# please educate me about the REAR locking differential coming on my Touareg



## spalding12 (Oct 27, 2003)

i don't mean to be a 4WD moron...
but please tell me the benefits of the REAR locking diff on my V8 (almost here)
as opposed to the standard center locking differential
i know that the smart folks here can help me understand better
i did order that option
and i'm glad i did
but... please remind me again WHY i should be glad about that
thanks so much in advance
greg


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## NYCARAUDIO (Jul 24, 2003)

*Re: please educate me about the REAR locking differential coming on my Touareg (spalding12)*

greg I can see you live in florida so you may never ever need to use that rear locking diff but I'll give you an idea of what it does. It enables your car to send up to 100% of power to one wheel if traction is lost on the other three. This is mostly for those off roaders out there like myself. Hey maybe you'll be in the 1% of people out there to take a 50k dollar truck off road.


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## spockcat (Jun 5, 2003)

*Re: please educate me about the REAR locking differential coming on my Touareg (NYCARAUDIO)*

Offroaders - Whitestone, NY? Isn't this next to the Whitestone Bridge? The only offraoding I've seen there is when they dump the bodies in to the bay.


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## spalding12 (Oct 27, 2003)

*Re: please educate me about the REAR locking differential coming on my Touareg (spockcat)*

well
i hope to go off road with this vehicle
so many friends with ATV's and 4wheelers
they like to make fun of me
i'm going to show them
LOL
greg
thanks spockcat, as always for enlightening me
greg


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## pantelisg (Oct 22, 2003)

*Re: please educate me about the REAR locking differential coming on my Touareg (spalding12)*

Greg Hi,
A locking diff generates equally the drive and torque transmited from the engine to either one of the axles or between the two wheels of an axle.
A 100% locking diff will transmit one revolution on the spinning (non tractive) wheel or axle and one revolution to the wheel or axle with traction.
An 80% locking diff wil transmit one revolution on the spinning wheel and 0.8 of a revolution to the tractive wheel.
If a locking diff is located at the center diff of the car then it distributes the drive and torque equally between the two axles.
If a lockind diff is located in an axle (as per your case) then it distributes the drive and torque equally between the two wheels.
So if you end up with your rear axle in a position where one of the two wheels start spinning and the electronic traction control gets confused you can still push the button and lock your rear diff.
If you do so you will be able to provide drive to the wheel of the rear axle that still has contact and traction on the ground and be able to push your Touareg out of trouble.
Before everybody jumps on me I will have to say that the above explanation of how a locking diff words is based on fully mechanical diff assemblies.
Viscous, multiclutch and electronic biasing differentials work on similar principles but are not as simple.
It is a wise choice to order your Touareg with the locking rear diff even if you never end up using it. It is good that it is there and in any case the money that VW charges for it as a factory option is less than that of the cost to install an aftermarket one (if it ever becomes available).
You may find it useful if you run into difficulties in sand, snow, mud or very slippery road condition or become crossaxled.
Just remember though that you must be gently on your throttle when you use it so as to avoid potential damage on the halfshafts and remember to unlock it when you drive on tarmac, especially dry one.
Take care
Pantelis
P.S. when the Touareg was first introduced to the media it was supposed to be offered with a front lockind diff also (as an option)


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## spalding12 (Oct 27, 2003)

*Re: please educate me about the REAR locking differential coming on my Touareg (pantelisg)*

Pantelis,
fantastic description
i really appreciate you taking the time to tell me about all of that
i'm feeling more educated all the time
thanks again
greg


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## pantelisg (Oct 22, 2003)

*Re: please educate me about the REAR locking differential coming on my Touareg (spalding12)*

Greg Hi,
glad to be of assistance.
Just wait 'til I get my Touareg.
They I will be the one to start asking questions.
Take care
Pantelis


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## Ted K (Jul 11, 2003)

*Re: please educate me about the REAR locking differential coming on my Touareg (NYCARAUDIO)*


_Quote, originally posted by *NYCARAUDIO* »_greg I can see you live in florida so you may never ever need to use that rear locking diff but I'll give you an idea of what it does. It enables your car to send up to 100% of power to one wheel if traction is lost on the other three. This is mostly for those off roaders out there like myself. Hey maybe you'll be in the 1% of people out there to take a 50k dollar truck off road.









Actually, I believe that's the exact opposite of what it means. 4XMotion, which is basically a version of Audi's Quattro, has EDLs, or Electronic differential locks. With EDLs, the computer can send up to 100% of the power automatically to any one wheel. However, the Treg has a standard center differential lock which is on the center console. By locking it, you force the truck to split it's power 50/50 between the front and the rear. This is useful when towing, going up hill, or in deep snow and moderate off roading when you don't want the computer to have to decide. Then, as an option, you can purchase a rear differential lock. This overides the EDLs and ensures that the power going to the rear is split evenly between the rear wheels. This is useful when doing very heavy off roading where hesitation for that split second while the computer shifts power could cause problems climbing. Unless you are planning on doing off roading in a major way, you'll never need to engage it.


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## DukeUsul (Jun 20, 2003)

*Re: please educate me about the REAR locking differential coming on my Touareg (Ted K)*

I thought what Ted K said. Here's what I have been reading on HowStuffWorks.com to educate myself on differentials and 4WD/AWD.
http://auto.howstuffworks.com/differential.htm
http://auto.howstuffworks.com/four-wheel-drive.htm
"The locking differential is useful for serious off-road vehicles. This type of differential has the same parts as an open differential, but adds an electric, pneumatic or hydraulic mechanism to lock the two output pinions together. This mechanism is usually activated manually by switch, and when activated, both wheels will spin at the same speed. If one wheel ends up off the ground, the other wheel won't know or care. Both wheels will continue to spin at the same speed as if nothing had changed."
Your T-Reg has differentials on both axles and one between the axles. If these were just open differentials, then when one wheel starts slipping if it loses all traction, then 100% of the torque gets applied to the spinning wheel. The wheel that has traction stops doing any useful work. This is the problem with open differentials. This is why we have things like limited-slip, viscous coupled, Toresen, and manually locking differentials. The purposes of these techniques is so that when one wheel loses all traction, torque is transferred (via a clutch plate in a viscous fluid, or perhaps by an Electronic Differential Lock) so that the torque is *not* sent to the slipping wheel, but it's sent to the wheel that has traction.
Our T-Reg's have this kind of mechanism. When one wheel slips, torque is transferred to the non-slipping wheels. Someone pointed out that on the T-Reg this is done using EDLs. Now on top of that, your center diff is manually locking and optionally so is your rear differential. This means that on command you can lock that differential so that torque is split 50/50 to each side. We can all do this front/back with the center diff, but you've got the option to do this on your rear axle as well.


_Modified by DukeUsul at 1:25 PM 11-2-2003_


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## MichaelW (Jun 22, 2002)

*Re: please educate me about the REAR locking differential coming on my Touareg (Ted K)*

EDL is a brake actuated traction control, ASR is power reduction.
The center differential splits power 50/50 and so does the diff in each axle. And with the weight distribution close to 50/50, you are starting off really good.
Now VW has added a clutch pack on the center differential for torque biasing duty. VW tries to keep the clutch pack locked up as much as possible, say flooring it at a stop light. In this regard it is similar to the Audi torsen quattro system.
So if you were going off road, the center diff and clutch would (un)evenly distribute power front and rear. Now you can get in trouble when you spin one wheel on the front and one on the rear. This would be checked by the brake actuated traction control, so power would go to both sides of an axle.
If you have the opt. rear (and maybe front) diff. lock. and it was engaged. power would go to any wheel that had traction (this requires skill and experience, as you can break this if not careful)


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## mmmmm127 (Oct 22, 2003)

Theory aside...
If I find myself in deep snow, minus 40 outside, an I sense that a wheel is spinning, any wheel front or back, who knows which ( it's 40 below) do i turn on (activate) my rear locking differential
TIA


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## mmmmm127 (Oct 22, 2003)

just as I thought !


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## DWPC (Aug 19, 2003)

*Some clarification*

All the discussions of 50/50 splitting power, etc. may get overly technical. Here's a simple explanation. A differential, by definition, allows wheels on a single axle to rotate at different speeds; necessary to get around turns. The problem is that if one wheel slips, the differential just sees that as different speeds (like going around a corner), and allows the driveshaft to transmit power to one wheel; the one thats slipping. A locking diff mechanically locks both sides together so they _must_ turn with the driveshaft. A limited-slip diff uses a clutch arrangement to "lock" the diff, but most release at low power and are as not effective as a fully locking diff. 
The locking diff on Treg is great for offroad and hauling trailers in poor traction, and some snow/ice conditions that can "fool" the electronics. It should not be engaged on firm, dry pavement since, with the wheels unable to turn at different rates, the vehicle "wants" to go straight and steering can become difficult. And its really rough on tires. A bargain at $500 or so on the Treg.


_Modified by DWPC at 8:16 PM 11-3-2003_


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## DURAMAX OWNER (Aug 11, 2003)

*Re: Some clarification (DWPC)*

My Chevy pickup has an Eaton locking differential that is fully mechanical. It works on the priniciple of locking when one wheel turns 1 1/2 to 2 turns more then the other non-slipping wheel. It really slams when it locks and transfers the torque to the wheel with traction after the other wheel is up to a pretty good speed. My brother-in-law thought he broke something when he was driving my truck with the 5th wheel trailer attached and stomped on it when the light changed after he stopped on a groved concrete road surface with a fair grade. The diesel has power enough to spin the wheels even with the trailer on the hitch and I learned to be careful. Forgot to tell him about it. I agree it feels like it could break something. I don't even want to try arguing warranty on this if something breaks.
I don't believe the Touareg would have this problem as you would not normally have it in locking mode in this kind of situation. I would be interested to hear if anyone has experienced a noticeable locking action on their Touareg. If both wheels are in dirt or snow it probably would not be as severe as on concrete.


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## freeheeler (Aug 8, 2003)

*Re: please educate me about the REAR locking differential coming on my Touareg (spalding12)*

Has anyone out there actually used their rear diff. lock and tested the difference between how the Treg responds between the center and rear locks?


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## MichaelW (Jun 22, 2002)

*Re: Some clarification (DURAMAX OWNER)*

The Eaton Gov-Lok is a 'part-time' locking differential.
The differential lock (rear) on the touareg is permanent lock, There is a bunch of stuff, ball ramps and cams in there.
The Gov-lok only works after there is a speed difference in wheels speed, VW no diff!


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## Outrageous (Jul 3, 2003)

*Re: please educate me about the REAR locking differential coming on my Touareg (spalding12)*

Be sure to activate your locking rear differential in high crime areas to help prevent theft!


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