An Engineer's Ultimate Guide To 3.21 VS 3.92 Axle Ratio

[lkjk]

While you are looking, if you check out limited slip vs electronic locking, e lockers are great for off road. They truly lock and only work at low speed. Limited slip is great for the road as it is full time.

Curious how a limited slip diff would be better on road...as in what scenario? Not disagreeing, I'm actually curious since my understanding is that the traction control in these trucks limits wheel spin by braking as needed, similar to the quadra-drive 2 (or quadratrack, i forget) in Jeeps. I believe a LSD would kick in if you had traction control off, specifically at lower speeds offroad (I'm not 100% on this, hence the Q). Based on that I would think it wouldn't matter on road for a truck or SUV.

I went elocker, no plans on doing any real offroading but since I ordered mine it was an easy choice to have control.

 

[lkjk]

I would also say go with the 3.92s and Etorque. having been in pure gas cars that shut down at stoplights, there's always a lag between engine start up and driving away, etorque gets rid of that lag.

Also, if you get 2mpg better with 3.21s, over 12,000 miles at $3.50/gallon, you're spending $329 a year less in gas (using 15 vs 17mpg). I doubt its a 2mpg hit, but even if it is thats not enough $$ to worry about

 

[theblet]

LSD locks the rear axle with clutch pack when one wheel starts spinning. It’s automatic. An elocker is an user controlled on/off manual locker. When disengaged you just have a traditional open diff. If difs weren’t open on the street your rear tires wouldn’t last a month.

 

[lkjk]

LSD locks the rear axle with clutch pack when one wheel starts spinning. It’s automatic. An elocker is an user controlled on/off manual locker. When disengaged you just have a traditional open diff. If difs weren’t open on the street your rear tires wouldn’t last a month.

I know what they are and how they are different, just curious if there's a real reason where an lsd is better on-road for a truck/suv than open

 

[theblet]

I’d say an elocker is better for rock crawling than lsd. For mudding they are probably pretty similar. Both are better than BLD IMO.

 

[Mountain Whiskey]

Curious how a limited slip diff would be better on road...as in what scenario? Not disagreeing, I'm actually curious since my understanding is that the traction control in these trucks limits wheel spin by braking as needed, similar to the quadra-drive 2 (or quadratrack, i forget) in Jeeps. I believe a LSD would kick in if you had traction control off, specifically at lower speeds offroad (I'm not 100% on this, hence the Q). Based on that I would think it wouldn't matter on road for a truck or SUV.

I went elocker, no plans on doing any real offroading but since I ordered mine it was an easy choice to have control.

I say this because a LSD is always there, it does not "kick in". It is a clutch pack in the differential. It allows some slippage, hence Limited Slip. It does not apply brakes. It makes sure both wheels have power. It works at all speeds in all modes.

The electronic locker locks the axles. There is no slippage. The wheels are locked to the same power. This is good off road in the dirt or in ruts when one wheel may leave the ground. On the road it would loose traction on a turn. This is why it only engages in 4 wheel low under I think 15 mph in a jeep. I assume the same for a Ram but not sure.

I like to be able to use momentum to climb the mountain to my house in the snow using traction from both rear wheels and one front.

I can also do a burn out in 2 wheel drive on pavement with both wheels.

Can't do these things with the electric lockers. I thought the electric lockers front and rear in my Rubicon would be great. My Sport with LSD out performed it on the road.

 

[HSKR R/T]

I say this because a LSD is always there, it does not "kick in". It is a clutch pack in the differential. It allows some slippage, hence Limited Slip. It does not apply brakes. It makes sure both wheels have power. It works at all speeds in all modes.

The electronic locker locks the axles. There is no slippage. The wheels are locked to the same power. This is good off road in the dirt or in ruts when one wheel may leave the ground. On the road it would loose traction on a turn. This is why it only engages in 4 wheel low under I think 15 mph in a jeep. I assume the same for a Ram but not sure.

I like to be able to use momentum to climb the mountain to my house in the snow using traction from both rear wheels and one front.

I can also do a burn out in 2 wheel drive on pavement with both wheels.

Can't do these things with the electric lockers. I thought the electric lockers front and rear in my Rubicon would be great. My Sport with LSD out performed it on the road.

Electronic locker on the Rams works in all modes, 2wd, 4hi and 4lo. Disengages at 25mph, will re-engage at 20mph. I think it must use front wheel speed, as in the snow last winter, I could be in 2wd doing donuts in a parking lot with 40-50mph rear wheel speed and locker was still engaged.

I can also get both wheels to spin in a burnout without the locker engaged on dry pavement as long as I stay straight.

As for LSD on the street, as mentioned, it's always there. It will work well before traction control would kick in. And doesn't apply the brakes to control wheel spin, so you won't lose momentum

 

[Mountain Whiskey]

Electronic locker on the Rams works in all modes, 2wd, 4hi and 4lo. Disengages at 25mph, will re-engage at 20mph. I think it must use front wheel speed, as in the snow last winter, I could be in 2wd doing donuts in a parking lot with 40-50mph rear wheel speed and locker was still engaged.

I can also get both wheels to spin in a burnout without the locker engaged on dry pavement as long as I stay straight.

As for LSD on the street, as mentioned, it's always there. It will work well before traction control would kick in. And doesn't apply the brakes to control wheel spin, so you won't lose momentum

The electric on Ram is better than the set up on a Jeep then. This is good to know. I had to over ride the settings on my Jeep with a Tazer. It is a safety thing really. They don't want someone with a solid locked axle coming into a turn on a wet road at 50 mph. That is a recipie for disaster. You know, they can't count on people to know how to drive themselves and build safety features in.

Hey, if you don't have your seat belt buckled and you open the door does the transmission throw into park? Really freaked me out when that happened in the jeep when moving in the driveway.

 

[HSKR R/T]

Hey, if you don't have your seat belt buckled and you open the door does the transmission throw into park? Really freaked me out when that happened in the jeep when moving in the driveway.

Yes, can't have seatbelt off and open the door

 

[theblet]

can you turn that off? It’s annoying as hell

 

[mmcbeat]

Yes, can't have seatbelt off and open the door

I have a set of these in my glove box. Haven’t had the need to use them.

 

[theblet]

Nice. Where did you get them? I like how it says "do not use" lol

 

[mmcbeat]

Nice. Where did you get them? I like how it says "do not use" lol

Amazon, search for “seat belt clip”.

 

[lkjk]

Can't do these things with the electric lockers. I thought the electric lockers front and rear in my Rubicon would be great. My Sport with LSD out performed it on the road.

Interesting. I've never owned a LSD, only lockers or open. I have a rubi and the elockers are great, but it only gets driven on roads to and from trails. Mine's a 2010 though, so pretty much absent of any electronics outside of the crappy traction control and a radio.

 

[Mountain Whiskey]

Interesting. I've never owned a LSD, only lockers or open. I have a rubi and the elockers are great, but it only gets driven on roads to and from trails. Mine's a 2010 though, so pretty much absent of any electronics outside of the crappy traction control and a radio.

I was just disappointed at all the limitations of the lockers on the Rubi. On the trail, yes, front and rear locked, 4 low extra low ratio was great.

I need transportation off the mountain to the city and back if the weather is bad. Extra traction of LSD at speed is better for me. Going up the mountain when it is slick requires a bit of momentum. The front lockers were great but the low gearing was too slow.

I hope the Ram does ok in the snow on road. Off road nothing out performs a jeep.

 

[Redfour5]

Curious how a limited slip diff would be better on road...as in what scenario? Not disagreeing, I'm actually curious since my understanding is that the traction control in these trucks limits wheel spin by braking as needed, similar to the quadra-drive 2 (or quadratrack, i forget) in Jeeps. I believe a LSD would kick in if you had traction control off, specifically at lower speeds offroad (I'm not 100% on this, hence the Q). Based on that I would think it wouldn't matter on road for a truck or SUV.

I went elocker, no plans on doing any real offroading but since I ordered mine it was an easy choice to have control.

"Curious how a limited slip would be better on road...as in what scenario?" I had a 13 quad cab WITHOUT limited slip. The mail boxes at the front of our subdivision on a slight slope gets polished in the winter and is very slick. My 2015 Outdoorsman had the limited slip. The 2013 would just spin in 2wd. Even in 4wd, it might slide sideways a few inches to get traction to go up the hill. I HAD to take the time to put it in 4WD then wait that second for everything to engage... The 2015 with limited slip would just hunt for traction and you could feel the limited slip working back and forth and it NEVER had a problem getting going.

That's the best scenario I can speak to where I distinctly noticed a positive difference... I'm a bit worried about that one with ONLY having the elocker...on the new one. I do have AUTO 4WD and it may become the go to setting to during the winter months up here in Montana. After thinking on it before purchasing, I'm thinking it will do a good job of compensating as it almost works like a 4WD limited slip...in a sense...and sort of makes the truck function like most "regular" All Wheel Drive (AWD) cars that have standard front wheel drive and AWD only kicks in when something slips. The only difference being standard rear wheel drive. We will see here in a few months.

 

[oldsouth]

A limited slip rear end has clutch plates that gives traction to the wheel that is not spinning. As far as I know, the Ram does not have electronic brake manipulation for traction. The electronic full locker locks the axle shafts together and is only meant for off road and slow speeds. I went with the limited slip as I find it more useful in general every day driving.

 

[theblet]

Most new rams have BLD instead of LSD/elocker. This gives the 4 wheel auto option.

 

[HSKR R/T]

Most new rams have BLD instead of LSD/elocker. This gives the 4 wheel auto option.

The 4wd auto function is in the transfer case and uses clutches to send power to front wheels when rear wheel slip is detected.

 

[HSKR R/T]

"Curious how a limited slip would be better on road...as in what scenario?" I had a 13 quad cab WITHOUT limited slip. The mail boxes at the front of our subdivision on a slight slope gets polished in the winter and is very slick. My 2015 Outdoorsman had the limited slip. The 2013 would just spin in 2wd. Even in 4wd, it might slide sideways a few inches to get traction to go up the hill. I HAD to take the time to put it in 4WD then wait that second for everything to engage... The 2015 with limited slip would just hunt for traction and you could feel the limited slip working back and forth and it NEVER had a problem getting going.

That's the best scenario I can speak to where I distinctly noticed a positive difference... I'm a bit worried about that one with ONLY having the elocker...on the new one. I do have AUTO 4WD and it may become the go to setting to during the winter months up here in Montana. After thinking on it before purchasing, I'm thinking it will do a good job of compensating as it almost works like a 4WD limited slip...in a sense...and sort of makes the truck function like most "regular" All Wheel Drive (AWD) cars that have standard front wheel drive and AWD only kicks in when something slips. The only difference being standard rear wheel drive. We will see here in a few months.

You may find the 4-high function a better option when needed, and 2wd for 90% of driving. Even in winter. 4 auto uses clutch pack in transfer case to send power to front wheels, so you lose a little power to the wheels, and is more of a wear item if used long term compared to regular 4-high.