Driveline vibration

[rick propas]

About 1000 miles ago while on a major road trip I developed a high speed vibration that started as a steering wheel shake at about 75 -80 mph and became a general vibration up from the driveshaft tunnel that became quite pronounced by 120 mph. Normally I would suspect tires and/or wheels, especially as I had been on some bad roads. But this seemed to happen just as I noticed an occasional jolt which seemed to come from the drive train under heavy high speed acceleration. Sometimes it is a single sort of hitch and sometimes a sort of jerk-jerk. There is no sound associated with any of this.

Thoughts?

[MDORPHN]

Originally Posted by rick propas

About 1000 miles ago while on a major road trip I developed a high speed vibration that started as a steering wheel shake at about 75 -80 mph and became a general vibration up from the driveshaft tunnel that became quite pronounced by 120 mph. Normally I would suspect tires and/or wheels, especially as I had been on some bad roads. But this seemed to happen just as I noticed an occasional jolt which seemed to come from the drive train under heavy high speed acceleration. Sometimes it is a single sort of hitch and sometimes a sort of jerk-jerk. There is no sound associated with any of this.

Thoughts?

I'd check wheel balance and then see if the jolt is still present.

Neil

[rick propas]

Neil, thanks. You really think that balance could do that? Cause the jolt? It feels like a distinct bump, a disruption of the drive.

[M3 Adjuster]

Originally Posted by rick propas

About 1000 miles ago while on a major road trip I developed a high speed vibration that started as a steering wheel shake at about 75 -80 mph and became a general vibration up from the driveshaft tunnel that became quite pronounced by 120 mph. Normally I would suspect tires and/or wheels, especially as I had been on some bad roads. But this seemed to happen just as I noticed an occasional jolt which seemed to come from the drive train under heavy high speed acceleration. Sometimes it is a single sort of hitch and sometimes a sort of jerk-jerk. There is no sound associated with any of this.

Thoughts?

I'm impressed that you decided to push from 75-80 mph with a vibration on up to 120

[MDORPHN]

Originally Posted by rick propas

Neil, thanks. You really think that balance could do that? Cause the jolt? It feels like a distinct bump, a disruption of the drive.

Proper procedure is to tackle the most obvious problems.

The vibration strongly suggests wheel imbalance so I'd address that first.

If the jolt remains, it should then be easier to diagnose.

Neil

[rick propas]

Neil,

You are absolutely correct. I should know that by now. Thanks!

Rick

[Pete_vB]

I suspect wheel balance as well, but if the jolt remains after that's checked perhaps look at the driveshaft:
http://www.1addicts.com/forums/showthread.php?t=971004

[rick propas]

I just spent the day with my car guys, and, yes, I have a bent rim, but from there I went to the dealer (I'm due for the ~20k service) and the lead technician thinks the "jolt" I've experienced may be a plug or injector that is confusing the engine management system. The car goes in on Tuesday when Kevin (tech) gets back from i3/i8 school.

[MDORPHN]

Originally Posted by rick propas

I just spent the day with my car guys, and, yes, I have a bent rim, but from there I went to the dealer (I'm due for the ~20k service) and the lead technician thinks the "jolt" I've experienced may be a plug or injector that is confusing the engine management system. The car goes in on Tuesday when Kevin (tech) gets back from i3/i8 school.

Glad vibration was simple.

A misfiring plug or a dirty injector would cause some rough running, but unlikely to produce what you describe as a "jolt."

In any case, a misfire would throw an OBDII shadow code. Did your tech mention any codes?

Neil

[rick propas]

Neil, I thought that diagnosis a bit strange, too. The car goes in on Tuesday for fluids, plugs (20K service), so we will see what sort of codes it has thrown, if any. What the tech said about the plug and/or injector was that it might have confused the management system, causing it to momentarily shut down and come back on, thus the jolt. We shall see.

[rick propas]

Just to follow up, and to make a long story short, not only was my rim dented, but my PS2s were all done, even though I had tread left. I got the dents (2) removed to 3/1000 and a new set of PSS and the car seems smooth to 120 mph.

The tires are not broken in so I cannot comment, but on my M roadster I did not like them nearly as much as the PS2s and when I nailed the accelerator in the coupé yesterday I got a flicker from the traction control light.

I see lots of folks loving the PSS, but so far in two applications I am underwhelmed by them.

I'd be interested to hear other comments and will cross post to a new thread.

[Dackelone]

Originally Posted by rick propas

Just to follow up, and to make a long story short, not only was my rim dented, but my PS2s were all done, even though I had tread left. I got the dents (2) removed to 3/1000 and a new set of PSS and the car seems smooth to 120 mph.

The tires are not broken in so I cannot comment, but on my M roadster I did not like them nearly as much as the PS2s and when I nailed the accelerator in the coupé yesterday I got a flicker from the traction control light.

I see lots of folks loving the PSS, but so far in two applications I am underwhelmed by them.

I'd be interested to hear other comments and will cross post to a new thread.

Give the tires some time to break in and wear off the release agent(grease). New tires are somewhat dangerous until you put four or five hundred miles on them. Then they are awesome!


Glad to hear you got your vibration sorted out.

Dack

[rick propas]

Thanks to everyone for your suggestions

Originally Posted by Dackelone

Give the tires some time to break in and wear off the release agent(grease). New tires are somewhat dangerous until you put four or five hundred miles on them. Then they are awesome!


Glad to hear you got your vibration sorted out.

Dack