Front Axle Engagement

[EricBu12]

How does the new 09 AA axle engage the 4X4? My old 01 had the slider on the rear of the axle.



Had an opportunity to use 4x4 last week. . the engagement is much smoother than my old one.

 

[Scrappy]

the frontend is locked and turning all the time, it is the transfercase only that selects 2/4wd.

 

[rbattelle]

Scrappy is right - they eliminated the CAD system starting in 2003. Most people think this is awful, but I actually like it. The only difference between the 3rd gen and 2nd gen systems is that in the 3rd gen the front driveshaft is spinning all the time.

But I'm willing to trade the CAD part count for spinning the front driveshaft all the time.

Ryan

 

[Bob V]

Scrappy is right - they eliminated the CAD system starting in 2003. Most people think this is awful, but I actually like it. The only difference between the 3rd gen and 2nd gen systems is that in the 3rd gen the front driveshaft is spinning all the time.



But I'm willing to trade the CAD part count for spinning the front driveshaft all the time.



Ryan

Accually the CAD went away about Jan 2002 (Build date) and the 2nd gen where DANA and the 3rd gen are AA&M

 

[mickeyblueyes]

Along with about 2 miles per gallon

 

[mwilson]

Between the crap Diesel that you get now and the constantly turning front axle I bet the loss is closer to 4 mpg on a 4 X 4.

Mike.

 

[Regcabguy]

From what I'm reading,the Dynatrac conversion guys are only netting 1-1. 5 mpg over stock. Regardless,stopping all that rotational mass and unnecessary wear makes sense. They must have a lighter steering feel too. I remember on my Toyota and Ford F-250,if you had the hubs engaged it was a much heavier feeling. I do prefer this over my old CAD setup on the '98. 5. I get slightly better fuel economy than my '98. 5 also.

 

[Bob V]

My '97 and my '05 are almost identical mpg

 

[rbattelle]

My '97 and my '05 are almost identical mpg

In terms of drivetrains, the only difference between the two is the front driveshaft is always spinning on the '05. Both trucks spin the entire front axle assembly constantly.



I've never really understood all the outrage at the 3rd gen setup versus the 2nd gen setup when they really differ only by the front driveshaft rotation.



Ryan

 

[Rams-n-Hogs]

My '97 and my '05 are almost identical mpg

My '96 and '04 were, too, until I started getting wild.

 

[brods]

In terms of drivetrains, the only difference between the two is the front driveshaft is always spinning on the '05. Both trucks spin the entire front axle assembly constantly.



I've never really understood all the outrage at the 3rd gen setup versus the 2nd gen setup when they really differ only by the front driveshaft rotation.



Ryan

It is not just the driveshaft that doesn't turn, the ring and pinion and their bearings do not turn either. Prior to getting locking hubs I measured the temperature of the front differential at the pinion bearing on my 05. After a long trip it was 143 degrees F. This shows there is friction and drag even when not using 4x4. Now keep in mind that while driving the gear oil and the entire axle housing in the air flowing under the vehicle will dissipate heat, yet the outside of the pumpkin was still 143F at the pinion bearing! So the there is more energy wasted and needless wear on more components than with the CAD system.

 

[Regcabguy]

When I changed diff. oil at 9200 miles my rear oil stunk to high heaven and was black as our engine oil. Conversely,the front was like honey. I'd love one of these kits,but it's going to have to wait for awhile. Probably income tax time.

 

[rscurtis]

rbatelle, you're almost correct on that. On the second generation, when the front axle is disengaged, all that is rotating is the differential gears, not the ring and pinion. The driver's side axle is turning forward, the passenger side axle is turning backwards, and the passenger side stub shaft is turning forward. This is why Gen 2's have a synchronized transfer case- to bring everything up to speed before the right side axle clutch is engaged. The ring and pinion may turn slowly due to differential drag, but it is nowhere near the engaged speed.

 

[steved]

The main issue with the early 3rd gen was the harmonic resonations that caused the dreaded "70 mph vibrations"... that was the reason I bought the DT kit.

 

[steved]

When I changed diff. oil at 9200 miles my rear oil stunk to high heaven and was black as our engine oil. Conversely,the front was like honey. I'd love one of these kits,but it's going to have to wait for awhile. Probably income tax time.

The difference was probably one is open and one is a LSD?? The black was clutch material...

 

[rbattelle]

You guys are right, I neglected the ring and pinion are also not rotating on the 2nd gen trucks. Duh.

Ryan

 

[Scrappy]

The difference was probably one is open and one is a LSD?? The black was clutch material...

nope, no clutches in a 3rd gen LSD, They are gear type. it was black because it spent its whole life under the load of moving the truck and whatever else. The front was just freewheeling.

 

[steved]

nope, no clutches in a 3rd gen LSD, They are gear type. it was black because it spent its whole life under the load of moving the truck and whatever else. The front was just freewheeling.

Ummm, better go look at a 3rd gen FSM, and specifically the exploded view of an AAM LSD. They do indeed have clutches, they are termed "shoes".



And they wear just like any other clutch.

 

[Scrappy]

got a link?

 

[steved]

Look in any 3rd gen Factory Service Manual...