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Auto 4 wheel and 4-Hi


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About 2 weeks ago on my way home from work I came up on my bro-in-law and his family in their '02 Yukon Denali. We talked for a minute with the windows down and then we both hit it. The road was wet from the rain and we were going about 30mph when we hit it. He took off while I spun my right rear. ( The G80 rear end didn't hook up :cool: ) I understand why he took off since their Yukon has All-Wheel drive.

 

Last night the roads were wet again when I drove home. This time I pushed the Auto 4 wheel button. I knew the front axle was engaged because I could hear it. I floored it a couple of times and didn't spin the wheels. When I was real close to home I pushed 2-Hi and drove straight for a couple hundred feet then turned in, to the right. I could still feel the front axle was engaged when turning. It seemed to disengage when I backed up to straighten out to get into my parking spot.

 

Is it safe to drive on the pavement with Auto 4 wheel button pushed?

So what is the difference between Auto 4 and 4-Hi?

 

Thanks

teamjnz

:D

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About 2 weeks ago on my way home from work I came up on my bro-in-law and his family in their '02 Yukon Denali. We talked for a minute with the windows down and then we both hit it. The road was wet from the rain and we were going about 30mph when we hit it. He took off while I spun my right rear. ( The G80 rear end didn't hook up :cool: ) I understand why he took off since their Yukon has All-Wheel drive.

 

Last night the roads were wet again when I drove home. This time I pushed the Auto 4 wheel button. I knew the front axle was engaged because I could hear it. I floored it a couple of times and didn't spin the wheels. When I was real close to home I pushed 2-Hi and drove straight for a couple hundred feet then turned in, to the right. I could still feel the front axle was engaged when turning. It seemed to disengage when I backed up to straighten out to get into my parking spot.

 

Is it safe to drive on the pavement with Auto 4 wheel button pushed?

So what is the difference between Auto 4 and 4-Hi?

 

Thanks

teamjnz

:D

 

 

 

 

Auto locks the front wheels but does not apply power until it detects wheelspin in back then it instantly applies power to the front through the transfer case. 4HI keeps power to the front at all times. I have noticed the auto working VERY well when driving on wet roads. When I hit a puddle on one side, I can feel the front kick in VERY quickly. I do not recommend using either Auto or 4HI in dry conditions. I also believe it will only unlock the front when you go into reverse for a few feet.

 

Also, the G80 won't engage at over 20mph (wheelspin) so if you spun fast, it would never kick in. G80 is better for offroad than for road compared to traditional POSI. IMO.

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Auto 4 wheel drive can be run anytime on hard pavement if you want. It does not engage until there is a wheel speed difference between the front & back. The bad side driving in auto 4 is the front axle is engaged hurting gas mileage. Never ever drive in 4x4 on hard dry pavement you will cause axle windup which means the axles & driveshafts will be under high tension and will break. :cool:

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Thanks guys.. Now I know what the difference is. One thing with the "axle wind up". When I turned into my parking spot I did notice "axle wind up". It seemed to let go when I put it in reverse. Bish confirmed this in his post. To me it seems this isn't good since it could cause damage if it doesn't disengage until the truck is reversed. :cool:

 

Comments..

 

teamjnz

:D

 

Bish, thanks for the G80 info :D

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Thanks guys.. Now I know what the difference is. One thing with the "axle wind up". When I turned into my parking spot I did notice "axle wind up". It seemed to let go when I put it in reverse. Bish confirmed this in his post. To me it seems this isn't good since it could cause damage if it doesn't disengage until the truck is reversed.  :cool:

 

Comments..

 

teamjnz

:D

 

Bish, thanks for the G80 info  :chevy:

 

 

 

 

Even in auto trac you will get axle windup in tight turns but that isnt a problem. It will unload by it self when you go straight.

You mentioned that when you put it in 2wd it felt like it was still in 4wd. Ifd you are under load even after pushing 2wd if the system was operating in auto trac engaged it will take either slowing down but usually just letting off the gas to unlock the system. If the fron axle is still engaged you should be able to ghear some noise not heard in 2wd. :D

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Thanks guys.. Now I know what the difference is. One thing with the "axle wind up". When I turned into my parking spot I did notice "axle wind up". It seemed to let go when I put it in reverse. Bish confirmed this in his post. To me it seems this isn't good since it could cause damage if it doesn't disengage until the truck is reversed.  :cool:

 

Comments..

 

teamjnz

:chevy:

 

Bish, thanks for the G80 info  :)

 

 

 

 

Even in auto trac you will get axle windup in tight turns but that isnt a problem. It will unload by it self when you go straight.

You mentioned that when you put it in 2wd it felt like it was still in 4wd. Ifd you are under load even after pushing 2wd if the system was operating in auto trac engaged it will take either slowing down but usually just letting off the gas to unlock the system. If the fron axle is still engaged you should be able to ghear some noise not heard in 2wd. :D

 

 

 

 

 

I think I understand. So I don't have to put it in reverse. Let off of the throttle just a little to take the pressure of the drivetrain and it will disengage itself. To much deceleration will keep the pressure on so it won't disengage just like accelerating or cruising with a load on the drivetrain. That makes sence..

 

thanks redvet :D

 

teamjnz

:flag:

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