Hubs won't unlock - The 1947 - Present Chevrolet & GMC Truck Message Board Network

schmidty_dog · 02-21-2005, 06:25 PM

I have a 1980 GMC K15 with an NP205 tcase and I can't get my auto hubs to unlock. I have verified that that tcase is in 2hi because i jacked up the front end and when i spin the tires they spin the driveshaft, but the truck is in park. I put the tcase in neutral and rolled the truck and the hubs were still locked and spinning the driveshaft. Any suggestions?

schmidty_dog · 02-21-2005, 07:49 PM

Ok, talked to a guy who works on transmissions and such, and he says that even in 2hi the front drive shaft will spin due to fluid pressure, which keeps the gears lubed. Power braked it just to make sure it wasn't locked in and only the rear tires spin so i'm sure.

LONGHAIR · 02-21-2005, 08:23 PM

Your guy is full of it. The gear lube could be thick/heavy enough to make the front shaft turn some but there is no "pressure" anywhere that would drive it.

Get rid of the Automatic hubs, they sucked when they were new......now they are 25 years old.

kblazer87 · 02-21-2005, 09:13 PM

Have you tried driving the truck in reverse to unlock the hubs? That sometimes works to unlock them. I agree with the others about the auto hubs. Manual lockouts are much better.

schmidty_dog · 02-22-2005, 09:55 PM

I've tried backing it up and that didn't work. I jacked up the front drivers side tire off of the ground and spun it freely with my hand. When I did that the drive shaft spun, but the other tire was obviously not locked, not totally sure if this one is locked or what, but the transfer case isn't engaging the gears. How hard is it and what do I need for installing the manual hubs. Any brands or anything suggested? thanks, chris

kblazer87 · 02-22-2005, 10:33 PM

If it is the internal hub type it is a very easy and quick change over. Warn and milemarker premiums are what I have run in the past. I haven't had a problem with either one. I have Milemarkers on the Blazer right now. You will need an allen wrench for the hub bolts and you will need a special socket for the spindle nut. If you don't want to buy one Autozone has them in their tool loaner program. They aren't much to just buy them though and if you are going to have four wheel drives it would be a benifit to have one. You will be ahead of the game if you also have internal and external snap ring pliers as there are a couple of snap rings to remove. Follow the directions for the new hub set and you will be okay.
Mike

schmidty_dog · 02-24-2005, 01:01 AM

Thanks alot for all the info everyone, very much appreciated. I'm thinking i'm going to get some premium mile markers on order soon. I guess the conversion kit is for FULL TIME four wheel drive and not Auto hubs??? Anyways, if i don't need the kit and the hubs will just work I won't buy the kit. Thanks again, chris

02-21-2005, 06:25 PM	#1
schmidty_dog Registered User Join Date: Feb 2005 Posts: 15	Hubs won't unlock I have a 1980 GMC K15 with an NP205 tcase and I can't get my auto hubs to unlock. I have verified that that tcase is in 2hi because i jacked up the front end and when i spin the tires they spin the driveshaft, but the truck is in park. I put the tcase in neutral and rolled the truck and the hubs were still locked and spinning the driveshaft. Any suggestions?

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02-21-2005, 07:49 PM	#2
schmidty_dog Registered User Join Date: Feb 2005 Posts: 15	Ok, talked to a guy who works on transmissions and such, and he says that even in 2hi the front drive shaft will spin due to fluid pressure, which keeps the gears lubed. Power braked it just to make sure it wasn't locked in and only the rear tires spin so i'm sure.

02-21-2005, 08:23 PM	#3
LONGHAIR just can't cover up my redneck Join Date: May 2004 Location: Columbus OH Posts: 11,414	Your guy is full of it. The gear lube could be thick/heavy enough to make the front shaft turn some but there is no "pressure" anywhere that would drive it. Get rid of the Automatic hubs, they sucked when they were new......now they are 25 years old.

02-21-2005, 09:13 PM	#4
kblazer87 Registered User Join Date: Nov 2004 Location: Lawrenceburg, In Posts: 78	Have you tried driving the truck in reverse to unlock the hubs? That sometimes works to unlock them. I agree with the others about the auto hubs. Manual lockouts are much better.

02-22-2005, 09:55 PM	#5
schmidty_dog Registered User Join Date: Feb 2005 Posts: 15	I've tried backing it up and that didn't work. I jacked up the front drivers side tire off of the ground and spun it freely with my hand. When I did that the drive shaft spun, but the other tire was obviously not locked, not totally sure if this one is locked or what, but the transfer case isn't engaging the gears. How hard is it and what do I need for installing the manual hubs. Any brands or anything suggested? thanks, chris

02-22-2005, 10:33 PM	#6
kblazer87 Registered User Join Date: Nov 2004 Location: Lawrenceburg, In Posts: 78	If it is the internal hub type it is a very easy and quick change over. Warn and milemarker premiums are what I have run in the past. I haven't had a problem with either one. I have Milemarkers on the Blazer right now. You will need an allen wrench for the hub bolts and you will need a special socket for the spindle nut. If you don't want to buy one Autozone has them in their tool loaner program. They aren't much to just buy them though and if you are going to have four wheel drives it would be a benifit to have one. You will be ahead of the game if you also have internal and external snap ring pliers as there are a couple of snap rings to remove. Follow the directions for the new hub set and you will be okay. Mike

02-24-2005, 01:01 AM	#7
schmidty_dog Registered User Join Date: Feb 2005 Posts: 15	Thanks alot for all the info everyone, very much appreciated. I'm thinking i'm going to get some premium mile markers on order soon. I guess the conversion kit is for FULL TIME four wheel drive and not Auto hubs??? Anyways, if i don't need the kit and the hubs will just work I won't buy the kit. Thanks again, chris



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