By lynden on Wednesday, July 25, 2001 - 12:46 pm: Edit

Okay, this is a dumb question and probably anoying to people but I'm trying to figure this out. When my diff gearshift is to the right and back (towards rear of vehicle) I'm in hi/reg. If I switch to the left and rear this is hi/lock. What has this locked? I thought it was the trans. case sending power 50/50 but it seems that people have said it locks the front and rear differentials??? Is this true. When pushed forward (low) is this now locking it 50/50?

Next question, should you feel anything when switching from right to left? When I move the shifter from right to left I feel nothing. When I push it forward there is a clunk and you can feel the transfer case lock in.

I might just be confused by the lingo. When I say "diff.", I mean the differentials in front and rear axles and using "trans. case" as the transfer case sending out the power through the drive shafts could someone explain all this to me.

Yes I've read the archives, and no I'm not stupid just pretty confused at this time.

Thanks in advance for any explanation.
Lynden

By L_Tilly on Wednesday, July 25, 2001 - 01:06 pm: Edit

I'm sure you'll get a more technical answer, but from my understanding here you go:

The move to the left locks the CENTER diff. A nice little addition that Discos have but many 4x4s lack. In normal 4w mode (lever right back or right forward) you are sending power to all four tires. If one tire gets spinning, all power will go directly to that one tire, leaving three useless. With the center diff locked, you isolate your forward and read differentials. Now, if you get one tire spinning the other tire on the same diff (f/r) will be useless, but the two tires on your other diff will still have 50% of the engine's power to work with.

Of course, if you happen to get one tire on each diff spinning then you're still SOL. That's where you want additional diff locks (Detroit/ARB). With your stock central diff and a rear locker, you are almost guarenteed to have at least one usable tire.

Someone please correct me if I'm wrong or left anything out.

L_Tilly lnctilly@mediaone.net
96 Disco "Beowulf" - NH, USA

By Blue Gill (Bluegill) on Wednesday, July 25, 2001 - 02:19 pm: Edit

back left is hi-lock = locking the center differential so power is split 50-50 front-rear.

forward is switching to low gears rather than high gears, then it's the same game with center lock

By Chris Merritt (Smokinbro) on Thursday, July 26, 2001 - 10:28 am: Edit

the centre dif is why you can operate the truck in 4X4 mode all the time. It allows the front wheels to turn faster than the rear so you can make corners without excessive drive line wear.

lock the centre dif and then the Disco is like most other 4WD's on the market. (NOte the manual recommends not to operate with the centre dif locked on pavement or other surface that will not allow your tires to 'slip' a little.)

By Blue Gill (Bluegill) on Thursday, July 26, 2001 - 10:56 am: Edit

one more thing, Lynden said: "When I move the shifter from right to left I feel nothing."

If you pay real close attention, you can feel the effects of center lock, mainly in slightly heavier steering. You'll really feel it if you lock the center and drive in tight circles on pavement, but your wallet will also feel it after you replace driveline components.

I use hi-lock when I'm running at high speeds for long distances on rough winding dirt roads - you know, the times when you put the Metallica in the disc player, crank it up, and hit the gas...soft tires and 50% power to the front really helps you hold the road, especially accelerating out of turns.

By Eric N (Grnrvr) on Thursday, July 26, 2001 - 11:32 am: Edit

You should also see a light turn on the dash when you lock (move to the left) which is yellow in the upper right looks like a little picture of your drive train.

By lynden on Thursday, July 26, 2001 - 12:03 pm: Edit

Thanks guys. I have one more question. Does the t-case have to be in N to switch from R to L? Meaning go forward to N, over to left and back to engage? On mine it doesn't lock on left or right side, you can toggle it back and forth, is this right or do I have a problem??? I don't have an owner's manual (why would you keep an owner's manual for a rig you're selling????) so I've been flying blind.

Thanks for all the help!
Lynden

By Blue Gill (Bluegill) on Thursday, July 26, 2001 - 01:03 pm: Edit

no need to put tranny in neutral to lock/unlock center diff (moving transfer case lever left/right). Also, be patient - it may take a few seconds for the dash light to illuminate thereby confirming that you've locked the center diff (moving transfer case lever left/right). HOWEVER, must be in neutral and rolling no more than walking pace to switch between high and low gears (moving transfer case lever front/back). Sometimes, if you're totally stopped, it's hard to engage/disengage low gears - a little movement forward or reverse can help. The transfer case will sound a constant beep when the t-case lever is in the middle neutral position. In that case, you're totally free-wheelin (both tranny & t-case in neutral). What year is your Disco? If I get a little free time, I can scan & post the pertinent pages from my 1996 owner's manual...(or photocopy & fax)...

By Blue Gill (Bluegill) on Thursday, July 26, 2001 - 01:16 pm: Edit

P.S. There's no such thing as a stupid question - only stupid people.

By lynden on Thursday, July 26, 2001 - 02:10 pm: Edit

Thank you everyone!!! I now feel I can opperate my vehicle with confidence that I know (or at least will look like I know to my passengers) what I'm doing. It all makes sense. I was a little thrown off by the depictions where it looks like there's a full H pattern. I was a little worried that mine wouldn't "lock" into place at top and bottom of H pattern. This releives a lot of wondering.

We have a '96 epsom green disco. Bought 1 1/2 months ago w/ 50K miles. We've loved it and take it 4x4ing every weekend (inlaws have some property in north idaho on edge of forestry land). Have some electrical glitches to work out but aside from that we like it a lot.

Thanks again for all the help!
Lynden

By peter matusov on Thursday, July 26, 2001 - 02:16 pm: Edit

Blue Gill and all,

just for the sake of clarity - for any diff,
when you lock the diff, it doesn't send power 50/50 to the (axle)or(drive) shafts.
what it does, it causes the shafts to turn at the same speed.

example: if you lock the center diff, and your front wheels are both off the ground, 100% of power go to the rear wheels, and 0% to the front.

any open differential makes equal the torque being sent to the shafts.

any limited slip differential operates between the open and locked differential - when there's no load on one shaft, it will bias the torque towards the shaft that does have load, and therefore make the rotation rates close.

FWIW,

peter

By Blue Gill (Bluegill) on Friday, July 27, 2001 - 06:15 am: Edit

good points, Peter.

By Chris Merritt (Smokinbro) on Friday, July 27, 2001 - 07:19 am: Edit

Blue Gill;

Sure there are stupid questions... lots of them....mostly asked by stupid people!!!

however, the Diff question doesn't count for either of the above.

By Stephen on Friday, July 27, 2001 - 07:27 am: Edit

Look on e-bay - there's regularly owner's manuals on there for sale.

Not sure I would lock my diff for gravel or sandy roads like peviously mentioned - I think your asking for trouble there?

By Blue Gill (Bluegill) on Friday, July 27, 2001 - 08:39 am: Edit

"Not sure I would lock my diff for gravel or sandy roads like peviously mentioned - I think your asking for trouble there?"

Then what is hi-lock for? Not rock crawling, that's lo-lock territory. The important thing to consider is the fact that on a loose surface (i.e. not pavement), the front tires can break free and therefore not bind up the system. Trust me, when I'm running long & fast trails in hi-lock, I'm breaking free all over the place. Most recent was the 20+mile trail from Crown King down to I-17; about a 6,000 foot elevation drop on roughly graded roads. Kind of a fun challenge to see if I can improve my time with every run...

By Stephen on Friday, July 27, 2001 - 11:09 am: Edit

BlueGill -
I put the question mark there only because I was not sure myself on that statement - I was hoping for someone to jump in. A month or two ago someone on the board here suggested I don't lock the diff on a gravel road as I will wind up the tranny. ?
But I think you're right - what else would hi-lock be for?
Stephen (still learning - endlessly.....)

By Ron on Friday, July 27, 2001 - 11:11 am: Edit

Don't lock it if you don't need it. Just my opinion. Ice yes. Sand yes. Gravel/dirt no.

Ron

By Blue Gill (Bluegill) on Friday, July 27, 2001 - 11:39 am: Edit

Agree with Ron - I run unlocked first, and only lock if I think I need extra traction. Sometimes I'll lock and it won't seem to make a difference, so I simply unlock it. At other times, the difference is amazing. I know that running locked increases friction, wear & tear, etc, but so does banging the damn truck around on the rocks. Buy hey, that's what I got a Disco for!

By gil on Friday, July 27, 2001 - 11:47 am: Edit

i run hi lock in the snow...

By Scott H on Friday, July 27, 2001 - 08:50 pm: Edit

gotta jump in, I had mine locked on gravel, dirt roads for maybe 100 miles in the middle of no where to try and help handling throught washboards (which it did). When I got back I noticed that I had axel grease all over one wheel. Took off the wheel and had actually sheered the bolds that go to the axel (I'm sure there is a technical name for these but I don't know what it is) I looked at all the others ones and 3 of the 4 axels needed those bolts replaced. Now I lock it in HI on Ice and snow, other than that I only lock it if I really need to. Be careful.

Scott H