Sorry if this in the wrong section, or has been asked before, but here it goes..

I have a 2002 4.0L 4X4, and I have a question about the wiring. I like to have my rear diff locked when I'm doing a little recreational driving, so I was wondering if it was possible to put the switch into 4 Hi and somehow manually disrupt the signal to activate the front drivetrain, kind of like an AC mod, which would allow me to choose to cut the signal or leave it normal, thereby giving me 2WD posi or 4WD Hi, respectfully.

Correct me if I'm wrong, but since I have live front axles and my rear diff. locks in 4X4 mode, and this all can be done on the fly while driving,it's just signals sent to the transfer case to activate the front and to the diff to lock it, right? How does all this work? Can I override it with an interrupter circuit or a relay? Any info on how the system works or if it can be done would be greatly appreciated.

Thanks.

 

No sir your rear differential does NOT lock when placed into 4wd. If you have a LS then it is always there and working. You would need to physicly install an electric locker to have that function, and even then you would have to switch it seperate from the 4wd.

 

The only thing that happens in 4wd is the transfer case engages the front output.

The front drivetrain normally freewheels until 4wd is selected.

When you have it in 4wd both front and rear are locked together.
so dont use it on dry pavement or you may experience breakage of some sort.

The differentials however act normally.. they are in no way locked. If you want them
locked you need to purchase a locker or selectable locker(what you were talking about)

Rand

 

ya man u got a LSD.....it works fine....just do a burn out and u will see 2 marks not 1 if u do see 1 u got a problum

 

well, I guess I got a problem then..
I was under the impression that it locked when in 4WD, cause when you test a vehicle to see if the 4WD is working, you put it in high and turn to see if the back end skips, why does it do that then? Is it not fully locked then?

But anyways, what's the best fix if it is broken down most of the time, I already got 4.10's in it. Is the whole gearset shot? Could it be like a tranny and if the fluid gets low or drains entirely, does not work, or what?

 

It does that because there is no differential in the transfer case, therefore both axles have to be spinning at the same speed. When you turn your front wheels have the weight of the engine over them and are more likely to grip, so the driveline has to make it up somewhere and it does this by making the rear wheels spin a hair faster than the truck is moving. That is why you should run 4WD on dry pavement un less you are driving in basically a straight line.

~HJ

 

Yes, exactly. If you have a rear locker ONLY and no 4WD (as I do), then the scrub from the rear tires is an indication of rear locker action. However, in 4WD, you get some of the same effect when turning because none of the tires run at exactly the right speed to distribute everything.

That's what distinguishes so-called "all wheel drive" -- a differential in the transfer case. Those vehicles can corner gracefully on pavement because all 4 wheels can turn at different speeds (as they need to) because of the action of all three differentials.

It sounds as if your truck is functioning normally.

 

I gotcha. Thanks for the info.
So if it is normal to be broken down most of time, even during burnouts and what not, and I do not have a messed up rear, what is the best choice for a locker? Any reccomendations? I have a 4.10 8.8 inch rear end, is it a 31 or 28 spline axle?

I did some research and I found my axle code , 97, which is an 8.8 inch, 4.10 gear, open rear end with 28 spline axle. So I guess that's why it never catches posi. Now, would it be easier and cheaper to find a donor truck with the right rear, or just buy some new internals for mine. I don't get too extreme with my offroading, I just want some better traction and some posi in the rear. Also, will an explorer 8.8 diff. cover bolt right up over mine, like alot of people have?

 

Sorry, what do you mean by "broken down" -- I must have missed something.

The choice for lockers are pretty good for the 8.8. You first need a budget I guess, or maybe you should define what you want first. I'll break down the locker types just a bit and my impression of them:

1. Automatic lockers: the "Detroit Locker", the "LockRiight", and the "NoSlip" (the latter two from PowerTrax/Richmond Gear) and their clones are all similar in their effect. When the differential is being driven or is resisting the driveshaft (in other words, force applied to the diff from the driveshaft), then the rear locks up. Advantage: some do not require full carrier replacement so install is cheap and easy, and they work well generally. Disadvantage: Makes applying power in turns risky so it can affect handling and it's not the most "streetable" choice. There is some discussion about the possibility of automatic lockers encouraging axle breakage -- a debateable point either way.

2. Selectable lockers Part I -- Air lockers: These are open diffs until locked. They use air pressure to lock and ALL selectable lockers require "professional" installation (you can do it if you know how to set up gears) and are generally more expensive. Advantage: tried and true as long as your air system is good. Used by many hardcore offroaders for years (like the ARB air locker). Disadvantage: air system is vulnerable to failure for many reasons. Failure of air lines internally can blow out seals under the wrong conditions (not likely), and they require the diff or cover to be drilled for the air line entry.

3. Selectable lockers Part 2 -- Mechanical lockers: LIke the Ox Locker, these units (and I don't know how many there are) use a mechanical cable like a parking brake cable to actuate the lock mechanism. A little trickier to install, but probably the most "reliable" of the lockers in some respects. Advantages: dead simple in principle. Disadvantages: getting the linkage installed correctly, and the neccessary modifications to the cover and/or housing.

4. Selectable lockers Part 3 -- Electric Lockers: I have one of these (Auburn ECTED) in my truck. Some are limited slips until locked, and there are two different types of these. My ECTED increases clutch loading to lock. Another one (which excapes me) uses conventional pin-locks like most selectables. Advantage: simplest and cheapest install of all selectable lockers, requiring little "external" equipment. Disadvantage: ECTED can wear over time and lose locking strength, still need an entry for the cable, long term reliability is not established for this genre in general.

5. "Lincoln Locker" or "spool": This is where the diff's spider and side gears are either welded tight together ("Lincoln locker"), or a spool piece is substituted for the gears. This locker is locked all the time and cause handing difficulties and tire wear in daily driver duty. It's usually done to trucks whose street use is minimal, or which are trailered to the offroad site.

That's a brief overview and my opinions of what's out there in general. Others will have more to say and it'll give you a starting point for your own research. Good luck!

 

what I meant by "broken down" was that in most cases, I am not catching posi, the big one wheel peel happens, but I guess this is due to the open rear end. So, what is the best thing for me? I do not do alot of heavy offroading, but I do some. Mainly, I just want a rear end that is posi unless I'm turning (LS), so would an EZ locker be good enough, or should I just get an electronic locker and be done with it. How big is the budget difference?

John, is your Auburn locker LS until locked or no, and how much does it cost?

 

Not so much in price ($150 or so) -- but the installation is a big pain on the selectable locker. I've done it, and worked on setting up gears twice now and understand it and can do it. But it's detailed an fairly precise work and many home users wouldn't attempt it.

The drop in lockers are good, but again -- do you try to power through turns hard? If you're in to maxxing out the handling of your truck on the street, I don't know as I'd recommend an automatic locker.

If you mainly want offroad push, or hard launch on the street, then an automatic locker is a good deal -- it's a little cheaper AND you can put it in yourself.

My Auburn is LS until locked, yes. It's about $550, plus a kit of shims is probably a good idea. You have to set the gear lash by shimming the carrier and I'm not sure there's any guarantee that your current shims will be "right" to get it both tight and centered. You can rearrange the shims -- but without some extra shims you might run into trouble.

You need a dial indicator with a magnetic base so you can set the lash when you install the selectable. That should be about the only "special" tool you need. You'll transfer your ring gear and ABS wheel from your old diff carrier to the auburn, then shim it in place.