Lockers with center diff lock???

[WestWA1990fj80]

I have recently purchased a 1990 FJ80 with a 4.0 and locking center diff. I was wondering if I would gain by switching to locking diffs front and rear vs the the locking center diff. I dont have any experience with a locking center diff so I am not sure about how it performs offroad. Any help is appreciated.

 

[Chris]

You keep the locking centre and ADD locking front and rear. Your 80 may well not have have a viscous centre coupling being a 1990 which is a shame as that is a great aid in simple loose surface conditions and snow. Locking the centre gives great traction. But locking the rear, well, that's a major difference. When you can't get going even with those, flick in the front and you're off!

 

[Ken Brenton]

Basically without centre diff locked any single wheel in the air (or spinning in loose sand or mud)will cause loss of traction. With centre diff locked you have the drive locked front and rear so you would need 1 front and 1 rear in the air to loose traction.
If you have axle diff locks than you could in theory drive with 3 wheels in the air as drive is locked to each wheel on the axle.
You should only drive with centre diff locked on loose gravel or sand, on tar you will have wind up front to rear and this can over-stress the drive train.
Rear diff lock gives you drive in mud, rock crawling scenarios but can cause the back to hang out as the wheels spin at the same speed in corners (no differential). Front lockers are only needed in really extreme conditions and cause massive under steer problems,, so need to be used with caution.
Most 80s will go most places with only centre diff locked but axle diff lockers just allow you to be able to take obstacles with less speed and therefore less damage risk. You can take obstacles without axle lockers by using more impetus with more risk. The vehicle without axle lockers is probably capable of more than many drivers can get out of it, more about driver off road experience than lockers

Edited after correction. The missing link restored

 

[Chris]

Drive chain Ken? Not in an 80 transfer box. All gears. And huge ones at that.

 

[clivehorridge]

Drive chain Ken? Not in an 80 transfer box. All gears. And huge ones at that.

Well I think "train" may be the word, but on its own it looks more confusing!

All the important things covered by Ken & Chris.

There's some very good diagrams available on the Internet. Google for differential or 4x4 and you'll get some pictorial assistance that may be easier to understand.

 

[clivehorridge]

I don't know if this helps...



https://encrypted-tbn0.gstatic.com/...3IKmbBSVxGXsVLvkqjqrpQ2b6G7OlXkSthEviHYA2NYGg

 

[Chris]

Ahh yes Clive. Drive train would make sense. Nice link. Link? Get it - chain, link.

Oh never mind..

 

[Gary820]

Its not often I use the diff locks, even the centre only goes in now and again. Even when others have traction issues don't really struggle for grip. The vc is prob helping with that though.

 

[clivehorridge]

The rear comes in handy on a steep incline that's muddy. Often one front and one rear will slip with the CDL only and the rear locker will push you up. I have a stretch like this on my local run when it's wet and there's a step half way up.

If I can keep the momentum going, the truck will ride the step, but if not then the front has to go in as well to pull it up.

I have that bit of the trip off to a tee

 

[WestWA1990fj80]

Thanks for all the advise I really appreciate it. I used to have a very heavily modified 06 wrangler unlimited. I had 37's and it had lockers front and rear. I just didnt have any room for my family in that rig so thats why I changed to the FJ80. Bullet proof rigs with all the room I need. Is there any problems I should be looking for with the 4.0l?