I have a 94 f250 351w with a Dana 60 solid axle swap, 6 inch lift with 39.5x15x16.5 tires ... It has a 4.10 LS rear axle in and I wanna make it posi so both tires are digging in the mud when mudding and hauling in the fields on the farm. I've heard that you can weld the differentials to make both wheels spin at the same rate, but I'm not sure how complicated and how well the welds would hold up !?!?! Also is there a locker or something that I can buy for my rear diff that locks it, a locker that could be manually locked and unlocked as I please would be great if there is such a thing haha... But something that would just lock the diff permanently would be fine to ... Any help and advice on welding my rear diff posi or a part that will lock them would be very much appreciated ... THANKS!!!

 

You said you have a LS and that you want posi... a LS is the same thing as posi. They're different names for the same thing.

Not complicated. Strength depends on how good of a welder you are. Done properly it should be plenty strong. However, I do not recommend doing this if you plan on driving this truck on the street at all. The tires need to be able to spin at different speeds to go around corners. Welding the gears prevents this from happening. The tires will chirp and skid and the truck will "hop" around corners and will have poor street manners.

Yes, there is such a thing. It's called a selectable locker.

 

If you already have an LS it just needs a rebuild with extra plates stuffed in to make it as tight as possible, an easy job you can do yourself that will only take an hour or so and cost about $100. Yes there are all kinds of full lockers you could install but it's gonna cost.. maybe $600 for the cheapest locker and more like $1000 for a selectable locker.. and that is just the parts not the install labor.

 

Posi is GM's name for it, Traclok is Ford's, there both limited slip, just FYI.

Don't weld ls diffs, you can't get reliable strength on the side gear welds as there not sitting against the carrier and the springiness of the clutch pack behind it will just help break the welds, yes you can weld all the gears and spiders together but then you put all the load on the cross pin and that wont hold up for ever especially with those big meats on there.

Your best bet is an ARB air locker, it's selcetable from open diff for nice highway and parking lot maners and locked for your mud runs and they are tough as nails. Going with an air locker also gives you added benifit of onboard air for tires and what not.

One other note, the ford lsd in these truck, even rebuild with extra plates are still garbage when one tire is off the ground, don't waste your time and money hopeing that it will do that.

 

I'll second ifrythings, but add that a Detroit locker isn't a terrible option either, unless you do much towing. It's generally less expensive than an ARB (although still not cheap) and it has at least as good of a reputation as ARB too. It's not as nice on-road as an unlocked ARB, but it's not too bad (except when towing). Personally I prefer Detroits off road because they always lock when you need them and always unlock when you don't, but that's probably a bigger deal when rock crawling (in mud just leaving an ARB locked probably is fine most of the time). But an ARB is a good choice too.

 

BS flag is waved here...what you describe is common to ALL Limited slip differentials. If one wheel has zero traction it gets 100% of the torque. The "fix" is to lightly apply the brakes.

 

No, that's not how clutch-type limited slips (such as Ford's Traclock) work. They simply have a friction clutch between the two sides. The tire with traction will always get at least as much torque as it takes to slip the limited slip unit (if you want to find out what that value is, put the truck in neutral, jack up one back tire and use a torque wrench to spin that tire, that's the slip torque of the limited slip unit).

The tire with the most traction will get that slip torque plus whatever torque the tire with the least traction supports. If the tire with the least traction gets zero traction, then the other tire gets only the slip torque.

Theoretically hitting the brake does nothing to help you get traction (except with a Truetrac, it definitely helps then). But with a clutch-type limited slip, an open diff or a locker, hitting the brake makes the tire with zero traction support some torque, so it sends that much more torque to the other tire. But it also makes it take that much more torque to turn that tire too. So the net effect is nothing.

In reality there can be a slight benefit to dragging the brakes. First of all, since the brakes are never PERFECTLY balanced side-to-side you have a 50/50 chance that the imperfection helps you and the tire with traction won't get quite as much brake as the other. Also simply adding more drag makes it easier to apply the power slowly enough that neither tire will brake free, and a tire that's not slipping (yet) will support more torque than one that is. So go ahead and try the brake trick, it does help a little. But it doesn't help the limited slip like you're saying at all.

 

So what you are stating is applying some brake is going to help. My point exactly. A highly contested subject every time it comes up.

 

Get a detroit locker and be done with it. I tow with mine all the time with zero issues, never once had the thought of wishing I could unlock it.

 

I heard you say two things that are wrong. One was that a clutch-type limited slip with one tire in the air won't send any torque to the tire on the ground. The other was that lightly applying the brakes makes a clutch-type limited slip send more torque to the tire with traction.

I will admit that lightly applying the brakes can help a little, but it has nothing to do with the limited slip. First is that you have a 50/50 chance of the less-than-perfectly balance brakes acting like cutting brakes to help you out. Of course that also means that you have a 50/50 chance of having them hurt you in that way if the imbalance is in the other direction.

Second is that static coefficient of friction is higher than dynamic. If you can apply power slow and easy enough so you don't spin a tire at all you'll get more torque out of the tire with low traction. This is exactly the same effect as starting an automatic trans in 2nd gear instead of 1st, and it helps just as much with an open diff or with a spool for that matter. It doesn't affect the performance of a clutch-type limited slip at all.

 

Depends on how heavy you tow and how much weight you have on the drove axle. The problem is that automatic lockers (like Detroits) only drive the inside tire in a turn (the outside tire is allowed to freewheel ahead to prevent scuffing). If you are towing a heavy trailer it will take a lot of force to get moving. And if you don't have a lot of weight on the drive axle you won't get much traction from your one-wheel drive, so you'll spin the inside tire. Of course once the inside tire is going as fast as the outside one the locker will engage and then you'll have 2 wheel drive again. So as long as you're OK with spinning the inside tire a lot you're fine.

I had a Lock Right in the rear of an F-150 for about 9 years. I flat-towed a 3500 lb Jeep while carrying a 1500 lb slide-in camper with that. It worked pretty well because of the weight of the camper. But when I wasn't carrying the camper I couldn't start around a corner without squawking a tire. And that's not a very heavy trailer (although flat towing is zero tongue weight, so that hurt me too). So I'm not against towing with a Detroit, I just wouldn't suggest a Detroit (or any other automatic locker) if a significant amount of heavy towing is expected. But that doesn't mean you can't tow if you get a Detroit.

 

What about an e-locker? Do they make them for a 10.25?

 

Just don't weld 'em like this:

 

That'd be locked all right!

 

what you describe happened a lot when I had a locker in my land cruiser. It very rarely happens in my pickup, only when I have the steering completely cranked over to one dude etc. When I'm towing I have zero issues but my trailer is around 6500 lbs. though.