I recently had my 08 Crewcab Silveado completly redone. I have put an air ride suspension kit on it but need some answers. I have a slight vibration every time I take off and when I slow down. I took it back to the shop that has been in business for 21 years. They first they messed up and put the axle to close and hd to replace the rear main seal for the tranny and they shimmed the rear axle and raised the tranny slightly. The vibration is still there and they said thats normal on all lowered cars. Can anyone tell me the problem and if this is true.  

it sound like your pinion angle is off, may need some rear end shims added/or a lowing type Carrier Bearing, I think you have a 2 piece drivehaft

Its not normal to have driveline vibration  

did the trans get damaged by the driveshaft jamming itself into the trans when the suspension moved over bumps maybe ruining a bearing or something that could cause a vibration  

I've got a buddy that lowered his Chevy and it done the same thing. It cramed the driveshaft to far into the tranny. I can't tell you how he fixed it because as soon as he found out what was going on, he traded it so he would have to fix it.  

I appreciate all the help guys. the first thing the company that did the air ride was replace the rear main seal because it was jammed. PISSED ME OFF. Over the weekend I was under the truck doing some mesurements and discovered some other issues. The welds that hold the air bags are two different heights and the axle is a .5" furthur foward than the other. PISSED ME OFF EVEN MORE. If they don't correct problem this week I am going to do a full charge back. Then I will take it to someone better and someone that pays attention to detail more.  

I feel for ya GttnLowN08. It is a shame that all pros in this biz can not take any pride in what they do. Most of the time it is the overlooked small stuff that makes the biggest headache... hope you get it worked all out.