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4x4 vs AWD and Explorer vs Mountaineer

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Old 01-17-2011, 11:17 AM   #1
Alan Lloys
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4x4 vs AWD and Explorer vs Mountaineer

Sorry to bring this up again.
I have read the all old threads and I feel pretty confident about my knowledge of the difference between an automatic 4x4 system (as used in the explorers) and an AWD system (often using a viscous coupling system as in gen 3 Mountaineers).

I had the gen 3 Mountaineer and know how the system worked. It was said to have about 35% torque on fronts and 65 % on rears in normal. When the rears slip and heat the viscous coupling they would lock and give 50%/50%.

I also understand the explorer automatic 4x4 system is giving approx. 5% front and 95% rears via an electric clutch. If rears slip, the clutch will engage in increments up to a full lock which gives 50%/50% torque spread. I even read through the patents on this.

Where my confusion comes up is that I believe the gen 4 Explorer and the Mountaineer is using the same system (minus the low range on Mountaineer). However Explorers are labeled as 4x4 while the Mountaineers are sold as AWD.
I know that the Mountaineer is no longer using a viscous coupling as I do not see a transfer case and I also have the option of locking 4x4 via the info center. This to me tells me that it is the electric version.

So I guess I have two possible explanations.
1) Ford is using the AWD description incorrectly on the Mountaineer as it is really automatic 4x4 (unless you call 5%/95% spread AWD) or
2) the Mountaineer is programmed differently to have a higher percentage of torque on the fronts before wheel slip is detected. (in ex. 35%/65%).

Anybody out there knows which it is (or if it is something completely different) ?

Again sorry for the long post. I just wanted to summarize everything I found out reading the old posts. However I did not find anything about how the same mechanical components can both be 4x4 and AWD dependent on which badge is on the vehicle.
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Old 01-17-2011, 01:00 PM   #2
paulyjsob
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I'd like to know more about this as well. I can feel a slight vibration in my steering wheel and a typical 4wd whining sound when accelerating around 2,000 RPM on my 07. It seems to apply more torque to the front at certain times..
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Old 01-17-2011, 08:45 PM   #3
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awd is 35/65% all the time.

and its staying all wheel drive, which in essence all wheels are drive wheels. the reason for the split is turning, nobody wants bind up on turns.

awd is not 50/50....
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Old 01-17-2011, 08:46 PM   #4
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Quote:
Originally Posted by paulyjsob View Post
I'd like to know more about this as well. I can feel a slight vibration in my steering wheel and a typical 4wd whining sound when accelerating around 2,000 RPM on my 07. It seems to apply more torque to the front at certain times..
how are your tires? do they match? same brand/type/size?

same tire wear? same air pressure in all?
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Old 01-17-2011, 09:03 PM   #5
paulyjsob
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I still have the original hankook tires. So I imagine equal wear. I have them rotated every 7000 miles.
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Old 01-18-2011, 06:24 AM   #6
Alan Lloys
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awd is 35/65% all the time.

and its staying all wheel drive, which in essence all wheels are drive wheels. the reason for the split is turning, nobody wants bind up on turns.

awd is not 50/50....
I think I understand what you are saying, but I also will politely disagree.
On the gen 3 with the viscous coupling it is in 35/65 mode when all wheels have grip. If the rear wheels slip the viscous coupling locks (that is the purpose of the viscous coupling) which will lock together front and rear driveshafts. With driveshafts locked the split will become 50/50.
This is a purely mechanical system. I actually had the viscous coupling fail in locked mode on my old Mountaineer which caused wheel skipping when making sharp turns.

My specific question is how the new systems work with the gen 4 explorer/mountaineer. Here the split is controlled by an electric clutch so one could program it for different settings. Specifically my question is if the Explorer is programmed at 5/95 and the Mountaineer at 35/65 (or something else).
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Old 01-18-2011, 12:33 PM   #7
thebrakeman
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Another possibility that you may not have considered:
Explorer auto-4x4 and Mountaineer AWD are identical for gen 4 vehicles (?).
That has been my assumption, and the only difference is:
1. Mountaineer has no low-range
2. Explorer has "hot-buttons" on the dash, while Mounty makes you go thru menus to lock front to rear.

I see no reason why they would have 2 different systems for otherwise identical powertrains (engine, transmission, axles?).

I've also heard that the systems could be different between V6 and V8 models. But then again, I would expect a V6 Explorer and V6 Mounty to be the same AWD/4x4 drivetrain. Yes, they could be different. But why have that level of complexity?




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Old 01-19-2011, 08:01 AM   #8
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Looking at the service manuals for '08 Mountaineers and Explorers, 3 systems are covered:

AWD - uses a mechanical center differential, not sure what vehicle gets this, perhaps a V6 Mounty?

1-Speed TOD (Torque on Demand) - this is what the V8 Mountaineer uses, even though it is labeled AWD, and

2-Speed TOD - this is what the Explorer uses.

The princples of operation for the 1 and 2speed TOD systems, essentially Control Trak, are virtually identical save the lack of a low range and separate controls to lock the clutch in the transfer case in the 1-speed system.

=Vic=
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Old 01-19-2011, 09:15 AM   #9
thebrakeman
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So, if I follow, in other words:
1. V6 Mounty AWD uses a viscous coupling to mechanically lock when spin is detected
2. V8 Mounty uses electic clutch system using data from wheelspeed sensors
3. V6 and V8 Explorers is same as V8 Mounty, plus a low range

Using these same 3 items, can somebody say what are the % torque splits under normal driving (no slip detected)?




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Old 01-19-2011, 09:27 AM   #10
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And if it's eletronic would it not be programable?
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Old 01-19-2011, 01:43 PM   #11
Alan Lloys
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Quote:
Originally Posted by thebrakeman View Post
So, if I follow, in other words:
1. V6 Mounty AWD uses a viscous coupling to mechanically lock when spin is detected
2. V8 Mounty uses electic clutch system using data from wheelspeed sensors
3. V6 and V8 Explorers is same as V8 Mounty, plus a low range

Using these same 3 items, can somebody say what are the % torque splits under normal driving (no slip detected)?
This makes sense and is kind of what I was thinking.
It makes sense that Ford are using the same parts for the two vehicles.
The discrepency then is why the single speed TOD for a Mountaineer is called AWD and the 2 speed TOD for an Explorer is called 4x4. I guess it is just a little artistic freedom from Ford as the Mountaineer has been AWD for a long time instead of 4x4.

But as Snowgoer asks, if it is electronic it should be possible to program the TOD system. So for instance in the Explorer it is 5/95 split while it is 35/65 in Mountaineer. It sounds like it should just be a little coding to make this difference.

Anybody else out there that would know if there is a difference in the programming between the two ?
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Old 01-19-2011, 05:42 PM   #12
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its mechanically controlled.

awd will do a 36/65 split 24/7

explorers is tod on auto / low / 4x4 high selectable. theres a motor on the tcase, to put it in the right gear.
mounty will not have a motor, it will just have a tcase, in any case, its 35/65 power split. never 50/50.

its an all wheel drive, does not mean its a 50/50 all wheel drive system, its a 35/65 split.
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Old 01-19-2011, 06:39 PM   #13
Alan Lloys
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its mechanically controlled.

awd will do a 36/65 split 24/7
A mechanical one with viscous coupling will be like this UNTIL wheels start slipping. Then the viscous coupling will lock front and rear axles together. Can we at least agree on that ? If front and rear are locked together they will get the same torque. I don't know if there are systems that do not lock when the liquid heats up. If so they would in fact function as you are describing.

Quote:
explorers is tod on auto / low / 4x4 high selectable. theres a motor on the tcase, to put it in the right gear.
mounty will not have a motor, it will just have a tcase, in any case, its 35/65 power split. never 50/50.
According to what Beargap is writing there is in fact a 1 speed TOD in the V8 Mountaineer. This is different than a mechanical AWD transfer case. I will tend to believe the repair manual.


Quote:
its an all wheel drive, does not mean its a 50/50 all wheel drive system, its a 35/65 split.
Anyway we need to make sure that we limit the discussion to gen 4 vehicles. The gen 3 had different mechanical systems for the Mounty versus the Explorer. As best I can find out for the V8 the only difference between the Mounty and the Explorer is the low range in the transfer case. AND possibly programming of the electronics. I guess that is what my questions was about, but it appears that no-one really knows.

I found a great video showing different AWD systems on a test bench here.
Sorry to interject Subaru commercial here, but regardless of their sales pitch I found it pretty interesting. This shows the issue with open differentials and the different AWD systems.
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Old 01-19-2011, 07:16 PM   #14
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A mechanical one with viscous coupling will be like this UNTIL wheels start slipping. Then the viscous coupling will lock front and rear axles together. Can we at least agree on that ? If front and rear are locked together they will get the same torque. I don't know if there are systems that do not lock when the liquid heats up. If so they would in fact function as you are describing.



According to what Beargap is writing there is in fact a 1 speed TOD in the V8 Mountaineer. This is different than a mechanical AWD transfer case. I will tend to believe the repair manual.




Anyway we need to make sure that we limit the discussion to gen 4 vehicles. The gen 3 had different mechanical systems for the Mounty versus the Explorer. As best I can find out for the V8 the only difference between the Mounty and the Explorer is the low range in the transfer case. AND possibly programming of the electronics. I guess that is what my questions was about, but it appears that no-one really knows.

I found a great video showing different AWD systems on a test bench here.
Sorry to interject Subaru commercial here, but regardless of their sales pitch I found it pretty interesting. This shows the issue with open differentials and the different AWD systems.
you have an all wheel drive vehicle, which means, on pavement dry road, you have a 35/65 power split, on sand, that does not change, on snow, its the same, in the air, its still 35/65 its all wheel drive. period.

4x4 is auto tod or torque on demand, or manually selected, those buttons 4x4 auto, 4x4 hi, 4x4 low.

the big difference is an awd vehicle will not have 4x4 bind up on turns, while a 4x4 will since it locks the front to rear, and all tires will have same speed wheel spin.

on awd not all tires will have same wheel spin, this is where vc come in to try let the wheels slip enough that you dont feel bind up but in certain situations you will since you bottom out the vc and they lock.

stop thining awd acts the same as 4x4 it dont.

as for the mounteneers that are awd with a 4x4 its 4x4 hi gear only or awd normal, what that means, is your in awd or you change gear in the tcase to 4x4 hi locking it. its sorta like an ex with only 2h and 4x4.... but your 2h is awd.

p.s 09 use a 40/60 split.

awd will be just a single tcase.

a 1 speed torque on demand will be auto or 4x4 hi
and 2 speed tod will be auto/hi/low.
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Old 01-20-2011, 06:39 AM   #15
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This makes sense and is kind of what I was thinking.
It makes sense that Ford are using the same parts for the two vehicles.
The discrepency then is why the single speed TOD for a Mountaineer is called AWD and the 2 speed TOD for an Explorer is called 4x4. I guess it is just a little artistic freedom from Ford as the Mountaineer has been AWD for a long time instead of 4x4.

But as Snowgoer asks, if it is electronic it should be possible to program the TOD system. So for instance in the Explorer it is 5/95 split while it is 35/65 in Mountaineer. It sounds like it should just be a little coding to make this difference.

Anybody else out there that would know if there is a difference in the programming between the two ?
I don't know, but I doubt the programming of the clutch-pack operation would be any different between the two. The system was designed by BorgWarner and was refined over a period of time to operate as smoothly as possible. Frankly, I knew more about the system as installed in Gen2 Explorers, but I think it is basically the same. The clutch-pack is engaging roughly 20 times per second and the duration of the engaged time varies from 4 or 5% in normal driving to fully locked (50/50) in the worst case. The system monitors relative drive shaft speeds and if the rear is going faster than the front, then the clutch pack engagement time is increased in 10% increments until the speeds are the same, then it ramps back down again. The change can occur in 1/3 of a wheel rotation, but can still be noticeable in certain situations like the rear being on ice. In either TOD system the driver can bypass the logic and lock the transfer case, although it is a bit more complicated in the Mountaineer.

=Vic=
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Old 01-20-2011, 07:04 AM   #16
Alan Lloys
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you have an all wheel drive vehicle, which means, on pavement dry road, you have a 35/65 power split, on sand, that does not change, on snow, its the same, in the air, its still 35/65 its all wheel drive. period.

4x4 is auto tod or torque on demand, or manually selected, those buttons 4x4 auto, 4x4 hi, 4x4 low.

the big difference is an awd vehicle will not have 4x4 bind up on turns, while a 4x4 will since it locks the front to rear, and all tires will have same speed wheel spin.

on awd not all tires will have same wheel spin, this is where vc come in to try let the wheels slip enough that you dont feel bind up but in certain situations you will since you bottom out the vc and they lock.

stop thining awd acts the same as 4x4 it dont.

as for the mounteneers that are awd with a 4x4 its 4x4 hi gear only or awd normal, what that means, is your in awd or you change gear in the tcase to 4x4 hi locking it. its sorta like an ex with only 2h and 4x4.... but your 2h is awd.

p.s 09 use a 40/60 split.

awd will be just a single tcase.

a 1 speed torque on demand will be auto or 4x4 hi
and 2 speed tod will be auto/hi/low.
So if the Mounty has AWD that always gives 35/65, then what does the AWD locked setting in the message center do ? Interestingly enough it illuminates a 4x4 light on the dash just to complete the confusion.

I am well versed on how AWD works. Bottom line is that I believe the gen 4 Mounty is labeled as AWD but really is a 4x4 TOD.
I looked up the replacement transfer case based on my VIN from a repair house and it is listed as a 4x4 single speed TOD.
Furthermore you can hear the front engage when the rears slip which again is not consistent with your description of an AWD. It is also not consistent with my experience on Gen 3 Mounty that is using the true AWD.

You seem very convinced in your posts here, but just because you say it three times does not necessarily make it right.

I will see if I can get any info from Ford on this as it seems I am not the only one with this question.

Based on my research now I can say for sure that the Mounty V8 has the single speed TOD transfer case. The only question left is if it is 5/95 like the Explorer or something else until wheel slip is detected.
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Old 01-20-2011, 03:54 PM   #17
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I disagree about a V8 Mounty being stuck at 35/65 no matter what. When my rear wheels slip in normal (unlocked) mode, I hear the rear spin for a fraction of a second, before I here and feel the torque transfer to the front wheels, and a lurch forward as more torque is transferred forward. If it were always 35/65, I wouldn't hear/feel such changes in behavior.

Also, if it were always in 35/65 split, with no transfer case, how do I have the ability to lock the axles? When I lock the axle together (thru the setup menu), the 4x4 light activates, and the user manuall warns me not to drive on dry pavement. This is 50/50, not 35/65.

A vehicle labeled "AWD" could be many things. There is no international standard by which Ford will be penalized if they use different labels for similar (or identical) powertrains. In this case, I think we have enough to backup that the V8 Ex and Mty have the same 4WD system, minus the low range.

Why the different name?
I believe it's simply because of the different target demographic. Not many Explorers actually go offroad, but even fewer percentage of Mountaineers go off road. If an Explorer shopper sees "AWD" he will think it's inferior, even if it's actually the same system.

Could also be for badging. If the V6 Mounty really is stuck in 35/65 AWD with a mechanical/viscous system, then it makes sense to use the AWD badge since this is typically what it means. But in order to keep the terminology (and the plastic letters on the hatch) the same, I guess they just stick with "AWD" for the V8, too.




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Old 01-20-2011, 05:01 PM   #18
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So if the Mounty has AWD that always gives 35/65, then what does the AWD locked setting in the message center do ? Interestingly enough it illuminates a 4x4 light on the dash just to complete the confusion.

I am well versed on how AWD works. Bottom line is that I believe the gen 4 Mounty is labeled as AWD but really is a 4x4 TOD.
I looked up the replacement transfer case based on my VIN from a repair house and it is listed as a 4x4 single speed TOD.
Furthermore you can hear the front engage when the rears slip which again is not consistent with your description of an AWD. It is also not consistent with my experience on Gen 3 Mounty that is using the true AWD.

You seem very convinced in your posts here, but just because you say it three times does not necessarily make it right.

I will see if I can get any info from Ford on this as it seems I am not the only one with this question.

Based on my research now I can say for sure that the Mounty V8 has the single speed TOD transfer case. The only question left is if it is 5/95 like the Explorer or something else until wheel slip is detected.
ok lets explain this better.

there are 2 awd systems used.

1 is full time awd, nothing in the message center. this is 40/60 split on all 08-10 cars, didnt look at 07 but guessing around 1/2 into mid 4th gen it switched.

there is also 1 locking awd, what this is, is similar to 4x4 but its torque on demand, so its 40/60 split, but it engages and releases the front diff. when needed when its overheated, it will lock to 4x4 this is the one that is located in the message center, you can eather lock it to 4x4 or keep it in awd, where it will engage/disengage the front for turning. this is the most uncommon one.

then you have the normal 4x4 system

the middle system is a on demand auto or 4x4 high since it will lock the diff.

the reason it is called an awd is there is no way to turn it off. you have constant 40 power to the front execpt on turn or locked to 4x4.
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Old 01-20-2011, 05:10 PM   #19
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Thebrakeman, you have it absolutely correct.
I wrote up a larger post that did not go through earlier today. I will post it here.

Waskly is also getting closer in his last post. Only difference is that the Mounty V8 AWD does not have the 40/60 split but is identical to the Explorer minus the low range. I also believe that his description of a mechanical AWD with viscous coupling is not fully correct.

It is all documented below:

OK, I think I have it all straightened out.
Apologies in advance for the long email, but I figured that others would like to know how these things work too.

First off I found an article from Ford here.

In excerpts:
"The V-6 Mercury Mountaineer uses a center differential that constantly splits torque 40 percent to the front wheels and 60 percent to the rear wheels"

So this clarifies that the Mounty V6 is using a viscous coupling style AWD system that is purely mechanical.

Under the "On Demand AWD" section it says:
"Ford Explorer and Expedition, the Lincoln Navigator and the V-8 Mercury Mountaineer — use a computer controller that monitors such things as steering angle, accelerator pedal position and engine speed to provide the precise amount of torque, front to rear, as needed."

This clarifies that these vehicles are all sharing the same system that is some times labeled as AWD or TOD 4x4 dependent on the vehicle. This system is primarily rear wheel drive (on these vechicles. Same system is used on front wheel drive vehicles). When the rears start to slip the electronics will detect it and gradually apply the electric clutch pack to give torque to the front wheels. Maximum torque is reached when the clutch is completely locked meaning that front and rear driveshafts are locked together.
The only difference between the Explorer 4x4 and the Mounty V8 AWD is the low range in the transfer case. All other components are identical.
There does not appear to be any programming differences between the Explorer and the Mounty. So I think the AWD designation on the V8 Mounty is a little misleading and was really just carried over from the previous years and to reduce confusion in comparison to the V6 Mounty.

Even Ford is confused as seen here in their 2010 line up. Here both Mounty and Explorer is listed as 4x4 - there is no mention of AWD.
And this post started with their internal engineer using the term On-Demand AWD with no mention of 4x4 for the explorer. So I guess they can't agree on what to call it either.

Now this only leaves the understanding on how these systems work:
The On-Demand AWD or automatic 4x4 on the Explorer and V8 Mounty will always have a small amount of torque to the front wheels. There is always a small amount of voltage applied to the electric clutch to ensure that the driveshaft is properly engaged and up to speed. This can be confirmed by people doing the brown wire modification with a lighted switch.
As rear wheels slip the electric clutch closes in increments until a full lock is achieved. There is a little disagreement on the terminology on this as some will call it 50/50 split and others up to 100% to front wheels. It is really the same thing. Imagine the rear wheels in the air and the front and rear drive shaft locked together. All the torque will go to the front as there is not traction on the rear. But the rears will turn in sync with the fronts as they are locked together.

Mechanical AWD as in the V6 Mounty and the gen 3 Mountys works differently. As mentioned I politely disagree with the statement from waskly.
Sorry to link to a GM forum here but post #3 has a nice description of the specific function of a viscous coupling. It can be found as a word doc also here.
There is also a good discussion from this very forum here.
In summary the mechanical AWD systems does not have a means of manually locking the front and rear drive shafts together. In normal operating conditions it will always have a split between front and rear shafts. Typically 35/65 or 40/60.
However when one shaft spins faster than the other, the liquid in the coupling will heat up and allow the clutch plates to move closer to each other. If the liquid heats up enough the clutch plates will lock. The GM instructions call this "hump mode". In this mode the front and rear drive shafts will be locked together and will have a 50/50 split (or up to 100% torque on whatever axle has traction).
This at least is the theory.

Once I understood this operation I can now understand why there are so many articles about AWD being undesireable for off-roading. In this mechanical system the clutch will lock together when the liquid heats up. However this lock will cause the liquid to cool down again freeing up the clutch - and if traction is still poor the wheels will slip again. So you can get a cyclic engagement of the clutch plates. This is why the instructions I showed specifies that being in "hump mode" too long can damage the viscous coupling.

So there we have it.
TOD AWD/4x4 system with low range for Explorer
TOD AWD/4x4 system with single speed for V8 Mounty
Traditional AWD mechanical system for V6 Mounty

This is what Beargap and Thebrakeman came up with also.
And now we know how the systems works too.

Last edited by Alan Lloys; 01-20-2011 at 05:22 PM.
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Old 01-20-2011, 05:50 PM   #20
waskly
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its 40/60 08 and up....

all the message center does, it lock it. where as it will not unlock when turning and you get bind up.

i would check 07 and down but im too lazy too actually load the wsm for it.
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