Open diff vs LSD

[Brakelate]

and the times that it would help, its nothing that engaging 4wd couldnt fix.

M'eh. Maybe.

I think honestly, I would rather have a vehicle with a good, tight, LSD and some decent tires as opposed to a "4WD" vehicle with standard street tires, and no form of traction aid, like a LSD or electronic traction control device.

Everything works fine on fairly clean, level asphalt. Go try the first little dirt trail incline. The 2WD, non-LSD trucks are sitting at the bottom digging a single hole with the right rear. A 2WD truck with LSD is about ten feet up, digging two ruts. The 4WD truck with "open" diffs (no LSD, etc) is about 12 feet up, digging two opposing holes. One with the right rear, the other the left front. The truck with the 4WD and rear LSD have made it through those holes and right up to the top, just about where it really gets nasty and loose. The guy with the 4wd and front and rear lockers is sitting on top of the hill watching. If he has a Winch, he is unspooling line to help his next closest buddy up for company.

Go find a trail leading up a hill. I am serious. You can literally look up the face and see these separate locations that have become dug out obstacles.

With better tires, articulation, Hp, grit, determination or being plain nuts, will get you a little further up the hill than as described above. Not much, and not without risk of damage or breakage. But, it occasionally will occur.

Neat thing about the Power Wagon, is it's rear end that operates as a LSD, until the Lockers are engaged. That is a neat trick. Combined with good tires, low gearing, suspension that will flex and the front and rear lockers, that is what really get's it's big ass places. Similar to the Jeep Rubicon's.

I hope that little visual story helps some grasp what occurs "off highway".
Wish I could find my old GoPro. I would go make a little film showing the different levels of traction management and how it looks, and how far it will take you on the same incline, sand pit or mud hole.

(Hmmm, me thinks that is a good idea for a video that might get some views and help some folks understand. Perhaps I will look into that).

Until then, grip the wheel, grit your teeth and Pin It Boys! (and girls).

 

[DannyMK2]

M'eh. Maybe.

I think honestly, I would rather have a vehicle with a good, tight, LSD and some decent tires as opposed to a "4WD" vehicle with standard street tires, and no form of traction aid, like a LSD or electronic traction control device.

Everything works fine on fairly clean, level asphalt. Go try the first little dirt trail incline. The 2WD, non-LSD trucks are sitting at the bottom digging a single hole with the right rear. A 2WD truck with LSD is about ten feet up, digging two ruts. The 4WD truck with "open" diffs (no LSD, etc) is about 12 feet up, digging two opposing holes. One with the right rear, the other the left front. The truck with the 4WD and rear LSD have made it through those holes and right up to the top, just about where it really gets nasty and loose. The guy with the 4wd and front and rear lockers is sitting on top of the hill watching. If he has a Winch, he is unspooling line to help his next closest buddy up for company.

Go find a trail leading up a hill. I am serious. You can literally look up the face and see these separate locations that have become dug out obstacles.

With better tires, articulation, Hp, grit, determination or being plain nuts, will get you a little further up the hill than as described above. Not much, and not without risk of damage or breakage. But, it occasionally will occur.

Neat thing about the Power Wagon, is it's rear end that operates as a LSD, until the Lockers are engaged. That is a neat trick. Combined with good tires, low gearing, suspension that will flex and the front and rear lockers, that is what really get's it's big ass places. Similar to the Jeep Rubicon's.

I hope that little visual story helps some grasp what occurs "off highway".
Wish I could find my old GoPro. I would go make a little film showing the different levels of traction management and how it looks, and how far it will take you on the same incline, sand pit or mud hole.

(Hmmm, me thinks that is a good idea for a video that might get some views and help some folks understand. Perhaps I will look into that).

Until then, grip the wheel, grit your teeth and Pin It Boys! (and girls).

most people wouldnt be in that situation, which is kinda my point. if your looking to seriously offroad your truck, your going to need. but for mostly on-road and the occasional light dirt trail or sand, you probably wont miss it. every situation ive had with my truck where it would help, ive always thought to myself that if i had it, i wouldnt have had to engage 4wd. ive yet to have a situation where i actually needed it. (and again, i dont seriously off-road my truck, only light stuff)

im willing to bet that if the OP really needed lsd for his truck for offroad use, it would have been the first thing he checked before buying it, and this thread wouldnt have even started in the first place.

 

[lonewolf2873]

I love when guys ask how to tell if they have it or not, and then get upset that they don't. Like, if it was that important, you would know it was missing. LOL

If you need to go to the build sheet to find out if you have it, you haven't been doing anything that needs it.

For ***** and giggles, since I looked at my build sheet so I must be one of those guys, exactly HOW would that LSD be working for me that I should notice? I've had my truck for 2 months, never had issue the few times we had snow and I'm driving asphalt daily to/from work!
That was simply an ignorantly blind statement you made. Your LSD does NOTHING for you until your off roading, driving in deep snow or climbing a steep hill. Am I to assume you climb mountains and save baby polar bears daily??
So you don't see it to miss it, anymore then I would!

 

[DannyMK2]

For ***** and giggles, since I looked at my build sheet so I must be one of those guys, exactly HOW would that LSD be working for me that I should notice? I've had my truck for 2 months, never had issue the few times we had snow and I'm driving asphalt daily to/from work!
That was simply an ignorantly blind statement you made. Your LSD does NOTHING for you until your off roading, driving in deep snow or climbing a steep hill. Am I to assume you climb mountains and save baby polar bears daily??
So you don't see it to miss it, anymore then I would!

id say your statement is pretty ignorant because you completely missed the point he was trying to make.

 

[Brakelate]

I guess we all have a different definition of "Seriously Wheel Your Truck".

A Open-Diff'd 4WD truck or a LSD'd 2WD truck / SUV whatever will absolutely get you down to your local fishing hole, camping spot or whatever it may be. In a light snow, through some small muddy spots or even a damp, slick leaf strewn trail. I drove a '89 Bronco II with 2WD, LSD and some good tires all over the place for years. A hand full of times, I sure wish I had ANY kind of 4WD to help out.

You would like to think MOST people purchase for what they THINK they might need it for, or by those who KNOW what they will encounter and what level of difficulty the obstacles they want to take on. Problem is, most purchase 4WD, and even all the top shelf goodies, just for show. In reality, there is a HUGE spread in what some consider "extreme" off road situations, or just a walk in the park. It all depends on one's experience, skill and confidence.

Most Off Roaders also seem to use the "next level" of traction, as a safety net. For example, I go alone. When I do, I run aired up, in 4HI with Diffs open or just the rear LSD. When I start to get stuck, or feel I am over my head, then I can just go to the next level. Be it 4Lo, Lockers, airing down or whatever. Same can be said about a 2WD light trail rig. See how far you get in 2WD, then have an "open" 4WD system as a back up.

Unless really going far out, or playing around, pushing the envelope, most never run headlong into the traction limit of their vehicles. BUT it does happen. Then it is like Insurance... that costly, pain in the butt, needless thing suddenly seems PRICELESS. Stuck far from home, in the cold, hot or up to your eyeballs in a unexpected, liquid filled hole is NOT when you want to suddenly realize that you should have better equipment.

Sure. Go in Pairs. Know your limits. Have a Plan. Have supplies and be prepared. But, Murphy's Law always catches us with our pants down... and I swear it will be in the worst storm, late at night, in the dark and miles from anywhere with no cell service despite your best intentions or prep work.

What is it? $400 for a LSD option rear end? That won't even pay a Tow Truck to get you off a freeway, let alone pull you out off hours on a holiday weekend in the sticks.

It is like warfare out there, at least in my eyes; Carry the most, best gear you can afford. Even then there are times where you will need "That one thing you don't have", but you'll feel better than if you sat there doing nothing.

Every Mustang I've ever owned has come with an LSD. And that's just for shredding tires, not saving baby polar bears. But, I wanted, and got one.

I don't think anyone is judging here. To each his own. IF you are 100% confident in your "open" purchase, then cool. After all these years, you know what YOU use it for. Hell, look at all the "Mall Crawlers" out there.

Not to throw some names under the bus, but I would rather driver Fancy's rig and never get it dirty, than be the one member with the nice standard cab (with good wheels & tires) that hit a unexpected hole miles from nowhere -with two wheels on the pavement- and have it kill my whole afternoon (other than spending some quality alone time with dad) while waiting for a Toyota to come pull him out.

That said, it happens. I have been there, and worse. I am not poking fun or judging. Just hoping some people read this and it gets them thinking.

 

[DannyMK2]

given the option to spend an extra $400 on a new truck to have the lsd, it would be foolish not to. no argument there. but that doesnt answer the OP's question, nor is it always as simple as $400.

theres no argument that having lsd is a nice option to have. but the fact of the matter is that the average person most likely will never need it, and from what the OP is looking to do with his truck, he probably wont need it either.

(for the record, i didnt buy my truck specifically without the lsd. i would have loved to have it, but some deals are too good to pass up and given past experiences, i know i can get away without it perfectly fine)

 

[Brakelate]

To answer your original question. There aren't really any cons to the LSD, compared to an open diff. Unless you consider the cost of buying, additives when changing oil, and repair costs.

There are not any pros to the open diff, other than cost.

In that case, the O/P got his question (mostly) answered in the above quoted response.

The last portion in the O/P about how much power will be delivered to how many numbers of tires, and when, has way too many variables to answer briefly and accurately.

Now I guess we can close this thread then?

 

[RangerGress]

20yrs ago I was stationed in Germany and had an open diff BMW. In the snow it would go sideways if you pressed on a little throttle. Was dicey getting up ski mountains.

These days I race BMWs. When the LSD diff starts getting worn we get wheel spin in the slow corners.

These days we have car control nannies that should keep the open diff from kicking the rear end out from underneath you. The nannies won't get you out of the ditch or snow tho. LSD might. IMO it's totally worth having.

 

[briguy]

dude! it's only a $50.00 option unless you order a stripped down tradesmen.

 

[earlzach]

A absence of a rear LSD will not / does not impact ride quality, truck life or anything else, other than cost as previously mentioned.

Lockers can be viewed as "extreme", and come with some drawbacks.

A Limited Slip Differential really has no drawbacks other than cost.

An Open Differential is just affordable.

They go in that order, top to bottom, in both terms of cost and effectiveness.

Folks can do a Internet Search on each, or I can explain all three here if needed to help folks understand each.

On wet or slick roads it most certainly makes a difference. And open end rear will be less likely to step out in a turn say from a stop and go intersection.
When you do break traction you will only tear up one tire.
When you have a locker and do a lot of tight slow moving turns such as puling into and out of driveways and parking lots you tend to slightly drag the inside tire causing premature wear.
Posi isnt just an install cost it has an in use cost.
Yes LSD is designed to slip a little but in most cases with out large meats for tires they stay locked up more than you think and drage tires.
Its the nature of a posi unit. Not as bad as a full locker or spool but still drags. It cant be passed off as not existant.
I know the difference I have way too many years of experience with 4x4s.
I opted out of LSD and chose 3.21. i was 6 years without a truck payment i knew i wanted the Ram again with the Hemi. But i also knew how to keep the long term economics down. 5 or so years ago I would not have allowed myself to not take the 3.92 lsd. But I also was able to really calculate how manytimes inthe 11 years I had my truck I needed it. Zero. So no brainer for me. Save in the long run.
But like everything It comes down to each thier own.
And it is more over all than just a 400.00 install. Just being clear.

 

[Z77Z77Z]

An lsd was one of my "must haves" when shopping for a truck, with the exception on being on call 24hrs and needing to get to work in the worst conditions, I don't plan on wheeling it, but as simple and dumb as it sounds, when I want to lay down black stripes I want two of them, not peg legging down the road.

 

[jeepguy_1980]

On wet or slick roads it most certainly makes a difference. And open end rear will be less likely to step out in a turn say from a stop and go intersection.
When you do break traction you will only tear up one tire.
When you have a locker and do a lot of tight slow moving turns such as puling into and out of driveways and parking lots you tend to slightly drag the inside tire causing premature wear.
Posi isnt just an install cost it has an in use cost.
Yes LSD is designed to slip a little but in most cases with out large meats for tires they stay locked up more than you think and drage tires.
Its the nature of a posi unit. Not as bad as a full locker or spool but still drags. It cant be passed off as not existant.
I know the difference I have way too many years of experience with 4x4s.
I opted out of LSD and chose 3.21. i was 6 years without a truck payment i knew i wanted the Ram again with the Hemi. But i also knew how to keep the long term economics down. 5 or so years ago I would not have allowed myself to not take the 3.92 lsd. But I also was able to really calculate how manytimes inthe 11 years I had my truck I needed it. Zero. So no brainer for me. Save in the long run.
But like everything It comes down to each thier own.
And it is more over all than just a 400.00 install. Just being clear.

Our trucks do not have posi. They have a more advanced LSD, which does not have the issues you mentioned. That's why when you jack the truck up and rotate one tire, it behaves like an open diff.

From Tech Authority (https://www.techauthority.com/en-US/Pages/Home.aspx) (The Dealer's service manual):



2013 - DS - RAM 1500 PICKUP - 5.7L V8 HEMI MDS V.V.T. (EZH)

03 - Differential and Driveline/Rear Axle - C235/CASE ASSEMBLY, Differential, Limited Slip Differential/Operation


OPERATION


The purpose of the Limited Slip Differential is to provide a torque bias within the differential allowing torque to be transmitted to the high traction tire in a variety of traction situations. The Limited Slip Differential is a torque sensing device and is not dependent on vehicle speed. Using the vehicle traction control system in combination with the Limited Slip Differential enhances the vehicles traction capability. The Limited Slip Differential is a non-preload design, this provides optimal fuel efficiency while still maintaining improved traction performance. The Limited Slip Differential operates as a torque sensing device because when torque is applied to the differential gear set the reaction forces of the bevel gears apply an axial force into the clutch system providing the torque bias. When the input torque is very low the reaction forces will decrease allowing the differential to act similar to an open differential (zero preload). Under normal operation the differential gears can be turned by hand.

Sent from my SCH-I545 using Tapatalk

 

[earlzach]

Our trucks do not have posi. They have a more advanced LSD, which does not have the issues you mentioned. That's why when you jack the truck up and rotate one tire, it behaves like an open diff.

From Tech Authority (https://www.techauthority.com/en-US/Pages/Home.aspx) (The Dealer's service manual):



2013 - DS - RAM 1500 PICKUP - 5.7L V8 HEMI MDS V.V.T. (EZH)

03 - Differential and Driveline/Rear Axle - C235/CASE ASSEMBLY, Differential, Limited Slip Differential/Operation


OPERATION


The purpose of the Limited Slip Differential is to provide a torque bias within the differential allowing torque to be transmitted to the high traction tire in a variety of traction situations. The Limited Slip Differential is a torque sensing device and is not dependent on vehicle speed. Using the vehicle traction control system in combination with the Limited Slip Differential enhances the vehicles traction capability. The Limited Slip Differential is a non-preload design, this provides optimal fuel efficiency while still maintaining improved traction performance. The Limited Slip Differential operates as a torque sensing device because when torque is applied to the differential gear set the reaction forces of the bevel gears apply an axial force into the clutch system providing the torque bias. When the input torque is very low the reaction forces will decrease allowing the differential to act similar to an open differential (zero preload). Under normal operation the differential gears can be turned by hand.

Sent from my SCH-I545 using Tapatalk

Nice information for sure.
My 03 would drag. As much as I loved the open end that was one thing I hated. in 11 years years I never knew it was supposed to roll free in turns. It never did.
Whelp I opted out of LSD for nothing. lol
I know Im not going to miss it. I doubt I was one that ever needed it.
As far as problems mentioned I assure you my 03 was all over the road when wet due to LSD or rear being locked up. It was very fun. But dangerous especially in a corner.
I dont need to worry much at all about that with my totaly open end.

 

[HemiRoar]

I dont have LSD, but recently we had some serious ice storms here in Toronto with that polar vortex, and in 2WD, the truck spun out but as soon I threw it into 4WD, no problem.

I initially though the open diff would cause problems, but I was the guy driving past AWD Escalades and Denalis in 25 cm of snow while in 4WD. Still took turns nice and easy of course.

 

[fadetoblack188]

so these trucks, even with open diffs do well in the snow in 4wd?

 

[jbr]

so these trucks, even with open diffs do well in the snow in 4wd?

This winter on Long Island I had my LSD kick in once in 2wd. Most of the time I had it in 2wd. If conditions got bad in the snow I would put it in 4 auto. I do like that feature.

 

[DannyMK2]

so these trucks, even with open diffs do well in the snow in 4wd?

the only time i could see limited slip helping you in the winter is if 1 tire was on ice when the other wasnt. ive had 2 rams with open diffs and 2 with lsd, they all got around great in the snow. only difference is its easier to do donuts with limited slip.

 

[toofart]

the only time i could see limited slip helping you in the winter is if 1 tire was on ice when the other wasnt.

^^ This.

When both wheels are on similar surfaces, an LSD doesn't add much. We have long winters where road conditions are unpredictable, and often one wheel on ice, one on pavement. Without an LSD you don't accelerate very fast from a stop and driving a part-time 4WD xfer case full time is not desirable.

 

[Etroze86]

The Canadian's have the right idea only reason I need an LSD is predictability in winter and very wet conditions. I know the rear end will step out if I push it but don't always know if it will with a non-LSD.

 

[TRCM]

This winter on Long Island I had my LSD kick in once in 2wd. Most of the time I had it in 2wd. If conditions got bad in the snow I would put it in 4 auto. I do like that feature.

LSD's don't 'kick in'. They are always on.

Traction control DOES 'kick in' when conditions are right.

If indeed you did feel it 'kick in', I'd venture to guess you don't actually have an LSD, and instead felt the traction control 'kick in', or you have an LSD unit that is in need of repair.