Front Axle Work vs Rear Work on a 4X4

[CDA 455 II]

What percentage does the front axle work/provides momentum-traction vs the rear axle?

For overland-kind of wheelin' both great and small.


Researching lockers for the front axle, reading 100s of opinions, prompted this question.

My W.A.G. would be somewhere in the neighborhood of 30%-front 70%-rear.


From said research; rigs with a fully locked rear does 80+% of the work while keeping the front diff open.

And then when needed; lock said front diff to get through a section of road, and then unlock said diff when completed.

 

[rockyota83]

on flat ground i would disagree with 30/70

the weight of the engine over the front axle on flat ground i would say the front axle is doing 55% and the rear 45%

start going uphill and it changes

i prefer arb lockers so i can turn them off and have open diffs, only use the locker when truly needed(tires slipping), turn it off when i dont so i can still turn better

 

[rockyota83]

worst case scenario

going down hill get stuck

cant turn around

cant use winch to go forward

only choice is to reverse up the hill

a locker in the front axle is your best option

 

[Lil'John]

I agree with the above. It would depend upon how much angle the vehicle is at as well as what direction you are powering.

I think the bias would be dependent upon front/rear weight bias.

Like the above, my normal rig has ARBs so I can use them when I need and not have a squirrely rig when I don't.

 

[YotaAtieToo]

Hard to really say, every rig is different, every obstacle is different. Short wheelbase rigs seem to get around pretty good in 2wd only, while my CCLB F350 is basically useless off pavement in 2wd.

My preference is selectable rear, auto front. Drives great on the road, and the front will usually allow you to steer decent. You can also unlock the rear to keep the rear from sliding on side hills or to pivot turn around things. For a broverlander type rig, arb's seem to be the go to, but auto lockers are also simple and just work. Personal preference there.

 

[montrose818]

spooled rear, selectable front. IMO.

 

[Stingray]

Detroit in the rear, E-locker in the front on Both Toyota rigs, I'm a Pussy with the throttle, and have good luck not breaking. I'd say neither rig is a buggy, but I do more than overlanding and haven't broke.

Nice to be able to unlock to steer. but that's my choice.

 

[rockyota83]

spooled rear, selectable front. IMO.

trail rig no, pure race car yes

 

[rockyota83]

Detroit in the rear, E-locker in the front on Both Toyota rigs, I'm a Pussy with the throttle, and have good luck not breaking. I'd say neither rig is a buggy, but I do more than overlanding and haven't broke.

Nice to be able to unlock to steer. but that's my choice.

if you ask a cone dodger spooled/locked front and open rear will turn better than open front and spooled/locked rear

 

[Hooligan]

if you ask a cone dodger spooled/locked front and open rear will turn better than open front and spooled/locked rear

Why is that, cuz the rear isn’t pushing the front around? The front is pulling through the turn instead of the rear pushing straight ahead.

 

[montrose818]

trail rig no, pure race car yes

Id be afraid of a spool in the front causing more breakage thus a selectable, guess it deends what youre running

 

[Byro]

Back in the day when we were kids and cheap a friend of mine ran a lunchbox in front and open in the rear on his TJ on 33s (D30/D35) kept the rear from breaking and we could swap front shafts pretty quick. That setup seemed to work well, once you got the front wheels up/over whatever it would pull itself up/over.

As of now I’m team spool/spool. I wanna make the line and not fumble with lockers.

 

[TRINDU]

All things created equal (no fear of broken parts, added wear, road characteristics, etc) a locked front open rear would be my preference over the opposite.

overland rig? Torsen/worm limited slip F&R. clutch packs suck.

 

[Phil]

Id be afraid of a spool in the front causing more breakage thus a selectable, guess it deends what youre running

why? When you are in the deep rocks, you are going to need it locked and it will be effectively spooled, and when you are in dirt, it won’t break.

you shouldn’t be considering a spool with anything 30 spline or less, in my opinion.

 

[CDA 455 II]

overland rig? Torsen/worm limited slip F&R. clutch packs suck.

I've been looking at Detroit Truetrac.

However; Detroit recommends 33" or smaller tire when using said Truetrac. 🤷‍♂️


I'm currently running HMMWV tires and will probably go bigger on the next set.

 

[TRINDU]

I've been looking at Detroit Truetrac.

However; Detroit recommends 33" or smaller tire when using said Truetrac. 🤷‍♂️


I'm currently running HMMWV tires and will probably go bigger on the next set.

Just read your sig.

Buy an elocker for the rear, or an entire rear 10.5 elocker rear. They're cheap (relatively speaking) either way.

 

[Tech Tim]

if you ask a cone dodger spooled/locked front and open rear will turn better than open front and spooled/locked rear

Why is that, cuz the rear isn’t pushing the front around? The front is pulling through the turn instead of the rear pushing straight ahead.

Pretty much.

For the cone dodgers, they're running hydro steering so it'll steer the tires no problem with the spool up front.

Then selectable in the rear so you can manipulate when and where you have traction.

 

[Tech Tim]

Hard to really say, every rig is different, every obstacle is different.....

Truth right there.

Having a front locker is huge when it comes to climbing rocks and ledges etc. Having that extra bit of drive up front to grab and pull is far better than trying to push the front end up and over something.

Having a rear locker is great when you are trying to go up a hill and weight bias is changing as the vehicle is going up at an angle.

Having to back up a hill and then the locker in the front is the best position as rockyota83 had mentioned earlier.

The best solution (for non-competition) is front and rear selectable, then you can turn them on/off as needed. More tools in your off-road driving toolbox.

 

[AK_F250]

I've been looking at Detroit Truetrac.

However; Detroit recommends 33" or smaller tire when using said Truetrac. 🤷‍♂️


I'm currently running HMMWV tires and will probably go bigger on the next set.

Is that just for the rear? I ran a truetrac front Detroit rear in this thing for years on 42s with zero issues. It worked really well in the front.

 

[Eric]

I'd say that on average your 70/30 split is reasonable. Its not just the static front/rear weight distribution that matters. Angle of incline was already mentioned but there is also weight transfer due to acceleration. In the limit you get 100 rear and 0 front, i.e. a drag car pulling a wheelie. For all around general purpose use a locked rear is superior to a locked front. Its physics not opinion. You seem to be leaning toward selectable front. I could not agree more. The challenge is find a reliable selectable locker. I gave up.

BTW, I'm thinking newer versions of the 4 link calculator do some weight transfer calculations?

 

[rockyota83]

The best solution (for non-competition) is front and rear selectable, then you can turn them on/off as needed. More tools in your off-road driving toolbox.

this 100%

another benefit to me is being able have more fun, if you have made it up and over the same obstacle 50 times it can get boring, turn off your lockers and try it with open diffs can make it funner and more challenging if thats what youre looking for

 

[Stingray]

if you ask a cone dodger spooled/locked front and open rear will turn better than open front and spooled/locked rear

I guess I can believe that, Just seems like a locked front wants to bind up, I always feared breaking it. Thus let the rear locker do its thing, and play on and off with the front. Climbing/crawling I would lock up the front, running between obstacles I run locked hubs in 4wd, but elocker unlocked so basically open.

 

[dentedsub]

The rear does most of the work, look at oem's for evidence, there's a reason they have a 14B in the rear and 10B in the front, or D44 rear, D30 front etc.
I would put the locker in the rear for sure, no questions because 90% of the time I lift a tire its the rear. The extra weight up front keeps the tires on the ground

 

[Treefrog]

BTW, I'm thinking newer versions of the 4 link calculator do some weight transfer calculations?

They do not. The weight bias is only used to calculated the weight of the chassis on each axle.

I would agree with the 70% rear mentality, especially when on the accelerating uphill. But on flat ground in 4wd, 50% split should be expected, after accounting for weight transfer and balance.

 

[RunningProblem]

Good video showing a bunch of uphills using from, rear, neither, and both on the same rig. It depends on how you drive and there is always going to be a moment where you wish you had lockers front, or rear, or whatever it is you don’t have. For over landing I guess I’d go rear first for no reason other than most of the weight is probably in the rear when you’re driving fully loaded. I’ve never done over landing and I’m buying mechanical lockers front and rear for my crawler toy.

 

[dentedsub]

I'm honestly surprised that it seemed pretty equal front to rear in that vid. Good find. Now my comment would be based on the rig the OP is putting the locker in. I would still do rear just because rear axles are usually stronger. Like some of the senarios in the vid above if you're in some twisty spot and spinning 2 tires so you engage the locker, now you have one tire doing almost 100% of the work, is your ifs half shaft going to pull your loaded rig up the hill? No.
Check this out,
https://www.fourwheeler.com/project-vehicles/131-0807-1991-chevy-4x4-truck-red-sled/
Cliffs;
Fred put an ARB in the front of a 3/4 chev with 454 to see what it could take and the answer was almost nothing.
Just something else to consider.

 

[Ghetto Fab.]

If the weight transfers to rear when climbing, then doesn't the rear by default have good traction? So wouldn't you want the locker in the end that had the least traction?

 

[dentedsub]

If the weight transfers to rear when climbing, then doesn't the rear by default have good traction? So wouldn't you want the locker in the end that had the least traction?

Would you rather double $10 bill or a $50? Which gives you the biggest total gain?

I'd actually like to see someone redo that test like the aussie above but find a hill they can do with the front locked and rear open or vice versa. Maybe it really doesn't matter though, and in that case I would still put it in the end that is most likely to survive.

 

[Ghetto Fab.]

Would you rather double $10 bill or a $50? Which gives you the biggest total gain?

The axle with the least amount of traction would be your biggest gain.

Its an interesting question, but I think we all know its completely dependent on such a wide variety of factors that its hard to compare.

I was in Moab once and my group found this dirt hill just past the exit of Hells Revenge I think. There's probably condos there now. Anyway, I'm in my toyota pickup, detroit rear and open front, and my friend was in a 4runner, lunchbox locked front, open rear. The hill was mostly loose gravelly rock and sand that got steeper as you went up and it was fairly wide. We both tried crawling it at the same time and he was able to best me up the hill by easily a truck length or more. We tried a few times with the same conclusion every time. We had the same wheel base, motor, trans, t-case gearing, tire size. He had no fiberglass top, but the weight is still a bit different and I don't recall what tires he had at the time. Not a completely apples to apples comparison, but as close as I'll likely ever see and it made me think differently about the common drivetrain convention at the time that the locker first goes into the rear axle.

 

[64Trvlr]

In my steel Willys wagon I had a spool in the rear, Detroit front. I swapped it to spool in the rear, TruTrac in the front I like it much better now.