2007 Sierra Classic 4x4 operation
 

Hi all,

I have a question concerning the operation of the 4 wheel drive system on my 2007 GMC Sierra Classic. I have owned 2 4x4's over the years, one being a 1989 Isuzu pick-up the other a 1996 Ford F-150. Both trucks had manual locking hubs. While I never watched to see if both front wheels were getting power (spinning) while in 4 wheel drive, I never had a problem getting stuck with either of those two trucks. My Siera has auto locking hubs and I have gotten stuck 3 times simply driving through a wet grassy pasture with a very slight incline. After getting stuck the second time, I had a passenger get out to watch the wheels, only the left front wheel was spinning (and the rear of coarse). Is this normal operation, only one front wheel getting power? Seems to me both wheels should be pulling. Am I incorrect?

I know that tires have a lot to do with getting stuck as well, both of my other trucks were running 31x10.50 R15 Good Year Wranglers. My Sierra has new 255/70 R17 Falken Wild Peak A/T tires. The Falkens have a fairly aggressive tread pattern so I cant imagine there would be a big difference between them and the Good Years.

I have done some fairly rough off road driving in my years and am really disappointed in the performance of my Sierra in 4 wheel drive. There is no question that taking my Sierra in places I had the Isuzu and Ford would leave me calling for a tow.

Any ideas or suggestions for better traction?

Thanks all!

The front differential is an open unit, meaning which ever wheel has the least traction will spin. The rear is a locking type unit that un-locks at about 25mph. I don't know about the Isuzu but the Ford may have had a locking type front differential which would have had both front wheels spinning. Next time try the Auto 4x4 button and see if it helps. Also let air out of the tires to give you a bigger foot print as if you were driving on sand.

Thanks for your reply. Yes, I would think the Ford must have been a locking differential as well as the Isuzu as I never had a problem getting stuck in much more slippery conditions. Seems to me this set up is almost useless .... I'd much rather have two front wheels pulling than two rear wheel pushing, especially if the front wheel is going to transfer power to the wheel with less traction ...... seems to me if it's going to transfer power to the wheel with the least amount of traction this set up is really no different than having a two wheel drive with a positive traction rear. Would you agree?

Normally a locked front differential is used with manual hubs. Almost all new vehicles have automatic disconnecting front differentials which disconnects one side of the differential to the wheel. For sure in a truck a locked front is much better for traction since most of the weight is up front. The down side is a locked front affects steering more.

If you wire one of your abs sensors in line with a on off switch in 4low you will have all 4 wheel drive