Curious rumble when pulling away from a stop

[AR11]

I'm experiencing an odd rumbling sensation and wonder if anyone has any ideas or similar experiences. It seems fairly innocuous but its bugging me that I can't identify it.

Conditions (all need to be occur for rumble to happen):
- Starting from a stop, AND
- Steering wheel at 90 degrees or further (like making a left at a 4-way stop), AND
- ~1/2 throttle or more

Observation:
- Rumble/scrubbing feeling similar to understeering on a wet road ("judder"?)
- Mostly perceived through seat / steering wheel
- Sensation stops once steering unwound past 90 degrees
- Subtle enough that passengers don't notice
- No tire screeching / marking on the road / odd tire wear
- Fairly reperformable
- Almost as subtle as hitting a rough patch of road
- Feels like coming from the front but hard to tell
- Doesn't seem like tires are rubbing the fender or anything

Other relevant facts:
- Totally stock engine /clutch / dog bone
- Stock wheels w/ Michelin PS4S in stock size (10k miles)
- Using spacers but happens with or without
- GC camber plates, Bilstein coilovers (not very low), aftermarket sway bars and LCA bushings

Any pointers? Thanks!

EDIT: sounds like this might just be Ackerman effect (see below)

 

[Diggs24]

Turning either way or just one way?

 

[AR11]

Good question. I notice it more when making left turns but think this might be because the left turn has a wider turn radius than a right turn and therefore longer window of time to notice the symptom. I have also experienced it turning right.

 

[Rollux]

My wife’s golf has just started making a similar noise - almost like a creaking. Have located it to the subframe shifting slightly under certain loads. Can reproduce it on a hoist with a 6ft bar on the subframe in certain directions.
will order a deadset kit at some stage to fix it.
Btw, her car is a stock 2013 1.4t Mk7 with 63kms. So obviously the washers lose their bite over time

 

[AR11]

Interesting. The symptom I'm experiencing can last as long as 2 seconds or so, which makes me think it isn't a groaning subframe. Funny signature line BTW. Good luck with the fix.

 

[Rollux]

Yep, similar here as for time it can last. It might just groan slightly or for an entire corner, esp when pulling out of an intersection (left turn for you) under moderate throttle. On an undulating open road corner the car almost sounds like an old wooden ship at times! It’s not spectacularly loud, but can hear and feel it.
Get it up on a hoist and lever the subframe - see if it makes the same noise. Took me about 20mins to locate it with the help of my work mates (I work at a shop) and it’s amazing how much pressure with the bar was needed to make it.
I loosened all the bolts and retorqued and it has lessened for now, but still there.

 

[AR11]

While my hunch is that it is not the subframe (because I wouldn't expect it to make a sustained noise) admittedly I have dropped the subframe in the past and acknowledge that it is a common issue so I'll consider a deadset kit and alignment.

Other ideas?

 

[KevinC]

My Z4M was doing this when making hard left turns, turned out that the fender liner had been dislodged and was rubbing when wheel was at full lock. Wasn't obvious until it was up on a lift.

 

[AR11]

The combination of steering input and throttle needed to generate the symptom kind of makes we wonder if it is CV joint related. Does this resonate with anybody? It seems like there are very few discussion about replacing cv joints / axles on this platform.

Edit: This may also be consistent with my perception that it occurs more frequently when turning left.

 

[emichel6888]

Mine does the same thing but it is nothing to be concerned about. It is caused by the "Ackerman effect" lots of high performance cars experience this issue, especially in colder weather when tires are stiff and don't have a lot of grip. Stiff suspension (bushings) and certain tires will make this effect more noticeable. When you turn the wheel the two front tires do not have the same angle (this is Ackerman steering) so one of the tires will drag a bit and under the right conditions that will cause a resonance.
I don't know what tires you are running but I have MPS4S, and from what I hear they are known do this more than most. Go on the Porsche, Ferrari, or Corvette, forums and search on Ackerman tire judder, you will see it is a well known issue. Suspension modifications and sticky tires cause it even with this car. So next time your passengers notice this issue, just look at them and say "race car"

 

[MattWll]

I had this lever, after the replacement everything was gone. Seeing anthers, is everything in place.

 

[AR11]

Mine does the same thing but it is nothing to be concerned about. It is caused by the "Ackerman effect" lots of high performance cars experience this issue, especially in colder weather when tires are stiff and don't have a lot of grip. Stiff suspension (bushings) and certain tires will make this effect more noticeable. When you turn the wheel the two front tires do not have the same angle (this is Ackerman steering) so one of the tires will drag a bit and under the right conditions that will cause a resonance.
I don't know what tires you are running but I have MPS4S, and from what I hear they are known do this more than most. Go on the Porsche, Ferrari, or Corvette, forums and search on Ackerman tire judder, you will see it is a well known issue. Suspension modifications and sticky tires cause it even with this car. So next time your passengers notice this issue, just look at them and say "race car"

Thanks for this reply. This is exactly what it feels like: as if my toe suddenly went off. I am, in fact, using MPS4S and have a fair bit of stiffened up suspension bits.

 

[zepharus1]

Thanks for this reply. This is exactly what it feels like: as if my toe suddenly went off. I am, in fact, using MPS4S and have a fair bit of stiffened up suspension bits.

I wan to say this is it also but im on stock suspension and the stock Conti sport contacts. It just dawned on me that I DID notice this was much less of an issue with my winter tires, yokohama ice guards. Maybe there is more to this than I thought

 

[Yellokilo]

I had this issue too. Persistent techncian sleuthed it.
Turns out that it was a worn engine/transmission mount inside the inside of engine compartment driver's side.

 

[AR11]

I had this issue too. Persistent techncian sleuthed it.
Turns out that it was a worn engine/transmission mount inside the inside of engine compartment driver's side.

Thanks for sharing. Any chance you got a look at the failed unit? Was it obvious from a visual inspection or was it more of a "guess and check" approach?