A “rear” diff in the front?

[Gobi Wan K]

thats what i was thinking too. My initial thought without looking at a diagram is that a clutch force differential would probably be fine in either direction, but a helical or planetary gear would not be.

your thoughts?

That sounds reasonable to me. I really am not an LSD guy, I like a locker. I traded in a Power Wagon on my JT and it had the electric rear locker with LSD and it was just annoying as it would drag and lock up when it shouldn't. I had it checked under warranty and they didn't find anything wrong. And then they made me pay for a fluid change at like $200 since the warranty didn't cover replacing the fluid, go figure.

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[redrider]

I would suppose it would work for a short while before disintegrating. The T case in 2H sends no torque to the front but the front wheels have a constantly changing speed differential due to steering input. Jeep/FCA Hello? Give us a REAL LSD option like Detroit/Eaton Positrac. They are robust and do not require special additives or rebuilds unless abused.

 

[KurtP]

I would suppose it would work for a short while before disintegrating. The T case in 2H sends no torque to the front but the front wheels have a constantly changing speed differential due to steering input. Jeep/FCA Hello? Give us a REAL LSD option like Detroit/Eaton Positrac. They are robust and do not require special additives or rebuilds unless abused.

why would it disintegrate? If no torque is being applied to the diff, there shouldnt be any axial force against the clutch pack To activate the diff. If im understanding the mechanics correctly, it would only ever be getting that force in 4wd.

i dont disagree that a helical or even planetary diff would be better, but none exists For this axle.

 

[Vincent]

I’ve been waiting for a year now to get an Eaton LSD! I wonder why it’s taking so long... Had them Fr/Rr on my JKU and loved it!

 

[KurtP]

That sounds reasonable to me. I really am not an LSD guy, I like a locker. I traded in a Power Wagon on my JT and it had the electric rear locker with LSD and it was just annoying as it would drag and lock up when it shouldn't. I had it checked under warranty and they didn't find anything wrong. And then they made me pay for a fluid change at like $200 since the warranty didn't cover replacing the fluid, go figure.

That would be annoying.

 

[redrider]

why would it disintegrate? If no torque is being applied to the diff, there shouldnt be any axial force against the clutch pack To activate the diff. If im understanding the mechanics correctly, it would only ever be getting that force in 4wd.

i dont disagree that a helical or even planetary diff would be better, but none exists For this axle.

The torque input comes from the different wheel speeds. The inside wheel follows a tighter radius and the outer wheel needs to spin faster to go a farther distance in the same amount of time. No power from the T/C needed. My 2cents. FWIW. Change my mind any time. Always open to the truth.

 

[KurtP]

The torque input comes from the different wheel speeds. The inside wheel follows a tighter radius and the outer wheel needs to spin faster to go a farther distance in the same amount of time. No power from the T/C needed. My 2cents. FWIW. Change my mind any time. Always open to the truth.

the differential force comes in from the speed differential, yes, but the interior spring is what balances the axial forces from the drive shaft. without both forces acting on the center spring and the axle clutch discs, there shouldnt be any force to the clutch packs. This is why it will limit the slip under throttle but allow wheels to move at different speeds when going around a corner.

it wont lock up as much as a locker, and i dont think as much as a helical. But the goal is to increase traction to the front wheels when left foot braking isnt an option like snow at speed etc.

 

[KurtP]

The torque input comes from the different wheel speeds. The inside wheel follows a tighter radius and the outer wheel needs to spin faster to go a farther distance in the same amount of time. No power from the T/C needed. My 2cents. FWIW. Change my mind any time. Always open to the truth.

 

[redrider]

Thanks for the video. I have seen it and many others like it over the years. I understand the theory of operation. My point being that the clutches must either slip excessively to compensate for wheel speed differential or stay locked and bind up the front. Probably wear out at least twice as fast as the rear. Leave the input shaft out. No connection to the T/C at all. If this were a viable set-up, it would have been all the rage. Cheers

 

[KurtP]

Thanks for the video. I have seen it and many others like it over the years. I understand the theory of operation. My point being that the clutches must either slip excessively to compensate for wheel speed differential or stay locked and bind up the front. Probably wear out at least twice as fast as the rear. Leave the input shaft out. No connection to the T/C at all. If this were a viable set-up, it would have been all the rage. Cheers

you could be right. Im trying to figure this out, if you know something i dont then by all means educate away. i didn't get to where i am in life by not listening to people who know more than me about something

 

[ShadowsPapa]

Thanks for the video. I have seen it and many others like it over the years. I understand the theory of operation. My point being that the clutches must either slip excessively to compensate for wheel speed differential or stay locked and bind up the front. Probably wear out at least twice as fast as the rear. Leave the input shaft out. No connection to the T/C at all. If this were a viable set-up, it would have been all the rage. Cheers

You may be forgetting the FAD............ this means the other axle can run the same speed regardless of wheel speed.

I saw a reference to spiral gears, etc. - the ring and pinion gear set are hypoid and backwards isn't good, fine for reverse, short term, but they are cut for turning the correct direction with the pinion doing the lead in that dance.

But there is a force on the clutch plates at all times.

The last one I worked on had a spec for break-away force of 45 ft pounds or more and it was good, less than that, it was worn or bad. (that means with one wheel up, the other on the ground, it was supposed to take at least 45 ft/lbs of force to be able to turn the wheel that was off the ground)
This one was bad...........but the dummy who worked on it before me had things put together wrong and in the incorrect order. A couple of the plates were literally blue.
(It was out of a performance car - he blew the pinion bearings out on his way back to Iowa from Kenosha. He had it trucked back and sent me the differential to rebuild)

 

[brianinca]

Clutch type (Track-Lok) and geared (TrueTrac) LSD's aren't directional. An easy way to discern this is hard braking into a sharp turn, the tire chirp tells you it all works.

TrueTrac is the way to go but dammit they aren't out yet for the new D44's!

i understand how they work in that sense. What Im trying to ascertain is whether Or not a LSD is “directional” or f/r specific. I have no idea and have gotten a different answer at each ask.

 

[ShadowsPapa]

Clutch type (Track-Lok) and geared (TrueTrac) LSD's aren't directional. An easy way to discern this is hard braking into a sharp turn, the tire chirp tells you it all works.

TrueTrac is the way to go but dammit they aren't out yet for the new D44's!

Correct in that the carrier with LSD isn't directional.
Only the pinion and ring gear are. But the components inside the carrier that make up the LSD aren't directional in themselves.

 

[DankjeeP]

I would suppose it would work for a short while before disintegrating. The T case in 2H sends no torque to the front but the front wheels have a constantly changing speed differential due to steering input. Jeep/FCA Hello? Give us a REAL LSD option like Detroit/Eaton Positrac. They are robust and do not require special additives or rebuilds unless abused.

Detroit is not an LSD, it is a locker, LSD has clutches that can slip. Detroit has teeth that lock, but are spring loaded to allow them to disengage temporarily if there is enough bind.

 

[ShadowsPapa]

Detroit is not an LSD, it is a locker, LSD has clutches that can slip. Detroit has teeth that lock, but are spring loaded to allow them to disengage temporarily if there is enough bind.

I installed lockers in the boss's wreckers years ago. It took a heck of a lot to break those things loose. Made a huge difference in those winter runs for him.
Limited slip, like you say - are typically clutch or cones and those in the JT allow the wheels to turn independently with no preload while the older ones like used in my cars will break loose with about 45 pound/feet of torque applied - but they'll grip like crazy under really high torque conditions.
Very different animals - just like you said.

This is "posi" or "Limited slip", AMC called their version "Twin grip".

Here's one I had a customer bring me to rebuild a couple of years back - a couple of the plates were blue, most were pretty scored -

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