Grand Am Series
Join Date: Jan 2011
Location: Eden Prairie, MN
Clunking and rattle in drivetrain (?)
I'm at the end of my rope on this, about to break down and take it to a mechanic. Here's the story. Sorry it's so long, but in addition to providing background I kinda want to vent.
First, the car: 2006 S sedan, manual transmission, Eibach Pro-Kit springs.
It started as a simple brake job (doesn't it always?). But for the life of me I could not get the rotors off, either side. I believe they're the original rotors and the car has 134,000 miles, much of that on icy/salty Minnesota roads. I beat the snot out of the rotors with various types and sizes of hammer, PB Blaster, tried a makeshift bolt-and-nut push system, even rented a puller. Nothing worked. So I got out a torch to heat the sucker up. Still no dice. So I heated it up some more. And them some more. And then the hub started smoking and I realized I had cooked the wheel bearing on one side. Oh snap.
So instead of replacing just the wheel bearing, I hunted down a complete, inexpensive knuckle/hub/bearing (for both sides) from a local junk yard in good working condition. I decided with the car's mileage I would just go ahead and replace the CV axles and lower control arms. Plus, it was the easiest way to get all of the old parts out. I simply cut the inner CV joint boot and yanked out the entire control arm/axle/knuckle/rotor assembly--no need to separate the ball joint, etc. I then popped out the remaining stubs out of the axles.
The installation went fine. I put in the new CV axles and lower control arms, and the new (to me) knuckles/hubs/bearings seemed to work just great. I did notice that the driver-side CV axle (SureTech brand, from Rock Auto) was a little short, i.e., the inner joint seemed to stretch more than usual in order for the other end of the axle to make it through the hub.
On my test drive I immediately noticed some clunking and rattling over bumps, and also when I accelerated or stopped quickly--all on the driver's side. This had never happened before. I immediately suspected a bad CV and got a free replacement from Rock Auto. I swapped it out, but it made no difference. I then replaced the tie rod ends (I had accidentally punctured one of the grease boots during one of the installs) and sway bar links, all good quality Moog parts. No change. Next, I replaced all three motor mounts with the Roca kit (during the removal I confirmed my original PMM was indeed busted). It helped some, but the clunking and rattle continued. Then I replaced the strut mounts, strut bearings, and bump stops. The struts are still in good shape. But again, no change.
At this point I was sure the problem was the too-short CV axle on the driver's side. So I bought a reman from O'Reilly and compared it to the SureTech. Sure enough, the SureTech was about an inch shorter. Good grief. Just last night I installed the reman CV axle. And...(drum roll)...the problem still persists!! Though, again, it's slightly better than it was. But I still have a very pronounced clunk/rattle.
Now, a detailed description of the noise: any time I go over bumps I hear a clunk/rattle noise and I can feel it definitely coming from the driver's side. I also hear it when I brake abruptly, and when I accelerate from a stop or when I accelerate after shifting gears. I can also replicate the sound when I'm cruising and then stomp on the gas. The feeling is as if there is some slop/play in the drivetrain.
Basically I'm down to two possibilities: (1) bad wheel bearing/hub; or (2) there is something wrong in the differential.
The noise seems worse that you would expect with a bad wheel bearing. I'm a decent driveway mechanic, but I've never worked on a FWD differential before. If a differential bearing or gear was out of whack, wouldn't that have prevented me from getting the axles in? I didn't have any problem lining up the splines and snapping them in place, and visually everything looked fine when I installed the axles. But maybe something is loose in there?
2006 Mazda 3s GT sedan whitewater pearl | 5-speed
Last edited by shaundarbie; 10-09-2014 at 06:05 PM.