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Thread: 98 disco 1 diff lock won't work

  1. #1
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    98 disco 1 diff lock won't work

    I recently bought a well-maintained 98 disco 1 auto. the cdl lever moves fine - shifts from hi to low with no issues and will shift side to side, BUT won't lock the diffs. i've taken the center console and boot out and can see the arms and lever work fine, rotating the switch, but no locking. I've made the adjustment from the top with an extended socket even. i even taken the nut and the arm off the switch to try moving it manually and still nothing. not just no light. i've jacked up the front wheel and there's definitely no locking. I've tried driving it forwards and backwards, but still no locking. I even changed the gear oil, and still no locking. I'm certain the switch is moving over enough, but whatever needs to happen inside the transfer case simply isn't happening.

    Any thoughts? Should I open up the transfer case and have a look? Should I replace the switch on top?

    Cheers.

  2. #2
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    Is this how you tested the diff lock?

    Definitive test. (Thanks to John JDNSW from a 2012 thread)

    Handbrake on
    Gearbox neutral (or T/C neutral)
    Jack up one front wheel
    With centre diff unlocked the jacked up wheel can be spun freely (well, relatively freely anyway) as the centre diff will operate as a differential, and the motion will spin the gearbox.
    With centre diff locked, front wheel can only be turned a small part of a turn, as the front output shaft from the transfer case is now locked to the handbrake.

  3. #3
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    Quote Originally Posted by Gvii View Post
    BUT won't lock the diffs.
    You said Diffs - There is only only diff lock which is the centre diff lock.
    REMLR 243

    2007 Range Rover Sport TDV6
    1977 FC 101
    1976 Jaguar XJ12C
    1973 Haflinger AP700
    1971 Jaguar V12 E-Type Series 3 Roadster
    1957 Series 1 88"
    1957 Series 1 88" Station Wagon

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    Quote Originally Posted by edddo View Post
    Is this how you tested the diff lock?

    Definitive test. (Thanks to John JDNSW from a 2012 thread)

    Handbrake on
    Gearbox neutral (or T/C neutral)
    Jack up one front wheel
    With centre diff unlocked the jacked up wheel can be spun freely (well, relatively freely anyway) as the centre diff will operate as a differential, and the motion will spin the gearbox.
    With centre diff locked, front wheel can only be turned a small part of a turn, as the front output shaft from the transfer case is now locked to the handbrake.
    Yes, I have tried this many times whilst trying to adjust the switch on top of the transfer case.

  5. #5
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    Quote Originally Posted by 101RRS View Post
    You said Diffs - There is only only diff lock which is the centre diff lock.
    Hm, yes, right...now, that doesn't particularly matter though. I described what i've done and just want to cdl to work, so it'd be great if you have any answers to my actual question? Cheers.

  6. #6
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    Quote Originally Posted by Gvii View Post
    ..... i've jacked up the front wheel and there's definitely no locking. I've tried driving it forwards and backwards, but still no locking. I even changed the gear oil, and still no locking. I'm certain the switch is moving over enough, but whatever needs to happen inside the transfer case simply isn't happening.

    Any thoughts? Should I open up the transfer case and have a look? Should I replace the switch on top?

    Cheers.
    Re the switch: if you ground the two wires whilst the ignition is on, or engine running, it will confirm if the light or an electrical fault is at play. Ign needs to be on at the least for the warning light to come on.
    Fuse F14 is where power comes from, but if it's the fuse, you will lose a few other warning lights at the same time. Can't recall exactly, but think oil warning light ... maybe?
    If you're under there, there should be two wires to the switch, one black(earth) check it for continuity to chassis to be sure it's OK, and with ign on and diff lock mechanism engaged, check the other wire(unfortunately BLACK and BLUE stripe!) for battery voltage .. ie. whatever volts your battery will be at.
    This will at least confirm power to the switch and if the power wire(Black-blue) is grounded the dash light WILL come on. If not either a bulb or other electrical problem down the line.

    If the electrics turn out OK, and it doesn't turn on the warning light with the mechanism engaged, then by the sounds of it the internal stuff is not working.
    With wheel jacked up and engaged, you shouldn't be able to turn wheel more than a few degrees(due to driveline slack).

    So, if this is the case, then sounds like at a minimum remove the side cover plate and see and feel what's happening at the linkages and dog clutch there.
    You can remove the spindle cover too(3 bolts) but won't see much from the sides, maybe enough from the top if you have console off, but it could be that the internal arm is not locating correctly into the shaft to move the dog clutch, or arm could be broken, or spinning on the spindle shaft or something.

    There are plenty of vids on Utube, my preferred vid makers for LR are Landrover Toolbox and Britannica Restorations .. but any will show you the easy to understand nature of the diff lock mechanisms in there.

    So, as an example of what you could try. If you pull the side cover off, and find that the spindle is not moving the arm rearwards, you should be able to manually force the arm rearwards, may have to twist propshaft a little to get gears meshed for the mecahism to engage. If you can do this with the one wheel jacked in the air test, it will confirm for sure if the actual diff itself is locking OK. If you can move the arm rearwards and the diff doesn't lock the wheel in the air, you have more serious issues down the line to the centre diff.
    Arthur.

    '99 D1 300Tdi Auto
    '03 D2 Td5 Auto

  7. #7
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    Quote Originally Posted by Gvii View Post
    Hm, yes, right...now, that doesn't particularly matter though. I described what i've done and just want to cdl to work, so it'd be great if you have any answers to my actual question? Cheers.
    Well I am sorry - we have has quite a few people who thought the diff lock lever worked diff locks in the CDL and diffs - you did use the term Diffs rather than Diff so just wanting to highlight that.

    But you seem to be on top of it - good luck.
    REMLR 243

    2007 Range Rover Sport TDV6
    1977 FC 101
    1976 Jaguar XJ12C
    1973 Haflinger AP700
    1971 Jaguar V12 E-Type Series 3 Roadster
    1957 Series 1 88"
    1957 Series 1 88" Station Wagon

  8. #8
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    Quote Originally Posted by AK83 View Post
    Re the switch: if you ground the two wires whilst the ignition is on, or engine running, it will confirm if the light or an electrical fault is at play. Ign needs to be on at the least for the warning light to come on.
    Fuse F14 is where power comes from, but if it's the fuse, you will lose a few other warning lights at the same time. Can't recall exactly, but think oil warning light ... maybe?
    If you're under there, there should be two wires to the switch, one black(earth) check it for continuity to chassis to be sure it's OK, and with ign on and diff lock mechanism engaged, check the other wire(unfortunately BLACK and BLUE stripe!) for battery voltage .. ie. whatever volts your battery will be at.
    This will at least confirm power to the switch and if the power wire(Black-blue) is grounded the dash light WILL come on. If not either a bulb or other electrical problem down the line.

    If the electrics turn out OK, and it doesn't turn on the warning light with the mechanism engaged, then by the sounds of it the internal stuff is not working.
    With wheel jacked up and engaged, you shouldn't be able to turn wheel more than a few degrees(due to driveline slack).

    So, if this is the case, then sounds like at a minimum remove the side cover plate and see and feel what's happening at the linkages and dog clutch there.
    You can remove the spindle cover too(3 bolts) but won't see much from the sides, maybe enough from the top if you have console off, but it could be that the internal arm is not locating correctly into the shaft to move the dog clutch, or arm could be broken, or spinning on the spindle shaft or something.

    There are plenty of vids on Utube, my preferred vid makers for LR are Landrover Toolbox and Britannica Restorations .. but any will show you the easy to understand nature of the diff lock mechanisms in there.

    So, as an example of what you could try. If you pull the side cover off, and find that the spindle is not moving the arm rearwards, you should be able to manually force the arm rearwards, may have to twist propshaft a little to get gears meshed for the mecahism to engage. If you can do this with the one wheel jacked in the air test, it will confirm for sure if the actual diff itself is locking OK. If you can move the arm rearwards and the diff doesn't lock the wheel in the air, you have more serious issues down the line to the centre diff.
    Thanks so much for that thorough walking through of the mission i may have ahead of me. It's pretty tight down underneath (I struggled just to get the toggle lever off the top of the tc. but i think this may be the way forward. I'll give it a stab in a few days time and see how things go.

    Many thanks!

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