Using front locker without the rear?

[Darkwing327]

Hi All,

Question that I am wondering about before changing my wiring around. 2005 TJ Rocky Mountain with factory Dana 44/D30s. I put ARB lockers front and back and wired them as per ARB's suggestion....Rear locker slaved off compressor switch...front locker slaved off of rear locker switch.

Went out wheeling a couple weeks ago and the other guys asked why I wouldn't wire them independently...and I could not answer that. In saying that, none of them could tell me why I should either, so we just kind of pondered it and moved on.

So my question is, is there any reason to do so? I understand the benefits and purpose of using the rear first, but are there other scenarios I just haven't hit yet in my limited experience where it would be wise to have the front locker independently selectable?

Oh, and one final question. From reading I understand that with the factory Rubicon Dana 44 LSD locker it is advisable to run the rear locked all the time in order to save wear and tear on the axle. Should I be doing this with my ARB or is it not necessary. To be honest 95% of the off road driving around here is done in 2wd (ie one wheel drive with the open diff).

Thanks much,
Darren

 

[mrblaine]

Hi All,

To be honest 95% of the off road driving around here is done in 2wd (ie one wheel drive with the open diff).

Thanks much,
Darren

At no point in time do you have 1 wheel drive with an open diff. That isn't how it works, at all. With an open diff, both sides receive exactly the same amount of torque. Since torque is a function of resistance, if a tire has very low traction and it takes a small amount of torque to make it spin, that exact amount is also delivered to the tire with very high traction and it won't spin because it has high traction. But, both are being driven, it just doesn't look like it.

 

[JDS123]

My ARB's are wired so I can only hit the front one if the rear one is on. I've never come across a scenario where I just want the front locker. I'd just leave it the way you have it.

 

[mrblaine]

My ARB's are wired so I can only hit the front one if the rear one is on. I've never come across a scenario where I just want the front locker. I'd just leave it the way you have it.

I use my front only a bunch when I know I'm going to do a front dig. Turns much easier with the rear unlocked.

 

[Darkwing327]

At no point in time do you have 1 wheel drive with an open diff. That isn't how it works, at all. With an open diff, both sides receive exactly the same amount of torque. Since torque is a function of resistance, if a tire has very low traction and it takes a small amount of torque to make it spin, that exact amount is also delivered to the tire with very high traction and it won't spin because it has high traction. But, both are being driven, it just doesn't look like it.

Gotcha.

The reason I put lockers in this year is because we spent a month down in Moab last year and I had off-road envy because I had zero confidence in the sand in my open/open TJ. I actually use my jeep to plow my 600' driveway and we laughingly called it 'no wheel drive' because if the snow was heavy enough it went nowhere and I had to break out the chains LOL. I didn't want this to happen in the desert sand.

FWIW I have been stuck twice in the snow since the locker install...the first time it saved my bacon. The second time I drove off the end of our driveway and couldn't quite understand why the lockers didn't help at all until I stepped out the door and sunk up to my chest Had to get the dually to act as an anchor point so I could winch out. Keep in mind that this is only when pushing a 7 foot wall of snow, other than that the TJ had been a fantastically capable daily driver for many years for me.

 

[Darkwing327]

I use my front only a bunch when I know I'm going to do a front dig. Turns much easier with the rear unlocked.

I can see that being beneficial. I have yet to come across anything that tight. Mostly logging forestry service roads around here.

 

[Darkwing327]

My ARB's are wired so I can only hit the front one if the rear one is on. I've never come across a scenario where I just want the front locker. I'd just leave it the way you have it.

Thanks for the input. I was generally thinking the same way. Wasn't really too much of a concern as if I absolutely found myself in a situation where I needed the front only, I could just pop the vent holding the switches out and move a wire.

 

[mrblaine]

Thanks for the input. I was generally thinking the same way. Wasn't really too much of a concern as if I absolutely found myself in a situation where I needed the front only, I could just pop the vent holding the switches out and move a wire.

Easier to switch them at the compressor.

 

[Jerry Bransford]

At no point in time do you have 1 wheel drive with an open diff. That isn't how it works, at all. With an open diff, both sides receive exactly the same amount of torque. Since torque is a function of resistance, if a tire has very low traction and it takes a small amount of torque to make it spin, that exact amount is also delivered to the tire with very high traction and it won't spin because it has high traction. But, both are being driven, it just doesn't look like it.

Here's the long version of that, something I wrote maybe 15-16 years ago. https://wranglertjforum.com/threads/how-is-torque-delivered-to-the-wheels-on-a-4x4.1738/

 

[JDS123]

It doesn't really matter which way they are wired. Either way will work fine for your uses.

 

[Jerry Bransford]

It doesn't really matter which way they are wired. Either way will work fine for your uses.

Lots of us would disagree with that.

 

[JDS123]

Lots of us would disagree with that.

For what reason? I've never needed to do a front dig and most TJ owners with ARBs have them wired the way ARB recommends without issue. The reason ARB recommends what they do may be slightly off-base, but that doesn't mean it makes much of a difference.

 

[rasband]

I have mine independent and am glad I do, for me the main reason is tight turns. I try not to be rough on the rear unlocked, but wrecking the Dana 44 rear is a known risk.

 

[pagrey]

I had zero confidence in the sand in my open/open TJ.

Never found lockers any use in the sand. Personally I think there aren't required, just low pressure on the tires. To me this isn't a difficult decision, if you are having trouble turning on trails locked then consider the mod. If you never run into the situation then forget about it. It just makes things easier, it's not going to prevent you from getting home that one time you would like it. You just might look like Austin Powers in a golf cart for a few minutes.

 

[TurboTJ]

Here's the long version of that, something I wrote maybe 15-16 years ago. https://wranglertjforum.com/threads/how-is-torque-delivered-to-the-wheels-on-a-4x4.1738/

Thanks Jerry, that is an excellent read. But I do have to take issue with your explanation why front and rear axle ratios may be off by .01 from each other. The ratio is determined strictly by the number of teeth on the pinion and on the ring gear. Any difference of .01 is probably just round-off error by whoever did the division. Would you not agree?

 

[pagrey]

Thanks Jerry, that is an excellent read. But I do have to take issue with your explanation why front and rear axle ratios may be off by .01 from each other. The ratio is determined strictly by the number of teeth on the pinion and on the ring gear. Any difference of .01 is probably just round-off error by whoever did the division. Would you not agree?

I don't think it's rounding errors or ring gear diameter. 41 ring gear teeth and 10 pinion teeth is 4.10 and 37 ring gear teeth and 9 on the pinion is 4.111111111.

 

[TurboTJ]

I don't think it's rounding errors or ring gear diameter. 41 ring gear teeth and 10 pinion teeth is 4.10 and 37 ring gear teeth and 9 on the pinion is 4.111111111.

Yes, you have proven my point. It is the ratio of the number of teeth and has nothing to do with the diameter of the ring gear. Then, maybe I was misinterpreting Jerry’s statement about the near impossibility of making the ring gear dimensions exactly the same. If a smaller diff requires a smaller ring gear that must have fewer teeth to fit, but the ratio is almost the same, then so be it. I just thought he was saying that manufacturing tolerances in the gears resulted n the difference.

 

[tworley]

I plan to wire mine so they can be operated independently. All it takes is jumping one of the power wires IIRC. Having the rear locked pushes you forward even when turning, and as Blaine said, turning with both locked can be a bitch.

 

[Jerry Bransford]

...Then, maybe I was misinterpreting Jerry’s statement about the near impossibility of making the ring gear dimensions exactly the same. If a smaller diff requires a smaller ring gear that must have fewer teeth to fit, but the ratio is almost the same, then so be it. I just thought he was saying that manufacturing tolerances in the gears resulted n the difference.

What I bolded and italicized is it exactly, it's not from manufacturing tolerances. The .01 difference means absolutely nothing offroad anyway. Even if they were exactly the same, like 4.56 and 4.56, and you were in 4x4, making turns and driving on curves would make more of a difference in the F/R rpms than the .01 difference does. On offroad terrain when in 4x4 the .01 difference means absolutely zilch, it's a non-issue and there'd be no benefit to them matching perfectly. None whatsoever.

 

[Zorba]

Very nice writeup Jerry. I knew some of it, but not all of it, and the trick with the handbrake is new news to me! Thank you. As for the .01 gearing difference, "you" probably get more than that from the tires!