MOT passed but 4WD question arose.

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Brian S

Brian S

Well-Known Member
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Braintree, Essex
I took my discovery for it's MOT today and it passed with no advisories. :D :D

There was a question about the 4X4 system though.

After he checked the rear brakes in the rollers (special 4x4 rollers that turn opposite rotation to use the drive shafts and not the props) he went to reverse out to do the fronts and the rear wheels just went round. The fronts did nothing.

He drove forward and backed out to do the fronts then after the front brakes were checked had the same problem but the rears doing nothing.

Put it into difflock and it drove out fine.

Does this seem right? I thought some traction was shared front and rear so if one end gets bogged the other would have traction.
 
If one axle has no traction the other will not drive unless you engage the centre diff lock. It's what the centre diff lock is for. It's working correctly.
 
hughesy is 100% correct for a Disco1. A Disco 2 should ues it`s traction control to gently apply brakes to spinning wheels, a Disco 3 has ETC and elec locking diff so both will get off the rollers easily. For a Disco 1 you actually have to move a lever yourself!
 
How many people know about Manual Traction Control? A great technique once mastered. It basically involves standing on the Brake pedal with the left foot and then slowly releasing the brakes and balancing the revs, this will trick the Diff into thinking there is traction and applying drive to the wheels. Its the basis that modern traction control works on. If used properly it will get you out of many a slippery situation. I used it when pulling that Bin lorry up the hill on Ice. Don't over use it because it will become less effective as your brakes heat up!
 
puppysandwich said:
How many people know about Manual Traction Control? A great technique once mastered. It basically involves standing on the Brake pedal with the left foot and then slowly releasing the brakes and balancing the revs, this will trick the Diff into thinking there is traction and applying drive to the wheels. Its the basis that modern traction control works on. If used properly it will get you out of many a slippery situation. I used it when pulling that Bin lorry up the hill on Ice. Don't over use it because it will become less effective as your brakes heat up!
Click to expand...

It's a real good technique, even more so when you have your diff locked up!

For some people they will rev the nuts off it and fail the hill climb, possibly bouncing over rocks, in and out of traction, shredding diffs, blue smoke coming from tyres! for others they will gently apply left foot braking and drive on up like there's nothing to it..!

a technique well worth learning, but be prepaired to stall it many times before you get it right!
 
Brian S said:
I took my discovery for it's MOT today and it passed with no advisories. :D :D

There was a question about the 4X4 system though.

After he checked the rear brakes in the rollers (special 4x4 rollers that turn opposite rotation to use the drive shafts and not the props) he went to reverse out to do the fronts and the rear wheels just went round. The fronts did nothing.

He drove forward and backed out to do the fronts then after the front brakes were checked had the same problem but the rears doing nothing.

Put it into difflock and it drove out fine.

Does this seem right? I thought some traction was shared front and rear so if one end gets bogged the other would have traction.
Click to expand...

What happened there is exactly correct.

Even in a 4 wheel drive car like a Disco / Defender, if any ONE wheel spins, ALL wheels lose drive. That is why you have DIFF LOCK to lock the differential between front and rear drive.

That way, if ONE wheel spins, while both wheels on that AXLE have lost drive, the other axle should drive as usual - unless it slips too.

CharlesY
 
puppysandwich said:
How many people know about Manual Traction Control? A great technique once mastered. It basically involves standing on the Brake pedal with the left foot and then slowly releasing the brakes and balancing the revs, this will trick the Diff into thinking there is traction and applying drive to the wheels. Its the basis that modern traction control works on. If used properly it will get you out of many a slippery situation. I used it when pulling that Bin lorry up the hill on Ice. Don't over use it because it will become less effective as your brakes heat up!
Click to expand...

I don't suppose it's as effective in a auto though is it?
 
Brian S said:
I don't suppose it's as effective in a auto though is it?
Click to expand...

I don't see why not, give it a try and let us know. You'll need to go out and find some really slippery mud though and get yourself stuck! :D

In fact I think there would be less likelihood of Stalling in an Auto.
 
I'm in love with the X6 :kiss:.... anyway I'm not in the motor trade but agree with pupps and I'm sure the rollers can be locked.. just to please the f-ing elf and safety as I have walked across them and it was ok..... perhaps I shouldn't :doh:

I must remember to ask my garage how he gets my disco off the roller.. some hope of me remembering to do that as the MOT is September. :D
 
The MOT was in Kwik Fit, not a 4x4 specialist. Also nor am I, just a discovery owner learning all the time.

I guess you learned everything about them before you brought your first one then. Good for you. :)
 
Brian S said:
The MOT was in Kwik Fit, not a 4x4 specialist. Also nor am I, just a discovery owner learning all the time.

I guess you learned everything about them before you brought your first one then. Good for you. :)
Click to expand...

Most people don't need to know everything about them. You tend to find that most people buy a certain type of vehicle for a reason. If you buy a 4x4 vehicle to use it offroad you kind of need to know how it works. If it's just to use as a Chelsea tractor then it doesn't matter.
 
I own the vehicle as a winter hack that I enjoy a bit of light off roading and laning in, nothing serious, but as I said I do like to learn as I go along hence the question. :)

Now I know so from now on in my life I can say I know how the discovery 4x4 system works.
 
puppysandwich said:
How many people know about Manual Traction Control? A great technique once mastered. It basically involves standing on the Brake pedal with the left foot and then slowly releasing the brakes and balancing the revs, this will trick the Diff into thinking there is traction and applying drive to the wheels. Its the basis that modern traction control works on. If used properly it will get you out of many a slippery situation. I used it when pulling that Bin lorry up the hill on Ice. Don't over use it because it will become less effective as your brakes heat up!
Click to expand...

Yeah, it works very well with an auto box too:)
 
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