Switch to turn off ABS for off-road use???

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Originally Posted by drivesafe

This one comes around about once a year on one site or another and the same arguments appear but cartm58 is the closest to what you should do when driving on gravel surfaces.

The correct way, and this takes HEAPS of practising to achieve, is to NOT slam the brakes on.

I have practised and practised and the best I can do when an unexpected emergence brake in needed on a gravel road is to instinctively jump on the breaks but as soon as the grey matter kicks in I back the break pedal pressure off a bit and the vehicle will then pull up pretty quickly.

It’s still not as quick as a non ABS equipped vehicle but there is one major difference and it doesn’t matter if you stand on the brakes or control the braking, ABS gives you the ability to control the vehicle while locking up the brakes usually means you either loose control or you have to release the brakes to get back steering control.

You are far better off having the ability to maybe able to steer around an obstacle at some speed that skid into it at a lower speed.

Next time you are on a wide, straight section of gravel road, take the ABS fuse out, get up to 60 and slam the brakes on and don’t take your foot off till you have stopped.

Go back, put the fuse back and do it again.

On average, depending on the surface, ABS will take about 1/3 greater distance but compere the stopping patens. The ABS will be longer but no matter what happened during the braking, you can keep it straight, while the non ABS paten will be anything but straight.

The best thing you can do with an ABS vehicle on gravel is to learn to drive with the advantages and disadvantages of it and in the long run the advantages far out weigh the disadvantages.

ABS vehicles, even on gravel, gives inexperienced drivers a far better chance of surviving an emergence braking situation.

Cheers.

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I totaly agree and just want to add that I have had a Jeep with ABS that had a loose gravel road switch factory fitted (I think it looked factory) on the dash and I found that on gravel the ABS under heavy braking it would pull 1 side or the other with no warning of which way it would pull but did still have steering control so was controlable although off putting and a little scarey.

With the switch off it would happilly lock the front wheels but would completely lose steering control even though I tried light braking medium and heavy braking and backing off the pedal wouldnt unlock the fronts until you were hardly braking at all.

I also agree that your speed is the biggest thing you can control in regards to being still in control in the event that something happens and you need to stop in a hurry but I do agree that on some gravel roads espesially if you know then well it can be/percieve to be relativly safe to travel at or around the 100kmh mark.

I would ask Drivesafe if my solution would be sufficient as he is the Guru in electrical stuff, Im just a lowly mechanic so maybe pick his brain on the specifics.

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Originally Posted by mcrover

I would ask Drivesafe if my solution would be sufficient as he is the Guru in electrical stuff, Im just a lowly mechanic so maybe pick his brain on the specifics.

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Got to be honest, the only way I have ever tried it was to pull the fuse. This was on my D1 and and I only did it the once after a mate and I argued over the same thing that is being discussed here.

BTW, I was, at that time, arguing to switch the ABS off on gravel roads.

The mate, at the time was doing test drives on new 4x4s for Overland Mag, was the one that put me onto practising with gentle braking.

That definitely works but no matter how much you practice, when an emergency stop is needed on gravel, instinct still has me jumping on the brake pedal, but milliseconds later I’m easing off.

Cheers

Please correct me if I'm wrong, but if the CDL is engaged, does this not disable the ABS and TC ?
If you are driving on loose gravel it is safe for the drive line to be centrally locked, plus it gives far better handling.

In response to the above about the CDL: On the older disco 2's the cdl does not disable the abs when engaged unless you turn the vehicle off then back on while leaving the cdl engaged. You can cut a wire to prevent this so that it behaves like the later models where the cdl does not affect abs.

A question: If you rigged up a switch to enable/disable the ABS fuse, would you be able to switch ABS on or off whilst driving, or would you have to stop and switch off&on to restart ABS?

(It's just when I am heading home at about 130kph and trying to look out for cows and damaged grids and older drivers :eek: I can't be bothered stopping when I'm going on and off the bitumen. And don't get me started about the school bus :mad: SO SLOW!!!! Stopping and slow speeds are for the weak and those who show pity and empathy for other road users :twisted:. KIDDING KIDDING!! Sorry guys couldn't help it!I know you are all trying to do the right thing by giving speed advice.)

But seriously I do believe there is a serious question in being able to switch ABS on or off.

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Originally Posted by dm_td5

In a D2 though if you were to "switch off" ABS, then you've just disabled TC and HDC as well.
In a Defender 110 Td5 you can do this at startup as the Wabco D unit has an ability to be shut off that isn't in the Wabco SLABS unit in the Disco's.

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How is this done in the Defenders?
I did here about this ages ago, but forgot how it was done ...

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Originally Posted by MT

Of course, you could always just drive at a speed appropriate for the road conditions.....;)

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How about that ah ;);)

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Originally Posted by Sandtoyz

How is this done in the Defenders?
I did here about this ages ago, but forgot how it was done ...

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See this thread: http://www.aulro.com/afvb/showthread.php't=34084

Quote:

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Originally Posted by drivesafe

This one comes around about once a year on one site or another and the same arguments appear but cartm58 is the closest to what you should do when driving on gravel surfaces.

The correct way, and this takes HEAPS of practising to achieve, is to NOT slam the brakes on.

I have practised and practised and the best I can do when an unexpected emergence brake in needed on a gravel road is to instinctively jump on the breaks but as soon as the grey matter kicks in I back the break pedal pressure off a bit and the vehicle will then pull up pretty quickly.

It’s still not as quick as a non ABS equipped vehicle but there is one major difference and it doesn’t matter if you stand on the brakes or control the braking, ABS gives you the ability to control the vehicle while locking up the brakes usually means you either loose control or you have to release the brakes to get back steering control.

You are far better off having the ability to maybe able to steer around an obstacle at some speed that skid into it at a lower speed.

Next time you are on a wide, straight section of gravel road, take the ABS fuse out, get up to 60 and slam the brakes on and don’t take your foot off till you have stopped.

Go back, put the fuse back and do it again.

On average, depending on the surface, ABS will take about 1/3 greater distance but compere the stopping patens. The ABS will be longer but no matter what happened during the braking, you can keep it straight, while the non ABS paten will be anything but straight.

The best thing you can do with an ABS vehicle on gravel is to learn to drive with the advantages and disadvantages of it and in the long run the advantages far out weigh the disadvantages.

ABS vehicles, even on gravel, gives inexperienced drivers a far better chance of surviving an emergence braking situation.

Cheers.

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Im with you drivesafe--- belting around in the 60s in HR panelvans looking for the "perfect wave" on old narrow sandy / gravel tracks down the southern coast of NSW gave me a great appreciation of speed control on braking-- lock the wheels, no control over steering and bingo! hello tree. I understand the nice idea of control that braking- break through the crust- build up a nice little mound of crud in front of the wheels to assist in slowing down, but hey-- who's the iceman that when a bloody great roo jumps AT you or whoa, what happened to the road--- we hit the brakes HARD-- give me steering anyday-- ABS leave it ON.:)

Who's kidding who...
HR's and brakes? They were mutually exclusive of each other!!!

... We've got a lot of information on the pros and cons of turning ABS on/off but I get the impression no one has actually deliberately done it apart from "accidently" when using the cdl?
Iv'e just attempted the "10 pumps of the pedal" trick mentioned in the link to no avail on my 2000 disco two.
Does anyone know the answer to my previous question - if you remove the fuse, will it activate/deactivate the ABS without having to restart the vehicle? And I guess if you stop with the fuse "out" when you restart can you just put it back in without resarting? My guess is no as per using the CDL... ?? (ie would a switch on this line be a simple "on/off" job or stopping and starting?)
Its rarely I'd turn off the ABS but if it's going to be a hassle I'd rather it on than off, but so saying it can be a bit hairy using ABS on loose gravel or slimy mud. It's great to be able to steer as people say but only when there is somewhere to go! At other times I'd rather just stop! (example - rounding a corner on a "closed in" track to find an unexpected gate or fallen tree).

On another note - as we're all putting our two bobs in about braking - here's some info and a few ABS questions:

Cadence braking ("pumping" the brakes) is best for drum brakes, or so i'm told. This is because drums do not tend to release well if you just lift your foot a tiny bit, and to get the wheels tuning again must be released a lot whereas...

Threshold braking (pushing pedal till tyres lock then releasing the brake pedal gradualy untill wheels start to turn) is better suited to discs, which will respond better and release quicker when the foot is lifted.

So saying, after getting used to both, what happens with ABS? If the wheels lock up and the modulator kicks in, does it matter how hard you stand on the pedal? Are the "modulations" strength related to pedal pressure?
My automatic reaction in a skid is to lift my foot (as with either cadence or threshold braking), with ABS should I do this or just stomp on it?I believe the latest landies have a "emergency braking" response in the ABS that I guess equates to stomping on the pedal??
Question questions...