Center Diff Lock Switch? (1 Viewer)

[lurker]

I would like to know how others Center Diff Lock Switch should work.

I installed mine along with the 7 pin mod and my question is about engagement and engagement speeds.

1) I have to dawdle with particular transmission gear selections and sometimes hi4/low4 selections to see the CDL and ABS illuminate properly.

I almost always have to select neutral at a complete stop press the CDL switch and wait 1 or 2 seconds for the lights to illuminate. Is this normal, the neutral part? Also this superstitious procedure doesn’t always work, just sometimes. As for example; today the first time I tried the 7 pin mod I started the procedure while shifting into neutral and press and depress the CDL switch as many times as I wanted and the lights would illuminate in the proper sequence at a complete stop. But as I drove around selecting different modes (while stopped) the lights would not always follow the owner’s instructions, sometimes the selection would stay illuminated in the improper selection and at other times only after 5 feet would the LC would decide to concede and revise its illuminated status (I was never sure if the transfercase was locking/unlocking or not, just light clicking sounds). I am the only person that has experienced this?

2) I have heard rumors that you can select say hi4 at 20 mph and press the CDL switch to lock the transfercase, but I dare not try this because of the instructions proper hi4/low4 engagement rules per the stock visor instructions. I know that hi4/low4 selection is a different animal, but this is somewhat close to the same effect.

There are a lot of instructions on how to do certain mods but sometimes it’s even harder to find how the mods should actually behave on LC’s gone wild.

 

[Big_Moose]

Depending upon conditions it takes a few moments for the ABS / CDL light to illuminate. This also depends upon the 'bind-up" of the TC, or the "gummyness" of the actuator motor, etc.

Cruiser is in AWD when in High range in stock form, or with the CDL switch off.
Cruiser is in 4WD High range with CDL switch turned on.
Cruiser is in AWD when in Low range with pin 7 mod / CDL switch off.
Cruiser is in 4WD Low range with the CDL swtich turned on (just like stock configuration).

You cannot switch from "High" range to "Low" range on the fly! Period!
You can engage / disengage the CDL switch on the fly with the pin 7 mod!

 

[RavenTai]

The CDL is like the other lockers in that they are spline to spline or tooth to tooth steel lockers it will not lock until it is lined up and the parts can mesh, if it is not lined up when you press the button moving will allow it to line up and it will then lock, having it in neutral allows the bits to move around somewhat to a similar effect, sounds like you are always trying this stopped?

<But as I drove around selecting different modes (while stopped) the lights would not always follow the owner’s instructions>

Not sure, are you driving then stopping again?

Also if there is some loading in the drive train (windup) like if you make a turn with it locked it may not want to disengage and may make a popping noise when it does

The CDL basically turns an on-road all-wheel drive T-case into part time 4wheel drive off road only

Or basically from a Subaru into a FJ-40, gives you the best of both worlds

You can engage the CDL at just about any speed (I did it yesterday @ 50MPH) but steering will be unpredictable and lurching, no problem at low speeds on loose ground but dangerous at high speeds or on pavement,

Go find a dirt road (the looser the better) and play with the CDL if you are moving and especially slight turns it should follow the switch within a few seconds

If it does not reliably follow the switch you have a problem of some sorts, lots of diagnostic info in previous threads, including one a few days ago


You might want to read the “diff’s for dummies” page again keeping in mind what you are seeing, it is a really good explanation of what all is going on

 

[lurker]

The CDL is like the other lockers in that they are spline to spline or tooth to tooth steel lockers it will not lock until it is lined up and the parts can mesh, if it is not lined up when you press the button moving will allow it to line up and it will then lock, having it in neutral allows the bits to move around somewhat to a similar effect, sounds like you are always trying this stopped?

<But as I drove around selecting different modes (while stopped) the lights would not always follow the owner’s instructions>

Not sure, are you driving then stopping again?

Also if there is some loading in the drive train (windup) like if you make a turn with it locked it may not want to disengage and may make a popping noise when it does

The CDL basically turns an on-road all-wheel drive T-case into part time 4wheel drive off road only

Or basically from a Subaru into a FJ-40, gives you the best of both worlds

You can engage the CDL at just about any speed (I did it yesterday @ 50MPH) but steering will be unpredictable and lurching, no problem at low speeds on loose ground but dangerous at high speeds or on pavement,

Go find a dirt road (the looser the better) and play with the CDL if you are moving and especially slight turns it should follow the switch within a few seconds

If it does not reliably follow the switch you have a problem of some sorts, lots of diagnostic info in previous threads, including one a few days ago


You might want to read the “diff’s for dummies” page again keeping in mind what you are seeing, it is a really good explanation of what all is going on

Thanks RavenTai,

I’m somewhat timid in my attempts to just throw the switch as you mentioned, but now that I have the official “I82much-mud training” I’ll try it on a loose dirt road.

I think your description of the spines lining up really helps explaining the behavior of the CDL lights. I did notice at one point that the lights were not paying much attention to my psionic, telepathic, or paranormal commands, but once I creped a few feet the light responded and click the spines must have aligned!

Mind you, I’m doing all this on a paved parking lot at a mind boggling speed of 1 or 2 mph; so and the balancing act of visions of birfields and $100 bills are shooting out of my front axle while I’m attempting to keep that 3rd eye on the CDL light are somewhat obtrusive.

Thanks for the help.

 

[RavenTai]

I’ll try it on a loose dirt road.

let us know if you get a good mind meld with the CDL

 

[e9999]

well, I don't know if this is standard or not, but when I hit the CDL switch, the locker engages instantly 99% of the time -well, at least I hear a noise (but could be the relay?) and the lights come on instantly. Been marvelling at that. Much much faster than the end lockers.
Now, though, I always did this stopped, but not necessarily in Neutral.
Eric

 

[landtank]

I've engaged it at speeds of 30+ mph. If doing it on the fly I make sure I'm heading straight before pressing the button. Disengaging the same. Usually this is done on snow covered roads, not dry asphault.

 

[RavenTai]

Disengaging the same. Usually this is done on snow covered roads, QUOTE]


I have never driven on snow, grew up in FL encountered ice a few times since i moved GA, dont like it at all

every few years we get a good snow here, maybe this winter the 80 will get a tase of it,

I take it the CDL is only used only when needed to get going then turned off again? lockers same? I would think this is one place havign the ABS function would be useful

 

[lurker]

Disengaging the same. Usually this is done on snow covered roads, QUOTE]


I have never driven on snow, grew up in FL encountered ice a few times since i moved GA, dont like it at all

every few years we get a good snow here, maybe this winter the 80 will get a tase of it,

I take it the CDL is only used only when needed to get going then turned off again? lockers same? I would think this is one place havign the ABS function would be useful

Raven,

I'm no expert by any means, but the reason I wanted the CDL was for driving in snow conditions.

I thought it would be great if I had one wheel on the ice and the other on the pavement.

 

[Rookie2]

Seems like for icey conditions the locked center diff. would only be benificial for climbing straight uphill. Seems like having the center locked on turns would encourage slidding.

I had to go pick up the stranded wife last year in very icey conditions (no CDL switch at the time) and was impressed with how well this rig got around. I just cruised around with no problems while everyone else was sitting there polishing the ice on very slight inclines. Unlocked 4-Hi was golden. Although the AWD helps, I think it has as much or more to do with weight and distribution than anything.


Rookie2

 

[Beowulf]

Lurker,

I think you've figured it out from the prior discussions but I will summarize:

The switches (center, rear, and front) are electronic and each switch starts the locking process. In the case of the center diff, it starts a motor that engages the splines that Raventai described. At the point that everything is properly locked, the mechanism sends a "completed" signal back to the ECU and the dash indicator is illuminated.

Sometimes this happens (almost) instantaneously; sometimes the splines take longer to align. If you'll look at pics of the rear diff lock splines you'll see there are only 5 or 6 big cogs. The center and front splines are much smaller; hence they lock quicker.

As you've discovered, you must stop, put the tranny in N, before you shift between low range and high range. The F&R diff locks should only be engaged in Low range. The center diff (with the CDL switch) can be engaged in either Low range or in High range.

-B-

 

[sjcruiser]

Beowulf,

Lurker,

<SNIP>

The F&R diff locks should only be engaged in Low range.

-B-

Is there any other rationale behind this other than the possible additional stress on the drive drains if engaged on High range ? I'm asking because I exercise my lockers every other months and have always done it in High.

Frank.

 

[cruiserdan]

Beowulf,



Is there any other rationale behind this other than the possible additional stress on the drive drains if engaged on High range ? I'm asking because I exercise my lockers every other months and have always done it in High.

Frank.

In the case of an unmodified 80 the front and rear can only be locked when the transfer is in low range. Of course the ends are blocked from locking if the vehicle speed exceeds 5mph.

Indeed it is possible to lock the ends in high in a vehicle equipped with a CDL switch. It is not at all advisable to operate the vehicle above 5-10 mph with the ends locked as sudden, unpredictable, movements are likely.

 

[landtank]

There is a difference in driving in snow and on ice. Driving in a storm when the plows haven't gotten out or it's coming down hard you are in 4~6" of the stuff and having the CDL in hi helps. Without the Center diff locked if you loose traction on 1 tire your forward motion stops.

 

[Beowulf]

It is not at all advisable to operate the vehicle above 5-10 mph with the ends locked as sudden, unpredictable, movements are likely.

We had 4 locked 80's on the Super Bowl snow run last winter. The depth (3' or more) had each of us breaking trail at high speed (30-40 MPH) for fairly long distances. Each of us had some exciting times where the vehicle would make a sudden right turn and you'd find yourself sideways across the trail or worse. A few near misses with trees and cliffs.

-B-