2wd Low

[stick]

Has anyone looked at a 2wd low hookup for the 03 4x4 yet? I glanced under one the other day and it wasn't anything like the 2nd generations. I know they changed to American axels, but how does the front axel engage?



Stick

 

[David Muench]

Don't hold your breath for an easy solution like the 1994-2001. 5 2nd gens. The front axle is always turning on the 3rd gens (and 2002 2nd gens), so you can't put a switch in the vacuum line (there is no vacuum line). The solution will probably be a modified shift fork for the transfer case, which would require splitting the t-case open to install it.



Or installing manual lockout hubs, dunno how feasible that will be.

 

[stick]

Well, that ain't good!



Stick

 

[n7gxz]

Stick,



I don't think that there really will be a need for a 2-low feature on the 3rd gen's. The transfer case that is used has a simular shift pattern to the old NP203's with the addition of a 2-high. Shift pattern is 2-hi, 4-hi, 4-hi-lock, neutral, 4-low, 4-low-lock. So what that means is that you can run in 4-low on pavement and if you need even more then you can put it in the 4-low lock postion.



Kevin

 

[David Muench]

Are you sure? I hadn't heard anything about them being full time 4wd. If so, that's great!

 

[DIESELMAN]

Originally posted by n7gxz

Stick,

..... Shift pattern is 2-hi, 4-hi, 4-hi-lock, neutral, 4-low, 4-low-lock.....

 

[n7gxz]

Well guys according to the press release on the TDR home page under the specifactions section it list the shift pattern for the transfer case as I stated earlier. Here's the linkwww.turbodieselregister.com/prelease090102/5_SPECIFICATIONS.pdf



Kevin

 

[DIESELMAN]

Originally posted by n7gxz

Well guys according to the press release... .

Kevin

Read those comma's as AND... ... 2WD, 4WD high AND Locked, Neutral, 4WD Low AND Locked.



It's the same NV271/273 as before. There is NO diff between the front and rear axles, just a big chain and gears. There are no full time 4WD positions.

 

[n7gxz]

If that's the case the what is the lock postions for?



Kevin

 

[DIESELMAN]

Kevin -



Walk out to almost any 4WD NV Part Time gear set.



The lever has a primary operating position, 2H. This is not called lock, but it is. In this position, the transmission output is transmitted through the transfer case without any rotational translation, ie, 1:1, to the rear end drive shaft only.



Pull the lever back and a couple of things happen causing what is essentially a chain to connect a short 'stub' shaft to the front drive axle. This is a direct locked connection between the front and rear shafts, hence 4 High Locked;



Pull the lever further and a jack shaft disconnects from the rear output shaft, this is neutral.



Pull further, and on some, over then further, and a second jack shaft connects to the first, then a small spline engages the original shaft. The first changes rotation and reduces the gearing, usuall 2. 71:1, and the second reverses rotation again and transfers power to the chain and rear output shaft.



Again there is no differential, torque is split equally to the front and rear, hence 4WD Low AND Locked.



The problem is, when driving on hard surfaces, the front and rear wheels being slightly different diameters, rotate at different speeds. This causes 'binding' between the front and rear that must be released by slipping on the traction surface. This is why you can run 4WD only on soft surfaces.



This is why it is sometimes difficult to pull out of 4WD when you run off the dirt onto pavement before shifting to 2WD. This is more prevelent on heavy trucks like the CTD where the front may have twice the weight on it and the tires have a smaller diameter because of it.



In older 'Full Time" 4WD systems, the jackshaft and chain is interupted with a differential. Some manufacturers use a clutch pack, some used spider gears. This is like the old QuadraTrak which required a friction modifier because of the clutch pack.



On these, a position called Lock is available to essentially lock across the differential giving Part Time 4WD, the front and rear axles are locked together. If the rear axle turns, the front MUST turn too. In Full Time 4WD systems, the rear can break free after a certain amount of torque difference between the front and rear.



This is why your old Power Wagon needed both a Hub Set and chain / spool for the transfer case to convert to Part Time 4WD.



Other systems like the ford use a part time 4WD that engages when a difference in wheel speed, sensed by a 'tone' wheel on each axle, is detected. This can be caused by going up a hill with under inflated tires, even when the traction is good. Causing the Ford to go into and out of 4WD, or AWD as they call it.



The NV271/3 is a Part Time 4WD system, no clutch, no differential, always locked in any 4WD position. Selecting 4WD Low Locks the Front to the rear without any chance for an Unlocked position, and the lack of hubs or an axle disconnector means 4WD is 4WD, period.



The Spec reads, " 2 WD High; 4WD High, Locked; Neutral; 4WD Low, Locked;



These are 4 positions, there is no unlocked position, all are locked. This isn't a RamCharger.



If I had more time, I would explain further.



I hope I've explained correctly, my daddy always said, "Its better to keep your mouth shut and let all believe you are an idiot, than to speak up and remove all doudbt!"



Just havin' Fun!

 

[klenger]

Putting it briefly, if it's in 4WD, it's locked. Got it.

 

[DIESELMAN]

I thought that was brief.....



BTW,, I type at about 160WPM and log in twice a day to check my network, the preceeding long message was just a test, had this been an actual technical reference, I would have billed you... ... 3 minutes.

 

[Casey Balvert]

Originally posted by DIESELMAN

I thought that was brief.....



BTW,, I type at about 160WPM and log in twice a day to check my network, the preceeding long message was just a test, had this been an actual technical reference, I would have billed you... ... 3 minutes.

Dieselman, you are my HERO.



Cheers, Casey

 

[klenger]

It took me 20 minutes to type in my response. I'm not very fast, but I am expensive, so my time would have cost $80. 00.

 

[stick]

So- It sounds simple to me-- not 2wd Low!



Stick

 

[DIESELMAN]

Originally posted by klenger

It took me 20 minutes to type in my response. I'm not very fast, but I am expensive, so my time would have cost $80. 00.

But that three minutes is billed 1 Hour Minimum, $85. 00, consultation fee, $135. 00, First time customer fee $265. 00, follow up consultation fee, $85. 00, Accounting and collections, $65. 00.....



Somebody owes me ... ... $635. 00:--)

 

[d90boy]

The main reason you can't use 4wd on dry pavement is that when you turn corners the front and rear axles to not follow the same track and thus want to travel at different speeds. This causes bind or wind up between the front and rear so at times it's difficult to get out of 4wd. Its the same scenario as the axle differentials, 4wd in a NP241 is like having a spool, it's locked solid. It would be nice to have some kind of twin stick transfer box to get 2hi-low and 4hi-low.

 

[RJOL]

Here's one solution for those who what full time 4X4:



http://www.milemarker.com/catalog/4-x-2-accessories.html



Maybe someone on the TDR has used them and can provide some info???

 

[n7gxz]

Originally posted by DIESELMAN

The Spec reads, " 2 WD High; 4WD High, Locked; Neutral; 4WD Low, Locked;

Dieselman,



Yes I know how transfer cases works, I've been inside of 203's and 208's. I just had missed the semi-colon when I was reading the specs. I had read them as commas.



Kevin