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  • Centre Diff Lock vs Rear Diff Lock

    Hello All,

    I am from Fiji and have been following this forum for quite a while now. I have just got delivery of my new Prado. It is 3.0TD Black exterior with ivory leather interior, comes with optional Active Traction Control pack, Vehicle Stability Control, 6 cd changer.

    I had the vehicle done for me on special order.

    I have noticed that unlike other Prados here in Fiji, mine comes with a centre Diff Lock instead of the rear diff lock as in other prados. The other prados have H, HL, N, LL for 4x4 whereas mine is H, N, L only.

    Can anyone tell me what the difference is between Centre Diff Lock and Rear Diff Lock, and the 4x4 gears?

    Cheers

    Jay.

  • #2
    I'm not sure what model you've got, but I'll give a bit of an explanation of 'diff locks' as they relate to my Aust delivered 95 series Prado. It may help.

    As sold by toyota here in Australia, the prado has a centre diff lock, with the lever for selecting H - HL - N - LL.

    With the centre diff lock unlocked (in H-High), if any single wheel looses traction, all engine power goes to that wheel and progress halts (as there is no locked diffs to prevent power going down the path of least resistance - the spinning wheel).

    With the center diff locked (HL-High Locked or LL-Low Locked), it ensures that power will always get to the front and rear axles. If one wheel looses traction (say a front wheel is lifted), drive to that axle will stop (all power going down path of least resistance - the spinning wheel), but the other axle (the rear axle in this case), will still receive power. Progress may then continue (driven by the rear wheels though, as the front will still be spinning in the air). To stop progress with the centre diff locked, requires one front, and one rear wheel to loose traction.

    A front or rear wheel diff lock, is a cross axle lock. This means that it takes both wheels to loose traction on that axle, to stop progress. ie: If you have a locker (say an ARB air locker) in your rear axle, and one wheel on the axle loses traction, the drive doesn't all go down the path of least resistance (the spinning wheel), as the locked diff ensures power still goes to both wheels on the axle. This should allow the wheel that does have traction to continue turning, and keep you moving.

    Unfortunatly I can't give you am explanation of why your vehicle has only a H-N-L setup. There are other vehicles I've seen with that setup here in Australia though (not prados). They work in one of two ways.

    - There is another 'diff lock' button somewhere that electronically locks the centre diff (like some 80 series land cruisers).

    - There is no way to lock the centre diff in high range, and it automatically gets locked when going into low range (like the some of the discovery models I think).

    I hope some of the information helps, even if it's not a specific answer to your question.

    John
    Ex 95 and 79 series owner, now FJ Cruiser owner.

    Comment


    • #3
      Gents,

      Thanks for the assistance.

      I have the 120 series Prado. It is a VX - Fiji Model. Our VX specs are different to the Australian VX specs. Our VX falls somewhere in between your VX and Grande. My Prado has all the Grande specs except for Cruise Control (not of much use in Fiji), Height Control & Navigator.

      Cheers

      Jay.

      Comment


      • #4
        AN UNERVING OBSERVATION

        As sold by toyota here in Australia, the prado has a centre diff lock, with the lever for selecting H - HL - N - LL.

        With the centre diff lock unlocked (in H-High), if any single wheel looses traction, all engine power goes to that wheel and progress halts (as there is no locked diffs to prevent power going down the path of least resistance - the spinning wheel).

        With the center diff locked (HL-High Locked or LL-Low Locked), it ensures that power will always get to the front and rear axles. If one wheel looses traction (say a front wheel is lifted), drive to that axle will stop (all power going down path of least resistance - the spinning wheel), but the other axle (the rear axle in this case), will still receive power. Progress may then continue (driven by the rear wheels though, as the front will still be spinning in the air). To stop progress with the centre diff locked, requires one front, and one rear wheel to loose traction.

        Ok, first of all, I know this is an old thread but I just wanted to use the above quote from 'prado4x4', the relevance of which will become apparant: just today I went through a little gully very slowly and lifted a back wheel, which stopped progress. 'Oh well', I thought 'at least I know the Toyota LSD is living up to its reputation.' So I put it in HL and tried again. It gave a half hearted little lurch forward and then settled back into the lifted rear wheel spin caper... 'Hmmm' I thought to myself again as I moved the lever into LL. Another little lurch forward and then same thing!

        NOW... I must admit that I was not trying to get out of a bog or anything, I was just interested to see what was happening back there, so I was not giving it the berries or anything. So, is the above quote correct and I therefore have transfer case/box probs, or is there more to the story... hmmmm? Anything will do! Paul.

        Comment


        • #5
          Without seeing your bog,I think you just experienced why we all need diff locks,lift one wheel no drive on that axle which often means on the diagonal opposite wheel was starting to also lift and loose traction.
          New 2015 150s GX 5 seater with floor mats, towbar and a big wish list
          Previously a 2004 120s 1KZ GX silver manual with stuff
          before that a 1996 RV6 90S with lots of gear

          Comment


          • #6
            Originally posted by paul2 View Post
            AN UNERVING OBSERVATION

            Ok, first of all, I know this is an old thread but I just wanted to use the above quote from 'prado4x4', the relevance of which will become apparant: just today I went through a little gully very slowly and lifted a back wheel, which stopped progress. 'Oh well', I thought 'at least I know the Toyota LSD is living up to its reputation.' So I put it in HL and tried again. It gave a half hearted little lurch forward and then settled back into the lifted rear wheel spin caper... 'Hmmm' I thought to myself again as I moved the lever into LL. Another little lurch forward and then same thing!

            NOW... I must admit that I was not trying to get out of a bog or anything, I was just interested to see what was happening back there, so I was not giving it the berries or anything. So, is the above quote correct and I therefore have transfer case/box probs, or is there more to the story... hmmmm? Anything will do! Paul.
            That sounds pretty normal for a stock Prado with out traction control. You should consider fitting a rear locker or a winch.
            [B]Declan[/B]: [SIZE=1]1997 GXL 4.5 Auto 80 series on [B][COLOR="#FF0000"]LPG[/COLOR][/B], ARB bullbar, 2" OME lift, 32" MTZ, GME UHF, rear ARB locker, Kaymar spare wheel carrier[/SIZE]
            [B]PLANNED[/B]: [SIZE=1]3 or 4" suspension lift, 2" body lift (maybe), winch, 35" MTZ + roadies, front locker, sliders, cylinder head rebuilt for [B][COLOR="#FF0000"]LPG[/COLOR][/B], Garret [COLOR="#4499ff"][B]Turbocharger[/B][/COLOR][/SIZE]

            Comment


            • #7
              Thanks for the feedback fellas but the front wheels were firmly grounded and it was on hard ground just the angle that lifted the rear hoof. But tell me, is this quote what is supposed to happen? (By the way how DO you do that talking box/ballon thingy around a quote? I like it!) -HEY! I DID IT!!

              With the centre diff lock unlocked (in H-High), if any single wheel looses traction, all engine power goes to that wheel and progress halts (as there is no locked diffs to prevent power going down the path of least resistance - the spinning wheel).

              With the center diff locked (HL-High Locked or LL-Low Locked), it ensures that power will always get to the front and rear axles. If one wheel looses traction (say a front wheel is lifted), drive to that axle will stop (all power going down path of least resistance - the spinning wheel), but the other axle (the rear axle in this case), will still receive power. Progress may then continue (driven by the rear wheels though, as the front will still be spinning in the air). To stop progress with the centre diff locked, requires one front, and one rear wheel to loose traction.
              I'll take it over that little spot again on the weekend and I'll get the missus to have a look at what is spinnin and what is trying to. Although I did leave it in gear when I got out (I know... don't try this at home kids!) and the back wheel was spinning gentle around oblivious to the fact that I wanted to go somewhere... but I didn't actually have a real good look at the front. But even so, if the above quote is the way things are, shouldn't that wheel have NOT been driving?? ...hmmm?

              Comment


              • #8
                You don't need wheels airborne to loose drive. If there isn't enough grip on just 1 wheel, with an open diff, all the drive from that axle with be lost. While both front wheels may have been on the ground, if a rear wheel is the air, normally the diagonally opposite wheel to the airborne wheel with have little if any weight keeping it planted on the ground, hence hardly any grip.

                If you weren't even getting wheel spin at the front, that could be a transfer case problem.

                I feel like I've been over this so many times so I'm being lazy and quoting myself now.

                Originally posted by williade View Post
                Here is a simple test you can do to check the operation of the centre diff lock. Jack 1 of the front wheels off the ground and have transmission in neutral and the transfer in H. You should be able freely spin the wheel that has been jacked up. Shift the transfer lever into HL. Try to rotate the front wheel. It may turn for a few degrees and then lock and won't turn at all. If that happens the centre diff lock is engaged completely, so check the instrument panel to see if the CDL light is on.
                [B]Declan[/B]: [SIZE=1]1997 GXL 4.5 Auto 80 series on [B][COLOR="#FF0000"]LPG[/COLOR][/B], ARB bullbar, 2" OME lift, 32" MTZ, GME UHF, rear ARB locker, Kaymar spare wheel carrier[/SIZE]
                [B]PLANNED[/B]: [SIZE=1]3 or 4" suspension lift, 2" body lift (maybe), winch, 35" MTZ + roadies, front locker, sliders, cylinder head rebuilt for [B][COLOR="#FF0000"]LPG[/COLOR][/B], Garret [COLOR="#4499ff"][B]Turbocharger[/B][/COLOR][/SIZE]

                Comment


                • #9
                  Ok will do. Ta.

                  Comment


                  • #10
                    Paul2,

                    Which model do you own? If memory serves me correctly, and I'm sure someone will jump in if I get it wrong, the VX and Grande use a separate centre-diff-lock button and not the HL-LL gear-stick.

                    In any case, do you see the little ambre "centre diff locked" light show up on the instrumentation console? If not, then you don't have the centre-diff locked.

                    LFaR.
                    [size=1][color=#770000]29Feb12:[/color][color=#777700]12GXLTD Auto, ARB Deluxe Winch bar, WARN 9.5xp Winch, IPF 900XS, Tow, Safari snorkel, Front + Rear Recovery points, ARB OME NC Sports, ATZ-4Rib[/color][color=grey], Silver[/color]. [color=orange][b]MaxTrax[/b][/color], [color=maroon]ScanGuage II[/color], [color=blue]ARB CKMA12[/color], [color=deeppink]UHF: GME TX3440 AE4018K1 UNH047SX[/color], [color=darkgreen]Bushranger Air Jack[/color], [color=green]Staun + ARB Deflators[/color], [color=brown]WindCheetah Roof Rack[/color], [color=green]Foxwing[/color], [color=red]Super Charge MRV70, Redarc BCDC1220[/color], [color=darkblue]ARB 60L fridge[/color], [color=blue]MSA Fridge Dropdown slide[/color], [color=darkyellow]DRIFTA Drawers[/color], [color=gold]TJM Bash Plates[/color], [color=brown]TG150[/color].[/size]

                    Comment


                    • #11
                      You don't need wheels airborne to loose drive. If there isn't enough grip on just 1 wheel, with an open diff, all the drive from that axle with be lost. While both front wheels may have been on the ground, if a rear wheel is the air, normally the diagonally opposite wheel to the airborne wheel with have little if any weight keeping it planted on the ground, hence hardly any grip.

                      If you weren't even getting wheel spin at the front, that could be a transfer case problem.

                      I feel like I've been over this so many times so I'm being lazy and quoting myself now.


                      Originally Posted by williade
                      Here is a simple test you can do to check the operation of the centre diff lock. Jack 1 of the front wheels off the ground and have transmission in neutral and the transfer in H. You should be able freely spin the wheel that has been jacked up. Shift the transfer lever into HL. Try to rotate the front wheel. It may turn for a few degrees and then lock and won't turn at all. If that happens the centre diff lock is engaged completely, so check the instrument panel to see if the CDL light is on.

                      In any case, do you see the little ambre "centre diff locked" light show up on the instrumentation console? If not, then you don't have the centre-diff locked.

                      LFaR.

                      Well gentlemen, I did the above test (williade) and the transfer cas is definately engaging and yes (LiveFreeAndRoam) the light indicating that the transfer case is engaging is coming on... AND I took it back to the little spot that caused the initial 'Unnerving Observation' and made another observation... Yes it is true as was indicated to me that the diagonally opposite front wheel was indeed starting to loose traction even though the ground is hard and the wheel is not right off the ground - that's why we need diff locks! Eh!? (although I do already have a winch BUT...yes wait there is more!... BUT I also notice that when I got to the little spot that caused the 'unnerving observation', that even though I HADN'T engaged the transfer case the FRONT WHEEL was spinning anyway! (along with the diagonally opposite rear one!) SO... this would lead me to the conclusion that the Prado is an ALL WHEEL DRIVE even when not engaged in 4WD is that right? (By the way my model is the GXL with H, HL and LL... and if there is another thread that I couldn't find ('cause I did look) that answers all these BASIC questions and observations (keeping in mind that I've only owned a 4WD for a little while) BY ALL MEANS TELL ME SO THAT I DON'T WASTE YOUR TIME AND MINE. Much appreciated for comments though. Paul.

                      Comment


                      • #12
                        If you have the VX you will have a centre diff lock button electronically controlled, in the Aussi version it is up infront of the auto and transfer lever, under ashtray. By pushing this button it will then lock the centre diff lock also indicated on dashboard, to the right of the auto gearstick is the button for DAC control standard on all the 120 VX's and grande's and now standard on the GXL 150 prado, 95's never had DAC control. The advantage is with the VX, Grande's in the 120 is you can use low range without locking centre diff lock which can be handy for reversing up steep slopes (better control and torque). Its a bit of a mixed bag with the centre diff lock in the grnade's and VX's as with traction control (which you will have) it will send the power to what ever wheel is getting traction and applying the brake to the wheels losing traction hence traction control (works great). Locking centre diff lock will give you 50/50 traction front and back. There was a lot of times when I had my 95 grande I didnt even use centre diff lock as the traction control did its job anyway, in my opinion just helps the traction control a bit more as it will send power equally to front and back. You will also note as soon as you lock in centre diff lock using the centre diff lock button your stability control will turn off which will also be highlighted on the dash. Unfortunately in the 95's and the 120's you cant turn off the traction control, unless you pull the fuse, where as the 150 by holding down the satbility control button it will also turn off the traction control which is great for on sand and other places you dont want it activating. Actual diff locks is another totally different thing as described by other posts above, it has nothing to do with traction control bottons. Say you dont have your centre diff locked, even If you have rear diff air locker and you have one front wheel up in the air all the power will be sent to this one wheel spinning in mid air (lease resistance) you will need to lock your centere diff lock so 50% will be sent to the rear axle and then using your rear air locker it will (hopefully) push you through..I believe the only prado in Australia that come with an actual DIFF LOCK is the new 150 Kakadu ?? Cant believe its not even in the new updated hilux ?? Hope this all makes sense. Cheers Steve
                        Steve M
                        Addicted PP Member
                        Last edited by Steve M; 08-12-2011, 10:46 AM.
                        Face lift 150 Prado V6 auto. No mods yet

                        Comment


                        • #13
                          Yes all Prados sold in Australia are full-time 4wd.

                          This is a well written explanation of the 80/100 series Landcruiser 4wd system which, for the purpose of this conversation, is the same as the Prado's.
                          http://www.lcool.org/technical/diffs/diffs.html
                          [B]Declan[/B]: [SIZE=1]1997 GXL 4.5 Auto 80 series on [B][COLOR="#FF0000"]LPG[/COLOR][/B], ARB bullbar, 2" OME lift, 32" MTZ, GME UHF, rear ARB locker, Kaymar spare wheel carrier[/SIZE]
                          [B]PLANNED[/B]: [SIZE=1]3 or 4" suspension lift, 2" body lift (maybe), winch, 35" MTZ + roadies, front locker, sliders, cylinder head rebuilt for [B][COLOR="#FF0000"]LPG[/COLOR][/B], Garret [COLOR="#4499ff"][B]Turbocharger[/B][/COLOR][/SIZE]

                          Comment


                          • #14
                            ""that even though I HADN'T engaged the transfer case the FRONT WHEEL was spinning anyway! (along with the diagonally opposite rear "" had you say had 3 wheels on the ground one in the air, all power would have gone to the one wheel that was in the air, this is where the centre diff lock button comes into play. If say you have 1 rear wheel in the air spinning away and three touching the ground if you locked the centre diff lock you will then distribute 50/50 drive to front and back, so then by having the centre diff locked in the locked position 50% of the power would then have gone to the front drive so chances are it would pull you through....If you had traction control it would have applied the brake to the wheel which was in the air spinning and sent the power to the other 3 wheels and if one of them started spinning it would have apllied the brake to that wheel and so on. Still not as good as lockers but will take you most places you want to go. Obviously you are like myself and have the GXL with out any of the option packs so no traction control, DAC control etc. I certainly miss the traction control my older 95 Grande had, never bothered with lockers but will at least get one in the 120 GXL V6 I have now........Cheers Steve
                            Face lift 150 Prado V6 auto. No mods yet

                            Comment


                            • #15
                              I don't think you have yet mentioned which model you own. If it's a GXL do you have any option packs? What I'm getting at is if you have Traction Control, then something is broken. If not, then what you are observing is normal.

                              that's why we need diff locks! Eh!?
                              Either a diff lock or some other traction aid. In a Prado with traction control, it would have easily pulled you out of this predicament.

                              LFaR.
                              [size=1][color=#770000]29Feb12:[/color][color=#777700]12GXLTD Auto, ARB Deluxe Winch bar, WARN 9.5xp Winch, IPF 900XS, Tow, Safari snorkel, Front + Rear Recovery points, ARB OME NC Sports, ATZ-4Rib[/color][color=grey], Silver[/color]. [color=orange][b]MaxTrax[/b][/color], [color=maroon]ScanGuage II[/color], [color=blue]ARB CKMA12[/color], [color=deeppink]UHF: GME TX3440 AE4018K1 UNH047SX[/color], [color=darkgreen]Bushranger Air Jack[/color], [color=green]Staun + ARB Deflators[/color], [color=brown]WindCheetah Roof Rack[/color], [color=green]Foxwing[/color], [color=red]Super Charge MRV70, Redarc BCDC1220[/color], [color=darkblue]ARB 60L fridge[/color], [color=blue]MSA Fridge Dropdown slide[/color], [color=darkyellow]DRIFTA Drawers[/color], [color=gold]TJM Bash Plates[/color], [color=brown]TG150[/color].[/size]

                              Comment

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