Loud knock on transition to braking, 2005 DB9
Discussion
Hello folks.
I've had a 2005 DB9 for about a month now. Lovely thing. While not much quicker than my old 4.2 XKR (which was modified), it does what it does in a much more engrossing way, and I'm so glad I changed marque rather than going for the newer 5.0 Jaguar.
It drives beautifully (though the ride is much harder than I'd expected), but I get an occasional loud knock as I begin applying the brakes, particularly switching from hard throttle to hard braking at speed, but only occasionally. It's a loud knock that really goes through the car - like a lump hammer hitting the floorpan. First time I heard it I thought I must have driven over a sharp-edged pothole.
I'm guessing there must be a major suspension bush that is allowing play, or a transmission mount. The sound seems to transmit evenly through the floorpan, but I'd say it has to be rear.
Are there any known issues that lead to this symptom?
I've had a 2005 DB9 for about a month now. Lovely thing. While not much quicker than my old 4.2 XKR (which was modified), it does what it does in a much more engrossing way, and I'm so glad I changed marque rather than going for the newer 5.0 Jaguar.
It drives beautifully (though the ride is much harder than I'd expected), but I get an occasional loud knock as I begin applying the brakes, particularly switching from hard throttle to hard braking at speed, but only occasionally. It's a loud knock that really goes through the car - like a lump hammer hitting the floorpan. First time I heard it I thought I must have driven over a sharp-edged pothole.
I'm guessing there must be a major suspension bush that is allowing play, or a transmission mount. The sound seems to transmit evenly through the floorpan, but I'd say it has to be rear.
Are there any known issues that lead to this symptom?
Hi Maverick, I know, just wondered if there might be a common reason for a loud under-car knock when applying the brakes hard. As for engine/transmission/suspension, I'm far from mechanically inept (my business is in the performance side of the motor trade) but I have no experience of these cars. It's certainly nothing like transmission shunt, it's an alarmingly loud (the reference of hammer on the floorpan was not exaggerated) thump under the car, sounds central or rear but very hard to tell.
And yes, definitely not serious about Eurocarparts - not until I can see if Halfords might include free fitting.
And yes, definitely not serious about Eurocarparts - not until I can see if Halfords might include free fitting.
Noises are notoriously hard to locate unless you know what it is ..... (obvioulsy)
If you're in the motor trade, this should be no problem for you, do not fear the Aston, its a glorified kit car, full of high tech parts, but a kit car none the less.
Not wishing to scare you, but if its not suspension and it occures on the hard change from acceleration to braking, then I wonder if the Torque Tube is the source of your noise, inside is this .....
Forgot what its called... I'm sure you'll tell me. But is this not supposed to ease the transition from engagement/acceleration/deceleration.....
If its broken will this not clunk like a hammer?
If you're in the motor trade, this should be no problem for you, do not fear the Aston, its a glorified kit car, full of high tech parts, but a kit car none the less.
Not wishing to scare you, but if its not suspension and it occures on the hard change from acceleration to braking, then I wonder if the Torque Tube is the source of your noise, inside is this .....
Forgot what its called... I'm sure you'll tell me. But is this not supposed to ease the transition from engagement/acceleration/deceleration.....
If its broken will this not clunk like a hammer?
It's nothing like any transmission shunt I've experienced before, which would be revealed as throttle is applied/released, it occurs (only occasionally) when the brake pedal is pressed hard and may be a major load bearing mount shifting in a damaged bush, or as suggested above potentially possibly a broken suspension component.
I'm sure more to do with the shift of loads through the suspension as loads change rather than the drivetrain itself. I'll get the car up on a ramp in a few days but just wondered if it might ring a bell with anybody as a known issue.
I'm sure more to do with the shift of loads through the suspension as loads change rather than the drivetrain itself. I'll get the car up on a ramp in a few days but just wondered if it might ring a bell with anybody as a known issue.
MaverickV12 said:
Forgot what its called... I'm sure you'll tell me.
Very funny - you know more about these matters than most of us.
When you previously showed this photograph, I was puzzled why the pressure plate is so rusty. Did it become rusty whilst installed (why), or after removal, but before photographing?
Jon.
Hi 8Tech, if I was in the car up on a ramp and somebody hit the middle of the floorpan with a hammer under the passenger seat, that would replicate what I hear - it's very loud, but because the shock goes through the body of the car, I can only guess at central/rear but it could be anywhere. Rear subframe mount suggestion above makes sense, as does fractured suspension arm - should be able to get it up on a ramp early next week and have a poke around. It's nothing like transmission backlash or brake pads, and louder than any kind of suspension knock I've encountered before.
Hi Genie, I'd missed your post but we found it was exactly that! Lower rear swingarm outer bush sliding under load, also has a detectable effect on tracking/wheel alignment which I started to notice (can't believe I hadn't done so before).
Wishbone assemblies are (surprisingly) reasonably priced and easy to swap over.
Wishbone assemblies are (surprisingly) reasonably priced and easy to swap over.
Beardog said:
Hi Genie, I'd missed your post but we found it was exactly that! Lower rear swingarm outer bush sliding under load, also has a detectable effect on tracking/wheel alignment which I started to notice (can't believe I hadn't done so before).
Wishbone assemblies are (surprisingly) reasonably priced and easy to swap over.
Ooo! I was close. I said front bush. Glad you found it.Wishbone assemblies are (surprisingly) reasonably priced and easy to swap over.
Gassing Station | Aston Martin | Top of Page | What's New | My Stuff