Info To Add
So for those with the V8 4wd you have a Toyota 8" turbo v6 rear axle and up front a Toyota 8" IFS clamshell. Factory runs A 3.73 final drive ratio
The V6 engine models come factory with a 3.93 final drive ratio and I believe the 7.5" IFS clamshell up front
Any-who.. Some one above posted some risks in locking the front IFS. they were correct in the one stress being added when you do select to engage the locker and were to make a turn, if you were on the road you would certainly bind up the front axle causing potential breaking of the CV axle shafts. Off road however loose dirt, mud, snow, ice will allow the inside tire of the turn to slip and not cause much added stress.
I wanted to add to this by saying a front locker isnt something you want to run locked all the time a front locker is at best only engaged when your driving straight such as a straight hill climb at a steep grade, or squared up to what your driving through. YOU NEVER WANT TO ENGAGE A FRONT LOCKER IF YOU ARE AT ANY KIND OF OFF CAMBER ANGLE TO THE TERRAIN YOUR ON. this is because when both front wheels are engaged together they both have the ability to spin this can cause for front end to slide side to side (like the rear would per say during a burn out scenario). If you were to be at an off camber angle attempting a hill climb or climbing over some rocks with the front locked your giving the truck the option to let the front slide left or right to a more off camber angle an potentially causing a roll over situation. It's been said as well as I've been reminded many times a front locker on IFS or a Straight axle will put you on your side faster than anything else out there lol. A front locker is only used when A.) your gearing ratios and rear locker won't get you through the terrain B.) you've high center'd and still manage to have one front tire on the ground and one rear tire on the ground and C.) durring straight steep graded hill climbs/decents
A rear locker can be engaged at all times off-road as the back tires can slip around turns and not cause any binding, On road you would only want this engaged per say if you were lauching at a drag strip in a straight line or locked on the road in snowy icy conditions but it needs to be known that durring a turn in slippery conditions your back end is going to fish tail a little if your at any kind of high speed.
Point being think of it this way a rear locker is a "I'm kinda stuck switch/prevent getting stuck switch" the front locker is a "I'm really really stuck an this will hopefully help switch/ this is a really steep hill and its straight up switch"
I think it was mentioned before but when i read it i felt it didn't quite explain this next concept well enough...
With Factory open front and rear diffs you actually produce more stress on the individual axles/ CV half shafts in off-road driving as typically only one is receiving power transfer from the engine to the ground. Also with open diff's you have to use momentum to get through many obstacles causing high wheel speeds (more stress on axles) and bouncing (more stress on axles)
when you add a locker you give both axles the ability to share the load equally in turn taking stress away from one axle and sharing it with the opposite side preventing broken axles. Also you gain the ability to crawl at slower more controlled speeds making for a safe pass as well as reducing stresses on your axle shafts compared to having an open diff.
yes theres more... When you purchase a locking carrier such as ARB, TJM, Spartan Locker, etc. your getting an extremely strong carrier also extremely expensive carrier. By beefing up your CV axles and Rear Axle shafts you in turn apply more stress to the carrier itself. In my experience its way easier to change an axle shaft than it is to replace an entire carrier. As to why its my preference to have a weaker axle shaft than the carrier so that if somethings going to break it's going to be either A.) a drive shaft U-joint B.) axle shaft Which are both less expensive and easier to replace than the differential.
Obviously you would never want to put a spool locker or limited slip in the front you would always want the front axle select-ably locked. The rear you can get away running a full time locker but you'll eat up rubber on dry pavement I know a few guys that run welded rear carriers where they weld the spider gears together creating a full time locker they drive on road fine but they do eat tires.
As far as the best budget way to go about adding lockers or upgrading any of your axle componants I've found its much cheaper to buy complete assemble'd IFS housings and rear third members from
Drivetrain Specialists East Coast Gear Supply They do great work and offer a 5 year warranty on ring an pinion installs. compared to pricing out all the parts it would take me to build the carriers myself against ECGS doing it theres about a 1000-1500 dollar difference pending your driveline setup (ECGS being 1000-1500 dollars cheaper)
Regearing is also an option with this modification as your building the whole differential you have the option to regear to accommodate larger tires or get more low end torque for steep obstacles.
I'm actually installing front and rear air lockers tonight I'll be adding chromoly axle shafts to the rear but i'll be running factory CV half shafts (new ones but factory) and regearing to 4.56 gears so i'll certainly give feed back to this thread as i gain experience from the upgrade and driving it. as far as price for me to add air lockers, rear shafts, re-gear, and high output on-board air It put me just over 4k after purchasing new rear hub bearings (mine were kinda toast), third member gasket, and gear oil(purchased enough for initial install, and a diff fluid change after 500 mile break in of new ring and pinion gears) you can select cheaper locker carriers or perhaps a limited slip in the rear and get the price down gaining the same ability I just wanted to go with what i knew was going to hold up to my driving style
