ARB Locker in a Spicer 25 Front Axle

I have said this before, check the wheel track of virtually any 4wd vehicle built except for the early jeeps and you will find that the front track is wider by about 2-3".
I like my dana 30 front. The only reason I have it is I wanted disk brakes on my 27 and ran across a deal on a perfect (1977) dana 30 with disk that had seen very few miles in 4wd and very low mileage overall.
I got it for $150 complete including the driveshaft and steering parts.
Put an aussie in it and regeared it myself.
The main differences aside from the ring gear and carrier are that the dana 27 has a heavier built center chunk, no much but I would guess around 8-10lbs of iron, the axle shafts in the dana 27 had spicer style u-joints instead of the rzeppa or Bendix, I think all the dana 27's also came with 10" brakes.

 

I learned about it via email. not cheap.

 

Don't do it, or you won't have that stock axle for long. A locker will send full front torque to one side of the axle, where an open diff or a Powr-Lok will just send half the torque, or slightly more. That axle is not strong enough to handle the additional torque you will give it. I put a Powr-Lok in my 25, though it took awhile to track one down. It works amazing, especially in deep snow, yet I am comfortable the axle is not getting more than it was designed for, as the Powr-Lok was an option on that axle.

 

I agree this is often misunderstood, but it is also why so many people start breaking things after they add a locker. Think of it this way: The engine produces a given amount of torque at a given RPM. Power = Torque x rpm. In the transfer case, it splits. In our simple t-cases, it splits half and half. If both tires are on the ground and have traction, accepting the torque, then it splits again in the differential, half to each side. In an open diff, if one tire starts to lose traction, the torque is applied to the slipping side, and very little torque gets transfered (and you'll hear your rpms go up easily). Nothing new there. In a limited slip, some of the torque gets 'used', but only through the clutch mechanism. In a locker, any torque coming to the diff goes to the non-slipping side, thus providing great advantage, except that axle is now getting twice the torque it would in an open diff, up to the point of loss of traction.

This is where people break things. In an open diff, if a tire gets stuck, lets say, on a rock where it has enormous traction, that traction doesn't help that much, as torque is only transfered until the other tire slips. In a locked axle, the torque will just keep rising to turn that tire. It will give out up to half of the torque coming from the transfer case. Pop.

 

Each axle is still recieving the same amount of torque wether the tire is gripping or not. Now the resistance on the tire may change but each axle is still recieving the same amount of power...or am I confused about what your saying :?

 

I expected to have to beef up the shafts to avoid breakage with an ARB - if we pretend for a moment that one could even be made to fit. I'm not anticipating this to be a kit-based project, like a Warn rear axle FF conversion, for example; more interested in whether it was even possible. From what I've heard so far, probably not, at least not without mucho $$$$.

The ARB idea is just one of those nagging questions I have had for a long time. As I said above, I'm really hoping to put one in the rear, along with the Warn kit - and it just seems a shame to buy the compressor and only use it for one axle. And then buy another type of locker for the front too. At least that's where this seems to be headed.... Can't argue with reality I guess!

 

Ok, think of torquing a nut. You have a fixed amount of power from your "engine". You start to turn the wrench. You have torque available, but it is not applied through the wrench (axle) until there is resistance (traction). This is most obvious with a torque wrench with a beam. If you try to apply more power without resistance, all you get is more speed. Remember, power is fixed, but torque is conditional.
Another way to think about it is to see what happens as you apply torque to loosen something. You apply power, which converts to torque at a slow speed. As the nut loosens, and if you still apply the same amount of power, your rpm suddenly increases, and you have to back off quickly on the power or you bust a knuckle.

It is all about having enough resistance/traction to actually have that torque applied. You are seldom in danger with a locked axle with just the weight of the vehicle providing traction to dirt. It is when you get into rocks, which can stop a tire more than just friction x weight that get into that overtorqued condition.

You are almost right in saying that each axle is still recieving the same amount of torque wether the tire is gripping or not. In fact it is receiving the same amount of power, and the mix of speed and torque is the result depending on traction available. Just remember the formula, Power = Torque x Speed. When the speed is low, as in a jammed condition, the torque can rise quite high for a fixed amount of power.