Vibration

J

john nicholls

New member
Aug 18, 2010
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I am stumped. Severe vibration at 35 which goes away at 45. Quite violent. Ran with the hatch open today and it is the engine. Had thought it was
tires but complete balance Friday killed that theory. What would make the engine shudder so and then go away. Comments and suggestions most
appreciated.
--
John Nicholls,
78 Royale w/455
Pensacola, FL
 
Did you check the CV shafts? I’m thinking one of the inners.

Dolph

DE AD0LF

Wheeling, West Virginia

1977 26’ ex-PalmBeach
Howell EFI & EBL, Reaction Arms, Sullybilt Bags, Manny Transmission

“The Aluminum and Fiberglass Mistress"

>
> I am stumped. Severe vibration at 35 which goes away at 45. Quite violent. Ran with the hatch open today and it is the engine. Had thought it was
> tires but complete balance Friday killed that theory. What would make the engine shudder so and then go away. Comments and suggestions most
> appreciated.
> --
> John Nicholls,
> 78 Royale w/455
> Pensacola, FL
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
 
Very possible. At Amana a guy had that same situation. Sure enough, got
it outta there and it was falling apart with dried up grease.
John Lebetski can tell ya more. I think it was on the passenger side.
Gotta lift it up and listen to both sides with a hose or screwdriver
(hillbilly stethoscope).

bdub

On Sat, Feb 16, 2019 at 6:47 PM Dolph Santorine via Gmclist <

> Did you check the CV shafts? I’m thinking one of the inners.
>
>
> Dolph
>
> DE AD0LF
>
> Wheeling, West Virginia
>
> 1977 26’ ex-PalmBeach
> Howell EFI & EBL, Reaction Arms, Sullybilt Bags, Manny Transmission
>
> “The Aluminum and Fiberglass Mistress"
>
> > On Feb 16, 2019, at 7:44 PM, John Nicholls via Gmclist <

> >
> > I am stumped. Severe vibration at 35 which goes away at 45. Quite
> violent. Ran with the hatch open today and it is the engine. Had thought
> it was
> > tires but complete balance Friday killed that theory. What would make
> the engine shudder so and then go away. Comments and suggestions most
> > appreciated.
> > --
> > John Nicholls,
> > 78 Royale w/455
> > Pensacola, FL
> >
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
Tire(s) out of round. Put front tires on rear and rear tires on front.

Front ride height can cause some strange things like that. At least measure it to see if it is way off.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
Long shot: Maybe the outer ring on your harmonic balancer has slipped.
--
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles,
Solar battery charging. GMCSJ and GMCMI member
 
With an assistant, hatch off, drive through that speed range and observe the axle shafts for any eliptical (out of round) motion. If the needle
bearings on the inner joint have failed the shaft can run off center and bind as far as free in and out telescopic motion. This will bind and cause
the entire powertrain to waddle on it's mounts. Also inspect the pass side support bearing to be sure the 3 bolts are snug. Also inspect that the
flange bolts are all present on both axle to final drive flanges. These can come loose if not installed correctly and cause excentric motion before
failure.
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
Hi John. It seems if the vibration was in the engine it would be an rpm vibration and would vibrate at that rpm in each gear. A mph only vibration
seems would be between the engine and the wheels. Physically get your hands on the shafts and joints and mid shaft bearings and try hard to find
loose motion. Check the differential mounts and bolts. Inner cv bolts..

> I am stumped. Severe vibration at 35 which goes away at 45. Quite violent. Ran with the hatch open today and it is the engine. Had thought it
> was tires but complete balance Friday killed that theory. What would make the engine shudder so and then go away. Comments and suggestions most
> appreciated.

--
C. Boyd
76 Crestmont
East Tennessee
 
John, first thing I would check would be drivers side inboard CV joint
flange bolts. They historically loosen with use, particularly when they are
improperly tightened to begin with.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

On Sun, Feb 17, 2019, 11:42 AM Charles Boyd via Gmclist <

> Hi John. It seems if the vibration was in the engine it would be an rpm
> vibration and would vibrate at that rpm in each gear. A mph only vibration
> seems would be between the engine and the wheels. Physically get your
> hands on the shafts and joints and mid shaft bearings and try hard to find
> loose motion. Check the differential mounts and bolts. Inner cv bolts..
>
>
>
>
>
>

> > I am stumped. Severe vibration at 35 which goes away at 45. Quite
> violent. Ran with the hatch open today and it is the engine. Had thought
> it
> > was tires but complete balance Friday killed that theory. What would
> make the engine shudder so and then go away. Comments and suggestions most
> > appreciated.
>
>
> --
> C. Boyd
> 76 Crestmont
> East Tennessee
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
Thanks all.
No loose bolts connecting inner cv joint to final drive, FD,. Did try to move the joints and there was some looseness on the drivers side at the FD
but all FDs that I have touched have some movement where the axle connects.
Checked tires for out of round while having them balanced. Ride height is low (3/8) on both sides and hace adjusted rears down also but has been like
that for years.
Would a slipped harmonic balancer affect only a specific speed range?
Removal of the axle is the next step but prior to that I am going to run a compression test to rule out anything like a misfire although one would
expect that to be worse at idle ( I think ).
--
John Nicholls,
78 Royale w/455
Pensacola, FL
 
John,

You haven't stated whether the vibration occurs when you rev the engine
through the 35 mph rpm range. Seems to me that might narrow the problem to
engine or running gear.

Ken H.

On Sun, Feb 17, 2019 at 8:22 PM John Nicholls via Gmclist <

> Thanks all.
> No loose bolts connecting inner cv joint to final drive, FD,. Did try to
> move the joints and there was some looseness on the drivers side at the FD
> but all FDs that I have touched have some movement where the axle connects.
> Checked tires for out of round while having them balanced. Ride height is
> low (3/8) on both sides and hace adjusted rears down also but has been like
> that for years.
> Would a slipped harmonic balancer affect only a specific speed range?
> Removal of the axle is the next step but prior to that I am going to run a
> compression test to rule out anything like a misfire although one would
> expect that to be worse at idle ( I think ).
> --
> John Nicholls,
> 78 Royale w/455
> Pensacola, FL
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
3/8" off on ride height will not hurt anything. I was just trying to make sure the axles were in a straight line and not causing excessive up / down
movement in a CV joint as you go down the road. I still suggest that you swap tires from front to rear and see if anything changes. I have seen out
of round tires that balance OK. I also have seen tires that track side to side just slightly and cause this problem.

As far as harmonic balancer goes, I have seen several that have slipped. Here are some balancer pictures from Roger Blacks coach:
http://www.gmcmhphotos.com/photos/data/3872/872_p10091.jpg
http://www.gmcmhphotos.com/photos/roger-5c-27s-harmonic-balancer/p10090.html
http://www.gmcmhphotos.com/photos/roger-5c-27s-harmonic-balancer/p10089.html
http://www.gmcmhphotos.com/photos/data/3872/thumbs/872_p10088.jpg

Here is what happened on Dan Gregg's harmonic balancer bolt came loose. Luckily we got by just replacing he balance and bolt.

http://www.gmcmhphotos.com/photos/gmcmi-2007-fall-convention-amana-colonies/p22634-at-the-rally.html
http://www.gmcmhphotos.com/photos/gmcmi-2007-fall-convention-amana-colonies/p22635-at-the-rally.html



--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
 
Try using a different gear when it happens. That will help determine if engine or after engine.
--
John Lebetski
Woodstock, IL
77 Eleganza II
 
You might check for a bad plug wire, or a bad spark plug, particularly if
someone has recently worked on the headers or the ignition system.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

On Mon, Feb 18, 2019, 6:37 AM John R. Lebetski via Gmclist <

> Try using a different gear when it happens. That will help determine if
> engine or after engine.
> --
> John Lebetski
> Woodstock, IL
> 77 Eleganza II
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
 
One other thing to check would be the motor mounts. You might be chasing two things, a bad inner CV joint and a broken motor mount. The bad inner CV on mine kept us from going to a GMCWS rally a number of years ago. I had just replaced them before that trip so couldn’t believe one could be bad, but it was. No visible evidence that it was bad but the coach vibrated at around 35 to the point I was not sure we should attempt the trip home. Over that the vibration subsided but never went away completely. In that search for root cause I also found one motor mount bad. I changed the mount and that joint and the symptoms went away never to return again.

Jerry
Jerry Work
Kerby, OR
 
Thanks all.
No loose bolts connecting inner cv joint to final drive, FD,. Did try to
move the joints and there was some looseness on the drivers side at the FD
but all FDs that I have touched have some movement where the axle connects.
Checked tires for out of round while having them balanced. Ride height is
low (3/8) on both sides and hace adjusted rears down also but has been like
that for years.
Would a slipped harmonic balancer affect only a specific speed range?
Removal of the axle is the next step but prior to that I am going to run a
compression test to rule out anything like a misfire although one would
expect that to be worse at idle ( I think ).
--
John Nicholls,
78 Royale w/455
Pensacola, FL

*************************
 
Fred, thanks for the reply. In fact, I am running Goodrich Commercial T/A tires. I will check for that issue. Wish Alex was closer.

--
John Nicholls,
78 Royale w/455
Pensacola, FL
 
Been having this issue too. I have these same tires on the motorhome. It will be getting a new set this season.

Tom
Eleganza 2
KCMO
 
Swap the tires and see first. If it persists, then it is possibly the
joints.

On Sat, Feb 23, 2019 at 9:43 AM tom geiger via Gmclist <

> Been having this issue too. I have these same tires on the motorhome. It
> will be getting a new set this season.
>
> Tom
> Eleganza 2
> KCMO
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

--
Jim Kanomata
Applied/GMC, Newark,CA
jimk
http://www.appliedgmc.com
1-800-752-7502
 
The left front tire opf the same make on my current coach turned out to have a belt separation which showed up at road speed. A set of Coopers, runs
smooth now.

--johnny
--
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
"I forgive them all, save those who hurt the dogs. They must answer to me in hell" - ol Andy, paraphrased
 
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