Dumb question about 4 wheel drive on my 72 C20 - Page 2 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Altec · 02-26-2011, 04:59 AM

Good info here. Maybe I can help get it all into one post.

Unlocked Hubs/2-Wheel Drive:
-Only the hubs spin. Drive shaft, and axle shafts do not turn. Least wear, and least drag on the system.

Unlocked Hubs/4-Wheel Drive:
-Drive shaft, and axle shafts spin. No power transfered to the wheels. Results in unnecessary wear on transfer case, ring and pinion, and axle shaft seals. also results in increased drag on your drivetrain. Lowering efficiency, and slightly higher percentage of power lose.

Locked Hubs/2-Wheel Drive:
-Same results as unlocked/4WD. More, or less. At full lock, or close to it some popping, and jerking can be felt in some cases. Result of the joints on the axle shafts binding.

Locked Hubs/4-Wheel Drive:
-Transfer case, drive shaft, axle shafts, and hubs all spinning. Increased wear, and lower efficiency caused by drag in the system.
-Dry surface use in Locked/4WD results in problems. Even with a open differential. The front tires are allowed to spin at different speeds, but since the front axle is now tied to the rear axle binding simply can not be avoided. Because the back of the vehicle will always take a different path then the front. The resulting effect is the "bucking" and other problems felt when trying this. The only way around this is with a transfer case with a built in differential. Options for this are slim. The popular choices are the NP203, and the NV245/247, and maybe a couple more.

**special-K** · 02-26-2011, 08:26 AM

I get binding in the '89 K1500 (IFS) I'm driving when I put it in 4wd just to back up my driveway. The road is clear and my driveway is snow & ice covered on an incline. I pull the lever just as I'm pulling in front of my house because it takes a moment to engage,pull past the drive enough,turn wheels,and back in. The steering wheel rocks back and forth and the truck is in an obvious bind. I have experienced this in every 4wd of every design that I have owned for the past 35 years. Before that,it was the Land rovers my dad owned since the '60s. I can't imagine someone not experiencing the same thing on dry pavement.

It just comes down to one very simple fact. It's best to use the system the way it was designed to be used...2hi/hubs free under normal circumstances and 4hi or 4lo/hubs locked when 4wd is needed or 2hi/hubs locked to 4hi for brief periods as needed. Heck,even when having a blast...4hi/hubs locked off road and throw it into 2hi to slide rear or just make a sharper turn...YEEHAW!!

RustyParts · 02-26-2011, 11:52 AM

Another reason to keep the hubs unlocked when not needed. The front axle is a steering axle and caster and camber is always adding and subtracting to the stresses on the axle.

Brettd85 · 02-27-2011, 03:00 PM

Thanks for the comments guys.

rayfinseats · 03-05-2011, 12:10 AM

Dumb question? Maybe you should have said, "Hey I don't understand something."

In 4x4 it eats more gas. IN 4x4 with the hibs unlocked you are still in 4x4 but the front wheels are free-wheeling, which still uses SOME more gas.

You're welcome. It confused me too when I got my first one.

If the factories were trying to make good vehicles instead of pleasing the greedy stockholders they would all have positraction....2 cents.

02-26-2011, 04:59 AM	#26
Altec Getcha Pull Join Date: Nov 2010 Location: MD Posts: 691	Re: Dumb question about 4 wheel drive on my 72 C20 Good info here. Maybe I can help get it all into one post. Unlocked Hubs/2-Wheel Drive: -Only the hubs spin. Drive shaft, and axle shafts do not turn. Least wear, and least drag on the system. Unlocked Hubs/4-Wheel Drive: -Drive shaft, and axle shafts spin. No power transfered to the wheels. Results in unnecessary wear on transfer case, ring and pinion, and axle shaft seals. also results in increased drag on your drivetrain. Lowering efficiency, and slightly higher percentage of power lose. Locked Hubs/2-Wheel Drive: -Same results as unlocked/4WD. More, or less. At full lock, or close to it some popping, and jerking can be felt in some cases. Result of the joints on the axle shafts binding. Locked Hubs/4-Wheel Drive: -Transfer case, drive shaft, axle shafts, and hubs all spinning. Increased wear, and lower efficiency caused by drag in the system. -Dry surface use in Locked/4WD results in problems. Even with a open differential. The front tires are allowed to spin at different speeds, but since the front axle is now tied to the rear axle binding simply can not be avoided. Because the back of the vehicle will always take a different path then the front. The resulting effect is the "bucking" and other problems felt when trying this. The only way around this is with a transfer case with a built in differential. Options for this are slim. The popular choices are the NP203, and the NV245/247, and maybe a couple more. __________________ '81 K10 454/SM465 '86 S10 Blazer '95 H-D Softail '96 Integra

02-26-2011, 08:26 AM	#27
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,863	Re: Dumb question about 4 wheel drive on my 72 C20 I get binding in the '89 K1500 (IFS) I'm driving when I put it in 4wd just to back up my driveway. The road is clear and my driveway is snow & ice covered on an incline. I pull the lever just as I'm pulling in front of my house because it takes a moment to engage,pull past the drive enough,turn wheels,and back in. The steering wheel rocks back and forth and the truck is in an obvious bind. I have experienced this in every 4wd of every design that I have owned for the past 35 years. Before that,it was the Land rovers my dad owned since the '60s. I can't imagine someone not experiencing the same thing on dry pavement. It just comes down to one very simple fact. It's best to use the system the way it was designed to be used...2hi/hubs free under normal circumstances and 4hi or 4lo/hubs locked when 4wd is needed or 2hi/hubs locked to 4hi for brief periods as needed. Heck,even when having a blast...4hi/hubs locked off road and throw it into 2hi to slide rear or just make a sharper turn...YEEHAW!! __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~

02-26-2011, 11:52 AM	#28
RustyParts Registered User Join Date: May 2006 Location: Wyman, Kentucky Posts: 403	Re: Dumb question about 4 wheel drive on my 72 C20 Another reason to keep the hubs unlocked when not needed. The front axle is a steering axle and caster and camber is always adding and subtracting to the stresses on the axle. __________________ 1972 GMC Jimmy, 4WD, 454 CI, 350 Turbo, 4" lift, 35" tires The math teacher said my son "Bubba" could be a mathmatical genius. cause he's got 13 fingers!

02-27-2011, 03:00 PM	#29
Brettd85 Registered User Join Date: Jan 2011 Location: Redmond, WA Posts: 81	Re: Dumb question about 4 wheel drive on my 72 C20 Thanks for the comments guys. Last edited by Brettd85; 02-27-2011 at 03:02 PM.

03-05-2011, 12:10 AM	#30
rayfinseats Registered User Join Date: Dec 2010 Location: sioux city, iowa Posts: 619	Re: Dumb question about 4 wheel drive on my 72 C20 Dumb question? Maybe you should have said, "Hey I don't understand something." In 4x4 it eats more gas. IN 4x4 with the hibs unlocked you are still in 4x4 but the front wheels are free-wheeling, which still uses SOME more gas. You're welcome. It confused me too when I got my first one. If the factories were trying to make good vehicles instead of pleasing the greedy stockholders they would all have positraction....2 cents. Last edited by rayfinseats; 03-05-2011 at 12:12 AM.



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