Powertrain vibration at 1600 - 2000 rpm (LQ1, 4T60E)

[GOT2B GM]

Ever since I had my car into the transmission shop about a month ago, I have a powertrain vibration between 1600-2000 rpms. I took it in because I lost 3rd gear. It doesn't matter if it's in Park, reverse, neutral or drive, it always does it. When it went into the shop, it was fine. I got it back and it was like this.

 

The parts they replaced are listed below:

 

772929 3rd Sprag Ass'y

K84900V Seal Kit

88292 Molded Third Clutch Piston

66972M Final Drive Package, 3.05 ratio(was showing wear)

1994253 PRNDL Switch (was corroded, sometimes had to wiggle to start car)

Dexron III fluid

TH440 Filter

 

I also had them replace the Knock sensor when they had the trans out because its easy to get at. I bought the sensor, and had them put it in.

 

Could a bad motor or transmission mount cause a vibration only at a certain RPM range???

 

And another thing that pisses me off if that when I got it back, there is what feels like a dead spot in the steering when it's turned straight. Almost like they didn't tighten the pinch bolt on the stub shaft on the rack.

 

I took it back a couple days after I had the work done, and they had the car for a day. They were like, oh there's no vibration, and they told me that my rack was bad. Unless my rack just magically broke when they had the transmission out....... :x I HATE taking my car to the mechanic's but I don't have the equipment or resources to repair an ATX.

 

Sorry for the long ass post. Any input is greatly appreciated.

[GOT2B GM]

Anyone??? please??

[19902drlumina]

well was it aligned after? the repair? might need to do that first. see if anybolts are lose. but sounds like a harmonic balancer since it does it in all gears evan park and neutral. i mean im not sure but i hope it helps. 2 minds are better than 1

[1990lumina]

My dad's Suburban has a major vibration in the driveline after we had the new engine installed....one of the mounts got fucked up...could be a mount.....

 

I'd be pissed right off if I was you if my steering got fucked up after that.....I recommend you going back to bitch again.....doesn't sound like a very good shop if they can't tell a vibration at a certain RPM...

[GOT2B GM]

They actually aren't a bad shop. They're awesome at transmissions, but that's about it. I think I'm going to address my steering issue first, hopefully just a loose pinch bolt. If it does end being the rack needing to be replaced, I'll use that opportunity to put in a new lower engine mount, just to rule it out as a cause of my vibration. I'm really just hoping that this vibration isn't something out of balance inside the transmission.

 

Has anyone replaced their steering racks and/or lower engine mounts?? What was the degree of difficulty??

 

 

Thanks for the replies.

[GOT2B GM]

In response to 19902drlumina, the car hasn't been aligned due to the fact that I am having issues, and I don't want to pay to have it aligned twice. The steering wheel is straight, and the car doesn't pull to either side.

 

Does the LQ1 even have a harmonic balancer??

[19902drlumina]

i have no clue i figured id just give some options i have done the mount and rack in pinnion on my old 93 park avenue wasn't to bad, i had to take out the back frame mount bolts and losen the front. if i rember right i paid 189 for it new rebuilt might be less. but about the aligning my buick would vibrate when it was out of alignment and i had all new balljoint/wheelbearing/tie rodends/rackandp/and struts

[19902drlumina]

but ures is anytime so it wouldne be an aligning issue sorry just woke up. doh

[GOT2B GM]

thats ok, thanks for the suggestions anyways