What's all the fuss about CDL button?

[clivehorridge]

"I also dont see that by locking the CD the steering would be overly affected.

Locking the front axle diff - yes, it's a nightmare to steer admittedly, and should be used with extreme caution, but I've done a lot of loose-grip off road kms with the CD locked and I've never noticed the steering become difficult. It's different, agreed and maybe a little heavier, but it's never indicated to me that it might do anything like push me straight on at a bend."

Agreed. sometimes i reckon the theory doesnt allways pan out in practice.

Maybe it's more likely the UK didn't get the CDL switch as a result of a risk assessment, on the assumption that any complaints would have cost Toyota a fortune in the event of a recall mod in such a mass market.

 

[Julian T]

My UK spec 80 has a cdl button as standard, and I have had no issues cornering in high range with the center diff locked, slightly heavier steering at times but never had the feeling she would plough straight on in a corner, locking the rear diff does introduce a degree of stiffness to her willingness to corner, but lock the front diff and it is a whole new ball game! steer? why would you want to do that, we are going straight seems to be what Thirsty's reply is to steering inputs.
Locking the center diff improves stability/handling when the road is slippery.

 

[chapel gate]

My gfs 96 rav had a dash cdl. So does her 2010 rav..

 

[clivehorridge]

My UK spec 80 has a cdl button as standard, and I have had no issues cornering in high range with the center diff locked, slightly heavier steering at times but never had the feeling she would plough straight on in a corner, locking the rear diff does introduce a degree of stiffness to her willingness to corner, but lock the front diff and it is a whole new ball game! steer? why would you want to do that, we are going straight seems to be what Thirsty's reply is to steering inputs.
Locking the center diff improves stability/handling when the road is slippery.

I concur, sounds like mine behaves.

I came off the bottom of a ski slope recently, and to traverse a muddy ditch I threw all the lockers, just in case. After emerging safely, I shut them all off and proceeded across the level grass to the asphalt road. There I steered it left on the asphalt, but, oh no I didnt! For some reason the front locker had stuck on momentarily. I couldn't even turn the steering wheel on asphalt.

Eventually it released and all was well. Front lockers should be used with great care.

 

[Dave2000]

These topics always throw up different opinions which is great but one thing everyone has to agree with (unless you just like to argue) is you cannot overturn the laws of physics. I 'exercise' my diff locks as soon as I am near a deserted beech (so most weeks outside of July and August and do the same thing every time.

Full circle, then centre diff full 360 circle (bigger circle), then rear diff even bigger circle, and finally front diff and a huge circle and muscle strain. The CDL when engaged WILL give a bigger turning circle as per Franks comments, the traction provided by the rear tyre pushing straight on will overpower the turning front wheels but there is a caveat at work here.

The word to look for is TRACTION, you should not have your CDL locked on high traction surfaces, if you drive fast enough into a corner and turn the steering wheel there is a possibility of losing traction but the speed would be quite high for this to happen, or the surface very slippery. The ideal situation would be ALL four wheels pulling (or pushing) in the direction you wish to go, with the CDL engaged the front AXLE is not allowed to distribute the power to where it wants to, i.e. the front wants to cover a wider arc than the rear, the CDL will defeat this and hence place a greater load on the tyres.

This is pure physics, but of course we can always find a reason to debate FACT!

regards

Dave

 

[clivehorridge]

These topics always throw up different opinions which is great but one thing everyone has to agree with (unless you just like to argue) is you cannot overturn the laws of physics. I 'exercise' my diff locks as soon as I am near a deserted beech (so most weeks outside of July and August and do the same thing every time.

Full circle, then centre diff full 360 circle (bigger circle), then rear diff even bigger circle, and finally front diff and a huge circle and muscle strain. The CDL when engaged WILL give a bigger turning circle as per Franks comments, the traction provided by the rear tyre pushing straight on will overpower the turning front wheels but there is a caveat at work here.

The word to look for is TRACTION, you should not have your CDL locked on high traction surfaces, if you drive fast enough into a corner and turn the steering wheel there is a possibility of losing traction but the speed would be quite high for this to happen, or the surface very slippery. The ideal situation would be ALL four wheels pulling (or pushing) in the direction you wish to go, with the CDL engaged the front AXLE is not allowed to distribute the power to where it wants to, i.e. the front wants to cover a wider arc than the rear, the CDL will defeat this and hence place a greater load on the tyres.

This is pure physics, but of course we can always find a reason to debate FACT!

regards

Dave

Can't disagree with any of that Dave.

Truth is or fact as you rightly call it, I've never used CDL on dry asphalt or concrete. (Except when I broke a front cv and used CDL to help limp me home!).

Using CDL off road, on wet or loose dry surfaces, I've not felt excessive effects on the steering, only because there's sufficient 'slip' in traction to prevent the differences in front and rear turning circle having too much effect. Slight heaviness is all I could report. Admittedly, when the rear locker is engaged, then turns are understandably more drastically affected.

I don't go to the beach too often (it's almost 300km away) but I do engage all the lockers at the least once a week.

As I said, all the points in your post tie in with my observations in the field, so to speak.

 

[Towpack]

The steering won't be affected by a locked CD on the road as the transmission 'wind up' this creates is between the F and R axles, not between the L and R front wheels which are still free to turn at different speeds. JMO

 

[Dave2000]

The steering won't be affected by a locked CD on the road as the transmission 'wind up' this creates is between the F and R axles, not between the L and R front wheels which are still free to turn at different speeds. JMO

I think the confusion here TP is if we replace the word 'steering' with 'direction', we could say the direction of vehicle is altered when turning with the CD locked. Does that make it sound more feasible?

regards

Dave

 

[frank rabbets]

Clive you are right about the torque. I was thinking of the 4WD always being applied in low range to stop transmission damage. There I was back in the 60's again when the Land Rovers had rear wheel drive only in high range (unless you pushed a yellow knob down which locked the prop shafts together [no middle diff]) but only 4wd in low range. Then the Range Rover permanent 4x4 came out but I don't think it had a middle diff lock and certainly not front and rear.

The rear axle takes a different line round a bend to the front axle and if the centre diff is locked the wind up between the prop shafts is not eliminated so this will affect the steering but not as bad as having one or both of the axles locked.

I wonder if the CDL switch was ditched if the car had a VC ?

 

[Dave2000]

I wonder if the CDL switch was ditched if the car had a VC ?

Good point Frank, all the CDL 'buttoned' apparently stock cars I have come across did not have the VC.

regards

Dave

 

[clivehorridge]

That would make sense Frank...

 

[chapel gate]

I fully understand, and im not denying the simple physics of all this, but as i said, in practice my car performs in the snow much better with the cdl engaged, be that cornering or driving in a straight line, for me this is a fact. When decending the hill in the picture, i have much more control and im able to reduce speed more by not having abs. For me this is a fact. So i either drive to what i know works, or drive by the laws of physics and theory. If id chosen the latter i would of wrote the cruiser off a long time ago...

Yes, i know were all driving by the laws of physics but you know what i mean

 

[Towpack]

I wonder if the CDL switch was ditched if the car had a VC ?

This sounds not only possible but probable IMO. The VC was fitted to vehicles with ABS from 1992 onwards. The VC was intended to provide superior performance in slippery on road conditions without the trans wind up problems of a locked diff so I guess Toyota's thoughts were that the ability to lock the diff in high range was neither necessary or desirable.

 

[chapel gate]

So why does the 100 series have a dash mounted cdl switch?

 

[Dave2000]

I fully understand, and im not denying the simple physics of all this, but as i said, in practice my car performs in the snow much better with the cdl engaged, be that cornering or driving in a straight line, for me this is a fact. When decending the hill in the picture, i have much more control and im able to reduce speed more by not having abs. For me this is a fact. So i either drive to what i know works, or drive by the laws of physics and theory. If id chosen the latter i would of wrote the cruiser off a long time ago...

The issue with ABS in deep snow is, if it is turned OFF or removed, you have more chance of building a 'wedge' of snow in front of locked tyres, in the same way gravel/shale builds up when off roading (is this why Toyota made the ABS switch off in LOW?), I can see in that circumstance the ABS would be at a disadvantage. if that had been sheet ice I would put my ABS equipped 80 up against yours in a straight up emergency stop though Mike, we all know how effective cadence braking is on slippery surfaces right?

regards

Dave

 

[frank rabbets]

Do the 100's with CDL switch have VC's.

Yes Dave I was sliding in my 1972 Range Rover straight towards the rear end of a Merc stopped at the lights. I was defo going to hit it. About 20 away I thought "nothing to loose" and hammered the brake pedal as fast as I could and stopped quite quickly. I had never tried it before !!

 

[Towpack]

I thought 100's had ATRAC instead of the diff locks and VC?

As for the ABS/no ABS debate I've deliberately tried mine on ice and snow covered roads and it worked perfectly as it should. I'll second Dave2000's comments in that I'd stack my LC against any non ABS equipped 80 on a slippery road. Saying you can "cadence brake" manually without ABS, well maybe, sometimes, but in a real emergency stop situation instinct takes over and you just hit the brake pedal with everything you've got, cue ABS. JMO

 

[chapel gate]

My fathers 2002 100 has cdl and rear dl.

Im not for a second suggesting a non abs cruiser will perform on a wet slippery surface, in a standing on the brakes situation as good as one with abs. On ice and snow i found it to be nigh on dangerous, taking that tiny bit of traction that can be sometimes found completely out of the situation.
I can only speak from my own experiences. As for the challenge, when the snow comes and ive changed to my winter rims ill gladly accept

 

[frank rabbets]

Towpack I had hit the brake pedal about 80ft before that stationary Merc knowing I was going much too fast to stop and seeing the ice polished all the way downhill to the Merc and through the lights. I was not slowing down at all but with 80 ft to go had plenty of time to think about it and decided to try the cadence and it worked. Yes if someone just pulled straight in your path you would just plant the brake pedal but on that occasion cadence saved me.

I wonder how many of our younger drivers (no forum members) have any feel for the difference in rear wheel drive, 4x4 and front wheel drive? These days with roads salted and in good condition, speed limits and safety built into the car I doubt it. I learned to drive on farm roads and soon appreciated that the rear wheels were driving lol. Main roads were gritted not salted. Minor roads were not attended to at all. Then I started driving the farm Land Rover with it's 4WD option. Then minis came out with front wheel drive. Happy days when you could really do what you liked.

 

[chapel gate]

There has been many a time when I have jumped in a strangers car. At there request. And got them unstuck by switching off all of the "snow aids"..