Locking the hubs - The 1947 - Present Chevrolet & GMC Truck Message Board Network

ian villeza · 05-09-2006, 03:14 AM

I was at the beach today and decided to lock my hubs and shift my 72 blazer on the fly from 2 HI to 4 HI. So I Blaze down the beach and everything is wonderful. Heading back onto the pavement I just could not seem to shift back into 2 HI on the fly. I eventually shifted back into 2 HI after I came to a complete stop, Reversed a bit and put the trans into neutral. So I drive home on the freeway with the hubs still locked and was wondering if it was my imagination or does having the hubs locked put more of a strain on the engine?

**pound41** · 05-09-2006, 07:48 AM

I have notice with mine a small difference when th hubs are locked in. I know there was a recent thread on shifting etc. I was told by the previous owner when I got my blazer 20+yrs a go who was a fanatic to put it in N to shift the transfer case. Correct or not thats the way I have always done it. I don't think these were intended to shift of the fly like the modern ones

blazerparts · 05-09-2006, 10:01 AM

Shifting the transfer case "on the fly" probably wasn't even a concept in the early 70's

*Medicanman71* · 05-09-2006, 02:19 PM

I've heard you can do it no problem in our trucks - i never have and hopefully won't ever have to. I think it's just looking for problems. PLEASE post a link to the shifting thread.

I only shift into 4x4 from N or Park. I also go in reverse a bit after i shift from 4x4 back to 2wd(2hi)... not sure you have to with our trucks/np205's but i've heard you must go in reverse for some trucks (toyotas?) after u go back into 2wd.

I havent been in 4x4 in tooo long (Esp for having a blazer!) , besides for completely rebuilting/getting new hubs... is there any thing i could spray in them before i go to flip them? I don't know that i'll have any problems, but i wouldnt be shocked if i did, and i'm just wondering what's best.

Don't 4 get the link to the shifting thread

RunTMCfan · 05-09-2006, 03:30 PM

I just had my 205 rebuilt. The guys at a very well respected shop here in East County San Diego said the Tcase showed typicall signs of shift on the fly use. The Tcase did last 30+ years. He said later model (what ever that means) 205's were much better at shifting on the fly.

I remember a thread a few months back about this subject. I personally do not shift on the fly. Don't really see the need here. No snow and other than the last few years, very little rain.

Big Block · 05-09-2006, 06:49 PM

If your hubs are still locked in you will definitely feel it. It is turning the differential and front drive shaft even though the t-case is in neutral. So I guess you mean put more strain on the engine the answer is yes. When the hubs are unlocked the front wheels free wheel. I hope that makes sense Ian.

makovai · 05-09-2006, 06:55 PM

I didn't even know shifting on the fly with a 205 could be done more than once

Meaning i thought you would eat the gears if you even thought about it. hmmm learn sumthin new everyday.

*Medicanman71* · 05-09-2006, 09:11 PM

Going to go out and give it a shot now, see what else you can bust?

ian villeza · 05-10-2006, 12:57 AM

Quote:

Originally Posted by Medicanman71

I've heard you can do it no problem in our trucks - i never have and hopefully won't ever have to. I think it's just looking for problems. PLEASE post a link to the shifting thread.

I only shift into 4x4 from N or Park. I also go in reverse a bit after i shift from 4x4 back to 2wd(2hi)... not sure you have to with our trucks/np205's but i've heard you must go in reverse for some trucks (toyotas?) after u go back into 2wd.

I havent been in 4x4 in tooo long (Esp for having a blazer!) , besides for completely rebuilting/getting new hubs... is there any thing i could spray in them before i go to flip them? I don't know that i'll have any problems, but i wouldnt be shocked if i did, and i'm just wondering what's best.

Don't 4 get the link to the shifting thread

http://67-72chevytrucks.com/vboard/s...light=shifting

1969 GMC · 05-10-2006, 06:59 PM

I actually think my owner's manual says that you CAN shift on the fly at low speeds from 2Hi/4Hi, but NEVER into low.

The newer NP205's have synchros because of the advent of auto-locking hubs. Other than that, they arent any better or worse than old ones.

Personally, I don't like shifting on the fly. I never did, either, but then my Rockwell exploded. Sooo yeah. :p

Also, alot of vehicles came from the factory with drive flanges instead of hubs in the front axle. All of these vehicles spin the front axleshafts, diff, and d-shaft constantly. I wouldnt say there is a noticeable difference in engine life, but perhaps gas mileage.
In the winter, I used to lock my hubs in at the first snow, and unlock when spring came, just shifted in and out of 4wd as needed. Worked fine for me.

05-09-2006, 03:14 AM	#1
ian villeza Active Member Join Date: May 2005 Location: Hawaii Posts: 153	Locking the hubs I was at the beach today and decided to lock my hubs and shift my 72 blazer on the fly from 2 HI to 4 HI. So I Blaze down the beach and everything is wonderful. Heading back onto the pavement I just could not seem to shift back into 2 HI on the fly. I eventually shifted back into 2 HI after I came to a complete stop, Reversed a bit and put the trans into neutral. So I drive home on the freeway with the hubs still locked and was wondering if it was my imagination or does having the hubs locked put more of a strain on the engine?

05-09-2006, 07:48 AM	#2
pound41 Registered User Join Date: Dec 2002 Location: Northern Virginia Posts: 1,269	Re: Locking the hubs I have notice with mine a small difference when th hubs are locked in. I know there was a recent thread on shifting etc. I was told by the previous owner when I got my blazer 20+yrs a go who was a fanatic to put it in N to shift the transfer case. Correct or not thats the way I have always done it. I don't think these were intended to shift of the fly like the modern ones

05-09-2006, 10:01 AM	#3
blazerparts No,I DON'T have Tourett's Join Date: Mar 2005 Location: Reno, NV Posts: 556	Re: Locking the hubs Shifting the transfer case "on the fly" probably wasn't even a concept in the early 70's __________________ '72 K5 CST 350/350 Daily Driver '69 GMC3500 Camper Special CST Flatbed 396/400 Upgraded to show truck '69 GMC 2500 L6292, 3spd beater

05-09-2006, 02:19 PM	#4
Medicanman71 Account Suspended Join Date: May 2005 Location: Where the Wild Things Are Posts: 696	Re: Locking the hubs I've heard you can do it no problem in our trucks - i never have and hopefully won't ever have to. I think it's just looking for problems. PLEASE post a link to the shifting thread. I only shift into 4x4 from N or Park. I also go in reverse a bit after i shift from 4x4 back to 2wd(2hi)... not sure you have to with our trucks/np205's but i've heard you must go in reverse for some trucks (toyotas?) after u go back into 2wd. I havent been in 4x4 in tooo long (Esp for having a blazer!) , besides for completely rebuilting/getting new hubs... is there any thing i could spray in them before i go to flip them? I don't know that i'll have any problems, but i wouldnt be shocked if i did, and i'm just wondering what's best. Don't 4 get the link to the shifting thread

05-09-2006, 03:30 PM	#5
RunTMCfan Registered User Join Date: Oct 2005 Location: San Diego, Ca Posts: 251	Re: Locking the hubs I just had my 205 rebuilt. The guys at a very well respected shop here in East County San Diego said the Tcase showed typicall signs of shift on the fly use. The Tcase did last 30+ years. He said later model (what ever that means) 205's were much better at shifting on the fly. I remember a thread a few months back about this subject. I personally do not shift on the fly. Don't really see the need here. No snow and other than the last few years, very little rain. __________________ Rob "RunTMCfan"

05-09-2006, 06:49 PM	#6
Big Block Big Block Join Date: Mar 2005 Location: Durham, N.C. Posts: 1,649	Re: Locking the hubs If your hubs are still locked in you will definitely feel it. It is turning the differential and front drive shaft even though the t-case is in neutral. So I guess you mean put more strain on the engine the answer is yes. When the hubs are unlocked the front wheels free wheel. I hope that makes sense Ian. Last edited by Big Block; 05-12-2006 at 07:36 PM.

05-09-2006, 06:55 PM	#7
makovai Senior Member Join Date: Feb 2006 Location: oregon city Posts: 335	Re: Locking the hubs I didn't even know shifting on the fly with a 205 could be done more than once Meaning i thought you would eat the gears if you even thought about it. hmmm learn sumthin new everyday. __________________ If it aint broke..............fix it till it is. www.fast77.com 1972 - 330 hp crate, 11" lift with 39x18 mickeys. 3/4 ton, cross steer, 4 wheel disc brakes 1996 Z71 w/ 35's

05-09-2006, 09:11 PM	#8
Medicanman71 Account Suspended Join Date: May 2005 Location: Where the Wild Things Are Posts: 696	Re: Locking the hubs Going to go out and give it a shot now, see what else you can bust?

05-10-2006, 06:59 PM	#10
1969 GMC Registered User Join Date: Feb 2003 Location: The Rubber City Posts: 5,498	Re: Locking the hubs I actually think my owner's manual says that you CAN shift on the fly at low speeds from 2Hi/4Hi, but NEVER into low. The newer NP205's have synchros because of the advent of auto-locking hubs. Other than that, they arent any better or worse than old ones. Personally, I don't like shifting on the fly. I never did, either, but then my Rockwell exploded. Sooo yeah. :p Also, alot of vehicles came from the factory with drive flanges instead of hubs in the front axle. All of these vehicles spin the front axleshafts, diff, and d-shaft constantly. I wouldnt say there is a noticeable difference in engine life, but perhaps gas mileage. In the winter, I used to lock my hubs in at the first snow, and unlock when spring came, just shifted in and out of 4wd as needed. Worked fine for me. __________________ 1969 GMC K2500 1996 Honda Accord 2007 Kawasaki KLR 650 Last edited by 1969 GMC; 05-10-2006 at 07:01 PM.



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