How you know when to use CDL?

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HomersCanyonero

HomersCanyonero

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I know how to activate the CDL (either in 4Lo or CDL switch in 4Hi). However, how do I recognize the situations when I need to lock the center?

I was on a somewhat steep and rocky dirt road, so I went to 4Lo and it locked the center. I didn't think there was much tire slipping, but the 80 got through without any issues.

If I see a winding dirt road with a little mud and mostly dirt on a slight incline, then do I lock the center when in 4Hi and 2nd gear?

I'm trying to learn when I should lock my center and when I should leave it alone. I just did the CDL switch, but not the Pin 7 mod. No front or rear locks.
 
Basically the 80 in its natural full-time 4wd state is very capable. But think of it as AWD. Locking the CDL basically is like turning the front selectable hubs on older truck to make true 4wd. The front and rear axles will be locked together. There is a good diagram and video in the FAQ.

You just need to feel out and learn the terrain you are on make judgement calls from there whether to use or not. I general don't touch mine and try everything with it off. I that does'nt work and mash that little button and try it again.
 
Your tires will also play a role in when you should be locking the CDL as they will dictate how much traction you have in an off-road situation. If you think of it in these terms it may help:
AWD = power to any one wheel, if you spin a tire all the power is delivered to that tire with the least traction
CDL'd/4x4 = power to any one wheel on each axle, or 50/50 power split between the front and rear axles

Best to just get yourself into low traction situations (safely), and play around to see how things work. With the CDL'd you'll have a harder time turning, you should really only have the CDL'd in situations where the tires will be allowed to slip to avoid driveline binding when turning. I see you're in SOCAL, so it's not like you'll have lots of opportunities to play in the snow like some of us on here, lol.
 
Anytime I would go off road in my 95' with CDL, even a dirt road, I would activate it. Why not? Give the mech some exercise and if you are in a situation where you may need the extra traction it's better to have it before you realize you need it.
 
Why would you start locking diffs if you are able to drive without them locked? A locked center can cause understeer on a dirt road. Every situation is different and I am generalizing here, but I keep everything open until it's needed or I anticipate the need.
 
jonheld said:
Why would you start locking diffs if you are able to drive without them locked? A locked center can cause understeer on a dirt road. Every situation is different and I am generalizing here, but I keep everything open until it's needed or I anticipate the need.
Click to expand...
^^ This is my train of thought.
 
I am not an expert, but here are my thoughts.

You are usually better off not locking any differential (center, rear or front) unless you need it. You will know you need it when you tires are spinning or your forward progress is halted. As soon as you are through whatever obstacle was holding you back, turn them all off.

An unlocked drive train is more "fluid" and is better able to absorb shocks without breaking. When the drive train is all locked up, loads to one axle/wheel cannot be shared throughout the system and will concentrate in the loaded axle. This can break stuff.

Fine control of your vehicle is diminished when locked as well.
 
I started using mine anytime the roads are very icy. I notice a significant improvement in traction at low speeds on ice with the CDL on, especially while turning or accelerating.
 
I think I understand how the locks work, but there are a few variables that I need clarification.

In 4Hi and going like 25 MPH, can I lock the center at this speed if I'm starting to get stuck in loose sand? Or do I stop and then engage the CDL in 4Hi while stopped?

If one tire is spinning and doesn't get traction, then lock the center. This will get me power on the axel that has traction.

If two tires on the same axel are spinning, then lock the center. This will get me power on the axel that's not spinning.

If two tires on different axles are spinning, then I can try locking the center and tap on the brakes to see if I can get traction. This is when the rear locker would come in handy in addition to the center lock. Most everyone claims that a rear lock and a center lock will cover most situations.

The only time you really need the triple lock (front, rear, and center) is when you have 3 tires spinning and two of the spinning tires are in the rear. The center and the rear locker probably are not enough. You can try tapping the brakes to get out, but this is the only situation where you really need to lock all 3 (and maybe you need the winch).

I'm going to watch more videos, but here are some scenarios to see if you would lock the center:

1. Very sandy terrain on the beach like Pismo or the sand going around Mono Lake. Do I lock the CDL if I'm going like 20 MPH on 4Hi, but I'm starting to slip a little?

2. I'm driving uphill (slight incline) on a dirt road in the mountains and I see that there's a stretch of road (for about a mile) that has a foot of fresh snow. Do I engage the CDL in anticipation, do I go 4Lo, or wait until I start slipping?
 
Last edited:
702FZJ80 said:
Anytime I would go off road in my 95' with CDL, even a dirt road, I would activate it. Why not? Give the mech some exercise and if you are in a situation where you may need the extra traction it's better to have it before you realize you need it.
Click to expand...

I don't have a switch for mine but I drop it down in low to lock it and/or use my front and rear ARBs quite often. I'm usually at high altitude and so I always go in to low as soon as I leave the pavement so it doesn't feel like such a dog. I'd rather walk right up an obstacle first time rather than have to back down and then try again. Don't really care to know if I can make it through something without them. I paid quite a bit of money for them so I'm going to use the hell out of them.
 
Do you have to stop driving to lock the center? Or can I use the CDL switch to lock the center while driving at 25 MPH? I don't want to break the center diff by engaging in speed.
 
up to ~50MPH you can freely switch it on.
there is a fork that lock CD. and as the front and rear drive shafts spining at the same corner speed when you drive forward - there is no problem to lock the CD.
 
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