red00lght

Anybody have this problem before? I'll leave a stoplight and as the rpms go up, a significant vibration is felt and then it goes away prior to shifting to second and doesn't reappear through the rest of the gears. It has been there for quite a while, but since I put on shackles it got way worse.

Thanks for any help!

jethro_3

1. Does the truck have a "Thunk" sound or feel when coming to or leaving a full stop? Check your u-joints for slack.

2. When you did the shackles did you go over 2"? If so did you get the pinion angle changed properly?

3. Go under your truck and check ALL the sensors and wires that possibly could have been touched. Even the ones that might not have been touched.

Just a few thoughts....

__________________

"The Sleeper" '05 6.0L VHO
Cam in and Low 14's happening at the track

Check out my Ride

red00lght

Thanks Jethro,

No thunk when leaving a stop...just an increasing shuddering feeling until I get to about 20mph.

I was hoping someone with these trucks had been through the same problem so I wouldn't have to go through the dealership guessing game!

jethro_3

Have you done anything with your brakes? What about a vacuum leak causing the idle issue? These things have a propencity for intake plenum leaks.

Sorry I haven't experianced your problem but try a search with intake leak as the search and see if the symptoms fit.

chuck16

I have this shutter but, I've gotten use to it now if I really tromp on it, it goes away. However, if I drive normally it's slightly felt. I can tell you this don't take it to a Tranny shop. I spent over $300 bucks having all 3 U'Joints replaced to no avail. The guy claimed they were bad but, they weren't all that bad. I guess the only light to having my U'Joints replaced is that now I have greasable ones.

From what I've read and from riding in different Silverados; it seems that the 4x4's don't have this problem and Chevy's only fix for this was to put a 2-piece driveshaft in. I found it gets a little better if you grease the ever loving crap out of the driveshaft connecting rod but, that only lasts a week or so.
Some guys say for the 2-wheel trucks to go to a 1-piece driveshaft. The only draw back to doing that is that you loose a bit of ground clearance. I went so far as to have my Driveshaft's balance and that made it a bit better but, not a 100%. I just live with it now, it doesn't seem to effect anything. I was thinking about replacing the shocks and seeing if that helps any but, I doubt it will do much of anything.

Let me know if yours is a 1 or 2 piece driveshaft and 4x4 or non 4x4. If it's 2 and not 4x4 you may want to look at going to the 1piece driveshaft. But, in all honesty, just drive your truck and ignore the little vibration....

__________________

GMMerlin

What you are describing is a launch shutter.
By installing shackles you have changed the pinion angle and thrown off the working angles of the driveshaft. The shutter is caused by the inability of the u-joints to cancell each other.


Information brought to you from a dealership tech..no guessing game here

__________________
Why do you never have enough time or money to do the job right the first time, but enough time and money to do it again?
Got all the certifications
25 years ASE Certified Master Technician
GM WCT
Yea..I work at a DEALERSHIP....got a problem with that?

Want to diagnose cars like the Pros? FOR SALE: OTC Perception 2 channel Labscope (badged as a Matco Reality)
This is my personal labscope that I use to diagnose waveforms, like new, comes with leads and training video
PM Me for details

red00lght

Thanks for all the info. Maybe that 1-piece driveshaft would be the fix or having the pinion angle reset? The truck is 2wd. It was shuddering prior to the shackles, but now it is so bad that even the wife asked me what was wrong with the truck (that is when you know it is time to get it fixed... ).

I'm kinda surprised....I put shackles on my Lightning a few years ago and didn't have any trouble.

red00lght

By the way,

Thanks for the info GMMerlin. No offense meant to you on the dealership guessing game comment. I've been through some bad times at dealerships with a 86 Cougar/99 Cobra/00 Lightning with problems that they could NOT figure out. Yes, I'm an ex-Ford man.