RRC T-CASE

[apexcamper]

I have a '94 RRC LWB and I ASSumed it had a locking center diff. Forward to back is low, neut, high and left to right is locked or not. as of today I am now not so sure. I had formerly owned a series I Discovery and "ASSumed" it was the same H pattern manual lock (my RRC knob had the cover missing...no markings)...I just never could get it to unlock.

When I bought the RRC, the front drive shaft was new in a box...owner said he didn't have the bolts to put it on...I weaseled him down on that. I got the bolts and went under to install...but I couldn't get the T-case to unlock and didn't want to install and drive locked on pavement.

I "ASSumed" that the owner had driven it locked for so long that it had seized that way, meaning I needed a new T-case or at least someone more technical to look at it. I have been on a couple of light trail rides in 2 wheel drive, and put maybe 5000 miles on the OD like that.

Today while reading another thread I learned that my RRC should have the Borg-Warner viscous coupled T-case. The guy I bought it from REALLY didn't seem like the kind to switch out for the LT 230...so I posted a "what gives" on the other thread (it was off topic, and not wanting to hijack that other thread, I started this one).

oryxexpeditions said that it sounded like the LT 230...but he had much less information than I posted here, and also said that the BW T-case can act locked...this made me second guess my "ASSumption" that it was the LT 230

Even with the T-case in neutral, the front drive flange feels securely locked to the rear drive shaft. The shift lever really doesn't feel like it has any side to side give, which I chalked up to the T-case being seized in the locked position, but maybe it REALLY doesn't have any side to side.

The T-case functioning as it should would be AWESOME...me having screwed it up by being ignorant would SUCK. I am now financially in a place to tackle this problem, so is it a ID-10T error or a real hardware failure.

Questions:
How can I tell which T-case I have from the underside?
How can I check it's functionality?
Did I screw it up since the front flange seems VERY secure to the rear drive shaft through the T-case?

any thoughts would be much appreciated.

 

[David Harris]

The two cases look quite different. See photos below. BW on the left, LT230 on the right with shifter linkage attached. Also, if your lettering was worn off the lever, then that leads me to think BW rather than LT230, since the LT230 lever has stamped lettering indicating gears/lock and probably wouldn't be missing/worn off. The BW lever only moves back and forth from H to N to L range. There is no manual locking position since the viscous does that automatically. As said before, with the front DS missing, the viscous will send all the power to the rear wheels, which have the traction. Without the viscous, all power would be sent to the front axle, which has no traction without the front DS, and you will go nowhere. That is why you have to manually lock an LT230 to drive it without a front or rear driveshaft. Your viscous may indeed be shot if you can't move it at all, even with a breaker bar on it.

David

 

[apexcamper]

@oryxexpeditions

AWESOME...I have the BW...so that is good!!!

Now how do I unlock it for road driving, or will just it just let go once I install the drive-shaft and how will I know...it shifts high-neutral-low just fine, and functions as it should in all three.

I can put the truck on a lift tomorrow...how can I do a functions check?

 

[Snagger]

As oryx explained, the locking and unlocking of the centre diff is done automatically. There are no controls to engage or disengage it. Think of it as a limited slip diff.

 

[apexcamper]

that's what I think of when I think viscous coupled, but sitting in the driveway right now, without a front driveshaft on, the front flange doesn't move AT ALL...even with the T-case in neutral...shouldn't there be some give to it, or does it need to start driving to release a mechanical lock?

My concern is I have damaged it be rear wheeling only...right now there feels like no slip at all...so install the front drive shaft, drive it around a little, put it on the lift and see if the front and rear can slip...is that the best way to be sure?

OR...am I way over thinking this and it just takes a lot of tension to make them slip...like clutch packs?
I have only tried to move it by hand

 

[David Harris]

@oryxexpeditions

AWESOME...I have the BW...so that is good!!!

Now how do I unlock it for road driving, or will just it just let go once I install the drive-shaft and how will I know...it shifts high-neutral-low just fine, and functions as it should in all three.

I can put the truck on a lift tomorrow...how can I do a functions check?

First thing to do is install the driveshaft. Then test drive it and see how it works. If you can drive it now, then for certain, the viscous coupling is locking up fine. When you test drive it, take some sharp turns and see if you feel any binding in the drivetrain. If you do, then the viscous is probably worn out, so it's remaining locked. This is bad for the drivetrain, and may be why the original driveshaft failed, as you said earlier. You will have to get a new viscous coupler, or replace the BW with an LT230.

 

[apexcamper]

@oryxexpeditions and Snagger

THANX GUYS...saved me a costly trip to the shop...I'll install tomorrow and let you know how things go...I should be back in the states in about 3 years, but either of you end up in southern Germany till then...beers are waiting

 

[David Harris]

Check this link out at Ashcroft Transmissions in the UK. It has further details and instructions on the viscous and you can buy a new one there too.

http://www.ashcroft-transmissions.co.uk/index.php?act=viewProd&productId=25

 

[apexcamper]

@oryxexpeditions: That link was exactly what I was looking for...super-rockin-Kudos

 

[DividingCreek]

I'd point out one thing no one has mentioned/ a word of caution. Extended driving without a front drive shaft tends to ruin/permanantly lock a viscous coupling. If you are lucky it will be fine. If the front tires start chirping when you make a slight turn chances are its ruined. Be sensitive to this when you reinstall the front shaft as its easy to pop a cv or break front pinion gears on pavement if the vc is locked.

 

[David Harris]

I'd point out one thing no one has mentioned/ a word of caution. Extended driving without a front drive shaft tends to ruin/permamnantly lock a viscous coupling. If you are lucky it will be fine. If the front tires start chirping when you make a slight turn chances are its ruined. Be sensitive to this when you reinstall the front shaft as its easy to pop a cv or break front pinion gears on pavement it the vc is locked.

Yeah. I think the extended use causes the fluid to cook and permanently thicken and lock up the whole unit.

 

[apexcamper]

@DividingCreek and oryxexpeditions: I'll be testing via that link oryxexpeditions sent...I totally agree and it is a major concern.

So much thanks

 

[Jerp209]

Hi,
If you find that you need a viscous let me know. I have a good one.

 

[apexcamper]

@Jerp209:

I'll let you know, thanks

 

[galen216]

When I bought my 94 RRC the BW was locked up tight and I had to remove the DS until I replaced with an LT-230. As doug mentioned with my driveshaft in it blew a CV in the front end. Personally, I wouldn't even spend the time to reinstall that driveshaft. I can guarantee you that BW is locked and you might as well plan on doing the LT-230 conversion now.