Not so good vibrations - The 1947 - Present Chevrolet & GMC Truck Message Board Network

White70C20 · 01-10-2013, 01:48 PM

As I've been driving my ol' 70 more, I've noticed a vibration. It's not a steady vibration, more intermittent. It feels like it's coming from the drivetrain, but I'm not sure. Besides U-joints, what else do I need to consider? Also, is it bad to drive it very far like this? Sometimes I take it to work (60 miles round trip).
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Longhorn 70 · 01-10-2013, 02:02 PM

Mine had a vibration caused by defective Transmission mount. Replaced it and much smoother....
It wasn't intermittent but did increase with speed or RPM.

White70C20 · 01-10-2013, 03:19 PM

Mine changes with speed too. There's about 5-6 seconds between each vibration.
Could it be something wheel related? I had the rear wheels balanced when I had the bigger tires put on, but it was vibrating some before then. I'm just curious if I can still drive it the way it is?
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1972SUPERSB · 01-10-2013, 03:20 PM

Maybe the driveshaft is not balanced correctly?
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geezer#99 · 01-10-2013, 03:21 PM

2 piece driveshaft has a steady bearing in the middle.

yuccales · 01-10-2013, 03:32 PM

Check your pinion nut, also see if you have a bunch of slop in your ring & pinion. I had a similar "harmonic" vibration in a 12 bolt rear in my Malibu. Found out the back lash was way off.

brad_man_72 · 01-10-2013, 04:41 PM

Driveshafy vibration. Ok so you already know the ujoints could be bad, good. If its a one piece the tranny yoke could have been flipped 180* and cause a vibration
If 2 piece tranny yoke could have been flipped, bolt on yoke could have been turned to one of the 8 or so wrong positions, rear driveshaft could be flipped 180* or in completely backwards. If it has a slip yoke it could be turned to one of the 20 or so wrong positions.

Oh then you have physical damage like dents, bends in the tubing worn weld yokes, bad ujoints, failed carrier bearing, worn tranny yoke, worn tranny bushing. Or if you have it a worn slip and stub.

If you narrow it down to the driveshaft and value your time and money take it to a pro, if i t needs ujoints get good ones, and have it ballanced.

As you're aware there's plenty of other things it could be. Good luck.
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CCCC · 01-10-2013, 06:15 PM

Didn't say whether your truck is auto trans or manual, or if it is 10, 20, 30 series.

Do you have the vibration when coasting - try it downhil? If so, that could eliminate thrust issue in driveline. If this vibe came on rather suddenly and occurs mainly when there is thrust on, I would check, in this order:
Loose/worn U joints
Loose/cracked Trans and Motor mounts
Carrier bearing wear (if you have one)

After those, would seem to be drive shaft misbalance, trans output issue (as noted by someone earlier), begining of flex plate breakage in auto trans, or wear in the diff assy.

This is not usually manual trans/clutch issue.

Good luck

White70C20 · 01-11-2013, 08:11 PM

Sorry, here's the details: 1970 C20 - 350, TH350, 4.10
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Longhorn 70 · 01-11-2013, 08:47 PM

OOOOHHHH I just thought of something else. I have seen some of the driveshafts that have a keyed center and some without. Could your front and rear driveshaft be clocked wrong??

White70C20 · 01-11-2013, 10:51 PM

Thanks for all the great ideas guys!

Still, part of my original question was: can it still be driven (somewhat reliably) the way it is? I am going to have it fixed, I just want to be able to drive it in the meantime, until I have time/money to have a professional take a look at it. I love driving the thing.
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White70C20 · 01-11-2013, 10:54 PM

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Scott>72-GMC · 01-11-2013, 11:10 PM

My truck shakes at higher rpms but does it while parked too so I'm sure it isn't the drive shaft on mine anyway. The biggest concern of course is causeing more damage than there is depending what it is if u snap a u joint and loose ur drive shaft obviously ur stuck if its a mild vibration and everything looks ok and ur just getting by for a short time in "my" opinion if it was me I might baby it but not for long bigger problems may happen
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White70C20 · 01-12-2013, 12:04 AM

Ok, that's what I thought. I'll have to do some investigating tomorrow morning.
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brad_man_72 · 01-13-2013, 01:21 AM

Quote:

Originally Posted by White70C20

Mine changes with speed too. There's about 5-6 seconds between each vibration.
Could it be something wheel related? I had the rear wheels balanced when I had the bigger tires put on, but it was vibrating some before then. I'm just curious if I can still drive it the way it is?
Posted via Mobile Device

Its best to know what the vibration is, I know a guy who cracked 3 transfer cases before he fixed his vibration (driveshaft out of ballance, I think it was shortened at home).
Some vibrations are less serious obviously, but your truck shouldn't Vibrate much, its obviously not a new toyota, but the vibration is a warning sign that something has gone wrong or something is about to go seriously wrong.

Its always cheaper to fix a small problem than to fix a small problem and whatever else it takes out.
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Scott>72-GMC · 01-13-2013, 01:48 AM

Quote:

Originally Posted by brad_man_72

Its best to know what the vibration is, I know a guy who cracked 3 transfer cases before he fixed his vibration (driveshaft out of ballance, I think it was shortened at home).
Some vibrations are less serious obviously, but your truck shouldn't Vibrate much, its obviously not a new toyota, but the vibration is a warning sign that something has gone wrong or something is about to go seriously wrong.

Its always cheaper to fix a small problem than to fix a small problem and whatever else it takes out.
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Agreed
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01-10-2013, 01:48 PM	#1
White70C20 Registered User Join Date: Oct 2012 Location: Kansas and Iowa Posts: 349	Not so good vibrations As I've been driving my ol' 70 more, I've noticed a vibration. It's not a steady vibration, more intermittent. It feels like it's coming from the drivetrain, but I'm not sure. Besides U-joints, what else do I need to consider? Also, is it bad to drive it very far like this? Sometimes I take it to work (60 miles round trip). Posted via Mobile Device __________________ White70C20 1970 Blue C20 - 250, 4 speed 1985 Ford Thunderbird 2005 Pontiac G6

01-10-2013, 02:02 PM	#2
Longhorn 70 Registered User Join Date: Dec 2012 Location: Chandler AZ Posts: 1,149	Re: Not so good vibrations Mine had a vibration caused by defective Transmission mount. Replaced it and much smoother.... It wasn't intermittent but did increase with speed or RPM. __________________ 1970 Longhorn, Front Disc, 350/4 bolt, 882 heads, HEI, Edelbrock, 700R4, HO-52/4.11. 1996 Corvette, Collector Roadster, LT4, 396, 450RWHP, 6sp, 4.11/Dana44/posi 5 point roll bar And let us not grow weary of doing good, for in due season we will reap, if we do not give up. Gal 6:9

01-10-2013, 03:19 PM	#3
White70C20 Registered User Join Date: Oct 2012 Location: Kansas and Iowa Posts: 349	Re: Not so good vibrations Mine changes with speed too. There's about 5-6 seconds between each vibration. Could it be something wheel related? I had the rear wheels balanced when I had the bigger tires put on, but it was vibrating some before then. I'm just curious if I can still drive it the way it is? Posted via Mobile Device __________________ White70C20 1970 Blue C20 - 250, 4 speed 1985 Ford Thunderbird 2005 Pontiac G6

01-10-2013, 03:20 PM	#4
1972SUPERSB Registered User Join Date: Sep 2012 Location: San Antonio, TX Posts: 1,026	Re: Not so good vibrations Maybe the driveshaft is not balanced correctly? Posted via Mobile Device __________________ Jeff 1972 Cheyenne Super SWB 350, Auto, Bucket Seats w/Console, Tach, Factory A/C, P/S ,P/B, Tilt 1998 Chevy 1500 Ext Cab 5.7, Pewter w/blue interior

01-10-2013, 03:21 PM	#5
geezer#99 Registered User Join Date: Aug 2009 Location: Bowser Posts: 13,736	Re: Not so good vibrations 2 piece driveshaft has a steady bearing in the middle.

01-10-2013, 03:32 PM	#6
yuccales Registered User Join Date: May 2011 Location: Northern Calif. Posts: 3,777	Re: Not so good vibrations Check your pinion nut, also see if you have a bunch of slop in your ring & pinion. I had a similar "harmonic" vibration in a 12 bolt rear in my Malibu. Found out the back lash was way off.

01-10-2013, 04:41 PM	#7
brad_man_72 the boat guy Join Date: Jul 2007 Location: springfield mo Posts: 2,339	Re: Not so good vibrations Driveshafy vibration. Ok so you already know the ujoints could be bad, good. If its a one piece the tranny yoke could have been flipped 180* and cause a vibration If 2 piece tranny yoke could have been flipped, bolt on yoke could have been turned to one of the 8 or so wrong positions, rear driveshaft could be flipped 180* or in completely backwards. If it has a slip yoke it could be turned to one of the 20 or so wrong positions. Oh then you have physical damage like dents, bends in the tubing worn weld yokes, bad ujoints, failed carrier bearing, worn tranny yoke, worn tranny bushing. Or if you have it a worn slip and stub. If you narrow it down to the driveshaft and value your time and money take it to a pro, if i t needs ujoints get good ones, and have it ballanced. As you're aware there's plenty of other things it could be. Good luck. Posted via Mobile Device __________________ 67, swb, fleet, tach, throttle, 5.3, 4l60e, 3.73's, fuel cell, 5 lug, p.d.b., 4-6 drop. great little truck 66, stevens drag/ski 18' silouette, 350, 2.02 doublehump heads. comp extreme marine 278 cam, vette 7 fin valve covers, old polished edelbrock intake, velvetdrive, casale v-drive, adj cavitation plate. 28, model a rpu project,

01-10-2013, 06:15 PM	#8
CCCC Registered User Join Date: Mar 2007 Location: San Pedro River, SE Arizona Posts: 734	Re: Not so good vibrations Didn't say whether your truck is auto trans or manual, or if it is 10, 20, 30 series. Do you have the vibration when coasting - try it downhil? If so, that could eliminate thrust issue in driveline. If this vibe came on rather suddenly and occurs mainly when there is thrust on, I would check, in this order: Loose/worn U joints Loose/cracked Trans and Motor mounts Carrier bearing wear (if you have one) After those, would seem to be drive shaft misbalance, trans output issue (as noted by someone earlier), begining of flex plate breakage in auto trans, or wear in the diff assy. This is not usually manual trans/clutch issue. Good luck __________________ CCCC 67 Sting Ray Coupe 327 4sp; 68 K10 Suburban 327 4sp; 69 K20 Lifted 383 4sp; 69 C80 Fire Truck 478 V6 5sp/2sp; 69 C20 Longhorn 327 4sp; 70 C30 Wrecker 350 4sp; 70 C30 Flat Bed 350 4sp; 71 C20 LWB 350 4sp; 72 K5 Blazer 350 4sp; 72 C30 Flat Bed Gooseneck Hauler with sleeper 350/TH400; 72 C20 Longhorn 402 4sp; 52 Mack LTL Supercharged Cummins 5sp x 3sp; 01 Dodge 5.9 HO Cummins 6spd; 02 Safari Trek 2430 8.1 Vortec on Workhorse Chassis; 03 Silverado 2500 HD 4wd Duramax/Allison Moved but still in the family 70 C20 Custom Camper 350/TH350; 72 K5 Blazer CST Highlander 350/TH350 Recently sent to new homes 72 C30 MoHome 402 4sp; 72 K5 Blazer Conv 350 4sp; 75 GMC 6000 Aerial 350 w Allison; 72 GMC 3500 Utility 350 4sp; 70 GMC 3500, 350 4sp

01-11-2013, 08:11 PM	#9
White70C20 Registered User Join Date: Oct 2012 Location: Kansas and Iowa Posts: 349	Re: Not so good vibrations Sorry, here's the details: 1970 C20 - 350, TH350, 4.10 Posted via Mobile Device __________________ White70C20 1970 Blue C20 - 250, 4 speed 1985 Ford Thunderbird 2005 Pontiac G6

01-11-2013, 08:47 PM	#10
Longhorn 70 Registered User Join Date: Dec 2012 Location: Chandler AZ Posts: 1,149	Re: Not so good vibrations OOOOHHHH I just thought of something else. I have seen some of the driveshafts that have a keyed center and some without. Could your front and rear driveshaft be clocked wrong?? __________________ 1970 Longhorn, Front Disc, 350/4 bolt, 882 heads, HEI, Edelbrock, 700R4, HO-52/4.11. 1996 Corvette, Collector Roadster, LT4, 396, 450RWHP, 6sp, 4.11/Dana44/posi 5 point roll bar And let us not grow weary of doing good, for in due season we will reap, if we do not give up. Gal 6:9

01-11-2013, 10:51 PM	#11
White70C20 Registered User Join Date: Oct 2012 Location: Kansas and Iowa Posts: 349	Re: Not so good vibrations Thanks for all the great ideas guys! Still, part of my original question was: can it still be driven (somewhat reliably) the way it is? I am going to have it fixed, I just want to be able to drive it in the meantime, until I have time/money to have a professional take a look at it. I love driving the thing. Posted via Mobile Device __________________ White70C20 1970 Blue C20 - 250, 4 speed 1985 Ford Thunderbird 2005 Pontiac G6

01-11-2013, 10:54 PM	#12
White70C20 Registered User Join Date: Oct 2012 Location: Kansas and Iowa Posts: 349	Re: Not so good vibrations Posted via Mobile Device __________________ White70C20 1970 Blue C20 - 250, 4 speed 1985 Ford Thunderbird 2005 Pontiac G6

01-11-2013, 11:10 PM	#13
Scott>72-GMC Registered User Join Date: Jan 2013 Location: New providence ia Posts: 1,018	Re: Not so good vibrations My truck shakes at higher rpms but does it while parked too so I'm sure it isn't the drive shaft on mine anyway. The biggest concern of course is causeing more damage than there is depending what it is if u snap a u joint and loose ur drive shaft obviously ur stuck if its a mild vibration and everything looks ok and ur just getting by for a short time in "my" opinion if it was me I might baby it but not for long bigger problems may happen Posted via Mobile Device

01-12-2013, 12:04 AM	#14
White70C20 Registered User Join Date: Oct 2012 Location: Kansas and Iowa Posts: 349	Re: Not so good vibrations Ok, that's what I thought. I'll have to do some investigating tomorrow morning. Posted via Mobile Device __________________ White70C20 1970 Blue C20 - 250, 4 speed 1985 Ford Thunderbird 2005 Pontiac G6



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