Service Manual - Does it contain AWD Transfer Case Design Details?

[Scott]

I have the free service manual available from a link on the internet. Apparently, all the chapters are not included. The 7000+ pages refer to the AWD, e.g. in routine maintenance, but not for repair.

Is there a chapter available to the public that has details on the AWD? If so, which chapter?

If yes, could someone capture the pages that explain how the transfer case works and a diagram?

My basic question: Does the transfer case have clutches to accommodate differences between the front and rear wheels; or is it like a differential with spider gears?

I need to buy the real manual, but was hoping for a quick answer. The online version of the manual is in PDF form. It is useful, but has a problem with searching: once a search is begun, Acrobat quickly demands all the system RAM, then you begin receiving prompts to increase the Paging File. I have one gig of ram and Acrobat consumes over 2.5gig of memory with no signs of stopping... but the computer sure gets slow shuttling memory to/from the hard drive.

Thanks in advance for any help.

Scott

[fnkychkn]

The MS140 is an all-wheel-drive transfer case system that divides power between the front and rear differentials and transmits power to both axles at all times. Its planetary center differential delivers approximately 62 percent of the engine torque to the rear axle and 38 percent to the front.


The transfer case name can be decoded as follows:

M = Magna
S = Steyr
1 = Single speed transfer case
4 = relative torque capacity
0 = Full time with an open differential

[DriveATransam]

0 = Full time with an open differential

so its an open dif in the front like a truck? well thats lame. does it have a posi out back?

[fnkychkn]

there is no posi, trac-lok, whatever you want to call a limited slip differential, front or rear

[DriveATransam]

wtf. i feel jipped. wtf is the point of awd if only 2 side wheels have traction. my truck had 3 wheels spinng atleast (good posi about back). ive seen a (i think 4 runner?) get stuck cause it had an open dif in back and front.

is this normal in awd cars? sorry to hijack the thread scott lol.

[The_Bishop]

Um, what do you think the traction control system is for? It aplies brakes to the slipping wheel to force more torque to the wheel with traction. Same concept, except it uses the brakes instead of clutches in the differential.

[Scott]

wtf. i feel jipped. wtf is the point of awd if only 2 side wheels have traction. my truck had 3 wheels spinng atleast (good posi about back). ive seen a (i think 4 runner?) get stuck cause it had an open dif in back and front.

is this normal in awd cars? sorry to hijack the thread scott lol.

You have it all wrong. The LX AWD implementation provides fantastic performance. I promise you will love it. I will share some of my experience from last winter later.

Scott

[Trouble]

There are no mechanical LSD's front or rear because the computer controls it all just like The Bishop said. Good old fashioned planetaries (which theoretically should be quite strong) vs spider gears...no viscous couplings which are generally somewhat fragile and with the fixed torque split, you get a consistent feel of a more 'rear wheel drive' configuration. This isn't a bad setup at all. I think Audi's is still perhaps better but this ain't too bad.
-Trouble

[DriveATransam]

well, i dont mind traction control doing the work...but how its doing the work is what i dont like. its applying the brakes! while it may very well be a good way, it doesnt sound like it will help in acceleration as much as having a posi out back. i like to stomp the gas and go. maybe im overreacting lol. my main concern would be how the car reacts with traction control 100% off. whats helping the car out then? i like to "play" in the snow. i guess ill see when snow comes along. ive never had an awd/4wd vehicle with traction control. might make the snow driving a little too easy? no?

you can definantly feel the front/rear bias in hard turns. a lot of understeer till you tap the gas and then its oversteer city.

[fnkychkn]

well, i dont mind traction control doing the work...but how its doing the work is what i dont like. its applying the brakes! while it may very well be a good way, it doesnt sound like it will help in acceleration as much as having a posi out back. i like to stomp the gas and go. maybe im overreacting lol. my main concern would be how the car reacts with traction control 100% off. whats helping the car out then? i like to "play" in the snow. i guess ill see when snow comes along. ive never had an awd/4wd vehicle with traction control. might make the snow driving a little too easy? no?

you can definantly feel the front/rear bias in hard turns. a lot of understeer till you tap the gas and then its oversteer city.
back in the early '90s the Eagle talon AWD used to have a viscuous coupler in the rear diff and another in the center diff. with 200HP, it was near impossible to keep straight in heavy snow.

[DriveATransam]

but atleast you had more than 2 wheels with power going to them ;)

the ranger i had to have the wheel full lock sometimes to go straight. it was freakin awesome! i loved it. one time i went for a couple blocks in heavy snow passing people as the truck was at a 45 degree angle to straight. of course spinning all the tires the whole time. or atleast 3 of them ;) im amazed nothing broke that day. parked the truck after wasting half a tank of gas in like an hour haha. smelled like something was burning. 32K miles on it in 2 years. never brought it in for warranty/repair once. lets see if the magnum holds up to my abuse :D i could also spin in 4wd if it was wet out. the 4.11s really hit hard off the line. im having a hard time spinning them in the magnum with esp off. must be too heavy and not enough gear.

[Scott]

Well, let’s see if I understand. Variation in front to rear wheel speed is accommodated by a planetary center differential. This means that whether the front to rear variation is result of turning or different tire sizes, gears are activated in the center differential and run when the wheel speed is different.



An example of the gear activation is in the following animation of a differential http://.auto.howstuffworks.com/differential3.htm (http://.auto.howstuffworks.com/differential3.htm), except the gear configuration is not spiders in a cage, but planetary. I can't get this URL to work as a link, just open your browser and paste it in the address field. Without a picture it is hard for me to visualize how planetaries do this job, but I can follow the logic.


Implications: Since activation of gears and their movement accommodates the front to rear wheel speed differences, there is no appreciable wear on drive train from turning or with the temporary use of a spare tire. But, these gears are probably not designed for continuous duty as would occur in a staggered wheel arrangement, where there is a significant difference in front to rear wheel circumference.



Hence, the Owner’s Manual is not contradictory when it warns against using unequal sized replacement tires, but provides no limitation on distance one could drive on a shorty spare tire. Replacement tires would affect long term wear, whereas a shorty spare is assumed to be temporary and therefore, would not activate the gear system in the center differential long enough to create meaningful wear.



Am I on the right track?





Scott

[fnkychkn]

Am I on the right track?
bullseye!

[Scott]

fnkychkn,

Glad to read that I'm on the mark. Thanks for weighing-in on this matter. :) Do you know if there is a transfer case section in the Dodge service manual that can be purchased by the John Q. Public?

One other puzzling question about the AWD: How 62/38 torque split accomplished? I have pondered/researched a past discussion where it was stated that the split was the result of gearing. However, I don’t understand how front to rear gearing can affect the distribution of torque while maintaining the same wheel speed.

Thanks again to you and the other guys,

Scott

[fnkychkn]

One other puzzling question about the AWD: How 62/38 torque split accomplished? I have pondered/researched a past discussion where it was stated that the split was the result of gearing. However, I don’t understand how front to rear gearing can affect the distribution of torque while maintaining the same wheel speed.
not entirely sure on that. i'll have to read up on it.

[RedRiderR/T]

Not to hijack this thread... but what happeneds if I forget to feed my parking meter and the city tow truck grabs my front wheels and takes off... what will AWD do then??

Will I be able to find my car by the skid marks or the transmission oil ??

[fnkychkn]

Not to hijack this thread... but what happeneds if I forget to feed my parking meter and the city tow truck grabs my front wheels and takes off... what will AWD do then??

Will I be able to find my car by the skid marks or the transmission oil ??flat bed towing is recommended. if TSB 21-011-06 has been performed, it should be fine. if not, the front wheels will try to rotate. most likely just overheat the clutch which will be removed if TSB is performed.