Brake Judder, replacing wheels as well as discs on DB9
Discussion
I have a DB9 with brake judder for the second time. First time new discs fixed it, but now it seems its the wheels that are distorted, and causing the discs to distort, so now the recommendation now is to replace both front wheels and discs ( and pads)
Is this a DB9 thing? Is it likely two wheels have distorted in this way? The car is 2008 and done 41k miles only
Is this a DB9 thing? Is it likely two wheels have distorted in this way? The car is 2008 and done 41k miles only
It's unlikely. Also you'd feel massive vibrations and the steering wheel turning in your hands if the front wheels were distorted like that.
Brake discs being warped is one thing that causes vibrations. On some cars it's very hard to eliminate as it's a design fault but there are ways.
On other cars it is to do with suspension parts wearing. The suspension arms are meant to hold the wheels steady but if the bushings become weak it can create an oscillation which gets bigger and bigger the harder you're trying to slow the car.
Brake discs being warped is one thing that causes vibrations. On some cars it's very hard to eliminate as it's a design fault but there are ways.
On other cars it is to do with suspension parts wearing. The suspension arms are meant to hold the wheels steady but if the bushings become weak it can create an oscillation which gets bigger and bigger the harder you're trying to slow the car.
As per the previous poster, it is unlikely to be the wheels, you would feel that whether you are braking or not. Also, I hjave nver heard of a wheel distorting on its own, unless you have hit a kerb or something else.
At 41k miles it possible some suspension bushes need to be replaced, although this can be difficult to diagnose.
Juddering under braking can be a number of differnt things and you really need to talk to someone who knows the DB9 very well for advice, are you on any Aston Martin/DB9 forums? Maybe they can help.
This is an example of a BMW (E32 7 Series) that is notorious for brake judder and all the possible things that can cause it:
http://www.meeknet.co.uk/e32/E32_Shimmy.htm
At 41k miles it possible some suspension bushes need to be replaced, although this can be difficult to diagnose.
Juddering under braking can be a number of differnt things and you really need to talk to someone who knows the DB9 very well for advice, are you on any Aston Martin/DB9 forums? Maybe they can help.
This is an example of a BMW (E32 7 Series) that is notorious for brake judder and all the possible things that can cause it:
http://www.meeknet.co.uk/e32/E32_Shimmy.htm
Can you run an on car wheel balancer…some have had good results..will find out if the rims or tyres are out of spec..I had some truck tires in Canada that were effectively oval..manufacturer replaced them..all good now..
With on-the-vehicle balancing, the wheel doesn’t leave the truck or trailer. In addition to balancing the tire, it balances the hub and the drum in relation to the truck’s suspension.
“The best benefit for on-the-vehicle [balancing] is that you’re balancing everything from the hub, drum, and on out, so it takes a lot more of the imbalance out and it does it all as one unit,” says Howard Williams, corporate technical sales specialist at Bee Line Company, an on-truck tire balancing manufacturer.
With on-the-vehicle balancing, the wheel doesn’t leave the truck or trailer. In addition to balancing the tire, it balances the hub and the drum in relation to the truck’s suspension.
“The best benefit for on-the-vehicle [balancing] is that you’re balancing everything from the hub, drum, and on out, so it takes a lot more of the imbalance out and it does it all as one unit,” says Howard Williams, corporate technical sales specialist at Bee Line Company, an on-truck tire balancing manufacturer.
Edited by Import on Monday 22 August 23:01
Remove the front wheels and using a magnetic dial gauge stand, measure the disc run out, both at the outer edge of the disc and on the wheel mating face. This will eliminate (or otherwise) the disc warpage. Also make sure the mating surface between the hub and disc is spotlessly clean.
I would tend to be looking more to the front suspension bushes though as the culprit, although a sticky caliper piston is the cause of 75% of BMW's with this issue.
Wheel or tyre distortion would cause the vibration whether you are braking or not. You can also pull up the handbrake independently whilst driving to see if the vibration is coming from the rear.
I would tend to be looking more to the front suspension bushes though as the culprit, although a sticky caliper piston is the cause of 75% of BMW's with this issue.
Wheel or tyre distortion would cause the vibration whether you are braking or not. You can also pull up the handbrake independently whilst driving to see if the vibration is coming from the rear.
8Tech said:
Remove the front wheels and using a magnetic dial gauge stand, measure the disc run out, both at the outer edge of the disc and on the wheel mating face. This will eliminate (or otherwise) the disc warpage. Also make sure the mating surface between the hub and disc is spotlessly clean.
I would tend to be looking more to the front suspension bushes though as the culprit, although a sticky caliper piston is the cause of 75% of BMW's with this issue.
Wheel or tyre distortion would cause the vibration whether you are braking or not. You can also pull up the handbrake independently whilst driving to see if the vibration is coming from the rear.
From personal experience (not on a DB9) the run out on the discs will be very small and within tolerance (<0.15mm on the outside edge). The problem is far more likely to be differences in friction along the diameter of the brake - change the discs for better quality ones. I would tend to be looking more to the front suspension bushes though as the culprit, although a sticky caliper piston is the cause of 75% of BMW's with this issue.
Wheel or tyre distortion would cause the vibration whether you are braking or not. You can also pull up the handbrake independently whilst driving to see if the vibration is coming from the rear.
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