Front Differential?

[MrJoe]

Back in 19-dickety-2 that would be sound advice but we've had overdrive transmissions in pretty much everything since the '80s. You're not going to be at redline at 70-75mph unless you're stuck in 2nd, maybe 3rd gear, for some reason.

I remember 19-dickety-2....lol

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[AcesandEights]

There are several examples of them not being exactly the same, but generally you want them the same: 4.10/4.11.

@buzpro You can't change anything without affecting something else. Every action has an equal and opposite reaction. Actually, you can change quite a bit and there will be a change, but it won't necessarily be adverse. The transmission is automatic and will choose the gear you need, or you can change it to where you want your RPM to be. Easy enough. These rigs will run 30" tires or 35" tires and they'll hunt a little for the right gear, but in a 10-speed trans, it's there somewhere. Those tires though, they're a gear too, and acceleration, braking, stopping distances will be impacted by that larger tire, and the tread pattern and the rubber compound and all of those things. The answer is a moving target. The one constant I can offer in this whole thing though is, anarchy is a valid political philosophy and ideology, so we have that going for us.

Oh, and don't forget to tie an onion to your belt.

 

[3Dogs]

Someone needs to tell my Scout II with a full locker in the rear that, I've been driving on the street for years with it.
Not to mention all the guys driving with a spool or Lincoln Locker

They're your tires/differential/axles. You can stress them all you want.

 

[buzpro]

There are several examples of them not being exactly the same, but generally you want them the same: 4.10/4.11.

@buzpro You can't change anything without affecting something else. Every action has an equal and opposite reaction. Actually, you can change quite a bit and there will be a change, but it won't necessarily be adverse. The transmission is automatic and will choose the gear you need, or you can change it to where you want your RPM to be. Easy enough. These rigs will run 30" tires or 35" tires and they'll hunt a little for the right gear, but in a 10-speed trans, it's there somewhere. Those tires though, they're a gear too, and acceleration, braking, stopping distances will be impacted by that larger tire, and the tread pattern and the rubber compound and all of those things. The answer is a moving target. The one constant I can offer in this whole thing though is, anarchy is a valid political philosophy and ideology, so we have that going for us.

Oh, and don't forget to tie an onion to your belt.

I'm having trouble hitting that moving target .... I want an answer that says if you do this you will get that .... i know its wishful thinking but as long as i have the ammo i will keep shooting .... who knows... maybe one day?

 

[Neps]

You know you can’t drive on the highway with the rear locked, right?

They're your tires/differential/axles. You can stress them all you want.

Thanks I was seeking your permission

Actually I was pointing out that you statement was incorrect. Only relatively recently have vehicles with lockers been able to unlock the rear axle to drive on pavement. People can and do drive at highway speeds with a locked rear axle all the time.

 

[AcesandEights]

You mean like a Detroit, welded/Lincoln, or my favorite around midday, the lunchbox? Yeah, lockers aren't a huge deal on road, but they can impact driveability/handling. You just get used to it. Having an e-locker though is the best of all worlds, known and unknown.

 

[Cased]

Just a note here a spool is different than a locker
One ratchets and one hops the inside tire in a turn

These Elockers are similar to a spool but can be disengaged so you dont break shit

 

[AcesandEights]

Fish-on!

 

[AcesandEights]

Auto trans, 4.27 gearing at 75mph in "10th" gear (.636:1)

32" tires - 2139 rpm
35" tires - 1955 rpm

In "9th" gear, with 35" tires it's 2118 rpm, so your auto trans will run where it needs to run. You won't have to worry about driveability. Off road, lock it into 4L and 1st gear and tackle any terrain.

1st gear is pretty low, 4.714, so you should still have plenty of acceleration going from 32" to 35" tires. Braking will feel a bit slow, but you'll get used to it pretty quick.

 

[Mattwings]

I think off road tires might help a welded up or spooled axle live a bit longer locked up “crudely “. I know back in the day when guys rans spools with cheater slicks or big 15” MT Drag tires, it was quite a scene when they would drive on the street. It wasn’t uncommon to have a lunchbox locker shoot a tooth out of the rear diff cover (my buddies 57 Chevy and Chevy 12 bolt, welded solid, shot a tooth through the grill and radiator of a 67 GTO at a stoplight) or hop half a lane in a turn around and smack another car. You couldn’t get me to drive a spooled car on the street these days

 

[grimmjeeper]

There are several examples of them not being exactly the same, but generally you want them the same: 4.10/4.11.

@buzpro You can't change anything without affecting something else. Every action has an equal and opposite reaction. Actually, you can change quite a bit and there will be a change, but it won't necessarily be adverse. The transmission is automatic and will choose the gear you need, or you can change it to where you want your RPM to be. Easy enough. These rigs will run 30" tires or 35" tires and they'll hunt a little for the right gear, but in a 10-speed trans, it's there somewhere. Those tires though, they're a gear too, and acceleration, braking, stopping distances will be impacted by that larger tire, and the tread pattern and the rubber compound and all of those things. The answer is a moving target. The one constant I can offer in this whole thing though is, anarchy is a valid political philosophy and ideology, so we have that going for us.

Oh, and don't forget to tie an onion to your belt.

The rule of thumb is that you need to have them within 1% of each other. I've seen Jeeps with a 4.11 front Dana 30 and a 4.09 rear Dana 44 from the factory. That's 0.02 off which is 0.5%.

There's always a little variance in tire size and what not. And the differentials accommodate it pretty well up to a point.

 

[Rocketeer Rick]

Individuals can "do" whatever they want. Ford can't. Driving a spooled or locked axle on high traction surfaces absolutely will necessarily turn your axle into a big torsion spring. Depending on how grippy the tires are, you'll either scrub the tires when you go around turns, or wind the wheel speed differences up and down in the axle shafts. That will eventually fatigue them and cause a shaft (or differential) failure. If you're willing to accept that, cool.

OTOH, Ford has to absolutely cover their butts in terms of liability and warranties. So, between that and the fact that they recognize that locking an axle also influences how well a vehicle steers, you can understand why they put limits on when the lock can be used. This is especially true on the front end. Since that is the steering axle, locking it compounds the resistance to being able to steer.

Another note regarding axle size designations, as noted, they are typically - but not always - labeled based on the ring gear pitch diameter. The pitch diameter is the theoretical meshing centerline, where the ring and the pinion come together. Since its theoretical, you can't directly measure it. That hardly matters anyway, since manufacturers take pretty big liberties with the naming.

Often, an updated design or different variation might get a modified number even if the basic geometry isn't changed. And, of course, rounding can be involved as well. A Ford 8.8 and a 9" actually have basically the same pitch diameter, ring gear pilot diameter, and IIRC, bolt pattern. But they have distinct names because they have some pretty noticeable differences in other important areas.

Dana traditionally didn't name their axle sizes in a diameter reference. Instead, they used a series of numeric designations that generally represented progressively larger sizes, ie 28, 30, 35, 44, 60, 70, etc. But recently, they've shifted to a more conventional scheme, as mentioned before, in metric sizes. But even then, there are variations of given sizes that have different numbers, but are primarily the same. The M190 is essentially a traditional Dana 30 in terms of basic size. The M200 seems to equate to a Dana 35. But as far as I've been able to discern, the M210, M220 are M226 are all variations of a Dana 44 size. The M230 is bigger, but not as big as a Dana 60. It might be more analogous to Dana 50.

So, by using the M190 in the front and M220 in the rear, with the M210 optional in the front, it is pretty much on par with what the Wrangler has traditionally done. They just did away with the base Dana 35-sized rear end.

 

[ZackDanger]

The rule of thumb is that you need to have them within 1% of each other. I've seen Jeeps with a 4.11 front Dana 30 and a 4.09 rear Dana 44 from the factory. That's 0.02 off which is 0.5%.

There's always a little variance in tire size and what not. And the differentials accommodate it pretty well up to a point.

 

[Tdifonzo]

Just get the 4.27 rear end. It will be ever so slightly more peppy with the stock tires and will be better if you ever decide to size up to 33s. Comes with the rear locker which could come in handy. And the best part yet, it comes with the Advanced Auto 4x4 which will be nice in the rain/snow.

Just do it.

 

[VoltageDrop]

You're just going to drop that here and not tell us WTF happened?

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