Thread: Very dangerous brake problem...

This is just one of the key reasons why people are fitting CDL's and probably one of the reasons why LR returned to using them. I would recommend the fitment of the CDL to prevent this situation and to give better drive traction.

ABS doesn't work (disabled) in reverse so I discovered.

Did you use HDC?

"If the vehicle is unable to complete a climb, do
not attempt to turn it around while on the slope.
Instead, adopt the following procedure to
reverse downhill to the foot of the slope.
1. Hold the vehicle stationary using both foot
and hand brakes.
2. Restart the engine if necessary.
3. Engage reverse gear LOW range (‘R’ for
automatic transmission).
4. Select hill descent control (HDC).
5. Release the handbrake. Then release the
foot brake and clutch (where applicable)
simultaneously, and allow the vehicle to
reverse down the slope using engine
braking and HDC to control the rate of
descent.
6. Unless it is necessary to stop the vehicle
to negotiate obstructions, DO NOT apply
the brake or clutch pedal during the
descent - even a light application may
cause the front wheels to lock, rendering
the steering ineffective.
7. If the vehicle begins to slide, accelerate
slightly to allow the tyres to regain grip.
When the vehicle is back on level ground or
where traction can be regained, a faster
approach will probably enable the hill to be
climbed. However, DO NOT take unnecessary
risks, if the hill is too difficult to climb, find an
alternative route."

Originally Posted by diesel

...then came down completely out of control! Backwards I will add...
...Descending backwards the front wheels lock & away she goes, no control at all. Very dangerous...

Has anyone experienced this?

I for one have experienced exactly this, and as Slunnie says, is why I and many others fit aftermarket Centre Diff Lock actuators. I have gone for the Ashcroft cable system. In this reply I'm assuming you have the CDL actuator in the transfer case...

It's important to understand WHY this happens, and why the CDL fixes it. When reversing down the hill without CDL, the much stronger front brakes combined with the lessened weight on the front wheels allow them to lock solid, thereby losing all steering and the majority of your braking. As there is no CDL, the rear wheels can continue to turn, and rotate the rear drive shaft into the transfer case, where that rotation is lost into the unlocked centre diff. However, when you engage the CDL, the rear wheel rotation into the transfer case is forced to the front drive shaft and the front wheels overriding the weak lock on them, and maintaining your braking and steering. The difference is night and day. With the CDL, you would (probably) have easily out performed the Prado...

TL;DR: Buy a CDL kit, it'll fix it

Umm 1 st rule of off roading never ever brake going down ( forward or backward ) a steep hill off road

Why well I think you have sort of found out why. The front / rear ( which ever is the highest ) will lock up and the chance of the car sliding sidewards are massive and then you will roll

You should be doing it as Stallie says

Ali

EBD does work in reverse BUT it doesn't work below a deceleration rate of 0.3g. If you have no traction that isn't going to happen.

Slunnie is on the money re HDC. Reverse has a lower target speed (5.6kmh) than the forward gears (7.0kmh). Still not ideal but will give you more control once it kicks in.

The other alternative to HDC is a technique called "driving through the brakes". FWDVic training courses teach this as the correct method, and it is taught in LROCV introductory 4x4 course. What you do is put the vehicle in low range reverse and gently easy off the brakes until the car starts creaking but not actually moving. Once you reach this point you keep the same pressure on the brake pedal. To descend you use the accelerator to overcome the brakes. As soon as you lift off the vehicle should come to a stop. It feels a bit weird and takes some practice but it does allow a very controlled descent. Same technique works for steep forward descents.

The pick of the aftermarket CDL levers is the one made by .50. His modified stock lever is about as close as you can get to the factory item, and is a big improvement over the Ashcroft style levers due to the fact it retains the sealed back. The Ashcroft levers (and copies) have an open back and rely on a rubber boot (which they have only recently begun supplying) to provide sealing from the elements. I initially had a copy of the Ashcroft installed and wasn't really happy with the increase in noise levels in the car, so changed over to a .50 lever which resulted in a noticeable decrease in noise levels. Given that they are both around the same price it's a no-brainer.

www.discovery2.co.uk / D2 CDL levers..... THE BEST!!

cheers
Paul

x2^^
Another method of retarding the descent is to apply the handbrake just a couple of notches, then the normal hill descent procedure as described very well above.
Just remember to fully release the handbrake once descent is completed.

Originally Posted by Reads90

Umm 1 st rule of off roading never ever brake going down ( forward or backward ) a steep hill off road

Remind me not to get into a four wheel drive with you...

the 3 golden rules of fourwheel driving are

1. Do I NEED to do this?
2. Is my vehicle capable of doing this?
3. Am I capable of doing this?

any No means you dont try it.

lets put it this way......

how would you handle the situation if you had become accustomed to the electronics taking care of it all for you and then one day while on the track you suffered a complete 3 amigos?

When I'm teaching people with electronics the first thing I try to instill is "The electronics are merely a warning system that indicate you are approaching the limit of either the drivers or the vehicles capabilities."