vibration on hard acceleration

[lorne rosenblood]

I have a mild vibration or shaking of the front wheels on hard acceleration particularly up a steep hill. I have Manny’s front end.
The front engine mount is only a few years old.
Any suggestions on where to look for the problem. CV joints?

Lorne Rosenblood
Victoria, BC

 

[gworobec]

Are you sure you are not breaking traction on the front wheels?

>
> I have a mild vibration or shaking of the front wheels on hard acceleration particularly up a steep hill. I have Manny’s front end.
> The front engine mount is only a few years old.
> Any suggestions on where to look for the problem. CV joints?
>
> Lorne Rosenblood
> Victoria, BC
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

Gary and Joanne Worobec
Anza, CA
1973 Glacier 23

 

[jerry work]

I have a mild vibration or shaking of the front wheels on hard acceleration particularly up a steep hill. I have Manny?s front end.
The front engine mount is only a few years old.
Any suggestions on where to look for the problem. CV joints?

Lorne Rosenblood
Victoria, BC

........,.....:

 

[Jim Hupy]

Lorne, we have had a fair amount of experience with torque steer. Like a
couple of others have stated, a bit less throttle helps, and I have found
that a bit of toe out (no more than 1/8") will help also.
Jim Hupy

> Nature of the beast. Many experience torque steer on acceleration uphill,
> especially while turning. Just lighten up on the gas until your wheels are
> straight again.
>
> Jerry Work
> Kerby, OR
> Message: 6
> Date: Sat, 22 Oct 2016 11:00:18 -0700
> From: "Lorne Rosenblood"
> To:
> Subject: [GMCnet] vibration on hard acceleration
> Message-ID:
> Content-Type: text/plain; charset="utf-8"
>
> I have a mild vibration or shaking of the front wheels on hard
> acceleration particularly up a steep hill. I have Manny?s front end.
> The front engine mount is only a few years old.
> Any suggestions on where to look for the problem. CV joints?
>
> Lorne Rosenblood
> Victoria, BC
>
>
> ........,.....:
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[robert mueller]

On the OEM front end the steering axis goes through the center of the tire contact patch.

The one ton front end (and wheel spacers) moves the wheels outwards which in turn moves the center of the tire contact patch
outwards away from the steering axis which will exacerbate torque steer and other problems.

I AM NOT SAYING THERE IS ANYTHING WRONG WITH THE ONE TON FRONT END!!!!!!!!!!!!!!!!!!!!!!!

Regards,
Rob M.
USAussie - Downunder
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426

-----Original Message-----
From: Gerald Work

Nature of the beast. Many experience torque steer on acceleration uphill, especially while turning. Just lighten up on the gas until
your wheels are straight again.

Jerry Work

From: "Lorne Rosenblood"

I have a mild vibration or shaking of the front wheels on hard acceleration particularly up a steep hill. I have Manny?s front end.
The front engine mount is only a few years old.
Any suggestions on where to look for the problem. CV joints?

Lorne Rosenblood

 

[johnny]

I'm betting wheelspin.
Which I didn't recognize in a minivan until someone watched as it strated up... Dodge with a bigger engine than the last few, I was punching it too
mucgh. Samesame with the coaches.

--johnny
--
'76 23' transmode Norris upfit, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.

"Sometimes I wonder what tomorrow's gonna bring when I think about my dirty life and times" --Warren Zevon

 

[Jim Hupy]

A stock GMC with an OEM front end will normally not torque steer or spin
the tires. But, put a bunch more horsepower and torque into the same coach,
and you most certainly will experience it, particularly while turning and
when weight transfers off of the front end. Adding extended wheel spacers
to the stock front hubs will do the same thing. So will the 1 ton.
Solution? Keep your foot out of the tie rods. Your fuel mileage will
improve too.
If you want to play with the big dogs, expect and prepare to pay for it.
I've been there and done that. Even got the T-shirt as evidence.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

On Oct 23, 2016 6:03 AM, "Johnny Bridges via Gmclist" <

> I'm betting wheelspin.
> Which I didn't recognize in a minivan until someone watched as it strated
> up... Dodge with a bigger engine than the last few, I was punching it too
> mucgh. Samesame with the coaches.
>
> --johnny
> --
> '76 23' transmode Norris upfit, 76 26' Eleganza(?) with beaucoup mods and
> add - ons.
> Braselton, Ga.
>
> "Sometimes I wonder what tomorrow's gonna bring when I think about my
> dirty life and times" --Warren Zevon
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[terry1]

Torque steer is not a vibration or even a thumping, it is a pull from uneven torque distribution that is not being cancelled out by the mass of the
vehicle and is instead transmitted to the steering system which is not an inflexible system. Uneven torque will exacerbate ANY looseness in the
mounting of the driving wheel system, front or back. You just don't notice it much in a rear wheel drive system because the lever arm is the length of
the wheelbase and unless you have a lot of power and traction you will have much greater control of the resultant torque offset. As others have said,
lengthening the axles will amplify the effect, but that is not what I would call a vibration. The wheel slippage could cause a vibration if the tire
is not round and is a possibility, but most drivers know when they are burning rubber or losing traction. I know it when I spin the right front tire
on takeoff in my GMC and in the FWD minivan, and it does not cause a vibration, just smoke and smell and a thumbs up from the spectators riding in the
back of the pickup truck at the corner store! :lol:

Going uphill, weight load is taken away from the front end and ANY play in that system is going to have more opportunity to show itself. You need to
check those 4 ball joints thoroughly and with less than full weight load on the wheels and do the same for the tie rod and other linkage joints.
Perform Rob Mueller's front end check carefully and then do it again with the system loaded at different amounts. Also check the front wheel bearings
for ANY play at different load heights and make sure the bearing assemblies are not loose in the knuckles. Make sure ALL of the engine mounts are
secure and the axles are tight to the final drive. Jack both front wheels off the ground by the bottom of the control arms, put stands under the
frame, and spin the wheels with the engine while turning the steering lock to lock. Use the service brake to apply some load to them and repeat the
test while observing the wheels from outside. Watch for any wobble or bounce in the wheels. This WILL require a qualified operator at the wheel,
someone that does not panic first and faint later. DO NOT get under the vehicle during this type of testing and DO NOT stand in the travel path in
case a jackstand breaks, and make sure it will not drive into a building or other obstruction if something gives way unexpectedly.
--
Terry Kelpien

ASE Master Technician

73 Glacier 260

Smithfield, Va.

 

[terry1]

Well, sorry Lorne, thought that was the original posting I replied to, so I C&P'd to the original one after noticing it farther down the page.
--
Terry Kelpien

ASE Master Technician

73 Glacier 260

Smithfield, Va.

 

[terry1]

Torque steer is not a vibration or even a thumping, it is a pull from uneven torque distribution that is not being cancelled out by the mass of the
vehicle and is instead transmitted to the steering system which is not an inflexible system. Uneven torque will exacerbate ANY looseness in the
mounting of the driving wheel system, front or back. You just don't notice it much in a rear wheel drive system because the lever arm is the length of
the wheelbase and unless you have a lot of power and traction you will have much greater control of the resultant torque offset. As others have said,
lengthening the axles will amplify the effect, but that is not what I would call a vibration. The wheel slippage could cause a vibration if the tire
is not round and is a possibility, but most drivers know when they are burning rubber or losing traction. I know it when I spin the right front tire
on takeoff in my GMC and in the FWD minivan, and it does not cause a vibration, just smoke and smell and a thumbs up from the spectators riding in the
back of the pickup truck at the corner store! :lol:

Going uphill, weight load is taken away from the front end and ANY play in that system is going to have more opportunity to show itself. You need to
check those 4 ball joints thoroughly and with less than full weight load on the wheels and do the same for the tie rod and other linkage joints.
Perform Rob Mueller's front end check carefully and then do it again with the system loaded at different amounts. Also check the front wheel bearings
for ANY play at different load heights and make sure the bearing assemblies are not loose in the knuckles. Make sure ALL of the engine mounts are
secure and the axles are tight to the final drive. Jack both front wheels off the ground by the bottom of the control arms, put stands under the
frame, and spin the wheels with the engine while turning the steering lock to lock. Use the service brake to apply some load to them and repeat the
test while observing the wheels from outside. Watch for any wobble or bounce in the wheels. This WILL require a qualified operator at the wheel,
someone that does not panic first and faint later. DO NOT get under the vehicle during this type of testing and DO NOT stand in the travel path in
case a jackstand breaks, and make sure it will not drive into a building or other obstruction if something gives way unexpectedly.
--
Terry Kelpien

ASE Master Technician

73 Glacier 260

Smithfield, Va.

 

[Jim Hupy]

I believe what Lorne described IS torque steer. Terry, your concise,
thourough, response contains several very good points about checking the
front end of perhaps any front drive vehicle. I am amazed by the expertise
on this net.
Jim Hupy

> Torque steer is not a vibration or even a thumping, it is a pull from
> uneven torque distribution that is not being cancelled out by the mass of
> the
> vehicle and is instead transmitted to the steering system which is not an
> inflexible system. Uneven torque will exacerbate ANY looseness in the
> mounting of the driving wheel system, front or back. You just don't notice
> it much in a rear wheel drive system because the lever arm is the length of
> the wheelbase and unless you have a lot of power and traction you will
> have much greater control of the resultant torque offset. As others have
> said,
> lengthening the axles will amplify the effect, but that is not what I
> would call a vibration. The wheel slippage could cause a vibration if the
> tire
> is not round and is a possibility, but most drivers know when they are
> burning rubber or losing traction. I know it when I spin the right front
> tire
> on takeoff in my GMC and in the FWD minivan, and it does not cause a
> vibration, just smoke and smell and a thumbs up from the spectators riding
> in the
> back of the pickup truck at the corner store! :lol:
>
> Going uphill, weight load is taken away from the front end and ANY play in
> that system is going to have more opportunity to show itself. You need to
> check those 4 ball joints thoroughly and with less than full weight load
> on the wheels and do the same for the tie rod and other linkage joints.
> Perform Rob Mueller's front end check carefully and then do it again with
> the system loaded at different amounts. Also check the front wheel bearings
> for ANY play at different load heights and make sure the bearing
> assemblies are not loose in the knuckles. Make sure ALL of the engine
> mounts are
> secure and the axles are tight to the final drive. Jack both front wheels
> off the ground by the bottom of the control arms, put stands under the
> frame, and spin the wheels with the engine while turning the steering lock
> to lock. Use the service brake to apply some load to them and repeat the
> test while observing the wheels from outside. Watch for any wobble or
> bounce in the wheels. This WILL require a qualified operator at the wheel,
> someone that does not panic first and faint later. DO NOT get under the
> vehicle during this type of testing and DO NOT stand in the travel path in
> case a jackstand breaks, and make sure it will not drive into a building
> or other obstruction if something gives way unexpectedly.
> --
> Terry Kelpien
>
> ASE Master Technician
>
> 73 Glacier 260
>
> Smithfield, Va.
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[Daniel]

Just another possibility that could ad to your problem.

Not on a GMC, but on a Fiat Ducato, frontwheeldrive, turbodiesel, 150 HP, I encountered same thing, last week, after I got the RV back from the
workshop, after big maintenance, greasing, oilchance, breakfluids etc ....
Already a half mile drive and in the first curve the outer frontwheel and the steeringwheel started to vibrate intens ...
With no accelleration and going straight almost nothing to sense.
If they had forgotten to tighten up the wheelnuts!
I directly went back, they checked and torqued both front wheels. No problem there.
Then lifted the RV again and looked at the steeringshaft etc .... "Ohh you need a new steeringshaft "

What the ..... @&&€',!,!.
I just went back from a long drive from the south of France and drove without problems through little villages, curved roads and highways at a speed
of 75 mph ...

Pfffff... Silence on the mechanics-side ...
Then I saw that the front tires were very high inflated ... Those Continental Vanco 2 FourSeasons 225/75 R16, on my Ducato Maxi chassis, need on the
front axle and a load of aprox. 1750 kg only 3 to 3.5 bar and they put more then 5.5 bar in them ...
That was the solution, after deflating and driving the same route, there was no problem what soever ...

Daniel
--
Daniel Jacobs, No GMC, but an admirer of them .... We'll see what the future brings ....

Always remember, the world is full of nice people!
So, if you can't find one, be one!

 

[terry1]

It's definitely a possibility James, as I have had many, many customers describe a problem and my interpretation of said description is way off base,
and I get a total surprise when I test drive or try to find out what the problem is. Hopefully Lorne will let us know what the culprit is when it is
discovered.

In a similar situation, I have a noise that sounds EXACTLY like the fan scraping the shroud when accelerating, but cannot find evidence of such
action. I was sure it was the goopy front motor mount, but replacing that made no change in the sound at all. Still no evidence of the noisemaker seen
and I can't duplicate the condition in the driveway, and couldn't get the sound recorded on the phone to post it for experts on the net to hear. Was
hoping it was the carb stud scraping the engine hatch, or the extra lid I had on the air cleaner (which was scraping the hatch), but neither of those
was the offender. So now I need to find that "qualified driver" I mentioned to drive the coach down the road while I hang my head down in the engine
compartment and find that noise before it stops. 'Cause when it stops, most likely the coach will too :? The noise is repeating at less than engine or
wheel RPM, but is definitely a repeating squeak, squawk, or scraping sound. Engine noise drowns it out when trying to record it on the cell phone with
the hatch open, so I'm gonna have to use regular ol' ears to find it
--
Terry Kelpien

ASE Master Technician

73 Glacier 260

Smithfield, Va.

 

[Keith V]

My new rebuild with a better cam, headers, 3.70 posi, but stock spindles torques all over the place when you get on it when turning from a stop. It's pretty cool I think.
Arrrgh arrrgh!

----------------------------------------

>
> A stock GMC with an OEM front end will normally not torque steer or spin
> the tires. But, put a bunch more horsepower and torque into the same coach,
> and you most certainly will experience it, particularly while turning and
> when weight transfers off of the front end. Adding extended wheel spacers
> to the stock front hubs will do the same thing. So will the 1 ton.
> Solution? Keep your foot out of the tie rods. Your fuel mileage will
> improve too.
> If you want to play with the big dogs, expect and prepare to pay for it.
> I've been there and done that. Even got the T-shirt as evidence.
> Jim Hupy
> Salem, Or
> 78 GMC ROYALE 403
>
> On Oct 23, 2016 6:03 AM, "Johnny Bridges via Gmclist" <

>
>> I'm betting wheelspin.
>> Which I didn't recognize in a minivan until someone watched as it strated
>> up... Dodge with a bigger engine than the last few, I was punching it too
>> mucgh. Samesame with the coaches.
>>
>> --johnny
>> --
>> '76 23' transmode Norris upfit, 76 26' Eleganza(?) with beaucoup mods and
>> add - ons.
>> Braselton, Ga.
>>
>> "Sometimes I wonder what tomorrow's gonna bring when I think about my
>> dirty life and times" --Warren Zevon
>>
>> _______________________________________________
>> 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