Front 4.89 rear 4.86?

[quic]

I've used the search feature with no luck, if there is a thread already here, please provide a link
I am running 35s and I went to rock auto to buy some 4.88 gears. Looking at Motive gears they offer 4.86 for the ford 9 inch and 4.89 for the dana 44, is that close enough?
I am probably not going off road that much but if that changes, I don't want issues, that being said I'm sure to drive in the snow in 4wheel high.
Any input or recommendations are welcome,

Thanks!

 

[1969]

Yeah should be fine from what I’ve read before. Although I’m sure someone will be along shortly to explain exactly why.

 

[DirtDonk]

Yes, it is more than close enough.
It is not often that they match exactly. Usually, the only time you find that is either with certain ratios that happen to match between one manufacturer and another, or when the front and the rear differentials are exactly the same.
I believe my F350 with Dana 60 axles front rear has the same matching gear.
But the design differences between a Ford 9 inch and a Dana axle are so many, it’s not likely you’re gonna find many matching ratios.
And as said, it’s not that critical anyway. Getting it somewhat close is critical, but not the end of the world if it’s a couple of hundredths off.

Some mud competition mud pullers actually put a notably, taller gear in the front to help with pulling stability under high torque and low traction conditions.
For the rest of us, close enough is close enough.

But remember, this is precisely why all the manufacturers recommend against running in four-wheel-drive on the dry pavement.
You can run with the hubs locked and the transfer case into wheel drive, or you can run with the hubs unlocked and the transfer case four-wheel-drive and not have any issues. But lock them both together on high traction surfaces and binding can and will occur.
Most high traction conditions are where you start to find binding. When tires are allowed to slip more often, binding is not an issue.
Same reason you’re all wheel drive cars and SUVs. Don’t want you to have One or two tires that have more wear on them than the others. Even a slight difference in tire diameter can affect the systems.
Same for running a locker in your differential where one tire has lower air pressure than the other.

 

[SteveL]

I wondered if the slight differences in r

 

[SteveL]

I wondered if the slight difference in front and rear ratios was to make up for different ring gear diameters. Would also be why matching axles like front and rear Dana 60s would have the same ratio.

 

[DirtDonk]

Since Dana 44 and Dana 60s come in high pinion versions too, I’m not sure if all gear sets match exactly. But it’s possible they still do.

 

[Broncobowsher]

Over thinking it. Tires are not locked solid to the ground. Even on pavement. Rubber flexes. The tread blocks will bend a tine bit under load and spring back when unloaded.

The gearing engineering is strictly tooth count, nothing to do with diameter. When it was enginered, how many teeth on each. If you really want to get deep into it there is sometimes some engineering that gets into harmonics and resonance. There are also hunting, non-hinting, and semi-hunting ratios. Most are hunting, where one single gear tooth will eventually contact every single tooth on the other gear after enough rotations. The harmonics and resonance typically deal with engine firing pulses. Even number pinion gears are very rare. A v8 has 4 pulses per revelution. Thus avoid any gearing that has a harmonic of 4. 6 cylinder, has a harmonic of 3 pulses, thus avoid a 9 tooth pinion. Some gears have a specific purpose, some are just a ratio to get one. For engineered the 9" and Dana engineered the front axle. They didn't consult each other, they did what there own engineering demands required.

It isn't even consistent with the front being a higher or lower ratio than the rear. The factory 3.50 gearing option in the 9" had 3.54 in the front. But the 4.11 rear had a 4.09 or 4.10 front (depending on if a Dana 30 or Dana 44). Now consider that 4WD is to be used in low traction conditions only, tire slip is expected. If not, you don't need to be in 4WD. And for people who can't figure this out, the "auto" setting in modern 4WD vehicles.

 

[quic]

I really appreciate the replies. I definitely have a better understanding now, ready to spend some money, lol

Thanks again

 

[JeepGuy]

Over thinking it. Tires are not locked solid to the ground. Even on pavement. Rubber flexes. The tread blocks will bend a tine bit under load and spring back when unloaded.

The gearing engineering is strictly tooth count, nothing to do with diameter. When it was enginered, how many teeth on each. If you really want to get deep into it there is sometimes some engineering that gets into harmonics and resonance. There are also hunting, non-hinting, and semi-hunting ratios. Most are hunting, where one single gear tooth will eventually contact every single tooth on the other gear after enough rotations. The harmonics and resonance typically deal with engine firing pulses. Even number pinion gears are very rare. A v8 has 4 pulses per revelution. Thus avoid any gearing that has a harmonic of 4. 6 cylinder, has a harmonic of 3 pulses, thus avoid a 9 tooth pinion. Some gears have a specific purpose, some are just a ratio to get one. For engineered the 9" and Dana engineered the front axle. They didn't consult each other, they did what there own engineering demands required.

It isn't even consistent with the front being a higher or lower ratio than the rear. The factory 3.50 gearing option in the 9" had 3.54 in the front. But the 4.11 rear had a 4.09 or 4.10 front (depending on if a Dana 30 or Dana 44). Now consider that 4WD is to be used in low traction conditions only, tire slip is expected. If not, you don't need to be in 4WD. And for people who can't figure this out, the "auto" setting in modern 4WD vehicles.

That if far too much math and reasoning to deal with two days out from a turkey coma and only one cup of coffee into the day.

 

[Broncobowsher]

That if far too much math and reasoning to deal with two days out from a turkey coma and only one cup of coffee into the day.

I was tired, didn't even fix my typos. I forgot about the harmonics of the bearing race diameters also playing into the engineering.

 

[jamesroney]

Over thinking it. Ford engineered the 9" and Dana engineered the front axle. They didn't consult each other, they did what there own engineering demands required.

I'm pretty sure that the guy at Dana Spicer that engineered the F250 axles and put 41/10 = 4.10 in the Dana 60 rear and 45/11 = 4.09 in the Dana 44 front was probably able to consult with himself...

 

[Broncobowsher]

I'm pretty sure that the guy at Dana Spicer that engineered the F250 axles and put 41/10 = 4.10 in the Dana 60 rear and 45/11 = 4.09 in the Dana 44 front was probably able to consult with himself...

You are assuming they were both designed by the same person for the same application. The early Dana 44 axles I know of were passenger car applications and the 60 was truck applications. Although both have found there way into everything. Chrysler loved putting the 60 into muscle cars and the 44 has found itself in a lot of trucks. And not everything for highway use either. Dana also supplied the axles for street sweepers and ditch witches. I remember finding a set of factory installed 7.17 Dana 60 gears in a ditch witch once.

 

[Yeller]

The reason for the 4.09 in the Dana 44 is it makes a skip tooth so the every tooth of the pinion makes contact with every tooth of the ring gear. Theory being the gear set runs quieter and more even and have less harmonics. The truck D60 is less concerned about harmonics and noise.

 

[Broncobowsher]

The reason for the 4.09 in the Dana 44 is it makes a skip tooth so the every tooth of the pinion makes contact with every tooth of the ring gear. Theory being the gear set runs quieter and more even and have less harmonics. The truck D60 is less concerned about harmonics and noise.

That is a hunting pattern. The 41:10 4.10 ratio does the same thing
The 3.00 ratio used in some of the 8" cars is a non-hunting ratio. A tooth on the ring gear will only mate with the same tooth on the pinion every single time.
A semi-hunting pattern would be the 3.50 ratio where a single tooth on the ring gear will mate with multiple teeth on the pinion, but not all of them.

The hunting pattern will wear all the teeth evenly (in normal conditions). The non or semi hunting pattern can get one tooth with uneven wear and induce noise/vibration.

 

[lilthom]

I have a 9" Bronco third member with 4:88 ring & pinion- bearings with Yukon Trac Lock. They are 28 spline and have less than 3,000 miles on them (not crawling miles).
I also have the matching D44 ring and pinion with 4 low ration carrier. I am selling these for $1,000 if they fit your needs.