Four Wheel Drive Launch question.
11-13-2005, 05:03 PM
#11
Originally Posted by mzoomora
The front shaft is not always turning. It is engaged only for 4wd use. When in 2wd the front disconnect and the front output of the t-case are both disengaged. When in 4-auto the front diconnect is engaged and the t-case is not.
11-13-2005, 05:09 PM
#12
12 Second Truck Club
iTrader: (5)
Join Date: Apr 2005
Location: Sittin on jackstands
Posts: 5,230
Likes: 0
Received 5 Likes
on
3 Posts
Originally Posted by dewmanshu
an understanding of the way the TCase works in order first...the TCase is ALWAYS on, the front shaft is always engaged...when you go "4WD" a plunger engages the front pinion. When it's in "auto" the pinion will engage when the pcm interprets wheel slip/spin...those good ole vss'. This is a good reason why you don't use auto with any good power...I already broke that plunger once.
In 4WD hi if you produce a good bit of power that plunger might come back to let it go back to 2wd...however...the constant force of "application" won't let it until you let off of it. Light might go to 2wd, but I seriously doubt that if your always WOT.
In 4WD hi if you produce a good bit of power that plunger might come back to let it go back to 2wd...however...the constant force of "application" won't let it until you let off of it. Light might go to 2wd, but I seriously doubt that if your always WOT.
This is not entirely true. I have a manual transfer case. My front drive shaft does not turn till the 4wd is engaged. Also as long as the transfer case has a load on it, it will not come out of 4wd into 2wd. The auto tracks are different, but I am not sure if they will or will not go into 2wd with a load on them, but I would guess that they will not shift into 2wd under a load for a little while.
11-14-2005, 12:54 AM
#13
How do I change this text
iTrader: (26)
Join Date: Jan 2005
Location: Behind the TIG welder
Posts: 7,294
Likes: 0
Received 2 Likes
on
2 Posts
mine shifts out of 4 wheel drive every time I hit the button, usually the first thing I do after I launch, it "Unlocks" when the truck shifts from second to third. but maybe I'm not making enough power to keep it locked in.
11-14-2005, 06:00 AM
#14
Originally Posted by Wilde Racing
mine shifts out of 4 wheel drive every time I hit the button, usually the first thing I do after I launch, it "Unlocks" when the truck shifts from second to third. but maybe I'm not making enough power to keep it locked in.
Its just whether or not with the Auto-Trak trans like mine, will the trans divert all or most of the power to the back wheels once the 2WD button is pushed.
I think it will, but I have noticed that even when I'm going slow and not hard on the gas, going from 4HI to 2wd you still feel some residual pulling from the front wheels.
Like when you have it in 4HI and you turn your wheels, you really notice it then, thats what I'm talking about.
Mainly its been a few people posting that it won't go back into 2WD after doing a 4HI launch that made me ask the question here.
There must be a big difference between the manual T-Case trucks and the Auto-Trak trucks. What it is?, I don't know enough on the subject to say.
11-14-2005, 06:05 AM
#15
I am sorry...if you have a push button 4wd setup, it is to my understanding that the front shaft is always spinning in autotracs/pushbutton setups. I wish I took pics when I repaired the front plunger that slides a splined "coupling" to connect it all. I can't speak for all of the different setups...obviously manuals are different.
With any amount of torque I couldn't imagine that coupling coming back off of the spline. Why bother...I say, but if it works for you...great. That vibration KySilverado is your front shaft...it's more than likely out of balance.
With any amount of torque I couldn't imagine that coupling coming back off of the spline. Why bother...I say, but if it works for you...great. That vibration KySilverado is your front shaft...it's more than likely out of balance.
11-14-2005, 02:33 PM
#16
Originally Posted by dewmanshu
That vibration KySilverado is your front shaft...it's more than likely out of balance.
Just thinking out loud... I have a pushbutton/AutoTrack. Think I remember the front driveshaft turning once when I had it on jack stands, in gear, running checking out a torque converter noise.... If it were the shaft out of balance wouldn't I feel the vibration always at 90. I only do when I'm in 4wd? Its not always vibrated. Came about sometime after I got the truck.
11-14-2005, 03:00 PM
#17
Originally Posted by KySilverado
Interesting thread. Still no conclusion to the discussion.
Just thinking out loud... I have a pushbutton/AutoTrack. Think I remember the front driveshaft turning once when I had it on jack stands, in gear, running checking out a torque converter noise.... If it were the shaft out of balance wouldn't I feel the vibration always at 90. I only do when I'm in 4wd? Its not always vibrated. Came about sometime after I got the truck.
Just thinking out loud... I have a pushbutton/AutoTrack. Think I remember the front driveshaft turning once when I had it on jack stands, in gear, running checking out a torque converter noise.... If it were the shaft out of balance wouldn't I feel the vibration always at 90. I only do when I'm in 4wd? Its not always vibrated. Came about sometime after I got the truck.
That vibration probably comes more about with "load" on the axel. My **** vibrates hard in 4wd but not that bad at all in 2wd...and my front u-joint is bad.
I just re-read my post....let me correct myself...the auto selection does move torque back and forth from the front axel to the rear axel depending where the sensors "see" the slip. Which now that I think about it this may be why some of you feel a "little" bit of the 4wd scenario even though you pushed the 2wd button after being in 4wd....it's kinda in auto. Moving most of the torque to the rear shaft....through the TCase.
Sticking it in low locks the front shaft to the rear shaft and drops it to a lower gear like 2.48:1 or something like that (in the TCase, 2 speed case that is).
yeh...that's it, 4wd locks the shafts together through the TCase and then the front axel locks(through that coupling deal)....you drive down the road WOT and then push 2wd...the TCase then unlocks the shafts however the inertia or "applicational force" (just made that up) is keeping the front axel locked...you may not be driving it with any torque being applied to the fornt, but the wheel spin is still directly linked to the axel (front).
sigh. How's that for babble. Long story short...I wouldn't take it out or ask it to come out while under a load, especially a WOT load. I believe parish stays in 4WD and WOT the whole way down the shoot.
Last edited by dewmanshu; 11-14-2005 at 07:38 PM.
11-14-2005, 05:39 PM
#18
Front driveshaft spins in 2wd end of story
I have the engine puilled out of my truck right now and me and mjhoward were pushing my truck out of his garage and the front driveshaft kept banging on the bottom of the body do to all the weight out of the front and the t-case was in 2wd. So if you have an autotrac t-case then oyu front driveshaft always spins. Also the front d-shaft doesnt have any weights on it that I noticed thus you would think that it would be out of balance. I know mine under load(full bolt ons and a 100 shot) would NOT shift out of 4wd the light would go off sometimes but it wasnt out of 4wd I know because in 2wd if I stomped it from like a 20 roll then hit the nitrous and sprayed thorugh the shifts when it would bang 2nd it would blow the tires off the back end but when I launched in 4wd and and then hit the button alot of times the 4wd light would go out but it was still in 4wd cause when second would come again spraying through the shift it would just shift hard and keeping going no tire squalling or anything. Just cause the light is off doesnt mean its out of 4wd.
I have the engine puilled out of my truck right now and me and mjhoward were pushing my truck out of his garage and the front driveshaft kept banging on the bottom of the body do to all the weight out of the front and the t-case was in 2wd. So if you have an autotrac t-case then oyu front driveshaft always spins. Also the front d-shaft doesnt have any weights on it that I noticed thus you would think that it would be out of balance. I know mine under load(full bolt ons and a 100 shot) would NOT shift out of 4wd the light would go off sometimes but it wasnt out of 4wd I know because in 2wd if I stomped it from like a 20 roll then hit the nitrous and sprayed thorugh the shifts when it would bang 2nd it would blow the tires off the back end but when I launched in 4wd and and then hit the button alot of times the 4wd light would go out but it was still in 4wd cause when second would come again spraying through the shift it would just shift hard and keeping going no tire squalling or anything. Just cause the light is off doesnt mean its out of 4wd.
Mine doesnt.