drivetrain question - Land Rovers Only

wimp · 11-03-2007, 06:04 AM

I have a Disco II with CDL....

when the CDL is NOT engaged, do I simply have 3 traditional open differentials? If so, I would assume I have ONE wheel drive. The drive wheel can be any of the four.

On the other hand, I thought that the Disco II was All Wheel Drive, meaning that I had open front and rear diffs.... and ,... a viscous coupler in the trasfer case, similar to an audi or subaru. Is this the case? This would mean that the CDL isn't doing much on snowy roads that the viscous coupler isn;t already doing.

A little confused, someone please clear this up for me?
thanks

Disco Mike · 11-03-2007, 07:03 AM

The terminology is questionable. You do not have all wheel drive, but because of the ETC you can technicaly have power to any wheel as needed thru the ABS.
Normally, you get power to the right rear and the left front with the ability of having the ETC move that power to the opposite wheels during wheel spin.
Lock your CDL and you have all the power split between the front and rear axles. Now you start feeling the extra power and still have the ETC to shift power from the left to the right whell but back and forth as when the CDL is disengaged.
As for the use of the CDL on snow, it if far better then just the ETC alone.
Mike

KDamericano · 11-04-2007, 10:11 AM

Yeah, what mike said. ETC is like an electronic limited-slip. Some manufacturers claim they work better, though I might disagree. I think they're just cheaper. If you think about it, you're using components that are already there (ABS, Wheel speed sensors, etc), and with a little computer programming - boom - you got traction control. The rover system is pretty good though, fortunately. I've driven my brothers VW that has ETC, and while it's better than nothing, it's not much better.

wimp · 11-05-2007, 06:48 AM

ok still confused....

without cdl engaged, and without traction control, do I have three open diffs?
will this alone be a one wheel drive system? If not, what mechanism allows power to go to two separate wheels at the same time (aside from traction control and CDL)
We are not talking about any viscous-type coupler here are we?

thanks in advance

Disco Mike · 11-05-2007, 06:55 AM

Yes, you have 3 open diffs.
The ABS system of the brakes by signals from the ECU control where the power should go based on signals from the 4 wheel speed sensors.
Mike

wimp · 11-05-2007, 07:01 AM

so are you saying that the disco 1 has no ability to spin two wheels simultaneously when the cdl is disengaged? seems odd that the discos are not all wheel drive except for the application of TC (which in my humble opinion is pretty damn horrible on snowy roads; its pretty good in the mud and when climbing a loose hill).
hmmm

ealex · 11-05-2007, 08:45 AM

It can spin as many wheels as you want it too. All wheel drive is also characterized by having no low range. When the CDL is disengaged, your LR has 3 open diffs. When engaged, you have 2 open diffs. Wheel spin is managed by the TC to simulate having limited slip diffs. Viscous couplers are nice, but they do wear out and do not deal well with lots of torque (why subarus have no low range). The "one wheel drive" is not a good term for 3 open diffs. You spin all four wheels when all four wheels have traction. When any one wheel loses traction its slip is limited by ETC, and you retain power going to all four wheels. When you lock the CDL, there is less "lag" in catching the wheel spin by ETC because you are guaranteed that power will be split 50/50 front and rear.

hevkev · 11-10-2007, 07:02 AM

Quote:

Originally Posted by wimp

I have a Disco II with CDL....

when the CDL is NOT engaged, do I simply have 3 traditional open differentials? If so, I would assume I have ONE wheel drive. The drive wheel can be any of the four.

On the other hand, I thought that the Disco II was All Wheel Drive, meaning that I had open front and rear diffs.... and ,... a viscous coupler in the trasfer case, similar to an audi or subaru. Is this the case? This would mean that the CDL isn't doing much on snowy roads that the viscous coupler isn;t already doing.

A little confused, someone please clear this up for me?
thanks

In the spirit of keep with the correct terminology, it's not "All Wheel Drive" but rather "Permanent Four Wheel Drive", mechanically, there is difference.

11-03-2007, 06:04 AM	#1 (permalink)
wimp '99 Disco II Join Date: Oct 2006 Location: Rhode Island Posts: 338 Gallery: 0	drivetrain question I have a Disco II with CDL.... when the CDL is NOT engaged, do I simply have 3 traditional open differentials? If so, I would assume I have ONE wheel drive. The drive wheel can be any of the four. On the other hand, I thought that the Disco II was All Wheel Drive, meaning that I had open front and rear diffs.... and ,... a viscous coupler in the trasfer case, similar to an audi or subaru. Is this the case? This would mean that the CDL isn't doing much on snowy roads that the viscous coupler isn;t already doing. A little confused, someone please clear this up for me? thanks __________________ '99 Disco II ACE / 2" OME lift 245 75 R16 Greatyear MT/R's

11-05-2007, 06:48 AM	#4 (permalink)
wimp '99 Disco II Join Date: Oct 2006 Location: Rhode Island Posts: 338 Gallery: 0	ok still confused.... without cdl engaged, and without traction control, do I have three open diffs? will this alone be a one wheel drive system? If not, what mechanism allows power to go to two separate wheels at the same time (aside from traction control and CDL) We are not talking about any viscous-type coupler here are we? thanks in advance __________________ '99 Disco II ACE / 2" OME lift 245 75 R16 Greatyear MT/R's

11-05-2007, 07:01 AM	#6 (permalink)
wimp '99 Disco II Join Date: Oct 2006 Location: Rhode Island Posts: 338 Gallery: 0	so are you saying that the disco 1 has no ability to spin two wheels simultaneously when the cdl is disengaged? seems odd that the discos are not all wheel drive except for the application of TC (which in my humble opinion is pretty damn horrible on snowy roads; its pretty good in the mud and when climbing a loose hill). hmmm __________________ '99 Disco II ACE / 2" OME lift 245 75 R16 Greatyear MT/R's

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11-03-2007, 07:03 AM	#2 (permalink)
Disco Mike Moderator Join Date: Aug 2004 Location: Parker, Colorado Posts: 5,771 Gallery: 0	The terminology is questionable. You do not have all wheel drive, but because of the ETC you can technicaly have power to any wheel as needed thru the ABS. Normally, you get power to the right rear and the left front with the ability of having the ETC move that power to the opposite wheels during wheel spin. Lock your CDL and you have all the power split between the front and rear axles. Now you start feeling the extra power and still have the ETC to shift power from the left to the right whell but back and forth as when the CDL is disengaged. As for the use of the CDL on snow, it if far better then just the ETC alone. Mike

11-04-2007, 10:11 AM	#3 (permalink)
KDamericano Senior Member Join Date: Oct 2006 Location: Denver Posts: 179 Gallery: 0	Yeah, what mike said. ETC is like an electronic limited-slip. Some manufacturers claim they work better, though I might disagree. I think they're just cheaper. If you think about it, you're using components that are already there (ABS, Wheel speed sensors, etc), and with a little computer programming - boom - you got traction control. The rover system is pretty good though, fortunately. I've driven my brothers VW that has ETC, and while it's better than nothing, it's not much better.

11-05-2007, 06:55 AM	#5 (permalink)
Disco Mike Moderator Join Date: Aug 2004 Location: Parker, Colorado Posts: 5,771 Gallery: 0	Yes, you have 3 open diffs. The ABS system of the brakes by signals from the ECU control where the power should go based on signals from the 4 wheel speed sensors. Mike

11-05-2007, 08:45 AM	#7 (permalink)
ealex Member Join Date: Jan 2007 Location: Colorado Springs, CO Posts: 55 Gallery: 0	It can spin as many wheels as you want it too. All wheel drive is also characterized by having no low range. When the CDL is disengaged, your LR has 3 open diffs. When engaged, you have 2 open diffs. Wheel spin is managed by the TC to simulate having limited slip diffs. Viscous couplers are nice, but they do wear out and do not deal well with lots of torque (why subarus have no low range). The "one wheel drive" is not a good term for 3 open diffs. You spin all four wheels when all four wheels have traction. When any one wheel loses traction its slip is limited by ETC, and you retain power going to all four wheels. When you lock the CDL, there is less "lag" in catching the wheel spin by ETC because you are guaranteed that power will be split 50/50 front and rear.

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