launch auto 4wd/4hi any difference
08-04-2005, 10:07 AM
#11
Staging Lane
Join Date: Feb 2005
Posts: 59
Likes: 0
Received 0 Likes
on
0 Posts
I would do whatever works best for your truck. Wheel hop is bad, so if running in 4hi makes it stop, then heck, go for it.
Auto-4wd works awesome on mine but it is lowered and does have a Hotchkis sway bar kit and bilstiens.
My point is, that I don't think there is any harm in running in either mode. I have about 24,000 pretty hard miles on my truck so far including multiple autocross runs.
Talking to engineers and my experience is one thing, if you guys can make me smarter, speak up.
Auto-4wd works awesome on mine but it is lowered and does have a Hotchkis sway bar kit and bilstiens.
My point is, that I don't think there is any harm in running in either mode. I have about 24,000 pretty hard miles on my truck so far including multiple autocross runs.
Talking to engineers and my experience is one thing, if you guys can make me smarter, speak up.
08-04-2005, 10:25 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
I think launching in auto would be o.k. if the T.M was used. But with no Torque Management, the transfer case can’t transfer power smoothly to the front wheels. Just a guess. I have the same chatter that 1slow01Z71 is describing.
08-04-2005, 10:30 AM
#14
Staging Lane
Join Date: Feb 2005
Posts: 59
Likes: 0
Received 0 Likes
on
0 Posts
You guys mention "chatter", can you describe where this is coming from?
Is it wheel hop or are you hearing something coming from the transfer case?
I have zero torque management and have absolutely zero wheel hop or "chatter" on my combination.
I am making decent (Radix 5.3) but not ridiculous power with my combination, and my truck weighs about 4500lbs as it is a RCSB.
Maybe you guys are pushing the limits of the Auto-Trac with the power and weight you are running?
Is it wheel hop or are you hearing something coming from the transfer case?
I have zero torque management and have absolutely zero wheel hop or "chatter" on my combination.
I am making decent (Radix 5.3) but not ridiculous power with my combination, and my truck weighs about 4500lbs as it is a RCSB.
Maybe you guys are pushing the limits of the Auto-Trac with the power and weight you are running?
08-04-2005, 02:03 PM
#15
On The Tree
iTrader: (5)
Join Date: May 2005
Location: Colorado
Posts: 128
Likes: 0
Received 0 Likes
on
0 Posts
My truck is a ECSB and weighs about 5700+ So my experiance is different than yours, since there is that much more torque on my suspension and drivetrain.
I don't have any "GM stamped" research to back up my opinion, but being an aerospace engineer myself, I can't see how having the front end half engaged and dumping it at 3000+ rpms is going to be any less stressfull than just launching in 4hi. Split second or none at all, why rely on a computer algorithm to figure out what to do when you know what you need to do anyways?
I don't have any "GM stamped" research to back up my opinion, but being an aerospace engineer myself, I can't see how having the front end half engaged and dumping it at 3000+ rpms is going to be any less stressfull than just launching in 4hi. Split second or none at all, why rely on a computer algorithm to figure out what to do when you know what you need to do anyways?
08-04-2005, 02:29 PM
#16
The chatter that I am talking about is when you punch it from a stop the front tires hop a little and you can feel the torque going back and forth between the wheels. I have a little more power on tap off the line that you John since I have a 3000 stall and shooting a 100 shot that is giving me more than that in torque plus I weigh alot more that would be my guess as to why you arent getting itplus your front end is lowered so I would venture to say if I dropped the front a bit the weight transfer would be better as far as keeping more weight on the front end and help with the chatter that I am experiencing.
08-04-2005, 02:48 PM
#17
12 Second Truck Club
iTrader: (5)
Join Date: Apr 2005
Location: Sittin on jackstands
Posts: 5,230
Likes: 0
Received 4 Likes
on
2 Posts
I saw a little article on your truck John. I missed the first one(s) though. I'm very interested, maybe you could pm me about getting the back issues with what I missed.
Back on topic. I can feel the wheel spinning going on in the front end as 1slow is describing and I too have a light (relativly speaking) RCSB too, I also have a big problem with torque steer when on the gas in 4hi, even at highway speeds (I use 4hi ocasionally in the rain) I also have the front end hop? from about 50-70 when I stomp it in the rain
Back on topic. I can feel the wheel spinning going on in the front end as 1slow is describing and I too have a light (relativly speaking) RCSB too, I also have a big problem with torque steer when on the gas in 4hi, even at highway speeds (I use 4hi ocasionally in the rain) I also have the front end hop? from about 50-70 when I stomp it in the rain
08-04-2005, 03:14 PM
#18
Staging Lane
Join Date: Feb 2005
Posts: 59
Likes: 0
Received 0 Likes
on
0 Posts
My truck has a Vigalante Convertor, FLT trans and the Radix is making about 7lbs.
Even in the rain I have had absolutely zero torque steer issues and no wheel hop to speak of. The truck launches incredibly straight.
My understanding of running in 4-Hi is that it does a 50/50 torque split wheras the Auto-4wd can bias to the front or rear as needed, ultimately switching back to 2wd as soon as traction is available.
4Hi still relies on the wet clutch in the Auto-Trac t-case to slip otherwise the drive line would "wrap up" going down the highway.
I am headed to Englishtown dragstrip on Monday. I will run the truck in 4Hi and Auto-4wd and let you guys know if I see a difference.
Regarding the truck articles, the first two are available online, just go to the link in my sig, it will take you there. The third article is on the stands right now. A fourth is coming out next month.
Even in the rain I have had absolutely zero torque steer issues and no wheel hop to speak of. The truck launches incredibly straight.
My understanding of running in 4-Hi is that it does a 50/50 torque split wheras the Auto-4wd can bias to the front or rear as needed, ultimately switching back to 2wd as soon as traction is available.
4Hi still relies on the wet clutch in the Auto-Trac t-case to slip otherwise the drive line would "wrap up" going down the highway.
I am headed to Englishtown dragstrip on Monday. I will run the truck in 4Hi and Auto-4wd and let you guys know if I see a difference.
Regarding the truck articles, the first two are available online, just go to the link in my sig, it will take you there. The third article is on the stands right now. A fourth is coming out next month.
08-04-2005, 04:39 PM
#19
12 Second Truck Club
iTrader: (5)
Join Date: Apr 2005
Location: Sittin on jackstands
Posts: 5,230
Likes: 0
Received 4 Likes
on
2 Posts
Thanks for the link. I don't personally have the auto trak, so mine is 100% rear, or 50/50. A buddy had one with the auto trak though. It worked great, and I have no engineers to back me up that I know of, but with my 4wd knowledge (which probably isn't as much as I like to think it is 
) Its just not a good idea to slam all that torque through the transfer case. Seems like it would "shock" the driveline, but I guess with the clutches slipping, it may not hurt anything. 
) Its just not a good idea to slam all that torque through the transfer case. Seems like it would "shock" the driveline, but I guess with the clutches slipping, it may not hurt anything.
08-04-2005, 05:24 PM
#20
Originally Posted by TheChronic
My truck is a ECSB and weighs about 5700+ So my experiance is different than yours, since there is that much more torque on my suspension and drivetrain.
I don't have any "GM stamped" research to back up my opinion, but being an aerospace engineer myself, I can't see how having the front end half engaged and dumping it at 3000+ rpms is going to be any less stressfull than just launching in 4hi. Split second or none at all, why rely on a computer algorithm to figure out what to do when you know what you need to do anyways?
I don't have any "GM stamped" research to back up my opinion, but being an aerospace engineer myself, I can't see how having the front end half engaged and dumping it at 3000+ rpms is going to be any less stressfull than just launching in 4hi. Split second or none at all, why rely on a computer algorithm to figure out what to do when you know what you need to do anyways?
were as when you are already in 4x4 everything is all ready locked in and the gears are seated
imagine you have a philips head screw driver bit on an electric drill you mash the button drill comes up to speed then you slam it into the head of the screw after a couple of times your gonna strip the **** out of the head of the screw (launching in 4auto) now take the same scenario and put the bit on the head of the screw correctly and apply the button (launching 4x4) which do you think is gonna cause more damage?