Engine wobbling sound

[hardingfv32]

No it is real. I have a good article by Gordon Blair that explains it. PM me with your Email if you want a PDF.

Brian

[bigpat]

I think you find it is high speed wheel chatter, where the tyres are coming off the wheelspin phase, and attempt to grab traction. You will typically find it only from standing starts.

Indycars (the real ones in the 90's & 2000's) were constantly doing it. The Penske's did it noticably, particularly away from pitstops. They also left "pulsed' tyre marks, also leading to speculation that it was traction control at the time.

Remember that the engine, clutch, and geartains in F1 have very little mass and inertia to absorb these shocks and pulsations from the system, which results in the chatter you hear.

[Callum]

I agree with bigpat, I think it sounds like high frequency tyre spin in a stick-slip type motion.

[hardingfv32]

i considered that, but the last video of a start in the rain does not support that explanation.

Brian

[rjsa]

It's redlining, nothing more than that.

[bigpat]

It's redlining, nothing more than that.

Not so.

Particularly on the Petrov video, you can clearly hear the revs are higher when wheelspinning, and drop to the point when the chatter re-starts.

There is no reason why the wheels wouldn't also chatter in the wet. Remember that they is still a fair bit of grip there, as the wets & inters are a particularly soft compound.......

[hammarby88]

Sure it isnt the clutches? They have dual clutches and in the start they drop one while controlling second with their hand, allowing some slip for best acceleration without stalling/spinning. So what you hear is the second clutch biting no?

[peanutaxis]

It's redlining, nothing more than that.

No. Because F1 engines don't even redline like your car does. When they hit the limiter along the straights they don't pulse on and off, they just sit there at 18,000 revs. Plus you can hear the revs rise AFTER the wobbling anyway!

[peanutaxis]

Sure it isnt the clutches? They have dual clutches and in the start they drop one while controlling second with their hand, allowing some slip for best acceleration without stalling/spinning. So what you hear is the second clutch biting no?

So why does the first clutch sound like the clutch in my car, and the second like....crazy wobbliness?

[spacer]

They don't have two clutches, just two clutch paddles operating the same clutch.

The sound coming from the transient between wheelspin and full traction makes sense, thanks.

[mzivtins]

I thought that the ranualts actually cut down to 4 or maybe even 2 cylinders mid corner etc, maybe this could be something similar in ther turo russo??

[hardingfv32]

Particularly on the Petrov video, you can clearly hear the revs are higher when wheelspinning, and drop to the point when the chatter re-starts.

This is not true. Watch the shift lights on the steering wheel.

Brian

[hardingfv32]

No. Because F1 engines don't even redline like your car does. When they hit the limiter along the straights they don't pulse on and off, they just sit there at 18,000 revs. Plus you can hear the revs rise AFTER the wobbling anyway!

There is no reason the rev-limit function on his car is different than F1. We have no knowledge of how a current F1 engine limits revs.

On long straights when the engine is at 18K, how do you know if it is on the limiter if you hear nothing? Could it not be geared correctly so as not to exceed 18K?

Brian

[bigpat]

An F1 engine is limited the same as any other, by spark cut.

You can hear when the car is on the limiter from on board cameras. As well as the shift lights, the driver can hear it. Nowadays, the cars are geared to be close to the limiter in 7th, with DRS activated. The Red Bulls, and Mc Larens in particular, can be heard banging the limiter on straights. Re watch on board with Hamilton trying to pass Schumi at Monza last year....

Brian, I watched the video, and the revs to rise after the chatter, albeit the point between chatter and the shift point is close when revs rise that quickly! Remember the shift light activates 1500-2000 rpm lower than the limiter in 1st and 2nd gear to allow driver reaction time. The shift light stays the same if he revs the engine higher. At the first point of chatter you will see only the left part of the lights illuminate. Remember that we don't know what the lights are set to show in the starting phase, and the cars have multiple modes on the steering wheels.

Re watch it, but don't be fixated on the shift lights, and listen carefully. You have to 'feel' it....

[Reca]

This is the rpm from the STR practice start analyzing sound of the BBC video, the "wobbling" part is between just over 3s and 4s (consider that the car is running away from the mic, so it's likely bit of impact on frequency, thus causing an underestimate of rpm measure, more and more as speed increases, from Doppler effect) :


This is on the contrary rpm from the video of Petrov's start posted by spacer: