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Slight vibration under acceleration

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Old Sep 19, 2009 | 09:43 PM
  #1  
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Slight vibration under acceleration

So after I got my DP this spring, I've been noticing what seems to be some slight front end vibration when under heavy acceleration.

If I am on a highway onramp, and I really kick the throttle, I get some very fast somewhat muted vibrations, I can feel in the steering wheel. Once I shift into 4th gear and the RPM goes down and it smooths out, the vibration goes away.

I have some suspension parts that are getting a little worn out, shocks for one, but I was also taking a look at some worn out swaybar bushings and the like.

Ideas?

Also got new tires/wheels at almost the exact same time I got the DP...so that could be a contributor I dont know.
 
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Old Sep 20, 2009 | 09:41 AM
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Nothing. Ok then.
 
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Old Sep 20, 2009 | 10:02 AM
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Lisa, what happens in stock or other tunes?

Tires could be unbalanced.

Sway bar shouldn't be a factor, you will feel/hear that under your feet while turning or hitting bumps while driving slow.

I have had warped brake rotors give me vibrations at certain speeds.

Maybe, bring it in and have the tires checked. See if that fixes it.
 
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Old Sep 20, 2009 | 12:25 PM
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Sorry I missed this, Lisa.
It sounds like your driveline is a bit out of angle and it's shaking the truck when it is under a very high load, such as acceloration.
You need to disconnect it, and flex the u-joints to make sure that none of them are seizing up, make sure that the spline shaft is lubed and that the carrier bearing is not failing.
When all that checks out, it's time to play with the shims for the carrier bearing.
If none of that has any effect, then it's "possible" ( a big maybe ) that your tranny is slipping, and producing that shuddering vibration.
 
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Old Sep 20, 2009 | 12:35 PM
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Originally Posted by Smokin'
Nothing. Ok then.
Wow Lisa.. Not having a good day??

I to would have jumped in, had I not had my nose in my Schoolwork.. sorry..

I agree with Dan though..
 
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Old Sep 20, 2009 | 01:02 PM
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Originally Posted by jhand124
Lisa, what happens in stock or other tunes?

Tires could be unbalanced.

Sway bar shouldn't be a factor, you will feel/hear that under your feet while turning or hitting bumps while driving slow.

I have had warped brake rotors give me vibrations at certain speeds.

Maybe, bring it in and have the tires checked. See if that fixes it.
The tires and wheels are brand new...and this didn't happen before with the old tires and old hypermax chip. Haven't tried it in stock.

Originally Posted by Kwikkordead
Sorry I missed this, Lisa.
It sounds like your driveline is a bit out of angle and it's shaking the truck when it is under a very high load, such as acceloration.
You need to disconnect it, and flex the u-joints to make sure that none of them are seizing up, make sure that the spline shaft is lubed and that the carrier bearing is not failing.
When all that checks out, it's time to play with the shims for the carrier bearing.
If none of that has any effect, then it's "possible" ( a big maybe ) that your tranny is slipping, and producing that shuddering vibration.
Yeah, it "feels" suspension or driveline related, does not feel like its coming from the tranny...but...feeling isn't everything.

If I do have a u joint that is seizing, or a carrier bearing going bad, would this problem be progressive?

I have several things I need to do to the truck so it sounds like I need to take it out of commission for a week or so and check this out. U joints could be a very real possibility, they've never been replaced.

Originally Posted by just another truck
Wow Lisa.. Not having a good day??

I to would have jumped in, had I not had my nose in my Schoolwork.. sorry..

I agree with Dan though..
Pat you read it wrong, I wasn't upset...just my way of bumping the thread. Sorry if that came off wrong.

Has been a rough week though.
 
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Old Sep 20, 2009 | 01:06 PM
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A slipping tranny will produce a rapid thudding sensation.
A driveline out of angle ( I suspect this more since you have a lift kit installed) will make a wobbling sensation that follows vehicle speed, regardless of what gear you are in.

EDIT: The slipping tranny can also be pinned down if it only happens in one certain gear.
 
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Old Sep 20, 2009 | 01:07 PM
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I'm out now, for a while, will check back in later today.
 
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Old Sep 20, 2009 | 01:09 PM
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Originally Posted by Kwikkordead
A slipping tranny will produce a rapid thudding sensation.
A driveline out of angle ( I suspect this more since you have a lift kit installed) will make a wobbling sensation that follows vehicle speed, regardless of what gear you are in.

EDIT: The slipping tranny can also be pinned down if it only happens in one certain gear.
See this is the odd part. It ONLY does this when under rapid acceleration. I can drive around town all day long, in all gears, and not feel any thud.

Also when I am cruising on the highway or whatever, its smooth as silk, at any speed.

Does not seem related to speed or a particular gear.

Have a good day. No hurries or worries, just something I've been noticing and want to identify in case their is a potentially big problem *tranny*. I sure as hell hope not. Its a machine, it can be fixed, and unlike a lot of these guys on this site I don't use my truck for my daily bread and butter.
 
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Old Sep 20, 2009 | 02:48 PM
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Another interesting piece of evidence: we just went out to the store, with a short jaunt on the highway. Only does it when I am on a highway onramp, at a downward pitch. On flat surface, fast acceleration from a start, no vibration.
 
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Old Sep 20, 2009 | 03:10 PM
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Originally Posted by Smokin'
Another interesting piece of evidence: we just went out to the store, with a short jaunt on the highway. Only does it when I am on a highway onramp, at a downward pitch. On flat surface, fast acceleration from a start, no vibration.
Well, I doubt it's the tranny then. Pulling up hill would exaggerate a slipping tranny or you would have the sense that the engine is revving higher than it used to.
.
Also give a careful listen to the sound of the engine. It might be giving signs of an engine miss under certain conditions, which would produce a noticable vibration.
Have you pulled the valve covers and made sure that the wiring harnesses are fully seated in the not so distant past?
 
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Old Sep 20, 2009 | 03:48 PM
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Originally Posted by Kwikkordead
Well, I doubt it's the tranny then. Pulling up hill would exaggerate a slipping tranny or you would have the sense that the engine is revving higher than it used to.
.
Also give a careful listen to the sound of the engine. It might be giving signs of an engine miss under certain conditions, which would produce a noticable vibration.
Have you pulled the valve covers and made sure that the wiring harnesses are fully seated in the not so distant past?
Hmm...interesting, I hadn't considered a misfire. I can feel the vibration through the steering wheel so I guess I automatically assumed something suspension or driveline.

Valve covers were off last winter when the glowplugs were replaced. I paid Kevin to do those (to pay him back for all of his free diagnostic help on my ICP nightmare) but I was under the hood with them the entire time. Everything looked fine, I would've noticed chaffed wires...and this problem didn't present itself until the DP and new tires this spring.

It's hard for me to duplicate the vibration..but I'll do some driving and see if I can pay attention to how the motor is running.
 
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Old Sep 20, 2009 | 03:59 PM
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I know this is going to sound crazy but I get vibration at idle with my black c99 international CPS. I have also been getting it at highway speeds but seems to depend on the road angle? I did not even think about it until Dan said something. I'm not sure if it might be related to my programmer. Wish I had AE to run some contribution tests.
 
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Old Sep 20, 2009 | 07:18 PM
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Originally Posted by Smokin'
It's hard for me to duplicate the vibration..but I'll do some driving and see if I can pay attention to how the motor is running .
Ok.
................................
 
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Old Sep 20, 2009 | 07:27 PM
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Originally Posted by Kwikkordead
Ok.
................................
Only places I can get the truck to repeat the behavior is pretty far across town. Truck starts, idles, and drives beautifully..

Thanks for the help Dan and guys. I got some major things going on next week, and we're going out of town..but I'm hoping I get a minute to crawl underneath and take a peak at driveshaft, u joints, etc.
 
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