[james008]

I have noticed recently when I push the car up to around 120mph the dash shakes pretty violently. The steering wheel doesn't shake at all and I don't feel any vibrations in the seat much, but the dash goes crazy. I tried to coast down from around 130 to see if the shaking was still there and it wasn't. Which led me down the road of maybe engine mounts?

WOT up to around 100 or 110 doesn't seem to produce anything, 120 mph seems to be about the magic number and it seems that as soon as I stop pushing the gas the shaking goes away.

Thoughts?

[james008]

Got an alignment and wheel balance. Also oil change and new spark plugs. Shaking is still there it is definitely related to engine because as soon as I let off the throttle the shaking goes away. Could be related to my tune? And or timing? Next step will to try and do some logs, waiting for my otg cable to try out MHD.

[Moutamid]

+1

want to know what is the cause

[Jaronbwall]

Keep us posted! I'm curious as well. My car is smooth as butter up to 130+mph

[AZBimmer]

I had the same problem at around 80 with same symptoms as you. I added a couple gallons of E85 as I found out Arizona 91 is not recommended for Cobb Sport Maps. The vibration has been gone since. I guess the tune didn't like the octane it was getting. Good luck.

[Jeff@TopGearSolutions]

4 options here:

- log your vehicle and see how it's performing

-remove the tune and see if the problem still happens

- add more octane via race gas or E85 and see if the problem persists

or

stop speeding...

[james008]

Put in 100oct still same vibration. It doesn't seem to matter what gear I'm in or if I'm slowly climbing to 120 or wot up to 120 same symptoms. As soon as I let off the gas vibration is gone.

Might it be time for a intake cleaning. I just dumped a full can of oil out of oil catch can after only 6 months.

Somewhat related:
http://www.e90post.com/forums/showth...ighlight=fixed

You might need to start looking deeper into the drivetrain.

[MDORPHN]

Originally Posted by FCobra94

Somewhat related:
http://www.e90post.com/forums/showth...ighlight=fixed

You might need to start looking deeper into the drivetrain.

Quite right. I'd take a hard look at the guibo.

Neil

[Jeff@TopGearSolutions]

Originally Posted by FCobra94

Somewhat related:
http://www.e90post.com/forums/showth...ighlight=fixed

You might need to start looking deeper into the drivetrain.

Originally Posted by MDORPHN

Quite right. I'd take a hard look at the guibo.

Neil

That would be my next suggest also:

Replaced the drivers side axle and diff bushings and vibration is gone.

In total, I replaced
-driveshaft
-bent wheel
-axle
-diff bushings

All had an impact on the vibration but I'm pleased to say it rides like a BMW again. Just in time for the Nurburgring in two weeks. Thanks for the ideas fellas...appreciate it.

[james008]

So interestingly I just had the driver side axle and pretty much all parts conected to it replaced a couple months ago. Including the wheel bearing and wheel carrier. Probably a good idea to take it back to the same shop and see what hey have to say.

[MDORPHN]

Originally Posted by james008

So interestingly I just had the driver side axle and pretty much all parts conected to it replaced a couple months ago. Including the wheel bearing and wheel carrier. Probably a good idea to take it back to the same shop and see what hey have to say.

Did the vibration begin after you got the car back or was it pre--existing?

Neil

[88atlas07]

Your best bet to diagnose whether or not its driveline (sounds identical to what I had) is to put the car up on some blocks and run it at the speed where youve notcied the vibrations. Make sure DTC if fully off, and even so, the cluster will light up with all sorts of ABS warnings and lights but they will all go away once you drive the car for a few hundred feet. Chances are you will see the shaking in one of the wheels which will point you in the right direction. My guess is a bad axle.

[james008]

Symptoms definately started after. I did a track day 6 months ago and no vibrations. Putting car in blocks and doing 120 mph safe?

[88atlas07]

Originally Posted by james008

Symptoms definately started after. I did a track day 6 months ago and no vibrations. Putting car in blocks and doing 120 mph safe?

Probably not the safest thing out there but if you support the car properly so that there's no chance of it falling off at that speed it wont hurt anything. Dont run it for a long time because the engine wont have any air flow to cool it at those revs but its fine for a minute or two.

Im sure there's other ways to diagnose it but this is the way I did it and it worked great.

[Jaronbwall]

Originally Posted by 88atlas07

Probably not the safest thing out there but if you support the car properly so that there's no chance of it falling off at that speed it wont hurt anything. Dont run it for a long time because the engine wont have any air flow to cool it at those revs but its fine for a minute or two.

Im sure there's other ways to diagnose it but this is the way I did it and it worked great.

That's a great idea. I would locate a shop or friend with a car lift instead because it's way more stable. They shouldn't charge you to borrow a lift for 10 minutes

[MDORPHN]

Originally Posted by james008

Symptoms definately started after. I did a track day 6 months ago and no vibrations. Putting car in blocks and doing 120 mph safe?

Well, if they started right after the work, I'd bring it back to the shop for them to double-check their work.

Neil

Originally Posted by MDORPHN

Well, if they started right after the work, I'd bring it back to the shop for them to double-check their work.

Neil

Agreed. This is obviously where you should start investigating. Why this information was left out of the original post, I have no idea...

[james008]

Originally Posted by FCobra94

Agreed. This is obviously where you should start investigating. Why this information was left out of the original post, I have no idea...

Never really thought a brand new rear axle would cause a dash to shake. My alignment was way out of spec so I assumed that was the cause. It has also been a few months since the install and I only noticed the vibration recently.

[james008]

Got 4 new tires vibration is gone. Not really convinced the problem is solved but symptoms are gone so for dding I'm okay with it for now.