Vibration 1700 rpm

[BGB autosport]

I've had my 2011 rapide a month or so, it's always had very slight vibration at around 1700 rpm (whist stationery) it's not there at 1500 and gone by 2000. I doubt most people would notice it.
It's needed plugs so did these along with coils and PCVs and was hoping it would solve it.
After the work it happily burst back into life, idles smooth, no misfires on the diagnostic but still has the same vibration, although does definitely drive smoother and more responsive.

It doesn't shake the car but you can feel it in the chassis, you can't feel it in the move. I wondered if it could be an engine mount or if it's just a characteristic of the engine.

Any thoughts or experiences?

[Longy00000]

I've got a later V12 in a Vanquish S and can't find any imbalance at 1700 rpm so perhaps not a characteristic as such.
Sorry can't help anymore but maybe this bump will bring someone else along

[BGB autosport]

Longy00000 said:

I've got a later V12 in a Vanquish S and can't find any imbalance at 1700 rpm so perhaps not a characteristic as such.
Sorry can't help anymore but maybe this bump will bring someone else along

Thanks for the reply, I'll carry on trying to find something amiss then!
In changing the plugs I found two issues that I thought may have contributed 1. One of the vacuum hoses to the fuel rail was disconnected and 2. The fuel rail vacuum hoses where switched. Both now corrected and still the same.

[dkatwa]

I had a similar issue on my DB9 and it turned out to be the heat shield (on the underside of the car, directly under the centre console) which was rubbing and causing a vibration and noise.

[Guycord]

I suspect it is the torque tube vibration/in-balance at a given shaft speed.

My V12V had a slight cyclical shake it at idle.

[LTP]

Guycord said:

I suspect it is the torque tube vibration/in-balance at a given shaft speed.

My V12V had a slight cyclical shake it at idle.

I doubt this. At idle the prop shaft that runs within the torque tube is not rotating.

[BGB autosport]

dkatwa said:

I had a similar issue on my DB9 and it turned out to be the heat shield (on the underside of the car, directly under the centre console) which was rubbing and causing a vibration and noise.

Thanks, I'll take a look, although I have no noise or rattle but will definitely check.

LTP said:

I doubt this. At idle the prop shaft that runs within the torque tube is not rotating.

This would kind of make sense, it's similar to what I've experienced with an out of balance propshaft but clearly design wise that was road speed related not rpm as it was post the gearbox. LTP, at what RPM would it start to spin? I have nothing at idle and only at ~1700. Could I test by having it in drive and increasing the revs whilst holding it on the brakes?

[LTP]

BGB autosport said:

LTP, at what RPM would it start to spin? I have nothing at idle and only at ~1700. Could I test by having it in drive and increasing the revs whilst holding it on the brakes?

Actually, I take that back. I was thinking manual or automated (ASM) manual gearboxes, as the clutch is attached to the flywheel. For the auto box there is a flex plate at the flywheel end and the torque converter is in the back as part of the transmission. So for an auto the driveshaft within the torque tube will always be spinning at engine RPM.

Apologies to you and Guycord

[BGB autosport]

LTP said:

Actually, I take that back. I was thinking manual or automated (ASM) manual gearboxes, as the clutch is attached to the flywheel. For the auto box there is a flex plate at the flywheel end and the torque converter is in the back as part of the transmission. So for an auto the driveshaft within the torque tube will always be spinning at engine RPM.

Apologies to you and Guycord

Pleased you've confirmed that, I was studying the parts diagrams confused as to how it couldn't do anything but tartare at engine rpm!
I'm guessing the only way to test this would be to drop the torque tube and run the engine. I've not found anything with these being an issue.

[BGB autosport]

I've still not tracked this issue down, it's done 3k miles since I got it and it's still the same. It had it's MOT last week and I asked they check the engine/gearbox mounts, no reported issues.

The crank pulley appears to be running true, a bit of corrosion but the rubber isn't split or bulging.

Presumably the only way to check the torque tube would be to remove it entirely, run the engine and see if the vibration remains. Or is there's another, easier way the test the drivetrain?

Open to any other suggestions!

Edited by BGB autosport on Thursday 26th May 21:10

[Speary8]

BGB autosport said:

This would kind of make sense, it's similar to what I've experienced with an out of balance propshaft but clearly design wise that was road speed related not rpm as it was post the gearbox. LTP, at what RPM would it start to spin? I have nothing at idle and only at ~1700. Could I test by having it in drive and increasing the revs whilst holding it on the brakes?

In a manual if the car is in neutral and the clutch engaged then the prop shaft is rotating at idle. Could be the same on the auto otherwise the system would have to keep the clutch disengaged when in neutral which would put unnecessary load on the clutch release bearing

[BGB autosport]

Speary8 said:

In a manual if the car is in neutral and the clutch engaged then the prop shaft is rotating at idle. Could be the same on the auto otherwise the system would have to keep the clutch disengaged when in neutral which would put unnecessary load on the clutch release bearing

Yeah, it's an auto but determined that the propshaft is always spinning at engine rpm, as the torque converter is at the back. Hence it appears my only way to test the torque tube is to totally remove it.

[Jon39]

Huge amount of work to remove the torque tube.
There is an independent specialist in Warwickshire, who appear to enjoy investigating obscure faults.
If you are not too far from them, they might be able to help you.

[BGB autosport]

Jon39 said:

Huge amount of work to remove the torque tube.
There is an independent specialist in Warwickshire, who appear to enjoy investigating obscure faults.
If you are not too far from them, they might be able to help you.

Yeah, I was expecting as much!
I have a lift, props etc, I was 'hoping' it would be possible to drop the rear subframe, gear box and pull it all back and down sufficiently to disengage the torque tube from the engine to allow me to fire the engine to check the vibration, without actually fully removing it.

I've not pulled the undertrays off to see if this would be possible yet.

Edited by BGB autosport on Saturday 28th May 08:19

[Jon39]

The following is pure thinking aloud, guesswork by me.

When the torque tube housing is in place (with or without the torque tube itself being present), does that increase the stability of the engine?

If it does, then running the engine without the torque tube housing in position, might result in vibrations anyway.

Could put everything back excluding torque tube prior to testing the engine, but of course the total amount of work then doubles.
I don't remember anyone on here discussing an out of balance torque tube, so perhaps it might be very unusual.

[BGB autosport]

Jon39 said:

The following is pure thinking aloud, guesswork by me.

When the torque tube housing is in place (with or without the torque tube itself being present), does that increase the stability of the engine?

If it does, then running the engine without the torque tube housing in position, might result in vibrations anyway.

Could put everything back excluding torque tube prior to testing the engine, but of course the total amount of work then doubles.
I don't remember anyone on here discussing an out of balance torque tube, so perhaps it might be very unusual.

You make a great point and thinking about the mount arrangement, it would likely allow the engine to and rock front to back. Back to the drawing board!

As you say there's next to no info of failures or issues with the torque tube on Aston martins, plenty for BMWs and Corvettes.

Edited by BGB autosport on Saturday 28th May 09:12

[jaga-jaga]

BGB autosport said:

You make a great point and thinking about the mount arrangement, it would likely allow the engine to and rock front to back. Back to the drawing board!

As you say there's next to no info of failures or issues with the torque tube on Aston martins, plenty for BMWs and Corvettes.

Edited by BGB autosport on Saturday 28th May 09:12

Hello there!

Please tell me if you managed to solve the vibration problem?
I have the DB11 AMR 2020 and it has the same problem with vibration at about 1700 rpm.
I've made diagnostics in several services, but they could not understand what was the cause of the problem...