Intense Vibration When Stopped/In Reverse

[Sauci]

Thought I'd post this over here as it's basically the same car and this section is more active.

Just installed some new H&R coilovers on my B8 A5 8 speed quattro with a buddy. While doing the install, I pulled the axle out of the cv joint. We managed to pop it back in and thought everything was good to go. When I started the car up, everything sounded good. However, once I shifted out of park, the car started vibrating like crazy. Don't think that it was misfiring as I've felt that on these engines before. As soon as I let off the brake and start rolling the vibrations stop but return as soon as I come to a complete stop. Shifting to neutral makes them stop however, reverse also causes these intense shakes. No issues with RPMs while moving nor while idling. No CEL or an indication the car thinks anything is wrong.

I'm not sure what is wrong, but it's extremely worrying and I don't want to damage anything further by driving on it if it's something serious. Could I have damaged the cv joint while reinserting it? I can't see in there as there is boot covering it and even though it took like an hour to figure out the right angle to get that popped back in, it seemed like everything was inserted correctly and where it needed to be.

Any help or suggestions would be greatly appreciated.

[JoshDub]

The CV joint wouldnt cause vibrations while idling.

[Sauci]

The CV joint wouldnt cause vibrations while idling.

I found this article that said it might at certain rpms.

http://myautomatictransmission.com/c...eplacement.htm

But I have no idea if this is credible. Lol

[JoshDub]

Speeds, as in motion. They are not talking about engine RPMS.

[Sauci]

Speeds, as in motion. They are not talking about engine RPMS.

Fair enough. Any idea what I should be looking into then?

[907DAVE]

You're exhaust is touching somewhere. Check it over and make sure everything has good clearance.

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[Sauci]

You're exhaust is touching somewhere. Check it over and make sure everything has good clearance.

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Touching what? The ground? Not that low.

[907DAVE]

Likely a cross member, or shield somewhere. Won't be hard to find... just take a look.

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[Sauci]

Likely a cross member, or shield somewhere. Won't be hard to find... just take a look.

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Just looked under there and doesn't seem like anything is touching. The flex joint between my HFC and downpipe is pretty close but still a good 1/2 inch of clearance.

[Joey9]

i think i have the same problem, I'm assuming its the motor mounts

[Sauci]

i think i have the same problem, I'm assuming its the motor mounts

I actually read an interesting post that I can't find the link to again that said because the axles are at different angles once the car is dropped the snub mount in the front needs to be adjusted. Which makes sense.

[blbroo]

I actually read an interesting post that I can't find the link to again that said because the axles are at different angles once the car is dropped the snub mount in the front needs to be adjusted. Which makes sense.

I'm pretty sure that our models don't have the front snub engine mount that the older cars did.

[Sauci]

Adjusted the coilovers and raised the car by about half an inch. The vibrations don't seem quite as bad but still definitely noticeable and doesn't feel like it should be happening. I know that a stiffer suspension will result in an increase in vibration some but this is more than that.

i think i have the same problem, I'm assuming its the motor mounts

I'm hesitant to believe that it's the mounts simply because there was no issue before I did the coilover install and the second I started it after having it on stands for a day, this started. I don't understand why they would go bad so suddenly and without any driving.

[Sauci]

Took it to get checked out a couple days ago. Motor mounts were shot. Well at least I know nothing is going to blow up now.

[Sauci]

So far, I have replaced the motor mounts, made sure the exhaust isn't touching, had the cv joint inspected and one of the boots replaced, installed a new PCV valve and nothing has worked. Ok, it may have worked slightly. The vibrations have decreased by about 40% but still much more than there should be. Seems to go away when I turn off the AC so i'm wondering if that has something to do with it.