Testing Lunchbox Lockers - Differential UpgradesPosted in How To on August 9, 2013 Comment (0)
Someone once said, “To be or not to be: that is the question.” We don’t know about that or what that question really means. It seems to us that one day around the age of three, we just were. Do you remember making that decision? ’Cause we don’t. Oh well, since we currently be…er, are…or whatever, we will stay as is for now and quit contemplating that obtuse question. Instead, since we are addicted to Jeeps and Jeep building, we decided to ask a different question: front or rear? That is, which differential to lock if you could only lock one? This may seem like an easy question to answer, but it’s not…necessarily. Why? Well, because your opinion on the answer to this question is probably the opposite of someone else who knows what they are talking about. What to do? Well, we decided to test this using our ’56 CJ-5 as a test mule. That way we could very unscientifically resolve this life-long question…or not.
To figure out the answer to this question, or at least provide ourselves with a venue to discuss the pros and cons of each, we contacted West Coast Differentials for a Powertrax Lock-Right for the Jeep’s Dana 30 front axle and No-Slip from Powertrax for the CJ’s Chrysler 8.25 rear axle. Once we had these traction-adding devices in hand, known commonly as lunchbox lockers, we installed one in our driveway, ran a trail, removed that locker, installed the other again in our driveway, then ran the same trail. What happened? Which worked better? Well, you are gonna have to follow along to see what happened and what we found.
Just to be clear, we are running these lunchbox lockers because of their affordability and ease of installation. We would not recommend using them to lock a 760X U-joint-wearing Dana 30 or a 29-spline Chrysler 8.25 with tires over 33s. The strain on the stock axleshafts and differential carrier would certainly end in failure. Even with 33s or smaller tires, we know that we may break axle parts. That’s the cost of having lockers!
Easy Decision Time
There are some situations where making the decision on where to put the locker is pretty easy. Generally, if you have a ’84-or-newer Jeep with a Dana 35 rear axle, you are playing with fire by adding a locker to it. In that case, we’d almost certainly put the locker up front first—unless you are gonna run 30-inch tires or less, in which case we might consider locking the Dana 35. With us, 99 times out of 100 we’ll tell you to avoid spending money on your Dana 35. Instead, save it for an axle upgrade.
The other time that making the decision of where to run a locker is easy is with any Jeep with a Rear Dana 44 with once-piece flanged axles. This axle is gonna be stronger and more reliable than the Dana 30 or 27 that would have accompanied it from the factory. Another instance in which we would opt for rear locker first is in Moab. Why? Well, all that driving on high traction slickrock in 4WD is gonna be hard on your Jeep’s steering, U-joints, axleshafts—heck, basically the whole front end of your Jeep.
Arguments for or Against
Most of the arguments that we have heard for one end of your Jeep versus another can be easily countered. For example, Jack might say that on a steep climb most of the vehicle’s weight is on the rear axle, so a rear locker would be better. Bob could argue that because more of the weight is on the rear, the rear tires are more firmly planted and less likely to spin even without a locker. In that case, Bob could use basically the same reasoning as Jack to say a front locker is better. The truth of the matter is that depending on the situation you find yourself in, having one end locked versus the other may be beneficial to you. On some obstacles your Jeep may benefit more from a front locker, some from a rear. Basically you are set until you get to the next obstacle on the trail, or even a different line on the same obstacle, where the opposite may be true.
So what is best? Well, honestly, having both axles locked is the best, and chances are once you’ve got one end locked up you are gonna want the other one locked! Our little CJ on narrow tires with two lockers will go places few would imagine it could. So the correct answer is if you want a locker and think it might help your Jeep do better off-road, buy one based on which of the two axles in your Jeep is strongest. Then start saving for the next locker and some upgraded parts, like one-piece shafts, chromoly shafts, chromoly U-joints, a bigger axle….Oh boy, here we go again!