I have a 2013 lt2 coupe auto trans. When driving around 60 mph and lift off on the gas, I get this vibration I can feel a vibration. When I get back on the gas there is also some vibration but goes away as speed increases. It does not happen at lower or higher speeds. Any Ideas??

 

I'd start by checking the balance on my tires.

 

So, driving steady 60, no vibration? If so, then backing off, or getting back on the gas changes the speed just slightly so that something triggers it--not 60 itself. Have you hit anything lately, like a curb, a bad pothole, RR tracks, etc.? Did this just start out of the blue? When? How many miles now on the car? Anything done to the car recently, like at a dealer, tire store, up on a lift? First ck is wheel/tire balance. Second ck is make sure all lug nuts are tightened to 100 lb/ft. Next might be even wheel bearing check. Altho unusual, it could be motor mounts (kind of early to happen tho).

 

Is it in a particular gear? If yes it's transmission related. If not, put the car on jack stands transmission in park, E brake off. Turn each rear wheel by hand and check for excessive play in rear axles. Remove lower flexplate housing and check driveshaft also.

 

Good idea I will try that. There are 2 more threads that also gave me some insight.

 

Torque converter or flex plate.

KW

 

I am new to the forum so I do not know how to answer all the threads. Hopefully the others will see this reply. First the car has only 14,000 miles on it. I took it to the dealer and they found the left rear bearing to be bad. The part is on order. They think this will fix my problem. I have 2 more questions. When they had it on the lift they pointed out there is a slight wear on the insides of the front tires. They recommended that I do nothing until the tires have to replaced and then have it aligned. I find this strange for a Chevy dealer to say this. The other question- when I do replace the front tires can I use non-run flats with run flats on the rear?

 

Aline after new tires. The wear pattern is set up already. Depending on just how much wear has taken place you could squeeze out a few more miles with an alinement now. If the tires have 14,000 I would wait. Just depends of the condition and amount of wear.

I would not mix rf with non rf only because of the handling differences between the two. If you are a around town commute driving then ok, I guess. But if you like to push the car some in the turns I would advise keeping with same type tire in all four corners. having to do with grip and responsiveness of the different tires.

The tire mix should only be a temporary fix and not something to do as a recommended usual procedure. it would not be the end of the world but in a performance car it does represent a mismatch. Again granny going to Sunday church ok, driving aggressively a no no.

 

Good idea. If the alignment is out or the tires have been out of balance for a long time they could be flat spotted and causing your vibration.

 

Depends on how much tread is left on the worn tire. If the wear bars are showing, them replace tires and align. If you have around 4k miles left, I would do an alignment now and buy new tires later. It is not recommended to mix and match tires.

 

And with Mike's LS3 too. A good (experienced) alignment tech will be able to see the current wear pattern and compensate for it, rather than just only referring to a spec sheet that doesn't resolve your problem. Adding a couple extra PSI in the fronts will help get you more miles too, before needing new tires.

My first thought on your vibration was the converter clutch dropping out of and back into lockup mode. If you watch the tach when you let off the throttle at a steady speed in 6th gear, you'll see it drop from around 1200-1400 to 600. There will be a vibration just as the RPM begins to drop. There will also be a vibration as the clutch hooks up again when you add some throttle to resume your speed. You probably won't feel much vibration if you add a lot of throttle or if your speed drops so much that it's no longer in the range for 6th gear.
This is just the way the transmission works. Mine has 126K miles and still works that way, just to show you it's not a problem.

Now if you have severe cupping on those front tires, that could indicate other suspension issues that could also cause a vibration and an alignment and/or new tires won't resolve that one.

 

Might need new brake rotors also.