Locker or Limited Slip or Open on expedition truck?

[TeriAnn]

Hi TeriAnn,
Were you on a Border to Border event?

Yes, the first one in 1998. I was #23. My journal is located at:

http://www.expeditionlandrover.info/blog/B2Breport.htm

 

[TeriAnn]

but me still being so new to the wonderful world of off-road travel, I don't feel like I have the expereince to really use them properly

May I make a suggestion as advice for any off road driver? Build up a lot of trail miles with a stock vehicle before making modifications. Well, if you have a Series Land Rover you can immediately go to a 24 spline rear axle upgrade because a 10 spline rear in a SII or newer is just plain under engineering.

Learn what a stock vehicle can do and explore its limits before adding 4X4 bells & whistles that you might not need. I'm one of those people who believe that learning to off road with open diffs makes a better driver out of you. Any klutz can lock a set of axles & force a vehicle through an obstical but you need to learn how to identify the best approach through an obstcal and how to get the most out of your vehicle to do it with open diffs.

Good tyres, on board air, open diffs & a buddy to help you get unstuck and lots of trail miles is a good way to learn how to drive without damaging your vehicle.

Some people immediately "gear up" to the point that they can force their vehicle through most any approach and never learn how to identify and drive the best and least damaging approach.

My advice, good tyres, 24 spline rear axles if you have a Series LR, on board air then put miles on the trail to expand your driving capabilities then when you are good enough, to explore the vehicle's limits (at first what appears to be vehicle limits usually are driver limits). Only when your skills allow you to reach the vehicle's limits and you wish to,drive beyond them, upgrade the vehicle to expand the limit you wish to drive beyond.

I've seen lots of newbies buy a rig, throw lots of money at random popular upgrades without knowing how they affect the vehicle's parameters then depend upon the upgrades as crutches to compensate for not knowing how to drive off road. Often times they break things a lot and can not keep up with an experienced driver in a less modified rig.

Your single most important upgrade is driving skills.

 

[TeriAnn]

To my knowledge they dont... they need some sort of resistance from the other side in order to initiate the torque transfer. If one tire is in the air, your not getting the 3:1 torque transfer. Though, a little finessing with the brake pedal and you can often start the transfer to the other tire. PITA in my opinion... while it works for some, I prefer to know I am either 100% open, or 100% locked... not some varying ratio inbetween

That is the standard thought out argument and the reason why there is never one single solution that is best for everyone and everyone's driving style.

Some people like the security of locked diffs, some people like to work front wheels with automatic torque biasing diffs and still others people prefer to see if they can get through with an open diff.

Kinda like fishing with some people using bait, others lures and still others flies.

Take care,

 

[Scott Brady]

Your single most important upgrade is driving skills.

I like you already :clapsmile

 

[DaktariEd]

Welcome to ExPo TeriAnn!

You advice about gaining experience with miles of trail driving is right on. I've been fortunate to be able to drive a lot of those miles and push a bit farther with the help of Scott & others on this forum.

Now, having locking diffs and remembering to use them is another matter...

Here's a recent experience of mine:

Yesterday I went with a rather large mixed-forum group with Mark (crawler#976) from Lake Pleasant up to Crown King. A great day BTW...thanks, Mark!

The road was very easy for the most part, but Mark had a couple of optional obstacles to tackle as desired. The biggest obstacle was a boulder-strewn climb for about 200 feet or so. Looked like a pretty tough climb.

I watched as Mark took his Tacoma up, marking the line he chose. So now I try to follow his lead. First 50 feet or so, not bad. But I was a bit too far left on one rock/boulder and couldn't make it up. I adjusted my line to the right a bit and gave it a bit more gas. The rear slipped right and dropped my rear into a nice hole, with my front end up and my bumper hung up on dirt & rock. Couldn't move! #$%^@!!!

I started clearing the rear with a shovel as we thought about getting someone to winch my read-end left so I could get going again.

Mark, comes walking down the hill to see what the holdup was, and I hear him utter something about "lockers?

LOCKERS?

Oh for crying out loud! I've got lockers front and rear!!! Geez! I completely forgot!

I flipped the compressor on, hit the front & rear locker switches and in a few seconds my trusty Rocinante pulled me up and out and up the hill without a fuss. :smiley_drive:

Yeah...ok...so...the lesson: Know your vehicle and engage the brain completely before tackling an obstacle. Go with a trusted, and well prepared group...I learned a lot just from this little "episode."

A little embarrassing, but I think it's a good lesson for newbies. I am still learning....while I am a very experienced camper, I've only attempted this type of crawling stuff for a couple of years....since I started hanging out here at ExPo.

I'm still an adventurer/explorer at heart but this crawling and climbing stuff helps add to my experience and may come in handy sometime when I am out on my own somewhere remote...
​

Oh, and TeriAnn, I almost bought that Dormobile owned by the lawyer up near Sacramento (I think you know him?). I called 30 minutes after he had someone else make an offer...bummer!

Glad to see you on the forum, hope we get to meet sometime. I'd love to meet you and see your rig...the interior (and everything else) looks awesome!

:sombrero:

 

[bigreen505]

Clutch style (most typical) LSD works on friction pressure. If the tractive road surface has a lower coefficient of friction than the resistance in the clutch packs, it will behave like a spooled axle. Ice, mud and snow are perfect examples. In those conditions, LSDs can be dangerous to the inexperienced driver, leading to excessive oversteer when installed in the rear axle.

I don't qualify as an experienced driver by any stretch of imagination, but I do have a lot of miles driving in snow. Clutch style LSD's IMO are dangerous in "low friction" environments, particularly with a side hill (read: road with a lot of crown on it) which would cause the truck to spin unpredictably with no chance of saving it in deep snow. Well that is not entirely true, in some cases backing of the gas quickly and abruptly, which should exacerbate oversteer, would unload the LSD and you would be okay.

Other "extreme" driving situations that would cause the excessive oversteer (though never resulting in a spin) was turning out of a parking lot onto a street. For reasons I can't explain, though maybe Scott will, warm snow and slight slush was worse than drier snow and left turns were much worse than right turns.

Not sure I ever explained this here, but that is why we named the Pathfinder "Odie" -- it liked to chase its tail in the snow.

 

[bigreen505]

That's one of those things that isn't quite obvious but you learn it after time. Cold snow sticks to cold snow.. water is slippery. An experienced mountain driver will often stop for a cup of coffee right at the beginning of a long snowy climb... to let his/her tires cool down. Hot tires won't mate with the cold snow at all, it makes a significant difference.

Interesting, but that wasn't really the issue. Turning to the left with a bit of gas I could spin the truck in its length with some practice. Didn't quite lock up the same to the right. Also was affected by what chemicals were put on the road. "Ice Slice" which makes a more sugary consistency of snow and snow with higher water content were the most problematic. I also had the back end take off on me very aggressively (didn't spin, but close) making a left turn (again with the left turns) accelerating from a stop light with a very light but fresh coating of mag chloride on the road.

My Trooper has the G-80 LSD in it, but I don't have enough miles driving it in snow to say anything intelligent about the LSD that I couldn't ascribe to other factors -- 4wd system, tires, snow temperature and moisture content, etc. Gut feeling is that the LSD is much tamer in "low friction" situations that the Pathfinder was, but seems to engage stronger in dirt/rocks. The Trooper does have snap oversteer tendencies in 2wd in both dirt and snow, for whatever that is worth.

 

[xtatik]

I didn't vote...the option for my truck isn't there.
I've enjoyed the performance of Nissan's "Active Braking Limited Slip" (ABLS)on my 06' Xterra.
So far it has worked unbelievably well for moderate terrain. On rougher stuff, combined with a rear e-locker and the secondary throttle mapping, I've had minimal if any wheel spin. I just make sure I carry all the requisite fuses..LOL!

 

[devinsixtyseven]

I think...ignoring TTORA and listening to TeriAnn is your best bet . That's some of the best advice I've read in a while.

Failing that...

Selectable lockers with axles at least 2x as strong as the factory axles...if one side is required to do all the work, you know the axle, hub, and joints can take the throughput. Not so easy to arrange for CV joints on an IFS rig.

I've put ~100K miles on and offroad with stock open diffs, and in a week or so will finally have a selectable locker in the rear (plus stronger axles)...I want to retain on-road handling but add bombproof reliability and capability in rough terrain.

The innards of the ARB lockers are very, very strong. That in itself is a good reason to put one in the front, whether you add the air line at the same time or not. Like someone else said, keep the axle you have, the 3rd member is stronger than the e-locker version...and Kurt has great prices on ARBs.

-Sean

 

[cruiseroutfit]

Driving style comes into play here, of course - but I don't automatically agree with your assertion that locking diffs put more strain on each side - here's why..

Not too mention that an open diff (and some styles of lockers) will cause the axle withOUT traction to rotate TWICE as fast as they would be if locked. When that tire bounces into some traction.. BOOM!

 

[Northern Explorer]

I am just now looking into this subject for my truck. My Z85 Chevy Colorado did not come with the automatic rear locker that the Z71 model comes with. I am probably going to install the Z71 locker in the near future. The Z71 comes standard with the Eaton G80. It will only engages below 20 mph.

Here are some good videos comparing the G80 to open and limited slip.

http://www.brightcove.com/title.jsp?title=1033870868

http://www.youtube.com/watch?v=p8nAbg5suFw&mode=related&search=

http://www.youtube.com/watch?v=y6_kOlUXYoI

 

[BigAl]

I have to vote locker for an "Expedition" truck. I run a spool in the rear of my jeep. If you want most traction with the least issues, that's the way to go. If you had asked about a daily driver or dual purpose truck, I'd vote open or LSD. If it's truely for expedition type travel then there is less need to compromise.

 

[devinsixtyseven]

If you are attempting to climb a deep mogul or rocky incline with locked differentials, chances are you'll be able to ooze smoothly over the whole ordeal without any shocks or sharp changes in torque. Typically the side without traction will unload softly because you're moving forward, and return to load (weight, traction, and axle torsion) smoothly as well because it's already going the same speed as your forward motion. Open differentials tend to require more use of momentum, more skinny pedal, and often will grab and lose traction abruptly.. it seems to me that's when the most load is dropped on a part.

That's an excellent point, since most people will use it exactly like that.

When I mentioned 2x stock axle strength, I was actually thinking of cases where only one side of the locked axle is on the ground and has full traction--climbing a boulder or something--and that side must support the full input torque from the driveshaft, vs balancing the load with both axles or spinning a tire, neither of which is particularly stressful (until the side and spiders eat themselves, or a rapidly spinning wheel gains traction under power!).

Granted that would be a case of using the locker as a substitute for suspension travel and IMHO not really the best idea, but it'll happen eventually, either through necessity or forcing through a bad line. I don't think a good driver would willingly put themselves in that situation without a very good reason, and certainly not in the middle of nowhere .

-Sean

 

[cruiseroutfit]

Sorry it took so long to get back to you but the info comes form several sources. http://www.4crawler.com/4x4/TrueTrac.shtml read through that and it says that there is a controlled amount of resistance along with a 2.5 to 3.5 biased ratio. Another source a local shop that likes to run the diffs for daily driver applications because they are the best all around no mess traction adder. The shop manager says his Cherokee will send power to the tire that has traction even if there is a tire off the ground. I can't tell you for sure because I don't have one but this is where I will spend my money because of the "no fail" apsects of the diff and the wet road mannors.

Read down lower in the article:

TrueTrac differentials require a certain amount of resistance at the ground (i.e. traction) in order to start the torque transfer. A TrueTrac differential may not transfer torque if the spinning wheel is off the ground or on a very slippery surface. If spinning occurs, often a slight application of the brakes, while carefully applying power, will slow the spinning wheel enough to allow the TrueTrac differential to transfer torque to the other wheel.

I can assure you this is the case with the TrueTracs I have dealt with... they provide little or no repsonse when on tire is up in the air. Some models might react differently? The author noted the same issue on his personal vehicle...

 

[7wt]

Read down lower in the article:


I can assure you this is the case with the TrueTracs I have dealt with... they provide little or no repsonse when on tire is up in the air. Some models might react differently? The author noted the same issue on his personal vehicle...

Whoops, thanks for the correction. I missed that part. Oh well, now I am confused as ever as I had it down between the Powertrax and the Trutrac. What to do, what to do?