1/4 wall) is thinner and stronger than the Early Bronco, (2.75 x 5/16wall) The 76-77 F150 Dana 44 is Thicker than the early Bronco at 2.75 x 1/2 wall. The 78-79 axle wedges are cast into the inner C, so the tube isn't continuous on either side. The high pinion turns exactly the same rotation as the low pinion, (otherwise it would drive backwards) but the gears are machined to be stronger in the reverse direction and are not driving on the coast side of the gears. Reverse rotation gears rotate the same direction as normal gears. The 78-79 Bronco has the exact same disc brakes as the 76-77 Bronco. It is a lot of work to cut down a 76-77 F100 housing. It is even more work to cut down a 78-79 housing to early bronco width. You cannot independently change the caster from the radius arm wedge angle on a 78-79 housing. 75-79 F100 knuckles have a different ackerman angle, and tie rod end taper, and use bigger and stronger axle shaft u-joints. 78-79 housings use different inner axle seals.

Passenger side is ~6 inches longer, Drivers side is 5/8 longer.

Lots of good information here. My personal favorite is the f 100 axle housing. I will not use the 78/79 axle housings if I was building a stock width bronco axle.

 

[jamesroney]

You can flip a low pinion axle so the right end is on the left and the left end is on the right. If you do that it will have a high pinion, but if you tried to use it the axle would rotate the wrong direction. "Reverse rotation" gears correct that. So yes, in a high pinion axle with reverse rotation gears everything will rotate the same direction as it does in a low pinion axle that's installed correctly. But reverse rotation gears are needed in a high pinion axle to reverse the rotation you would otherwise get.

Uhm, I'm not sure that you have given this a lot of thought. So I'll try to explain. lets start with the rear axle. Note that all references are based on looking at the pinion. A standard Hypoid ring and pinion puts the ring gear on the RIGHT side of the pinion gear. When the ring gear is on the RIGHT, then if you rotate the pinion clockwise, the pinion pushes DOWN on the ring gear. That makes the car travel forward.

As you move the pinion up, you eventually get to a spiral bevel arrangement, where the pinion is in direct alignment with the axle shafts. Again, rotating the pinion clockwise pushes the ring gear down in the front. The only way that a pinion gear turning clockwise can push a ring gear down is if the ring gear is on the right. As you move up to where a high pinion is located, the ring gear is STILL on the right, and still pushes down in front when the pinion turns clockwise.

If you flip a low pinion axle, the ring gear will be on the left of the pinion. No matter what you do...if you rotate the pinion clockwise, the ring gear is going to move up in front, and the car is going backwards. If you put in a high pinion gearset with the ring gear on the left...no matter how you spiral it, the car is going to go backwards. You might have noticed that high pinion and standard pinion both use the same cover. A high pinion axle is not a flipped over low pinion axle. The pinion stay on the same side.

Reverse rotation gears cannot correct that. Nothing can correct that. It's physics. They only move the contact patch to the drive side of the tooth when turning counter-clockwise in a front axle.

I sure hope I'm right...

 

[Nothing Special]

Uhm, I'm not sure that you have given this a lot of thought. So I'll try to explain. lets start with the rear axle. Note that all references are based on looking at the pinion. A standard Hypoid ring and pinion puts the ring gear on the RIGHT side of the pinion gear. When the ring gear is on the RIGHT, then if you rotate the pinion clockwise, the pinion pushes DOWN on the ring gear. That makes the car travel forward....

Actually I have. Let's start with a standard low pinion rear diff as you describe. You are correct that from the perspective of looking toward the pinion (backward with respect to the truck), the ring gear is to the right of the pinion gear, and rotating the pinion clockwise pushes down on the front side of the ring gear, pushing the truck forward. No disagreement there.

Now take the same differential and put it in a front axle. The pinion is still low. Nothing is changed except that the pinion is now pointing to the rear. But that also changes your perspective. Staying with the perspective you set, we will continue to look at the pinion, but that means we are now looking forward with respect to the truck. From the perspective of looking at the pinion the ring gear is still to the right of the pinion so when you turn the driveshaft clockwise it still pushes down on the pinion side of the ring gear. But now the pinion is on the rear of the axle, so pushing down on the pinion side of the ring gear pushes the truck backward.

However, since we turned around to look at the pinion of the front axle we've reversed our perspective on the driveshaft. So with the trans in a forward gear the driveshaft is actually turning counterclockwise from this perspective. With the ring gear to the right of the pinion gear now the pinion gear is pushing up on the pinion side (back side) of the ring gear and it's pushing the truck forward. Therefore the same gears work in either a low pinion rear axle or a low pinion front axle. It's just that you're driving the opposite sides of the teeth, strong side in the rear, weak side in the front.

OK, now instead of putting the rear diff we started with in the front axle in a low pinion arrangement let's put it in the front as a high pinion. Same diff, same parts so it still has to do the same things. To get the diff positioned like this we can imagine just rotating the housing while the tires stay put. That would make the pinion point backward and be above center, a high pinion front axle.

And again we'll keep the perspective of looking at the pinion, but again, this has reversed our perspective with respect to the truck because we're again looking toward the front of the truck. From this perspective now the ring gear is on the LEFT of the pinion gear, because we didn't move the ring gear at all when we flipped the axle, and we only moved the pinion back and up, we didn't move it side-to-side at all.

So now when we rotate the driveshaft clockwise from this perspective the pinion gear pushes UP on the pinion side (back side) of the ring gear and the axle pushes the truck forward. But remember that we're now looking at the driveshaft from the opposite direction, so actually when the trans is in a forward gear the driveshaft is turning counterclockwise, the pinion gear pushes the back side of the ring gear down and the axle drives the truck backward.

That doesn't work very well, having a low pinion rear axle pushing the truck forward while a high pinion front axle pushes it backward. So you correct that by putting reverse rotation gears in a high pinion axle.

 

[jamesroney]

Actually I have. Let's start with a standard low pinion rear diff as you describe. You are correct that from the perspective of looking toward the pinion (backward with respect to the truck), the ring gear is to the right of the pinion gear, and rotating the pinion clockwise pushes down on the front side of the ring gear, pushing the truck forward. No disagreement there. (James...OK)

Now take the same differential and put it in a front axle. The pinion is still low. Nothing is changed except that the pinion is now pointing to the rear. But that also changes your perspective. Staying with the perspective you set, we will continue to look at the pinion, but that means we are now looking forward with respect to the truck. From the perspective of looking at the pinion the ring gear is still to the right of the pinion so when you turn the driveshaft clockwise it still pushes down on the pinion side of the ring gear. But now the pinion is on the rear of the axle, so pushing down on the pinion side of the ring gear pushes the truck backward. (James...need to clarify your frame of reference. When we are looking forward, the ring gear is still to the right...but we now turn the pinion Counter-Clockwise...because we are looking at the pinion from the back. If you turn the driveshaft clockwise, then ideed it will back up.)

However, since we turned around to look at the pinion of the front axle we've reversed our perspective on the driveshaft. So with the trans in a forward gear the driveshaft is actually turning counterclockwise from this perspective. With the ring gear to the right of the pinion gear now the pinion gear is pushing up on the pinion side (back side) of the ring gear and it's pushing the truck forward. Therefore the same gears work in either a low pinion rear axle or a low pinion front axle. It's just that you're driving the opposite sides of the teeth, strong side in the rear, weak side in the front. (james 100% agree)

OK, now instead of putting the rear diff we started with in the front axle in a low pinion arrangement let's put it in the front as a high pinion. Same diff, same parts so it still has to do the same things. To get the diff positioned like this we can imagine just rotating the housing while the tires stay put. That would make the pinion point backward and be above center, a high pinion front axle. (James-yes, but you have now moved the ring gear to the left of the pinion. So it will drive backwards. No different front or rear. Flip a rear axle in the back, and it will run backwards.)

And again we'll keep the perspective of looking at the pinion, but again, this has reversed our perspective with respect to the truck because we're again looking toward the front of the truck. From this perspective now the ring gear is on the LEFT of the pinion gear, because we didn't move the ring gear at all when we flipped the axle, and we only moved the pinion back and up, we didn't move it side-to-side at all. (james- you lost me. are we still with a normal LP axle flipped, or did we change? If you flip the axle, you move the ring gear to the left of the pinion.)

So now when we rotate the driveshaft clockwise from this perspective the pinion gear pushes UP on the pinion side (back side) of the ring gear and the axle pushes the truck forward. But remember that we're now looking at the driveshaft from the opposite direction, so actually when the trans is in a forward gear the driveshaft is turning counterclockwise, the pinion gear pushes the back side of the ring gear down and the axle drives the truck backward. (James - I don't think so. If you rotate the driveshaft clockwise on your flipped axle, it woudl indeed go forward. but as you say...the transfer case rotates the pinion CCW in forward.

I'm trying to keep up...my comments in your post above. Can we just stay focused on one end or the other? I'm getting lost between front and rear, flipped and low pinion vs high pinion.

If we stick with a normal low pinion axle in the front...can we agree that flipping it moves the ring gear from the right to the left and that no gears of any kind will reverse them?

 

[Madgyver]

Keep it simple. run that 79 axle as is. adjust your upper coil mounts to it. add trackbar riser on axle if lifted. My opinion

 

[papy]

Keep it simple. run that 79 axle as is. adjust your upper coil mounts to it. add trackbar riser on axle if lifted. My opinion