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Road speed while in diff lock


beaker

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Mum had a flat tyre about 12 years ago (around 80000 miles ago). She changed the tyre ok, followed the book, difflock on, handbrake on, in gear and chocked. The chock must have slipped a little when it was up on the jack and the 110 was on a hill and this got the jack stuck under the light guard and she couldnt turn the ratchet over!! She had to call the RAC to get it off the jack! Anyway, he arrived, got it off the jack and told her the diff lock light must be jammed on and there was no way the diff lock was stuck on (of course it hadnt disengaged and he didnt reverse it at all). She drove about 50 miles on the motorway at 60ish, then 20 mil;es on winding lanes to get back to the village. I went out the next day and the light was still on, reversed it out of the garage and it came off!

I guess it did no real damage, but would it have increased wear in the transmission/cause other parts to fail sooner than they would? I can make i clunk with every gear change if i'm not smooth - the gearbox is reconditioned, it has a GKN OD fitted, so i suspect it is wear further down the transmission

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If I'm driving in high ratio with the diff lock on, is there a maximum speed I should be doing so as not to damage the diff?

not really, like Bowie said, it's more the surface that matters.

I drove 500kms+ on dirt roads in Namibia with the diff-lock on, doing an average of 80-100kmh last year without any issues.

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I've just replaced a seized centre diff. Before that (when it was seized) it was the same as having the centre diff locked. I did a few road up to about 50 miles on tarmac. It was fine up to about 55 mph after that you could hear the transmission wind up. At first I thought it was a wheel bearing on the way out but it turned out to be the cetre diff. No damage done to mine but obviously dont do it deliberatley. If you do it by accident I think you would be unlucky to cause any damage unless you did 100 miles plus or started doing high speeds (60 plus).

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Well :ph34r:

In the snow the A3 and surrounding roads were terrible, some inpassible some even closed :)

and I was having a ball in Locked high range "Slightly Tweaked" 4.5 EFI V8 and booting it with the road to myself it seemed. Unsure of the speeds, but "Not Slow"

As others have said, NOT lockjed for tarmac or you'll get a BANG

nige

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Mum had a flat tyre about 12 years ago (around 80000 miles ago). She changed the tyre ok, followed the book, difflock on, handbrake on, in gear and chocked. The chock must have slipped a little when it was up on the jack and the 110 was on a hill and this got the jack stuck under the light guard and she couldnt turn the ratchet over!! She had to call the RAC to get it off the jack! Anyway, he arrived, got it off the jack and told her the diff lock light must be jammed on and there was no way the diff lock was stuck on (of course it hadnt disengaged and he didnt reverse it at all). She drove about 50 miles on the motorway at 60ish, then 20 mil;es on winding lanes to get back to the village. I went out the next day and the light was still on, reversed it out of the garage and it came off!

I guess it did no real damage, but would it have increased wear in the transmission/cause other parts to fail sooner than they would? I can make i clunk with every gear change if i'm not smooth - the gearbox is reconditioned, it has a GKN OD fitted, so i suspect it is wear further down the transmission

Backing up a short distance is usually a good way of unlocking the centre diff.

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A couple of years ago I went about 150 miles or so round the M25 & back at about 70mph with the centre diff locked, (the light wasn't working at the time,) I only noticed it when I got off the M'way and wondered why it handled a little strange round a roundabout.

Done loads of miles in it since then and there appears to be no long term damage.

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I'm sure my 90 has a sticker on the fusebox cover (just in front of the gear leaver) saying not to exceed 15mph when diff lock is engaged. I did once for about half a mile without realising I was still in difflock. The car was feeling like it was really struggling to move. I started to panic thinking I had destroyed my old girl and imagining the worse. I got 2 miles down the road before realising I still had the handbreak on too ha ha :rolleyes:

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As others have said speed isn't the issue as such.

Transmission windup is the problem, i.e. the front axle turning slightly faster than the rear (or the other way round!).

If your wheels and tyres are exactly the same rolling diameter then driving in a straight line will not cause wind up, if they are slightly different diameters then windup will occure, different brands of tyres, wear levels, pressures etc will all cause different diameters. The greater the distance and the geater the difference the more wind up you will get. Turning a corner will also cause wind up as the front axle travels further than the rear whilst turning.

When the wind up gets to a certain point something WILL break, if you are off road or on a slippy surface then it is likely to be the traction between the tyr and the road, basically a tyre will spin out slightly and releave the tension in the transmission.

If you are on a good high traction surface such as dry tarmac or concrete then it may well be the transmission which breaks instead normally a half shaft or CV.

Generally once the transmission starts to wind up you will feel it in the steering with it trying to pull to the side, thats a good point to stop and work out whats wrong, often just putting a tyre on the verge or a manhole cover will cause the tyre to spin and prevent damage, best solution though is to follow the instructions in the hand book and only use difflock when the traction is bad.

This applies to a centre difflock but the princable is the same for a cross axle difflock.

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Thanks for all the replies. It's just that living in Aberdeenshire we seem to have an awful lot of the 'white stuff' at the moment and driving around on compacted snow and ice I've had the diff lock in just to give me that extra bit of security. It means that I can troll around at 40 mph without to much slipping and sliding. I was just a bit concerned that I might be doing some damage somewhere but it seems not. One thing in Westerns post about easing of the power when engaing and disengaing, I was always under the impressiong that you had to stop first? :unsure:

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No, you can flick in and out of difflock on the move. Changing from high to low you need to do at standstill. Changing from lo to hi can be done on the move, but despite tring forever to get it right, my transmission sounds like it wants to destroy itself when i do this, so i prefer to do it at a standstill also!

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No, you can flick in and out of difflock on the move.

Yep, just make sure your wheels are all straight and just to be safe, press the clutch in before dis/engaging the CDL.

Changing from high to low you need to do at standstill. Changing from lo to hi can be done on the move, but despite tring forever to get it right, my transmission sounds like it wants to destroy itself when i do this, so i prefer to do it at a standstill also!

As long as your speed is < 5kmh, you can do either on the move. A bit tricky to get right though :)

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