lsd

[MoparNorm]

An air locker?

If I had the money I'd probably upgrade to something better I suppose.

Mine came with the truck at 90Kmiles. I drained the fluid, replaced it with synthetic and the addative and it's been good to me. Now has about 160K behind the 6B Cummins. Only complaint I really have is that the back tires will wear before the fronts...

I prefer the air over the electric.
Only a mechanical connection of an air line to worry about and if you add an air tank you have the ability to air your tires up or down and run tools.

If your Sure Grip was working properly, you would wear down the FRONT tires first, not the rear!
Example, the rear wheels working in concert tend to push the fronts,placing more wear on the fronts when turning (that's the advantage of selectables, you turn them off when not needed).

If your rears are wearing faster, they are spinning too much! ; )

[QuantumJo]

Other than not being selectable, what disadvantages are associated with a LSD?
Were they offered / can they be run in the front axle as well?

[MoparNorm]

Other than not being selectable, what disadvantages are associated with a LSD?
Were they offered / can they be run in the front axle as well?

There are many types of LSD, some like the Sure Grip work seamlessly, some require brake/throttle applications, all have their shortcomings and while some provide fairly good advantages over an open diff, none provide 100% positive traction in all situations.
So one must decide what type of terrain and how often they use their rig, to decide on a Sure Grip or selectable.

The biggest disadvantage is not being able to count on 100% traction. In sand, snow, or mud, or with one wheel off of the ground, you may not be able to generate enough friction to force the clutch packs to lock the opposite wheel (hence the brake reference).
If a locker gives you 100% traction and the open diff gives you 50%, count on a Sure Grip type diff to provide you with 75%, but not in all situations, or all of the time.

Some folks run them in front, I wouldn't, because they will become very unpredictable when cornering on pavement, you might not get them to lock at all when needed off road and they might lock when you least expect it when turning in the rain on pavement.

Years of frustrating experiences led me to selectable lockers.

[2x1972]

If you are looking for a selectable locker, i would suggest an OX Locker. No air lines to blow off, no electricals to short. its cable operated, using a lever that you mount anywhere in the cab, and tough as, well, a dodge :)

However in your situation i wouldn't bother with a locker, since the Cummins isn't your wheeler. Eaton makes a limited slip diff that is completely clutch-free, called the Truetrac. It uses helical gears instead of clutches, thus requiring no extra maintenance, and a stronger unit with a much longer life.

[MoparNorm]

If you are looking for a selectable locker, i would suggest an OX Locker. No air lines to blow off, no electricals to short. its cable operated, using a lever that you mount anywhere in the cab, and tough as, well, a dodge :)

However in your situation i wouldn't bother with a locker, since the Cummins isn't your wheeler. Eaton makes a limited slip diff that is completely clutch-free, called the Truetrac. It uses helical gears instead of clutches, thus requiring no extra maintenance, and a stronger unit with a much longer life.

Having rebuilt an Eaton or two, I can say they are generally a good diff, but if you look closely at how those gears actuate, you will find springs the size of ball point pen springs, between you and walking... = )

[2x1972]

I have never heard of these failing, have you known them to be an issue? I know nothing is perfect.... but they seem like a much better alternative to clutch type limited slips.

I have known clutch type LSD's to cause NEITHER tire to turn when under a heavy load with high traction involved. This was an extreme situation, with the puller trying to get moving uphill, but either way, an open diff would have been better, as there is no clutch to slip, so at least one tire would have been moving. Clutches can only take so much load before they slip. The front tires were spinning away (open diff) but no movement with the rear, or the truck at all, therefore turning me off to clutch LSD's.

[74w300uteline]

OX locker

Thats looks perfect for my needs!! but I cant find where OX makes a dana 70 locker.

[2x1972]

Ox

Thats too bad. Im sorry for the miss information, a thought they offered it for the D70. Seems like they should though.... lots of guys run em.

Did a little looking and everything (selectable) i found was ARB Air Lockers... They are good lockers mechanically, built well. But I just dont like the complicaton of the air compressor and lines.

[KRB64]

Talking about the different types, their virtues and behaviors, my CTD when loaded (9,000lbs on a tag along) and on a steep blacktopped hill starting off has a slight shudder type feel. Is that considered "normal" for a stock LSD?

[2x1972]

That sounds like what i was trying to describe earlier. Since all that load is being transferred through the clutch in your diff, it has the possibility of slipping, just like an overloaded or worn clutch in the transmission. If you have ever experienced clutch shudder when diving a vehicle with a worn clutch, this is the same thing, just a different clutch. Most people don't ever notice that kind of thing in their diff, because they don't put that kind of strain on their vehicles. Clutch-type limited slips just aren't the best thing for heavy duty use.

[KRB64]

Thats what I was thinking it was. The hill out of our marina and the other one out of our boat mechanic's is so steep I imagine a tire would break loose if it wasn't LSD, but I'm sure others do it with an open unit. The bad part about the boat mechanic's hill is that there's a stop sign at the top!

[2x1972]

my 72 w200 sits on 39's, and i wheel it as much as i can (when i'm home "sob"), and last time before i left for the air force i broke the transmission-tcase intermittent... er, mother-in-law shaft... in the middle of a good lil mud pit. So my girlfriend tried to pull me out, to no avail, with her 78 f150 that sits on 35's. it has a factory limited slip, and as she would try to pull me out, her front tires would spin, due to the open diff, but the rears didn't move at all. Eventually a stock late 90's 24v 3/4 ton rescued me, open diffs, all terrains, first pull. I don't like clutch-type limited slips.

[MoparNorm]

I have never heard of these failing, have you known them to be an issue? I know nothing is perfect.... but they seem like a much better alternative to clutch type limited slips.

Ha! I wasn't working on them for practice...= ) I have no idea how common it is/was, two out of 6 units went bad and they may have changed that design by now.
What happens is there is a stamped steel actuator that releases a machined block, operated by those springs, it "flips" into place to lock the spiders and actuate the gears into "locked" mode.
The the machined block can fail if there is too much torque shock. These are non-serviceable because there is not replacement "machined block" *
My cure was to disassemble and take the broken pieces to a machinist who made me a high strength replacement part at 3 times the Rockwell hardness.

When rebuilt they lasted for several more years and they may still be on the road, or in NY as a chinese toaster...

I can agree, the clutch packs leave a lot to be desired, don't work well except when new, and they start wearing out on day one...



* sorry for the lack of terminology, it's been many years since I repaired one = )

[74w300uteline]

email sent to OX corp

requesting they consider adding Dana 70's to their product line.

[2x1972]

MoparNorm: Thats new info to me. I had never heard of this problem! Thanks for sharing. I believe Eaton/Detroit backs these units with a lifetime warranty, but warranties dont help you get off the trail....

74w300uteline: Good plan. =)