Is my center diff lock working? (1 Viewer)

[montanacruiser]

I've done some research and can't find what I need. When I lock my center diff I really don't see any improvement in performance. I was driving in the woods in some snow tires started spinning going up hill locked it and didn't get any further. My light that indicates its on works.
This may be some thing else but when I spin my tires locked the cruiser feels like something is bouncing. Like the transmission moving or something.
Do you guys see a jump in performance with the center locked or do you think I have a problem? Is there a way of telling if it is working? Any help would be appreciated.
Thanks

 

[Salue]

It kind of sounds like it is working if you shift it to lock and the light comes on because that would mean the actuator is moving the gear to lock and pushing the CDL sensor switch to trigger the light. Did you add a CDL switch or are you pulling the lever to L? Have you tried locking it with just the key in the on position but not started? When you do that you should be able to hear the actuator motor make a whirr noise down under the rig and a little click down by your kick panel.

Salue

 

[veggieguy]

if you jack up one front wheel and it won't rotate, then you have just confirmed the cdl is locked.

 

[montanacruiser]

I sure the cdl switch is stock on my rig. I will try switching it on while the truck is off and I will try the jack trick. with the jack truck is off with switch on?

 

[veggieguy]

I sure the cdl switch is stock on my rig. I will try switching it on while the truck is off and I will try the jack trick. with the jack truck is off with switch on?

yes, put the switch on so the centre diff light comes on, which means your diff should be locked. then jack up one front wheel to see if it rotates. doesn't matter whether the truck is on or off at that point. if the wheel won't rotate, the diff is locked. then turn the key to on and switch off the centre diff lock. If the light goes out and the front wheel rotates, then you have a properly functioning centre diff lock.

on another note, when you said it felt like your truck was bouncing and the tranny "moving", that's an indication of your front and rear wheels being locked together and fighting to get traction, which makes the whole truck bounce and lurch. another indication that your diff lock works. maybe you were just too stuck!!

 

[Kennyfzj80]

I don't think being in 4L helps if you're spinning in snow.

CDL does diddly squat for me in the snow. I think there are some threads here regarding snow driving.

I think you're better off with chains or some kind of track pads.

Also try the 7 pin mod. (Installing switch for 4H).

 

[abruzzi]

Another quick test is to find a dry parking lot and do a couple of big figure eights. With cdl off it should be nice and smooth. Then engage the cdl, and try the same figure eights. This time it should be less smooth, push harder toward straight. The cdl doesn't have nearly the obviousness of the front and rear lockers, and it doesn't provide the kind of anti torque loss that front and read do.

 

[montanacruiser]

Thanks guys I have figured its working. I think I was just in to deep of snow. What veggie guy said about the bounce makes sense. Looks like I need front and rear lockers to go where I want. Thanks again for all the help.
I am a little confused on the 7 pin mod. I thought that was just for keeping the cdl out in L? I think my cdl works in H with no mod. Am I wrong?

 

[DesertLx450]

I'm not sure about the 80's from 1991 to 94, but on the 80's lc from years 1995 to 97 the there was not stock CDL switch. The truck will only turn the CDL on when switched to Low. Its easy to add one yourself (buy one on ebay etc, and theres already a plug behind the dash) which allows you to turn CDL on in high. I haven't done the 7 pin mod, but my understanding is that your right, it allows you to go into 4Low without out locking CDL.

 

[montanacruiser]

I have a 94 80 and it does have a stock cdl switch that you can turn on In H. I dint know 95 and up they were not stock. learn something new every day.

 

[ppc]

91 and 92 have the CDL switch standard. No 7 pin mod because the tranny is not electronically controlled. If the switch is there on 93-97 then it was added by a previous owner. Standard, the CDL locked automatically when switched to low range. Also has a viscous coupler and electronically controlled tranny.

 

[Cfbrenton1]

If you are going into deep snow, you are better off pressing the CDL switch before you start spinning. By the time you are spinning you are losing or have lost momentum and you are behind the eight ball.

 

[BILT4ME]

I was in a parking lot today and pulled up onto a pile of snow. The rear was on wet pavement. I EXPECTED to have the front tires spin, and that the rear would push me deeper into the snow. Instead, the front tires spun, but the rears did NOT. I thought it was because the CDL did not lock up. So, I put it in LOW RANGE to see if it would push it up, but the rears still did NOT spin.

Is that correct or is there possibly a problem with my CDL not locking?

 

[superstan26]

I was in a parking lot today and pulled up onto a pile of snow. The rear was on wet pavement. I EXPECTED to have the front tires spin, and that the rear would push me deeper into the snow. Instead, the front tires spun, but the rears did NOT. I thought it was because the CDL did not lock up. So, I put it in LOW RANGE to see if it would push it up, but the rears still did NOT spin.

Is that correct or is there possibly a problem with my CDL not locking?

Sounds like you have a problem. If your cdl was locked, and you were not making progress in the direction you were trying to travel with a front tire spinning a rear should be spinning as well.

 

[Riley]

Please clarify, you put into low range but did you lock the CDL?

I recall you have a CDL switch so you would need to lock it and not put into low range.

 

[superstan26]

Please clarify, you put into low range but did you lock the CDL?

I recall you have a CDL switch so you would need to lock it and not put into low range.

If in hi he would need to activate cdl by pushing button. Lo locks cdl automatically in oem configuration, although some guys bypass with 7 pin mods on newer cruisers, our UN plugging a connector on 91-92.

I was in a parking lot today and pulled up onto a pile of snow. The rear was on wet pavement. I EXPECTED to have the front tires spin, and that the rear would push me deeper into the snow. Instead, the front tires spun, but the rears did NOT. I thought it was because the CDL did not lock up. So, I put it in LOW RANGE to see if it would push it up, but the rears still did NOT spin.

Is that correct or is there possibly a problem with my CDL not locking?

Sounds like you have a problem. If your cdl was locked, and you were not making progress in the direction you were trying to travel with a front tire spinning a rear should be spinning as well.

Having said that I trust that you are aware that the same tire does not always spin.
If your cdl lock is engaged, and you're not making progress with tires spinning there will be one tire spinning both front, and rear. The spinning tires may alternate sides of each axle in a nearly equal traction scenario, but there will only be one tire per axle spinning at a time.

For instance if you had your truck on Jack stands with the cdl locked all four tires will rotate equally under the power of the engine (if there isn't more resistance at any given wheel because of friction due to bearings, or dragging brakes etc.). If there were resistance applied to the either front wheel, the opposite would continue to spin, as would both rears. The same goes for the rear axle if resistance were applied to either rear tire the other would spin, as would both fronts. If resistance were applied to a front, and a rear tire then the tire that is unrestricted on each axle would continue to spin. However, if equal pressure were applied to both tires on either axle at the same time then the truck would have traction, and progress would be made.

I know this post is redundant, but without getting into specifics about power distribution it's often easiest to illustrate useful power (power transferred to the ground) like this:

4wd hi (cdl unlocked)= 1wd (any single wheel off if the ground you're stuck.

4wd hi (cdl locked)= 2wd any front, and rear tire off the ground at the same time you're stuck.

4wd lo (unmodified cdl locked) = 2wd any front, and rear tire off the ground at the same time you're stuck.

4wd hi, or lo (cdl locked front. Or rear)=
3wd

4wd hi, or low 3x locked = true 4wd

Clear as mud?

 

[Sarmajor]

91 & 92s lock the center diff when transfer case is shifted to Lo
CDL switch allows locking Center diff in Hi.
Factory front & rear diff locks will not engage unless center diff is locked and switch on transfer case confirms locked.

 

[084runnerltd]

I've done some research and can't find what I need. When I lock my center diff I really don't see any improvement in performance. I was driving in the woods in some snow tires started spinning going up hill locked it and didn't get any further. My light that indicates its on works. This may be some thing else but when I spin my tires locked the cruiser feels like something is bouncing. Like the transmission moving or something. Do you guys see a jump in performance with the center locked or do you think I have a problem? Is there a way of telling if it is working? Any help would be appreciated. Thanks

Did you actually see your wheels spinning after you pressed the CDL button.

I had the "bouncing feeling" too the first time we had bad weather and I used the CDL ....I was stuck in a small mount of snow.

My problem was that I wasn't in "L" so there wasn't enough torque to get the wheels spinning....I would just kind of rock. Once I figured it out I was good to go.

Just an idea....

Sent from DynaTAC bag phone

 

[jonheld]

91 & 92s lock the center diff when transfer case is shifted to Lo
CDL switch allows locking Center diff in Hi.
Factory front & rear diff locks will not engage unless center diff is locked and switch on transfer case confirms locked.

OK folks. In a stock configuration, all fulltime 4WD 80 Series (1991-1997) automatically lock the CD when shifted into low range on the transfer case.

1991-1992 FJ80s came standard with the CDL dash button to selectively lock the CD in high range.

Read your owner's manual.

 

[superstan26]

OK folks. In a stock configuration, all fulltime 4WD 80 Series (1991-1997) automatically lock the CD when shifted into low range on the transfer case.

1991-1992 FJ80s came standard with the CDL dash button to selectively lock the CD in high range.

Read your owner's manual.

This is true. Didn't realize it was a debate, but true never the less.