Tcase comparo? D1 vs RRC
 

Wondering what all the differences are between the 2 tcases. I understand the locked vs unlocked and chain vs gear driven....anything else? For the RRC without a lock option, what is the nominal split and does it shift power front to rear as needed? Is it silicon based coupling inside or ??? Is the D1 the same when in unlocked mode?

If I end up with an RRC - which is looking more likely at this point - I think I'd probably swap in the D1 tcase (LT230 correct?). The RRC I'm specifically looking at right now is a '90...any concerns with a swap for this age truck?

Cheers.

Jack

Just do what I did and buy an 87-88 RRC they came fitted with LT230's. BW's are obviously quieter.. but no other but issues except I think you have have to swap an output shaft and change the mounts out. If you do go this route I have LT230 mounts for a swap let me know if you need them..

Thanks, that is helpful and I'll let you know on this.

Anyone know the nominal torque split and how much, if any, it can transfer front to rear when needed? Again, not sure of the coupling method.

Thanks.

Jack

When unlocked, the differential is open in the LT230. With no loss of traction, the torque split is 50/50. With a loss of traction, the torque will of course go to the prop shaft with the lesser amount of traction.

When locked, the split is a permanent 50/50.

(Does this count as talking to myself?)

Looks like the transfer case has a center differential just like the LT230 but I have never owned one or worked on one so I'm not 100% sure. Download the RRC RAVE and you should be able to find out more info on it.

If you do the swap you will need the LT230 transfer case, the frame mount on the right side of the frame rail, the front driveshaft from either a DI or early LT230 equipped RRC and you will need the complete shift linkage as well. The swap is straightforward. The only thing you'll notice, in comparison to the BW, is a bit more whine thanks to it being gear driven vs. chain driven.

Rover had to move the RRC more upscale in the late 1980's with the introduction of the DI. There really wasn't a lot of difference between a RRC and a DI when it came to drivetrain. They had to justify the steep price differential and the BW helped. The target customer for the RRC (when it was new) appreciated the fact that so onerous a task as manually locking the center differential was taken out of their hands. Hell, why do you think so many DI's have frozen linkages. Most original DI owners wouldn't know a locked differential from a locked barn door!

I should also mention that you should get the forward portion of the transmission tunnel cover which includes the rubber boot and sound deadening material. You'll have to enlarge the space in the center console to give you enough room to shift in the H pattern. So it would also be wise to get the DI shift knob and boot. Use the bottom of the boot as a template for how much you'll need to enlarge the cutout on the center console.

Thanks, very helpful!

I'll do some more research on the tcases. The reason I asked about the split was out of curiosity. I previously owned a BMW 325iX and the center diff on that had a viscous coupling. Under normal conditions the nominal split was 37F/63R (weight distribution of the car under full acceleration) but during adverse conditions could send up to 95% of the torque to either end. It was silicon based and a sealed unit.

I was just curious what the Rovers had.

Cheers.

Jack