Binding while turning

Hello,
Ever since I bought my 1994 80 series I noticed that when turning sharply, as when in a parking lot, the driveline felt like it was binding. It seems as if this binding is not consistent; sometimes there seems to be little or no binding, and sometimes there is quite a bit. The binding is never enough to make the tires chirp, but enough to make the tires scrub. I have been reading threads written by people with similar problems and everything seems to point to the viscous coupler. I jacked up one front tire and was unable to turn it so it looks as if the coupler is locked. Before I go any further and consider replacing the VC I would like to confirm two things.

One, that the viscous coupler can be damaged so as to become locked. Someone posted the FSM section from an LX450 that details the viscous coupler equipped transfer case and it shows that if the VC gets hot it goes into a state called "humping", in which the air bubbles trapped within the VC expand and cause the plates in the VC to come in to contact with each other and effectively lock the VC. Is it possible to have the VC in a state of perpetual "humping"? Sounds pretty funny. It does seem as if the driveline bind is worse after the vehicle has been run a while. Or is it more likely that if the VC has been abused and gets overheated that the fluid in the VC gets thicker and effectively locks the VC?

Two, that my center diff lock is not locked, causing the binding. I have done the CDL switch mod and the 7th pin mod and the CDL light goes on and off with the switch. I would like to confirm that the indicator light shows the true state of the CDL. When I had the one front wheel up in the air I tried spinning it with the CDL both off and on. The wheel was locked in both cases but it felt different between the two states. The was a little more "play" in the driveline with the CDL unlocked then with it locked. This makes me think that it is indeed the VC that is damaged since it is my impression that when the CDL is locked the VC is bypassed.

I will try the wheel spin test again tomorrow morning when the vehicle is cold to see if there is any difference. Has anyone done this test and could give me their impression of how hard the wheel was to turn when the vehicle was both cold and hot?

Thanks a lot.

David Sword

I never received any response to this thread. What I would like to know is if the CDL indicator light is off is the CDL unlocked? Or is there a situation in which the CDL can still be locked and the CDL light is off. I know the CDL light works.

Thanks, David Sword

You should search locked CDL. There was a thread in the last few days where someone had the same problem.

you did put the T-case in neutral when you did the wheel in air test correct? if not you will not get it to turn when the other axle is on the ground.


I did something very similar recently, I had pulled my front locker actuator to help Dan with his, when going back in needed to fully lock the locker had only the right front tire off the ground, T-case in neutral, trans in park, parking brake set. and had my finger in the hole pushing on the teeth of the locker, cant really think of how to describe the resistance, it had some, but was still easy to move with one hand from an awkward position under the truck. of course when the locker lined up and slid home the tire could no longer be moved


I would be surprised if your VC is permanently locked,

are you certain that all of your tires are the same size? are some worn and some not?

I learned something from your locker actuator reinstall though...I got mine in phase and all is well

Thanks again Raven.

as for your other question the CDL light in the cluster is grounded by a switch that rides on notches in the "shift lock fork shaft", so this light is a direct reading of that shafts position, I guess the shift fork could be broken and therefore not respond to the shaft position. but that is pretty unlikely.

in that same PDF from the New Car Features manual that you refer to there is a good drawing of the relationship between the indicator switch and the locker workings.


see page 74:

http://webpages.charter.net/raventai/HF2AV TRANSFER.pdf

DanKunz said:

I learned something from your locker actuator reinstall though...I got mine in phase and all is well

Thanks again Raven.

Click to expand...

Good to hear

Now where are my exhaust doughnuts?

RavenTai said:

you did put the T-case in neutral when you did the wheel in air test correct? if not you will not get it to turn when the other axle is on the ground.

Click to expand...

You will if you put the tranny in neutral.

One wheel up, TC in hi, tranny in neutral: raised wheel should spin freely.

Curtis

trans in neutral will work also, I used the T-case because I did not want to go get my keys.

Raven and everyone,
Thanks. I will try the one wheel up with the t-case in neutral.

David Sword

Jacked one front tire up and put the t-case in neutral. Still locked. The CDL light goes on and off with the switch but I don't hear anything indicating something is locking or unlocking.

Thanks, David Sword

Got more information. Pulled the front driveshaft. Front output flange is locked with the CDL switch on and off. It has a little play back and forth, maybe an eight of a turn. I can hear the CDL actuator working and if I turn the front output flange back and forth I can feel when the CDL locks in. This leads me to think that the viscous coupling is locked but I wanted to see if the list confirms this diagnosis before removing the rear of the t-case. Is there a way to test if the viscous coupling is toast?

Thanks, David Sword

I am not aware of any way to tell if the VC is what has locked up your T-case or if is it is something else like a damaged center differential, the external symptoms would be the same, but it does appear the differential is not doing what it is suppose to be doing.

it is starting to look like a tear down and investigate, I woudl start by removing the rear drive shaft and repeat this test just to be certain, you could also drain the fluid and see if there is any significant metal in it, the VC is a sealed unit if there is metal in the T-case gear oil it points elsewhere. both of these will be needed to be done in the course of removing the T-case anyway.

If you do take the T-case apart make sure you clean out the oil galleys that feel lube to different parts of the T-case, some have been found with these plugged.

Raven,
I am suspecting the VC because when I got the cruiser it had mismatched tires on it and might have been damaged by that. I have read other posts where people have remoed the VC and then put the input side in a vice and turned the output side. I would at least be able to tell if it is locked. I might be looking for a new, or used but working, VC for a replacement if anyone has one.

Thanks, David Sword

Not sure I woudl put the VC in a vice might crush the outer shell onto the inner plates, once apart you should e able to use the shafts of the tcase to engage the spline inside the VC and use those to turn it, at low RPM the resistance from the VC is not that high.


It has always been suspected that driving with miss matched OD tires will damage the VC, I am not aware of any body who actually did it,


I do not know how much a new one is but I have heard that the VC can just be deleted if too expensive basically it then operates like the HF2A T-case in a 91/92 FJ80 three open diffs where any of the 4 tires can spin on low traction surfaces unless you lock the CDL.

here in the south east that would not be much of a loss, though those who drive on ice may disagree.

Pulled the rear housing off the t-case and took out the viscous coupler. It was that purplish color that metal gets when heated and bathed in oil. Pretty sure it is fried. Put rear housing back on and t-case works as it should, like a diff when unlocked and locked when locked. Am getting a used t-case with 80,000 miles for $500 and will take out VC and put in mine. Will keep extra t-case for parts.

David Sword