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| Front end vibration [message #159947] |
Fri, 10 February 2012 20:17  |
Bruce Hart
Messages: 1501
Registered: October 2011
Location: La Grange, Wyoming
Karma: 5
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I recently purchased a 1976 Palm Beach out of the Tucson area. The drive around town was pleasant and everything felt tight. It has 16.5" rims with very low mileage Michelin tires (7years old). The coach was in storage I believe for 4 to 5 years before it was put up for sale. On our trip to Phoenix at 60mph we notice a vibration in the front drive area, not teeth shattering but very noticeable. It would smooth out after 1/2 mile or so and would vibrate again at 60mph if I had slowed down and sped up. We drove it home to Colorado 1200 miles later. today I went to drain the black water tank and noticed that the vibration was there at 60mph put as I slowed down I felt another vibration in the steering wheel until I got down to 10 to 15 mph. No vibration when accelerating but I noticed a vibration as I was slowing down and also felt a pulsing in the brake pedal. I feel that there is a front end component, tie rod end, steering arm or something to do with the steering that is causing this vibration as it has gotten worse as I slow down now. At first I thought that maybe the tires need to be balanced but with the vibration now at the slower speed tells me different. As best that I could tell the bushing looked ok and there are new shocks all around.
Could this be the beginning of a bearing(s) going bad with 128k miles on the coach?
Any Ideas?
Bruce Hart
1976 Palm Beach
1977 28' Kingsley
La Grange, Wyoming
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| Re: Front end vibration [message #159952 is a reply to message #159947] |
Fri, 10 February 2012 21:31  |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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Vibrations can come from many sources and once you get used to the coach you can start to pin down the source. Most vibrations are speed dependent and can be isolated with some more diagnostics. First of all, I would not even remotely panic and assume the worst. First possibility is tire unbalance, then tire/wheel uniformity, then U joint wear or incorrect angles, and them possible wheel bearing issues as a long long distant possibility. Front suspension wear and worn shocks can make the coach more susceptible to vibration but you still need a source to excite it. The pulsing in the brake pedal can be run out of the disks or drums but the GMC is not known for that. I would suspect corrosion on the rotors that will clear itself after some use. Also, many times there are 2 or 3 sources for vibration that manifest themselves at various speeds. If it has been sitting, I would exercise the coach for a while and see what happens, but i don't think you need to worry too much yet. Be carefull about feedback suggesting the end of the earth on this one 
Bob de Kruyff
78 Eleganza
Chandler, AZ
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| Re: Front end vibration [message #159957 is a reply to message #159947] |
Fri, 10 February 2012 21:52 |
RadioActiveGMC
Messages: 1020
Registered: November 2010
Location: Hot AZ desert
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I stink at hardcore trouble shooting. But when my 23ft drives on most of the trip up to PHX on I-10 like you took the road surface is horrible. I get a vibration that comes then goes and comes back then goes, and comes back and goes. I was sure it was a tire issue but the road surface does it. The truck rut, and car ruts with the staggered tires on the GMC make it weird.
***"Gettin There"-1973 23' Sequoia-
Michael, Onans smell, "Go solar/wind power!"
[Updated on: Sat, 11 February 2012 09:10] Report message to a moderator |
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| Re: Front end vibration [message #159972 is a reply to message #159947] |
Sat, 11 February 2012 00:57 |
Craig Lechowicz
Messages: 541
Registered: October 2006
Location: Waterford, MI
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Seven years is getting up there in tires, especially if you don't know what they've been through. Generalizing is usually not a great idea, but typically a vibration between 55 and 65 is usually tire balance, especially if you feel it in the steering column or wheel. A slow speed vibration, especially down in the 10 or 15 mph range (maybe more like a shake or a wallow) could be a broken or shifted belt in a tire, which relates to the age comment. It might be worth rotating the rearmost tires to the front, and seeing if you notice anything different. Pulsing in the brake pedal is most often caused by the brake rotors having thickness variation between the inner and outer sides. (usually referred to as out-of-round, but it's really the two sides not being parallel with each other). So, as Bob says, it could be more than one set of issues. I wasn't sure if by slowing down, you meant while braking, or while traveling at slower speeds. Usually, things like bearings and c/v joints are more noticeable under power than they are under coast, so if driving slow, maybe tires, and if while braking, maybe brake rotors.
Just a few thoughts.
Craig Lechowicz
'77 Kingsley, Waterford, MI
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| Re: Front end vibration [message #160001 is a reply to message #159947] |
Sat, 11 February 2012 14:18 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Tires may be flatspotted or they have take a "set" from sitting. This was more an old days problem but with 16.5s the tire may be of earlier design or construction. You need to check all the front end parts (about a 20 min job with a helper) and grease the front end. Rob M posted a check list to follow so you cover all the joints for slop. Also the steering stablizer can be bad if it is leaking or even if it is not. I had one that was not leaking but had about 3/4" of loose play before it got to the working part of the stroke. Looked great, worked horrible. 3/4" of L/R play is a whole lot of steering angle, so it was not working at all basicly. If the front end is all good then you can look to the tires and if they are still worth putting money into, you can check for visible runnout while they are on the balancing machine. Don't want the Flintstones square tires. No ammount of balancing will fix it.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] Front end vibration [message #160012 is a reply to message #160001] |
Sat, 11 February 2012 16:52 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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G'day,
I revised the steering checklist after vetting it at Bean Station last year and found out there were better ways of checking some of
the parts in situ.
I changed it a lot and sent it to the editor (Byron) who read it, found it a bit confusing, and explained why. I re-read it through
his eyes and agreed he was right.
I am working on re-revising it now.
Now here's the funny bit - I just looked at it and the Steering Stabilizer ISN'T mentioned. DOUH!
Byron, I reckon that's hilarious - forest / tree syndrome!
Regards,
Rob M.
PS - Thanks John!
-----Original Message-----
From: John R. Lebetski
Tires may be flatspotted or they have take a "set" from sitting. This was more an old days problem but with 16.5s the tire may be
of earlier design or construction. You need to check all the front end parts (about a 20 min job with a helper) and grease the front
end. Rob M posted a check list to follow so you cover all the joints for slop. Also the steering stablizer can be bad if it is
leaking or even if it is not. I had one that was not leaking but had about 3/4" of loose play before it got to the working part of
the stroke. Looked great, worked horrible. 3/4" of L/R play is a whole lot of steering angle, so it was not working at all
basicly. If the front end is all good then you can look to the tires and if they are still worth putting money into, you can check
for visible runnout while they are on the balancing machine. Don't want the Flintstones square tires. No ammount of balancing will
fix it.
--
John
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: Front end vibration [message #160020 is a reply to message #159947] |
Sat, 11 February 2012 18:32 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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What stabilizer??? I thought someone misinstalled a shock..
No really, I think you need to disconnedt one end of the stabilizer to to test it in situ. (OR then half in situ). Rob, at the last rally I helped Dave Lenzi in shaking down about 6 coaches and we found 3 that had the same problem. The clamp that holds the intermediate shaft to the bottom of the steering column was not homed properly. The shaft needs to be on the splines far enough so that the bolt of the clamp is in the relief that is cut into the shaft. 3 were not fully on and though unlkikely, could present a saftey issue, and it forces the intermediate shaft to be too far collapsed. Don't forget the lower column bearing slop test as well as that poor thing really attracts the road grime in the ball bearings and gets gritty and then wears. Too bad GM didn't put a fitting on that part but being nylon it would have had to be a higher end piece that cost more. Other than that, the most common slop zones were the drag links and the relay arms.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] Front end vibration [message #160033 is a reply to message #160020] |
Sat, 11 February 2012 19:50 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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John,
Agree on the stabilizer, it's basically a shock absorber it should be resistant to pulling either direction.
Agree on the clamps on both ends of the intermediate shaft.
The bottom bolt goes through a cast iron (forged?) clamp and needs to be torqued tighter than the hinges of hell!
IIRC the OEM bolt is a grade 8 NC 7/16 - 14 and I replaced it with a grade 8 NF 7 - 20 as it could be torqued higher.
Other items you mentioned are covered.
Regards,
Rob
-----Original Message-----
From: John R. Lebetski
What stabilizer??? I thought someone misinstalled a shock..
No really, I think you need to disconnedt one end of the stabilizer to to test it in situ. (OR then half in situ). Rob, at the last
rally I helped Dave Lenzi in shaking down about 6 coaches and we found 3 that had the same problem. The clamp that holds the
intermediate shaft to the bottom of the steering column was not homed properly. The shaft needs to be on the splines far enough so
that the bolt of the clamp is in the relief that is cut into the shaft. 3 were not fully on and though unlkikely, could present a
saftey issue, and it forces the intermediate shaft to be too far collapsed. Don't forget the lower column bearing slop test as well
as that poor thing really attracts the road grime in the ball bearings and gets gritty and then wears. Too bad GM didn't put a
fitting on that part but being nylon it would have had to be a higher end piece that cost more. Other than that, the most common
slop zones were the drag links and the relay arms.
--
John
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] Front end vibration [message #160059 is a reply to message #159947] |
Sun, 12 February 2012 09:15 |
Douglas Norton
Messages: 191
Registered: April 2008
Karma: 0
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Two things I would check: Raise the front wheels one at a time and spin each wheel slowly (in neutral with the rear wheels blocked) to see if there are any bubbles related to tread separation or other out of round issues. Also note if the breaks grab at any part of the rotation. I had a stuck caliper and that heated the rotor. A hot rotor can warp and then you get the pulse. Check your break pads to see if one side of the coach has more wear than the other, a sign of a stuck piston or caliper. Very old tires that have been sitting can develop a flat spot or memory. If you plan to replace the tires, that would be the easiest way to rule out the tires and have someone check your brakes at the same time. Also, if the breaks have locked up (usually rearmost tire) one or more tires can have a flat spot. If a tire with a flat spot got rotated to the front, that could be an issue. Hope this is helpful. Doug Norton
________________________________
From: Bruce Hart <hartsgmc@gmail.com>
To: gmclist@temp.gmcnet.org
Sent: Friday, February 10, 2012 6:17 PM
Subject: [GMCnet] Front end vibration
I recently purchased a 1976 Palm Beach out of the Tucson area. The drive around town was pleasant and everything felt tight. It has 16.5" rims with very low mileage Michelin tires (7years old). The coach was in storage I believe for 4 to 5 years before it was put up for sale. On our trip to Phoenix at 60mph we notice a vibration in the front drive area, not teeth shattering but very noticeable. It would smooth out after 1/2 mile or so and would vibrate again at 60mph if I had slowed down and sped up. We drove it home to Colorado 1200 miles later. today I went to drain the black water tank and noticed that the vibration was there at 60mph put as I slowed down I felt another vibration in the steering wheel until I got down to 10 to 15 mph. No vibration when accelerating but I noticed a vibration as I was slowing down and also felt a pulsing in the brake pedal. I feel that there is a front end component, tie rod end, steering arm or something to do with
the steering that is ca
using this vibration as it has gotten worse as I slow down now. At first I thought that maybe the tires need to be balanced but with the vibration now at the slower speed tells me different. As best that I could tell the bushing looked ok and there are new shocks all around.
Could this be the beginning of a bearing(s) going bad with 128k miles on the coach?
Any Ideas?
--
Bruce Hart
1976 Palm Beach
Milliken, Co
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| Re: [GMCnet] Front end vibration [message #160060 is a reply to message #159972] |
Sun, 12 February 2012 09:24 |
Bruce Hart
Messages: 1501
Registered: October 2011
Location: La Grange, Wyoming
Karma: 5
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On Fri, Feb 10, 2012 at 11:57 PM, Craig Lechowicz <
craig.lechowicz@sbcglobal.net> wrote:
>
>
> Seven years is getting up there in tires, especially if you don't know
> what they've been through. Generalizing is usually not a great idea, but
> typically a vibration between 55 and 65 is usually tire balance, especially
> if you feel it in the steering column or wheel. A slow speed vibration,
> especially down in the 10 or 15 mph range (maybe more like a shake or a
> wallow) could be a broken or shifted belt in a tire, which relates to the
> age comment. It might be worth rotating the rearmost tires to the front,
> and seeing if you notice anything different. Pulsing in the brake pedal is
> most often caused by the brake rotors having thickness variation between
> the inner and outer sides. (usually referred to as out-of-round, but it's
> really the two sides not being parallel with each other). So, as Bob says,
> it could be more than one set of issues. I wasn't sure if by slowing down,
> you meant while braking, or while traveling at slower speeds. Usually,
> things like bearings and c/v
> joints are more noticeable under power than they are under coast, so if
> driving slow, maybe tires, and if while braking, maybe brake rotors.
>
> Just a few thoughts.
>
Is there any physical evidence of a belt that has slipped or broken.
Thanks to everyone for your replies.
> --
> Craig Lechowicz
> '77 Kingsley, Waterford, MI
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Bruce Hart
GMC Wannabe
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Bruce Hart
1976 Palm Beach
1977 28' Kingsley
La Grange, Wyoming
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| Re: Front end vibration [message #160173 is a reply to message #159947] |
Mon, 13 February 2012 05:13 |
MIGUEL MENDEZ
Messages: 179
Registered: August 2004
Location: Montclair, California
Karma: 3
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Senior Member |
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For a few years, I worked in the wheel ind. , American racing, Eagle wheels, eagle alloy, KMC and so on, many, many times we would get a guy bring in his truck or car woth vib problems after many trips to the front end shops, only to find, the tires are seperated, at the wheel houses, we have DOT wheel tester, we would mount a new tire on a rim, spin it to 100 mph actual rotationg and the slam it to the ground, most of the times the tire would blow apart, but our test was for the wheel, so, we spun his tire at 65 MPH and that was when we noticed the bubble seperation.
not all radial seperation is seen by the eye but felt at speed, and no, not all RS blows apart right away, Betty G drove from atasadero to newport for a rally, i got there aroung 10 pm after helping a few brake downs on the road, she was right at my parking spot, with 4 other WELL know gmc'ers all telling her what her problem is, ie... shocks, steering dampner, bearings etc....., she wanted me to tear her unit apart right then and there, after listening to the big guys, i look at betty and told her, sounds to me like RS now, can i park my GMC so i can hook up????.
as it turns out, she came to my doot a 5 am, knocked am i wike up, happy as a lark just to tell me, she in fact had a big bubble on her right front?????, please, even though a tire looks good, with nipples still on it, does not mean it is still serviceable, i would never in my life put on a spare tire that has been hanging back there for 7 years and never rotated in to service.
just my thoughts
Miguel
1978 Royale Pain in the %$@, side bath w/ a 403 that i love.
GMC name : The other woman
http://www.mgmgmc.com
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| Re: [GMCnet] Front end vibration [message #160550 is a reply to message #159947] |
Thu, 16 February 2012 15:09 |
Bruce Hart
Messages: 1501
Registered: October 2011
Location: La Grange, Wyoming
Karma: 5
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Senior Member |
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I got a day off from work and took the GMC to a local tire shop. It just
so happened that the owner of the tire shop was a former owner of a GMC
MH. Rob the owner was not there but his son was, as I pulled up to the
front door three of the employees were pointing their fingers at my coach.
I told one of them that I had a bad vibration at 60mph and they said to
start with balancing. Had the front two tires balanced and found one had a
slipped belt, only detectable by spinning it. It was suggested to swap out
the two front rear wheels to put on the front. One of those wheels was
bent and caused a bit of a wabble. It was also pointed out to me that the
right side CV joint was leaking grease and the boot band was missing.
Boot was not torn just not attached.
The owner's son told me of the trips to Florida his family had taken when
they still had their GMC.
That did the trick, no vibration at 60, 65, or 70mph.
On Fri, Feb 10, 2012 at 7:17 PM, Bruce Hart <hartsgmc@gmail.com> wrote:
>
>
> I recently purchased a 1976 Palm Beach out of the Tucson area. The drive
> around town was pleasant and everything felt tight. It has 16.5" rims with
> very low mileage Michelin tires (7years old). The coach was in storage I
> believe for 4 to 5 years before it was put up for sale. On our trip to
> Phoenix at 60mph we notice a vibration in the front drive area, not teeth
> shattering but very noticeable. It would smooth out after 1/2 mile or so
> and would vibrate again at 60mph if I had slowed down and sped up. We drove
> it home to Colorado 1200 miles later. today I went to drain the black water
> tank and noticed that the vibration was there at 60mph put as I slowed down
> I felt another vibration in the steering wheel until I got down to 10 to 15
> mph. No vibration when accelerating but I noticed a vibration as I was
> slowing down and also felt a pulsing in the brake pedal. I feel that there
> is a front end component, tie rod end, steering arm or something to do with
> the steering that is ca
> using this vibration as it has gotten worse as I slow down now. At first
> I thought that maybe the tires need to be balanced but with the vibration
> now at the slower speed tells me different. As best that I could tell the
> bushing looked ok and there are new shocks all around.
> Could this be the beginning of a bearing(s) going bad with 128k miles on
> the coach?
> Any Ideas?
> --
> Bruce Hart
> 1976 Palm Beach
> Milliken, Co
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Bruce Hart
GMC Wannabe
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Bruce Hart
1976 Palm Beach
1977 28' Kingsley
La Grange, Wyoming
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