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Thread: Why do I need a locker? I thought I had 4X4! Reply to Thread
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  Topic Review (Newest First)
12-02-2019 01:16 PM
Fourtrail
Quote:
Originally Posted by Tgrichards View Post
So, what's the recommendation for a 15 JK Sport? I'm thinking "lunch box locker" for the rear axle. Would you prefer the cable or electric? I'm thinking OX brand, and just doing the rear axle.

'lunch box locker' isn't cable or electric. a 'lunch box locker' is an automatic locker that replaces the spider and side gears in the factory open rear differential carrier. if you are looking at an OX, cable or electric, you are looking at a a full case selectable locker, that will replace the current open or factory limit slip differential. the full case locker will require having the backlash reset, which normally means a trip to a mechanic with knowledge of setting up differentials.
12-02-2019 12:37 PM
cranbiz Where do you live, is it a daily driver or primarily a trail rig. What type of trails do you run?

Personally I like selectable lockers. I run ARB's in mine.

A lot of people like the Truetrac for an auto locker. The OX locker is nice. I believe they have ironed out the issues that plagued it in it's early life. The nice thing about them is if the actuator fails, you can use a manual override to get off the trail.

I would not put an auto locker in the front if you live in areas that get winter weather and I also wouldn't put an auto locker in a Dana 30.
12-01-2019 07:13 PM
Tgrichards So, what's the recommendation for a 15 JK Sport? I'm thinking "lunch box locker" for the rear axle. Would you prefer the cable or electric? I'm thinking OX brand, and just doing the rear axle.
06-30-2018 07:42 PM
Jerry Bransford
Quote:
Originally Posted by jeepster4245 View Post
You will notice the locker in the rear... If you put the locker in the front it only activates when in 4wd... in 2wd on the street you wont know it is there...put a LS in the rear for better manners on the street.
How much ownership time do you have with a Detroit Locker? There are lots of things we install onto our Jeeps that can be noticed but that doesn't necessarily mean it's a bad thing or unliveable. I happily drove my daily driver TJ for years with a Detroit Locker in its rear axle.
06-30-2018 04:12 PM
jeepster4245 You will notice the locker in the rear... If you put the locker in the front it only activates when in 4wd... in 2wd on the street you wont know it is there...put a LS in the rear for better manners on the street.
06-29-2018 05:40 PM
1badsho If your jeep primarily is driven on the streets but you want it to be a formidable foe when going off roading, can you go with a detroit locker in the rear and do something less aggresive in the front like LSD ...

based on a Vin decode I have dana 44's in the rear and dana 30's in the front
04-23-2017 02:07 PM
biffgnar
Quote:
Originally Posted by WesttownWilly View Post
I never fully understood the open differential until reading this (particularly the low torque output when one wheel is spinning) which begs the question why on earth would a company that specifically designs, manufactures and markets vehicles to go off-road ever install them to begin with - is it just to save a buck?
Look at the Rubicon markup. Part of that is for lockers. When so many jeeps never leave the pavement give people options.
04-23-2017 08:06 AM
WesttownWilly I never fully understood the open differential until reading this (particularly the low torque output when one wheel is spinning) which begs the question why on earth would a company that specifically designs, manufactures and markets vehicles to go off-road ever install them to begin with - is it just to save a buck?
03-27-2017 05:00 PM
cranbiz Well, Jerry, I know they are the same vendor. It was not an install issue.

Anyways, I had 2 choices, reinstall the spider gears or install something the shop actually had available. The shop wasn't going to wait 6-8 days or more to wait for Powertrax to make a decision.
Sure, I could install a replacement locker but that would need to wait until the new gears are broken in and I replace the break in fluid.If money wasn't an option, then I could have gone a lot of ways, one of then just buying and overnighting another locker but alas, money WAS an option.

I got to say, looking at where the locker failed, does make me wonder if it could be a continued issue down the road.
03-26-2017 08:49 PM
Jerry Bransford You simply got a defective No-Slip which is highly unusual, I ran one hard for years without problem. That'd be a step backwards going with the cheaper Lockrite. Same manufacturer for both lockers you know right?

And keep in mind that even the very best made products aren't always 100% problem free. Odds are you wouldn't have any issues with the replacement. Just make sure it is properly installed. Who knows, maybe the first one was not.
03-23-2017 06:49 PM
cranbiz My brand new Powertrax No Slip has a cracked gear, not even 100 miles on it and less than 5 minutes in 4 low, on dirt, and one trip up a RTI ramp.

The shop installing my new gears today called me and sent over a picture. I called Powertrax and they will only inspect it and then make a determination if it's covered in 6-8 days. Needless to say, while I love the idea of how it works, I'm not putting another one in, going with a Lock Right for many reasons, the biggest being it was available today and it's $150 less. I'll put up with some banging and clunking at this point. The Jeep is at the shop for gears and I really don't want to pull it apart again if I can help it. Fortunately, I can still return the No Slip thru Amazon (less than 30 days old) so I'm not out anything except return shipping.
02-05-2017 04:49 PM
DblCabMN Nice post - very informative
02-01-2017 11:18 AM
Ricsan Great info here, thanks all...
06-28-2016 09:54 AM
Jerry Bransford
Quote:
Originally Posted by TJoker View Post
I have Spartan auto lockers in mine. I will tell you that if I had it to do again I would go with a electric locker in the front. It makes a lot of popping sounds when you turn and sometimes it scares the crap out of me. I ended up pulling mine out of the front and putting a open carrier back in. It isn't that bad at all in the rear differential.
Don't let your bad experience with Spartan lockers scare you away from all automatic lockers up front. Not to mention I have read of similar bad experiences with the Spartan locker.

I ran the No-Slip automatic lunchbox locker up front for years and you really couldn't even tell it was there in 2wd. You could only tell it was there once you shifted into 4x4.
04-26-2016 10:15 PM
spencershots
Quote:
Originally Posted by Jerry Bransford
Here's something I wrote years ago that was recently revived on another forum... I thought it might be useful here too. Q: Why do we need lockers, I thought I had four wheel drive!!?? A: We need lockers for tough terrain because the differentials installed into our front and rear axles have a characteristic that can turn our 4x4 Jeeps into 4x2 Jeeps in low traction situations. A factory differential (sometimes called an "open differential") has a characteristic in that when one wheel loses traction, that wheel will start spinning ineffectively. You've seen that happen before, I'm sure. The bigger problem is that one spinning wheel on an axle causes both wheels to lose power to the point you can't move your Jeep... so even though the wheel on the other non-spinning side may have excellent traction, that non-spinning wheel won't receive enough power to keep you moving. Why? Because the differential screws up and only "sends power" to the wheel that is spinning. That is not technically totally accurate but it illustrates the problem very nicely, with a more technically accurate explanation as follows. So the engine, via the drive shaft and differential, is seeing very little resistance from the axle with the spinning tire. So what? If the engine sees little resistance, it develops little torque. Low resistance to the engine, low developed torque. Lots of resistance to the engine causes it to develop lots of torque. Connect a dynamometer to an engine without a load on it and it'll show very little developed torque. Now put a brake of some kind against the engine output shaft (to add resistance) and the amount of torque developed by the engine will suddenly and dramatically rise. No resistance, very little developed torque... high resistance, a high amount of developed torque. When a wheel starts spinning, the reduced resistance the engine sees from the axle causes the engine to dramatically reduce the torque the engine develops and sends to the axle. Here's what else is going on that is a key to understanding this whole thing... a stock factory differential ALWAYS ALWAYS ALWAYS splits the torque it receives from the engine 50:50 to each wheel. Exactly 50-50, every time. So when one wheel is spinning and the engine torque decreases dramatically because of that, the OTHER wheel that still has good traction is seeing 50% of the greatly reduced torque. In fact, the torque sent to the axle is reduced so greatly that when the differential divides it 50-50, there is insufficient torque for the wheel with good traction to keep you moving. This means you're stuck! So when you're driving on a dry paved road, both tires are receiving equal amounts of power and the high traction they're seeing from the dry road helps the engine to develop maximum torque. Both tires are pushing equally with lots of available torque. Now jack up a wheel (or lift it with a rock on a trail you just drove over) and you're not going to move even though the other tire is still on the ground. The tire in the air is spinning like crazy, causing the torque that axle receives from the engine to go right into the toilet. So, when one tire on the axle is spinning, you don't have enough power for the other tire to keep you moving. For obvious reasons, all this is a huge problem for a 2wd vehicle (just one axle to drive you). It works exactly the same for a 4x4 but you have one more axle to assist in keeping you moving. But if one tire per axle has poor traction, you are stuck... since one spinning tire per axle is enough to reduce all developed torque from the engine down below the point the Jeep needs to move forward. OK, we know what the problem is now, what's the fix? One, you could STEP ON THE BRAKES a little... which would stop the tire(s) from spinning so more torque would be developed, which should be enough for the OTHER tire that still has good traction to get you moving again. Stepping on the brakes forces the engine to work harder so it develops more torque which is sent to the wheels... so that gets more torque sent to the wheel (both actually) that still has traction so you may be able to get unstuck. Yes, stepping on the brakes (to a point best learned by practice) works rather well in these situations. Just about all drivers used to know that technique when few roads were paved... but it's just about a lost art now. So what does a locker do? It mechanically LOCKS the left and right wheel together to overcome the above problems. It won't allow one wheel to start spinning while the other sits doing nothing. The left and right wheels are mechanically locked together. Automatic lockers keep the left and right sides locked together except when you turn left or right, where it will automatically unlock the outside wheel during the turn until after the turn is completed at which time it locks up again. When the locker unlocks for a turn, the outside wheel is allowed to rotate faster than the inside wheel so it doesn't hop and skip during the turn. The inside wheel is driving during a turn with an automatic locker-equipped vehicle. The locker automatically locks again once both wheels are turning at the same RPMs again. The problem with an automatic locker is that most are not very street friendly when installed in the rear axle. Because they keep the left and right wheels locked together except when forced to unlock for a turn, they can cause unusual handling characteristics like rear-end waggle, tire chirping, disconcerting loud bangs and snaps from the locker, and even sideways sliding down slippery off-camber slopes where they earned the nickname "low-side finder"... which can sometimes produce a high 'pucker-factor' at times. For offroading however, locker's negatives are far outweighed by their benefits in challenging conditions. But in many Jeeps like the TJ, an automatic locker is fine when installed in the front axle. Since the front axle doesn't receive torque in 2wd, a front automatic locker unlocks easily enough for turns that you may not even notice its presence. Only in 4x4 is the front axle receiving torque which makes it harder for the locker to unlock for turns. About the only conditions where an automatic front locker would not be good in the type of 4x4 system a Wrangler TJ has would be on icy or snow-covered roads where you need 4x4. In 4x4, a front automatic locker would cause understeer (make the Jeep want to drive straight in a turn) which would not be good if the road was slick from snow or ice. A manual locker is "open" (unlocked) until you actuate it. The ARB Air Locker and the cable-actuated Ox-Locker are examples of manual lockers. These are good because they remain unlocked until you choose to lock them. This eliminates the handling problems automatic lockers have on the streets. By the way, a locker is installed inside the differential and it replaces the "spider" gears that make a differential work they way it does. So some Jeepers add lockers in the rear, others add them to the front. I happen to think locking the rear axle first does the most good, but I have installed automatic lockers into both axles which works pretty darned well. But if your rear axle is the notoriously weak Dana 35c that comes stock on all Wranglers except the Rubicon and Unlimited, avoid installing a locker into it and install the locker into the front axle instead. Since the front axle rarely receives more than 50% of the torque that the rear axle does, it can usually handle a locker without problem with reasonably sized tires. But if your rear axle is the optional and far stronger Dana 44, by all means install a locker into it if your trails are tough enough to make a locker desirable. So what's a limited slip differential? First, it is not the same as a locker. It is more or less an automatic brake for the spinning tire... it performs kind of like when you use the step-on-the-brakes technique so the spinning side gets coupled to the non-spinning side for more resistance so more engine torque can be generated so the non-spinning tire receives more torque from the engine to help get you moving again. It operates as a brake somewhat by coupling the added resistance of the side with more traction/resistance to the side that has less traction/resistance. A LSD depends on some tire spin to get it working so it's not as efficient for challenging terrain as a locker is. But then generally speaking, a LSD is far more "driver friendly" on the streets, which is why we all don't just have lockers in our Jeeps. Hope this helps a little.
this is so helpful
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