Freeway driving - The 1947 - Present Chevrolet & GMC Truck Message Board Network

wpvtx · 12-07-2007, 11:53 PM

Ok - the scoop here,

4 speed - NP205 - 31" tires - 86 suburban dana 44 in a 1970 stepside.

Hubs unlocked - 2 high - 70MPH = no vibration.

Hubs locked - 2 high - 70MPH = severe vibration.

Hubs locked - 4 high - 70 MPH = very severe vibration.

Hubs locked - 4 low - 10 MPH = no vibration.

Transfer case shifter rattles all the time.

Visually inspected all u-Joints - look good.

Anyone got an idea on were to start?

Thanks

68K20 x Drill · 12-08-2007, 01:05 AM

Front driveshaft sloppy at splines or bent.
Check tie rods and ball joints.
Look inside the diff for stray parts?
Put it up on 4 stands and run it till you see vibration.
^Bad idea, so be extra careful.

Blazer1970 · 12-08-2007, 06:35 AM

Definitely check the slip joint in the front shaft. The tires, wheels, hubs, and rotors turn all the time. There is nothing in the front axle that will cause a "severe vibration" while driving. Even if the steering u-joints are completely shot it is not real noticable when running straight down the highway. That leaves the front driveshaft.

wpvtx · 12-08-2007, 12:38 PM

Thanks for the ideas - starting to fell a little frustration. Every time I drive the truck Im finding more and more wrong with it.

By the way this is the best forum out there - A great goup of people.

68K20 x Drill · 12-08-2007, 01:44 PM

Do both hubs actually lock?
And are the yokes for the front shaft loose?

**Zoomad75** · 12-08-2007, 04:47 PM

Your description of the vibration is exactly what I had last year. Driving with the hubs locked in even in 2Hi will cause the driveshaft to spin. Even though there isn't any power going through it, mine would rattle the t-case shifter at highway speeds. Unlock the hubs and the noise was gone. With the hubs locked in and in 4hi it was even worse the faster you went.

Result of my issue was the CV in the front shaft was wiped out. The u-joints were dry, but more importantly the ball/socket of the CV was wasted. This allowed the entire assembly to flop around. All I had to do was rotate the shaft by hand with the hubs unlocked and in 2hi. It was a tell tale clunk in either direction.

That would be the #1 item to look for. If you do have a tendancy to run around with the hubs locked with the t-case in 2hi, you might want to check the wheel bearings out. Running with the hubs locked in when you don't need it puts more stress on the wheel bearings. This was pretty common on the full time 203 t-case equipped trucks, running with the hubs locked is just like that. Somebody that had my truck before me did that because my wheel bearings were wasted too. But I had fixed that before the driveshaft got sloppy.

If the CV needs rebuilt, you'll need to take it to a shop to get done. That is unless you got the tools needed to do it. I got a buddy price on my and it still ran me $50

JAKES 68GMC · 12-08-2007, 05:52 PM

Quote:

Originally Posted by wpvtx

Every time I drive the truck Im finding more and more wrong with it.

Don't feel bad, thats a pretty big club.

wpvtx · 12-08-2007, 07:03 PM

Thanks for the replys,

As for the front CV joint - it has been removed and a standerd universal jiont installed - the driveshaft has been resized and balanced it is from a cherokee, it was to long.

So, ill look into the wheel bearings and give this driveshaft anouther whurl on the balancer at a local shop.

Im going to have to just go out and get my fat belly under this thing.

Thanks agian.

wpvtx

Blazer1970 · 12-09-2007, 06:46 AM

Quote:

Originally Posted by wpvtx

As for the front CV joint - it has been removed and a standerd universal jiont installed - the driveshaft has been resized and balanced it is from a cherokee, it was to long.

This is your problem. You need the double cardan joint in there. The u-joint angles on the front shaft are not designed for a single joint at each end.

LONGHAIR · 12-09-2007, 02:14 PM

If the vibration comes through the steering wheel at all, it could be a rusted (frozen) axle joint. I have seen them get so stiff that you could not bend the joint by hand after the axle was out of the truck. If the hub is unlocked the joint will work its way to the easiest way to bend and stay there. With the hubs locked in a stiff axle will cause steering wheel vibrations, beat-up the inside of the spindle, wear-out the guts of the lockout hub, it may also make the steering not want to straighten out after a turn.

12-08-2007, 01:05 AM	#2
68K20 x Drill Registered User Join Date: Apr 2007 Location: Freedom CA Posts: 488	Re: Freeway driving Front driveshaft sloppy at splines or bent. Check tie rods and ball joints. Look inside the diff for stray parts? Put it up on 4 stands and run it till you see vibration. ^Bad idea, so be extra careful. __________________ 68 Chevrolet k20 Longbed 350 SM465/205, Dana 44, 14bolt, Power steering, Power Disk Brakes, 35" BFGs. 84 Chevrolet Suburban K20 6.2 Banks turbo TH400/NP208 Now with G80 68 GMC C20 Parts? Truck And a few cars

12-08-2007, 06:35 AM	#3
Blazer1970 Registered User Join Date: Dec 1999 Location: Old Mission, MI, USA Posts: 2,507	Re: Freeway driving Definitely check the slip joint in the front shaft. The tires, wheels, hubs, and rotors turn all the time. There is nothing in the front axle that will cause a "severe vibration" while driving. Even if the steering u-joints are completely shot it is not real noticable when running straight down the highway. That leaves the front driveshaft. __________________ Tim Last edited by Blazer1970; 12-08-2007 at 06:40 AM.

12-08-2007, 12:38 PM	#4
wpvtx Registered User Join Date: Apr 2007 Location: Burnsville MN Posts: 51	Re: Freeway driving Thanks for the ideas - starting to fell a little frustration. Every time I drive the truck Im finding more and more wrong with it. By the way this is the best forum out there - A great goup of people. __________________ 1970 Chevy K10 350 CID with 4 speed 4" lift with 86 Dana 44 Front disk brakes Electric fan/Internal regulated Alt.

12-08-2007, 01:44 PM	#5
68K20 x Drill Registered User Join Date: Apr 2007 Location: Freedom CA Posts: 488	Re: Freeway driving Do both hubs actually lock? And are the yokes for the front shaft loose? __________________ 68 Chevrolet k20 Longbed 350 SM465/205, Dana 44, 14bolt, Power steering, Power Disk Brakes, 35" BFGs. 84 Chevrolet Suburban K20 6.2 Banks turbo TH400/NP208 Now with G80 68 GMC C20 Parts? Truck And a few cars

12-08-2007, 04:47 PM	#6
Zoomad75 K5Camper Join Date: Mar 2004 Location: Pueblo, CO Posts: 1,513	Re: Freeway driving Your description of the vibration is exactly what I had last year. Driving with the hubs locked in even in 2Hi will cause the driveshaft to spin. Even though there isn't any power going through it, mine would rattle the t-case shifter at highway speeds. Unlock the hubs and the noise was gone. With the hubs locked in and in 4hi it was even worse the faster you went. Result of my issue was the CV in the front shaft was wiped out. The u-joints were dry, but more importantly the ball/socket of the CV was wasted. This allowed the entire assembly to flop around. All I had to do was rotate the shaft by hand with the hubs unlocked and in 2hi. It was a tell tale clunk in either direction. That would be the #1 item to look for. If you do have a tendancy to run around with the hubs locked with the t-case in 2hi, you might want to check the wheel bearings out. Running with the hubs locked in when you don't need it puts more stress on the wheel bearings. This was pretty common on the full time 203 t-case equipped trucks, running with the hubs locked is just like that. Somebody that had my truck before me did that because my wheel bearings were wasted too. But I had fixed that before the driveshaft got sloppy. If the CV needs rebuilt, you'll need to take it to a shop to get done. That is unless you got the tools needed to do it. I got a buddy price on my and it still ran me $50 __________________ Rob Z. 1975 K5 350/465/205/D44/12b 4" lift on 35's- RIP 1991 K5 8.1L/NV4500/241/D44/14b FWC Camper

12-07-2007, 11:53 PM	#1
wpvtx Registered User Join Date: Apr 2007 Location: Burnsville MN Posts: 51	Freeway driving Ok - the scoop here, 4 speed - NP205 - 31" tires - 86 suburban dana 44 in a 1970 stepside. Hubs unlocked - 2 high - 70MPH = no vibration. Hubs locked - 2 high - 70MPH = severe vibration. Hubs locked - 4 high - 70 MPH = very severe vibration. Hubs locked - 4 low - 10 MPH = no vibration. Transfer case shifter rattles all the time. Visually inspected all u-Joints - look good. Anyone got an idea on were to start? Thanks __________________ 1970 Chevy K10 350 CID with 4 speed 4" lift with 86 Dana 44 Front disk brakes Electric fan/Internal regulated Alt.

12-08-2007, 07:03 PM	#8
wpvtx Registered User Join Date: Apr 2007 Location: Burnsville MN Posts: 51	Re: Freeway driving Thanks for the replys, As for the front CV joint - it has been removed and a standerd universal jiont installed - the driveshaft has been resized and balanced it is from a cherokee, it was to long. So, ill look into the wheel bearings and give this driveshaft anouther whurl on the balancer at a local shop. Im going to have to just go out and get my fat belly under this thing. Thanks agian. wpvtx __________________ 1970 Chevy K10 350 CID with 4 speed 4" lift with 86 Dana 44 Front disk brakes Electric fan/Internal regulated Alt.

12-09-2007, 02:14 PM	#10
LONGHAIR just can't cover up my redneck Join Date: May 2004 Location: Columbus OH Posts: 11,414	Re: Freeway driving If the vibration comes through the steering wheel at all, it could be a rusted (frozen) axle joint. I have seen them get so stiff that you could not bend the joint by hand after the axle was out of the truck. If the hub is unlocked the joint will work its way to the easiest way to bend and stay there. With the hubs locked in a stiff axle will cause steering wheel vibrations, beat-up the inside of the spindle, wear-out the guts of the lockout hub, it may also make the steering not want to straighten out after a turn.



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