Mysterious problem and a strange soloution.

defender300 · Nov 2, 2009

Hi ppl,

I have a defender 90 300 tdi 1995 model with 65,000 KMs on the clock. When it is travelling above 40km/h, it vibrates and is noisy. However, if I park the car on the side and move the differential gear forward and backwards...and sideways to engage and disengage the diff lock and then resume my driving, the car suddenly becomes lighter, quiter and very smooth. It almost seems like if Iam driving a different car. This good phase however lasts only for a couple of hours and then back to the old regime. Can any of you please assist me and tell me what is causing this strange phenemenon and how I can permanantly have my car in the 'good phase' without having to move around the small gear after every few hours. Thanx.

rgds,

Hammad

Trewey · Nov 2, 2009

change the oil in your transfer box for a start.

defender300 · Nov 2, 2009

already did that last month.....changed the oil in the front and rear diffs too....

jai_landrover · Nov 2, 2009

DIfflock adjusted incorrectly and drops in after some time/vibration? Possibly?

defender300 · Nov 3, 2009

had the four wheels jacked up today and each wheel was free to turn independently.....so the diff lock is not engaged....had the handbrake drum opened too and that was fine too...the shaft was free to turn there.....but the problem persists.....if i move around the small gear lever....car turns smooth suddenly....should i open the gear covering from inside the car and peek in?

defender300 · Nov 3, 2009

had the four wheels jacked up today and each wheel was free to turn so the diff lock is not engaged.....opened the hand brake drum and no problems there either.....should i open the gear covers from inside the the car and peek in?

Sean · Nov 3, 2009

defender300 said:
had the four wheels jacked up today and each wheel was free to turn independently.....so the diff lock is not engaged....had the handbrake drum opened too and that was fine too...the shaft was free to turn there.....but the problem persists.....if i move around the small gear lever....car turns smooth suddenly....should i open the gear covering from inside the car and peek in?

take off the gear lever rubber cover and check that the diff lock mechanism is working correctly and properly adjusted

CharlesY · Nov 3, 2009

defender300 said:
had the four wheels jacked up today and each wheel was free to turn so the diff lock is not engaged..

That is NOT a safe assumption.

What you describe is a classic sign of DIFF LOCK ENGAGED on a hard grippy surface.

A good way to check DIFFLOCK on or off is to jack up both wheels on one side of the car, leave the engine STOPPED, IN GEAR, and the transfer box also IN GEAR, handbrake ON firmly.

Now try to turn ONE of the jacked-up wheels.

If the whole thing feels jammed up and the wheel won't turn the diff is LOCKED. Try to turn the other jacked-up wheel and it should be the same. Jammed apart from all slop and free play in the system.

BUT ...

If the other wheel on that side turns in the opposite direction the centre diff is FREE, NOT LOCKED.

CharlesY

defender300 · Nov 3, 2009

CharlesY said:
That is NOT a safe assumption.

What you describe is a classic sign of DIFF LOCK ENGAGED on a hard grippy surface.

CharlesY...thanx for your comment....i have a feeling ure right.....i just checked the transfer levers beneath the gears and things seemed fine at that end at least but whats going on inside the transmission box...god knows!!!

In relation to what you just wrote....when i jacked up the four wheels today....the rear wheels seemed to turn in opposite directions but the front wheels only turned on their own.....which means when i turn the LEFT FRONT WHEEL clockwise...the RIGHT FRONT WHEEL did NOT turn anti-clockwise...any guidance on whether this may be an indication of differential LOCKED??

Oddie · Nov 3, 2009

When you turned the left front, SOMETHING would have to have turned else you got a shot halfshaft / diff - is it possible that one of the back wheels turned and you didn't see it, in which case the diff isn't locked?

defender300 · Nov 3, 2009

odenne said:
When you turned the left front, SOMETHING would have to have turned else you got a shot halfshaft / diff - is it possible that one of the back wheels turned and you didn't see it, in which case the diff isn't locked?

Odenne....iam quite sure that none of the wheels turned when i turned the front left one..

jai_landrover · Nov 3, 2009

defender300 whare abouts are you?
mabe one of us could ave a look see and show you what we mean

defender300 · Nov 3, 2009

jai_landrover said:
defender300 whare abouts are you?
mabe one of us could ave a look see and show you what we mean

Jai iam in Lahore, Pakistan

... although we have defenders being made here now as well but thats quite recent and there r no trained mechanics for defender.....they just do and check what I tell them to....recently some devious minded mechanic poured diesel into my front differential in place of ep-90....i think it survived that abuse but am not sure.....

CharlesY · Nov 3, 2009

Oh God ..... here goes .....

There are FIVE things can turn, four wheels and THE GEARS above the centre diff.

If you jack up an END (back or front) there are several possibilities what can happen.

If the centre diff is LOCKED then ONE thing could turn if you turn ONE wheel that is off the ground - the other wheel on that axle will turn in the other direction.

If the centre diff is LOCKED then the REAR AND FRONT propshafts are solidly connected, and as the OTHER end wheels are on the ground BOTH propshafts are locked stationary.

If the centre diff is FREE to work as a DIFFERENTIAL, then TWO things could turn if you turn ONE wheel that is off the ground - (1) the other wheel on that axle may turn in the other direction or (2) the propshaft to that axle will turn because it can rotate the centre diff cage, BUT ONLY IF the handbrake is OFF, and the gears are in NEUTRAL somewhere.

You all need to think through this centre diff business carefully.

If the centre diff is FREE, if any ONE wheel of the four slips you have lost ALL traction. NO wheel will drive. The one spinning wheel may spin at FOUR TIMES the "road speed" of the car. Gettit? TWO DIFFS involved .... FOUR times the speed..

If the centre diff is locked, and any one wheel slips, the other wheel on THAT axle will also transmit NO DRIVE but THE OTHER AXLE will continue to drive until one or both wheels slip.

Complicated huh?

But Logical.

CharlesY

jai_landrover · Nov 3, 2009

Well I Know some damn fine Landy Mechanics in Kabul but thats a tad too far East for you in Lahore Pitty you wasn't on the Afghany boarder they would jump at the chance of a couple of days out. One guy drove all day to reach burger king at the yanks base Kabul

defender300 · Nov 3, 2009

CharlesY said:
Oh God ..... here goes .....

i really appreciate u taking the time to explain this to me...iam sure it would help many other readers too.....charles what should i tell the mechanic tomorrow...in case the diff is self locking....how to remedy this?

CharlesY · Nov 3, 2009

defender300 said:
CharlesY said:

Oh God ..... here goes .....

i really appreciate u taking the time to explain this to me...iam sure it would help many other readers too.....charles what should i tell the mechanic tomorrow...in case the diff is self locking....how to remedy this?

Click to expand...

There are far better people than me on this forum who can explain about setting the levers and linkages to stop this happening.

You MUST be able to be sure that the sideways throw of the transfer lever POSITIVELY engages and DISENGAGES diff-lock-up.

Even after you operate the lever to DISengage it, the diff may remain LOCKED, and the light may stay on.

This happens because the shafts are "wound up" and are trapped due to strain.

To UN-strain the shafts and make it free the diff, REVERSE the car slowly and swing the steering as far as possible from one side to the other a few times. This will undo the strain by making the FRONT wheels go further than the back wheels.

CharlesY

defender300 · Nov 4, 2009

CharlesY said:
defender300 said:

Ok....i'll try that too.....could this problem be related to the connecting shaft?

Click to expand...

jai_landrover · Nov 4, 2009

it usually happens when somone changes a gearbox and winds the pivot bolt in too far so you dont get enough throw at the bottom.
Another common one is not having the plastic inserts where the pivot pins go
Jai

defender300 · Nov 4, 2009

jai_landrover said:
it usually happens when somone changes a gearbox and winds the pivot bolt in too far so you dont get enough throw at the bottom.
Another common one is not having the plastic inserts where the pivot pins go
Jai

i dont understand...which pivot bolt and which pivot pin r we talking about?

Mysterious problem and a strange soloution.

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