How does the center diff gets lubrication? (1 Viewer)

[atijerino]

This is probably a neeby question. I will flame and punish myself if it is, so you guys don't have to bother.
I am just curious to find out how does the center diff gets lubricated? Does it share the gear oil from the transfer case, transmission or it has its own lubrication?

Thanks,

______________________
Antonio
1994 FZJ80

 

[cruiserdan]

Good question actually.

The coupler is a sealed unit within the transfer case. It requires no service nor can it be repaired if it fails.


D-

 

[best4x4xfar]

Hey Antonio,

The confusion probably comes from the fact that the ’93 and up 80 Series trucks used a Viscous coupling center differential. While it performs the function of a differential, it is not the same as a gear differential like you may be imagining. There is actually no physical connection between the output shafts, instead they are connected by the friction of the viscous fluid inside. As a result, it doesn’t actually need any lubrication like a typical geared differential does, however most vehicles that use a traditional differential as a center diff do use the transfercase gear oil to lubricate them. Here are a couple of links that explain how a viscous coupling works better than I can..

http://auto.howstuffworks.com/differential9.htm

http://www.4wdonline.com/LandRover/Mech/VC.html

 

[landtank]

There is a diff in the transfer case, even the later ones. The gears are lubricated with gear oil from the case that is pumped to them from an oil pump which is located near the back and driven off of the output shaft.

The viscous coupler is there to transmit drive accross the diff in the event of a wheel slipping at one of the axles.

As a side note: this is why running tires of different sizes, even new/worn tires, can be dentrimental to the VC, because the rotation difference will cause the VC to be engaged for extented periods of time.

 

[robbie]

Rick is right and scott is wrong for the most part. Dan describes the VC on the back(Rear output of the T-case) of the 93-97 trucks with ABS(if no ABS or if rear drums then the t-case is very similar to the later ones but with out the VC), but not the center diff. There is a center diff and a small pump and lots of spash and spray of the upper gears also. Out put bearings are also lubed to a degree with the pump. I have now had a couple of t-cases open, the last one I opened was non sealed bearing on the rear output, the front output was sealed on one side to trap oil between it and the seal with a flow hole allowing lube to flow away from the bearing. Even with the lube these bearings do wear and will need replaceing with the seal when they start to leak. later robbie

 

[Rookie2]

... and scott is wrong for the most part

D'oh!

FWIW, I found the links informative .

 

[nakman]

Rick is right and scott is wrong for the most part.

LMAO!!!!!! good to see you've still got your wits about you, Robbie! later

 

[best4x4xfar]

Assume = A** of you and me (Sorry)

Rick is right and scott is wrong for the most part. Dan describes the VC on the back(Rear output of the T-case) of the 93-97 trucks with ABS

I stand corrected, and apologize. I made an assumption (yup, I know what it means) that I shouldn’t have, based upon transfer cases I’ve seen over the years with viscous coupling center differentials. I’d love to find exploded view drawings of the transfercase on the ’93-’97 Cruisers (anyone?), especially hearing that the viscous coupler is on the back of the t-case and there is a differential inside, I am having a very difficult time picturing this configuration in my mind in a way that would work. Sorry for the confusion, hopefully at least the VC links were of some use…

 

[alia176]

Scott,

Your assumption is prolly based on LRs where the VC is "cooled" by ATF in the Borg Warner Tcase.

 

[landtank]

I stand corrected, and apologize. I made an assumption (yup, I know what it means) that I shouldn’t have, based upon transfer cases I’ve seen over the years with viscous coupling center differentials. I’d love to find exploded view drawings of the transfercase on the ’93-’97 Cruisers (anyone?), especially hearing that the viscous coupler is on the back of the t-case and there is a differential inside, I am having a very difficult time picturing this configuration in my mind in a way that would work. Sorry for the confusion, hopefully at least the VC links were of some use…

Don't feel bad, I made the same assumption a few years back and was equally embarassed

 

[4x4CPOSEADOG]

What type of fluid is use on Viscous Coupler? As an aviation mechanic, we also work on viscous dampner part of helicopter. We use glycerin and heavy clear oil as a damping fluid.

 

[alia176]

Should be a Silicone based fluid I believe.

 

[cruiserdan]

The exact contents of the coupler have not been disclosed to my knowledge. Since Toyota considers it non-servicable there is no reason for them to provide information regarding the "secret sauce", or anything else for that matter, within.

 

[RavenTai]

I’d love to find exploded view drawings of the transfercase on the ’93-’97 Cruisers (anyone?),

The HF2AV is the most elaborate T-case I am aware of, gear drive, pressure oiled, differential, differential lock and viscous coupler. Only thing missing is 2wd

There the fluid is described as Silicone Oil, still not enough info to pick a fluid to fill it with, even if you could refill it witch from what I hear you cannot.

 

[shawn]

he said secret sauce, huh huh.

 

[4x4CPOSEADOG]

RAVEN TAI, YOU ARE DA MAN! I like those technical stuff in a PDF form.

So that HF2AV applicable to all FZJ 80 or just for LX 450?

 

[RavenTai]

Most FZJ-80's 93-97 came with the HF2AV as far as I know, Slee's site says the drum braked semi-floating FZJ-80's (rare? And only early ones?) Come with the older HF2A T-case carried over from the 91-92 FJ-80's, I have read that the HF2A is very similar to the HF2AV only lacking the Viscous coupler.

For future reference the 96-97 LX450 drive train is identical to the 96-97 Land Cruiser, the differences are almost completely limited to portions of the interior, electrical and exterior styling. And even a majority of parts in these categories are the same are the LC

You can get 1,259 more of those PDF's for $10 and a day of your time, that one is from the "New Car Features" manual

https://forum.ih8mud.com/showthread.php?t=13741

 

[Beowulf]

Raven,

Thanks again for posting the details from the NCF manual. If anyone is interested in more detail of the FZJ80 center diff then there are 4 or 5 pics that LandToy80 posted when he disassembled his xfer. I think I can repost those pics if you cannot find them. It might make this thread more complete with those pics.

I discovered one thing in that link that I will challenge for accuracy. The link that Raven posted said that during humping, temperature, pressure, and resistance increases. I've found through much experimentation that resistance decreases during humping. YMMV.

-B-

 

[e9999]

snip

I discovered one thing in that link that I will challenge for accuracy. The link that Raven posted said that during humping, temperature, pressure, and resistance increases. I've found through much experimentation that resistance decreases during humping. YMMV.

-B-

ditto! the temperature increases during humping, and indeed in my experience, whenever I was humping (in my younger days, married now... ), their resistance was decreasing fast and turning quickly to begging...

 

[Beowulf]

Landtoy80 originally posted a number of pics of his disassembled t-case in this thread but the images were lost during one of the forum upgrades. Maybe he will repost the images here or in his original thread.

-B-