Topic: Locker Theory: Driver-Adjustable, Front-Locker only

[chrisfranklin]

Using open differentials now, but I was thinking about a installing a driver adjustable locker (ARB/OX) but just in the front D30.  I like the driver-adjustables because they seem to allow the best combo of traction: 2WD, 4WD H/L, locked 4WD H/L.  

Like most folks here, probably, I don't have a ton of extra cash and want to maximize my fun off-road for minimal investment without any hidden long-term expenditures (by hidden long-term expenditures, I mean the following: locker amplification of tendency for rear D35 breakage and possible auto-locker change in drivability that could cause an accident on a slick highway.  And, I also know that weight tends to shift rearward when hill-climbing (inevitably where you want most of your traction off-road).  So, why not just go with a front-only, driver-adjustable locker?

The aussielocker.com site, which deals in auto-lockers,  has a FAQ where it is suggested that one install one of their lockers in the front if you are only going to run one (due to weight shift on hills).  It also pointed out that, with a front locker, though your Jeep's weight will be to the rear because of climbing, your engine's torque will be spread evenly to the front and rear axles; furthermore, since your rear axle tends to be keeping your tires on the ground because of the hill-climb weight (if your articulation is ok), you rear is going to tend to have traction; a front-locker adds to this by keeping the rear from being overloaded with torque and/by keeping the front axle in the game.  So. basically, I am just taking Aussie's points and applying them to a front driver-adjustable.  

Ideally, you want two driver adjustables, but if your money is mostly already spoken for and you really like your current ride (no plan to  buy a Rubicon Unlimited or anything), then is the front-only, driver-adjustable locker, an ARB/OX, the best move? Am I overlooking the front-only auto-lockers?   Do I overestimate the effect a rear locker will have on the breakage potential of the stock, D35 axle on 29-31 inch tires? :D

[trailerrails]

That is what I have always said, I usally tell people who have manual hubs just to get a mini spool, cheep, easy to install, nothing to break. If they need 4wd on the street, like in snow, only lock one hub. People get all scared of front lockers because they think they will not be able to turn anymore. Thier turning radius will be decreased but that will only affect them when trying to turn around, they may have to back up one more time. During normal trail riding it will not affect them at all.

If they decide to spend a little extra coin and get a OX or a ARB or one of the electric lockers that are out there then they will experince even better performance when turning and street driving.

It looks like you made up your mind already, just do it and start a new trend. An OX in the front would be the best bet. I am a fan of OX.

[Jeffy]

The problem with a front locker only is several fold.  First the front axle is not as strong as the rear, which is why you can get aways with larger tires.  Second, when climbing obsticals that require a locker, weight is shifted towards the rear.   There are many times when you don't need 4wd at all but want extra traction, too.

One thing to think about is that in Austrailia, they do not rockclimb.  They deal with mud and sand conditions.

In the US, running a front locker first isn't anything new.  People used to do it in the 80's.  If I remember right, they were doing muddy trails and little or no rocks.

If you're running a YJ, then I'd highly suggest going with upgraded U-joints and axle shafts if you plan on running a locker.

[chrisfranklin]

I tend to defer to your widsdom, Jeffy, since you are running dual ARBs and are greatly experienced

But, is the D30 really not as strong or stronger than the stock D35  (I figured maybe you could get around the weakspot D35 just by augmenting what I was under the impression was the "stronger" front D30 axle)?

First the front axle is not as strong as the rear, which is why you can get aways with larger tires.

I don't quite understand your point about larger tires in the aforementioned, even if I think of typos.

Interesting point about a 2wd locked rear and non-4wd circumstances where you want the traction.  Didn't think of that one (course, my 4 cyl can't even spin one wheel when I'm on the gas from a stoplight  ); but, yeah, rear is good to have for some non-4wd conditions.

The Aussie site wasn't too specific about terrain, Australian or otherwise, and seemed to be talking more about the physics involved with traction, rearward weight transfer and torque distribution.  I agree, when I think Australia 4x4, I think Snorkels and 1000 mile long dirt roads in the "Outback."    

If you're running a YJ, then I'd highly suggest going with upgraded U-joints and axle shafts if you plan on running a locker.

Are you suggesting the aforementioned for both the D30 and D35 on a YJ?

In the US, running a front locker first isn't anything new.

Yeah, I know. I've read a few people doing it, actually fairly recently and/or doing some kind of ARB/OX front and auto locker, rear.

[Jeffy]

I don't run ARB's.  I'm old school with a Detroit in the back and a TrueTrac in the front.

Look at the Dana 30 and the Dana 35.  The reason why they use a smaller axle for teh front is because they cna get away with it.  You never see a larger axle used for the front then teh rear unless it's for some special application.  The Dana 30 can take up to a 33" safely without too much trouble.  A Dana 35 can take up to a 32 (even thoug many just go up to 33 and live with the concequences).

The reason why the Dana 30 is able to take a larger tire is not because it's stronger.  It's because it sees less stress.  Like I said before when climbing, the weight shifts over the rear wheels.  The front end then goes lighter so the front does not have the added weight to deal with.  This also equates to traction.  A light front end isn't going to help you any.  Typically, the front will slide around until it hooks up and then shifts enough weight that it's able help pull the vehicle up.  The majoriety of the weight will still be on the rear.

If you're going to run a locker in the Dana 30 of a YJ, you will want to upgrade teh shafts and the U-joints.  THe stock U-joints are 260x series while most XJ's and all TJ's use a 297x series U-joint.  This U-joint is stronger because it's a bit larger and is also used on the Dana 44.  THe two-piece axle shaft isn't really problem but to upgrade to the larger U-joints you will need to ditch the disconnect.  Although, you have a '94 which might already have the larger U-joints.  Still it's probably good to get rid of the disconnect since it's just another weak link to worry about.

One of the reason's I'm running a True-trac up front and not a locker is because of the axle strength.  With larger tires, the traction is increased.  This can and does increase the applied torque of the axle as it tried to turn the wheel.  Instead of spinning the tire which releases the torque, the shaft may break if the torque surpasses the strength og the axle shaft or U-joint.  I currently run 35x12.5's on stock U-joints.  I'm relatively easy on the drivetrain so it's held up so far.  I'm not investing much into the axle because I probably won't be keeping it.  I bought the LSD used from a friend and I installed my own gears, so there is a minimal investment.

[BK2LIFE]

ok heres my 2 cents.  lock the front.  dont even waste time with the rear unless your doin some serious stuff.
i have an aussie locker.  it is an awesome unit. there is no better bang for your buck than the 229 it costs to buy one.. except for maybe changing the 2.5 throttle body to the 4.0 unit. i have a 92 yj, so it has the vacuum disconnect.  there is a way to convert your vacuum to a bike cable, costs about 15 bucks, and you are manually lockin the pass axles together.
anyways, since my axle is a vacuum unit, i welded my spiders together (quick cheap fun)  the same was mentioned above about the mini spool, same concept.
i have "spool" in front and aussie in rear.  i "spooled" my front before the aussie, and i can tell you i could climb over things these other guys couldnt.  now my jeep is stock, 2" body lift, 31x11.50 tsl's, these other guys are lifted, 33's 6cyl, blah blah blah.  i have since then, welded others axles, and they too are amazed at the difference.  depending on your driving style, the d30/35 is fine, but you cant be overrevvin it and tryin to get somewhere, if you grab traction youll break.  that is the same for any axle though.  
finally, the weak link on the d30 is the axle ujoints, i have broken them,  get stronger ones youll be happier in the long run.
oh yeah heres proof: http://photobucket.com/albums/y36/BK2LIFE/jeep/

[SMC4WD]

Awesome!!  And here's my .02cents...

I'm running ARB's front and rear (D30/F9")...   At my work we had a debate regarding front or rear first.  It was a poll kinda going around the office.  Now mind you I work for a company with a reputation of lockers, so there was a lot of knowledge in the room...  Alot!!

The reason the subject came up was an incident I had, with a comparison with a friend of mine.  This incident was prior to my rear ARB, and the front was a lock-right (the equivalent to an Aussie).  The scenario was a rock in front of a 4WD shop we used to work at.  We both had the same year Jeep, we both had very worn factory limited slips in the rear, but I had the lock-right in the front.  He attempted to 'pose' himself proudly on the big rock in front of the store.  He approached it, gave it some gas, and spun the rear tires in the grass...  So much so he was asked to stop because he was tearing up the lawn.   Then I approached the same rock.  I put my front tire on the rock, gave it a little gas and up I went...    

Look at the poser....  Ya, I see the rear end off the ground... those RS9000's didn't extend as much as the Bilsteins do :)  And the tires on there (I think) are 33's...  But right now I'm running 35" BFG Mud Terrians




So the controversy at my work began.  And as Jeffy put it, they agreed.  Strength and traction, aide the lockers.  As a general rule, the rear axle is much stronger than the front.  (Not in the case of a D35, but it's mostly the rule).  The weight while your assenting a hill, or an obstacle require the assistance of the rear.  The over weight is always on the rear.  The 99.99% driving power (2wd or 4wd) goes to the rear.  Everyone there said the rear.  I still wanted to disagree.

So I did the logical thing.  Took out the D35 and replaced it with a Ford 9", 31 spline, disc brakes and an ARB.  On the front I kept the D30, but I pumped it up with the 30 spline air locker, chromoly inners, OX ujoints Nascar axle seals, and the Warn hub conversion kit.  I am running 4.88 gears.  

I'm still sticking to the locker in the front...

[chrisfranklin]

Jeffy, you ought to do a "once and for all" Locker Test (kind of like I've seen done with Car and Driver and awd vs 2wd vs fwd cars or w/radar detectors)

Get people with similarly equipped Jeeps, say 6 TJs, same engine and transmissions, tires, lift, axles, gearing.  Do three different Trails with different terrain.  Shoot video.  Post.  Shouldn't cost much to do, other than gas and maybe getting some guys to do front-only locker installs.

Jeep 1: Front driver-adjst locker only
Jeep 2: Rear driver-adjst locker only
Jeep 3: Front and Rear driver-adjst locker
Jeep 4: Front auto locker
Jeep 5: Rear auto locker
Jeep 6: Front and rear auto locker

Test is about how each set up performs off-road in different conditions, circa 2006 (Obviously the front/rear setups will perform best,  but newbie/budget guys (me) want to find out (see) how well the front only or rear only rigs will perform and which is ultimately a better starting point, front or rear (I don't know if limited slips diffs count, though)

I've seen  a few articles on lockers, but its mostly about  rear install and performance and then any improvements once a front is added.  Nobody has done front only vs rear only, at least that I've seen.
(Course, if you guys know some links where they do a front-only vs rear-only locker OHV test, please post 'em)

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