vibration when hubs unlocked - The 1947 - Present Chevrolet & GMC Truck Message Board Network

704x4 · 12-20-2003, 06:21 PM

I have been running my 70 k20 (79 fame) with no front drive shaft for the last two years to do away with the full time 4x4. I fainally got around to putting mile marker hubs and conversion kit in my 203 this winter. At first it worked fine, but the other day when i left home it started vibrating so bad that I couldn't drive over 30mph. So i pulled over checked everything visually, and it looked ok so i pulled back out on the road and it drove fine. Later that night it start vibrating again, but only over 60mph with the hubs unlocked. When i lock the hubs it doesn't vibrate anymore. I thought it was the front drive shaft, but im confused why it doesn't vibrate when the hubs are locked and the tcase is in 2wd. Any suggestions on where to start would be appreciated. Thank you!

rogf4 · 12-20-2003, 11:06 PM

Does it have a two piece rear shaft? Sounds like a carrier bearing or u joint Make sure u bolts on u joints are tight and in the center of the yolk

Scrub · 12-20-2003, 11:48 PM

What is vibrating? Steering wheel?
How much is this really related to having the hubs in or out. If you turn them out will it start right up?

Problems like this aren't cut and dried. You are going to have to do some experimentation.

How are your front brake rotors? They all get warped and need to be turned now and then. The usuall cause is water splasing on a hot drum (I think). I have to do mine about every 3 years. If they are bad, you will get more vibration when braking. Turning in the hubs might just putting enough load on the axle to stabilize the asembly and stop the vibration.

drink2mny · 12-21-2003, 02:58 AM

Did you mess with the bearings in the hubs??

there really isn't much that could cause a vibration up front.

weights off the rims.
bearings loose.
balljoints bad.
a broke belt in a tire..

these are some to check if it happens with the hubs unlocked.

1969 GMC · 12-21-2003, 05:15 AM

when I got my truck, if I put it in 4WD it would sound like a machine gun and rattle horribly, so bad that I couldn't drive at speeds over 25. turns out, the u joints on the front driveshaft were bad, causing the shaft to hit my exhaust pipe, and since it was offbalance it made the whole truck shake when in 4WD. maybe this helps?

12-20-2003, 06:21 PM	#1
704x4 Registered User Join Date: Feb 2002 Location: Greene, Iowa Posts: 150	vibration when hubs unlocked I have been running my 70 k20 (79 fame) with no front drive shaft for the last two years to do away with the full time 4x4. I fainally got around to putting mile marker hubs and conversion kit in my 203 this winter. At first it worked fine, but the other day when i left home it started vibrating so bad that I couldn't drive over 30mph. So i pulled over checked everything visually, and it looked ok so i pulled back out on the road and it drove fine. Later that night it start vibrating again, but only over 60mph with the hubs unlocked. When i lock the hubs it doesn't vibrate anymore. I thought it was the front drive shaft, but im confused why it doesn't vibrate when the hubs are locked and the tcase is in 2wd. Any suggestions on where to start would be appreciated. Thank you! Attached Images __________________ 70 3/4 ton 4x4 FOR SALE Greene, IA

12-20-2003, 11:06 PM	#2
rogf4 Registered User Join Date: Nov 2003 Location: whitesburg,Tn Posts: 223	vibration Does it have a two piece rear shaft? Sounds like a carrier bearing or u joint Make sure u bolts on u joints are tight and in the center of the yolk

12-20-2003, 11:48 PM	#3
Scrub Collector of rusty Items Join Date: Dec 2001 Location: Sisters,Oregon USA Posts: 731	What is vibrating? Steering wheel? How much is this really related to having the hubs in or out. If you turn them out will it start right up? Problems like this aren't cut and dried. You are going to have to do some experimentation. How are your front brake rotors? They all get warped and need to be turned now and then. The usuall cause is water splasing on a hot drum (I think). I have to do mine about every 3 years. If they are bad, you will get more vibration when braking. Turning in the hubs might just putting enough load on the axle to stabilize the asembly and stop the vibration. __________________ Scrub Sisters, Oregon - Home of the Sisters Rodeo. 70 GMC 1,000,000 + miles 72 K-20 project, 456 Dana60 front, Corp14 rear w/locker, 265R19.5 tires 20-ply. Warn 12k winches both ends, Cross-over steering with raised tie-rod, Powerbox steering, 4500 watt 120-AC power, Air, Hydraulic aux power, 4 inch lift, 5000 lb air-bags both ends.

12-21-2003, 02:58 AM	#4
drink2mny Registered User Join Date: Jun 2003 Location: spokane wa Posts: 2,189	Did you mess with the bearings in the hubs?? there really isn't much that could cause a vibration up front. weights off the rims. bearings loose. balljoints bad. a broke belt in a tire.. these are some to check if it happens with the hubs unlocked. __________________ Support The Board

12-21-2003, 05:15 AM	#5
1969 GMC Registered User Join Date: Feb 2003 Location: The Rubber City Posts: 5,498	when I got my truck, if I put it in 4WD it would sound like a machine gun and rattle horribly, so bad that I couldn't drive at speeds over 25. turns out, the u joints on the front driveshaft were bad, causing the shaft to hit my exhaust pipe, and since it was offbalance it made the whole truck shake when in 4WD. maybe this helps? __________________ 1969 GMC K2500 1996 Honda Accord 2007 Kawasaki KLR 650

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