Getting a rhythmic thumping noise from rear of car!

[desertg8]

First thought it was the rear tires since they were down to the wear bars. So I replaced them today with new tires. It is still there as loud as ever and the sound increases and gets faster with the speed of the car. A few months ago I had a rear stud replaced. They said the hub had melted on to something else and they had to order a new hub or wheel bearing. Not sure as I am not a mechanic. What does this sound like to you???

[TomPierce]

We need a little more information.

Does the thumping correlate with the wheel speed or the engine speed?
Describe the symptoms. Does putting on the brakes make it go away, etc.

You'll get a better answer that way :)

[wyome]

Are there little people in the trunk that want out mebbee ?

[desertg8]

The sound increases with the speed of the wheels. Speed. The rpm of the engine has nothing to do with the sound. Yeah, those litttle people can be loud. I am going to bring it to Pontiac tomorrow.

thump, thump, thump. rhythmic. if i go 60 it is louder than when i am going 30. also when i do put on the brakes i believe the sound does go away.

[wyome]

Had a loose caliper bracket do that once...mebbe a u-joint is failing on ya.

[desertg8]

what about the litttle people theory??? ha ha

I had the pads replaced a couple of months ago also. The tech who did the work is going to be in tomorrow.

[desertg8]

Tech is going to drive it in a few hours. Definitely in the right rear where he worked on it before. The reason I know this is when I go into a right hand curve and the pressure is put on the left wheels there is no noise. As soon as the car straightens out there is noise.

[rjones916]

If it is side to side, when you take the weight of one side it is louder, and the weight on the other there is no noise, it is gonna be a hub bearing....they are covered under powertrain till 100,000miles.

-Ryan

[desertg8]

Yes, we were both correct. It is a hub bearing. When we put it in the air the wheel was very loose. Also I noticed the car at the drag strip would pull to the right. Obviously there was some friction going on in the right rear. Lucky the darn thing did not fall off.

[rjones916]

yea, the rears are kinda a pain cause they are press in, make sure it gets installed using the correct press adapters and correct amount of tons, I think last one I installed I went between 8-9tons

[dandragonrage]

Obviously there was some friction going on in the right rear. Lucky the darn thing did not fall off.

Just FYI... if the bearing completely fails, it will freeze up, locking the wheel up. Apply gas and something is either going to break HARD or your diff will simply burn out the clutch for that wheel.

[texn884]

Sounds like Hub bearings

[dandragonrage]

Sounds like Hub bearings

He already got that figured out - I just added my last post to make him/people aware of what would probably happen if it failed completely.

[texn884]

Opps.

[Panzer Leader]

As soon as the tranny is replaced I will ask them to check both the calipher and hub bearings.

[Napalm]

OP: So you say you had one hub replaced already and the shop/mechanic didnt' at least recommend replacing the other.

I know it sounds over kil, but I always do them in axle sets. IE LH and RH at the same time. UNLESS, I replace one and its already bad (never happened to date though).

Just making sure I read your first post right.

[desertg8]

I will back up a bit. I stripped a stud a few months ago. When they pulled the hub off to replace the stud the mechanic told me it was stuck to another part. Therefore at that time they replaced the bearing. Obviously they did not replace it correctly or the replacement part was bad. So it is the same bearing on the same wheel within a few months.

[Napalm]

I will back up a bit. I stripped a stud a few months ago. When they pulled the hub off to replace the stud the mechanic told me it was stuck to another part. Therefore at that time they replaced the bearing. Obviously they did not replace it correctly or the replacement part was bad. So it is the same bearing on the same wheel within a few months.

Thanks. I was cornfused. (yes i speeled it wrong on purpose)

So is all well now.

[Panzer Leader]

Might be the setting on the sub woofer. LOL

[desertg8]

No, all is not well. It has been in their shop since Saturday. They said they ordered three parts. But only two came in. I said what are we waiting for? They said a nut! It is on back order. I just hope it is not coming from your country. Odd, that they would have to replace a nut.

[Napalm]

WTF are they replacing now? hub or knuckle? are they maybe replacing the rear

What happened to require the replacement of the studs? Did they smurf up the parking brake?

[Panzer Leader]

Well look at it this way. At least they acknowledged the problem. Hope you are back on the road soon.

[rjones916]

only nut back there is the axle nut that I can think of...most parts for this car seem to come out of Rancho Cucamonga, Califonia for some reason and take some time to get. When I got in my little fender bender I didn't have my car for 2 months and most of that time was waiting for little odds and ends special order parts from across the country/world haha. Try to be patient and hopefully they will fix it correctly this time!

[desertg8]

And the saga continues! They got the axle nut yesterday. I get an e mail today. The new hub they installed is dropping wheel speed causing the abs light to stay on. So now they have to order again a new hub. It will be nine or ten days before I get her out of the shop because of a bearing that they probably installed incorrectly the first time a few months ago.

[1ChargedG8]

Man is just hilarious, i was taking to a friend of mine that's a tech at Mazda dealer in town and he told me that most of the techs they fired because of lack of performance/productivity at work end up working at our dealer!!!

[desertg8]

well i did a google and in 99.9 percent of the cases it is the abs sensor. and when i asked the dealer they concurred with me. but the sensor is actually inside the hub of our vehicles. so that is why they have to order a new hub. next week should be fun though. my hp tuner kit should be here. i will bring pencil, notebook, the tuner, and pay attention to what you can teach me on the basics.

[rjones916]

on the rear the speed sensor, it is actually external and bolts to the knuckle, they may have damaged on removal...the hub contains the tooth reluctor wheel that gives the sensor something to read....the only way a brand hub would malfunction is if one of the teeth got chipped on install or they installed it backwords(most likely what happened). Jeezzz, don't know about this shop....

[desertg8]

And the saga continues. Now I am getting a shaking/vibrating from the entire rear end when I accelerate half to three quarter throttle. I drove it to the dealer this morning and 90 percent of these symptoms mysteriously disappeared. The service advisor just told me it was abs doing it's job. Now tonight it came back violently. As long as I am coasting and not going on it or accelerating moderately you can hardly notice it. I jacked up the rear right and now the tire will rotate some forward and backwards. Before it would not rotate at all. It is not shaking as though it is loose. I did it with the rear driver's side one and I can rotate it front and back. No looseness on the tire. I noticed at the track a few weeks ago I was getting what I thought was a miss from the engine or something. I have a feeling it was rear tire giving me that sensation at higher speeds. What is going on?

[GT Drew]

Ask them how they installed the hub. Did they disconnect any ot the control arms from the knuckle. Are there hub rings on your rims? Bet they lost one when they put the new hub on.

[desertg8]

it was real bad this morning. like going flipping through a deck of cards at high speed or putting one in your rear bicycle rim when you were a kid. this time he heard it. at dealer now. i think it is something external that they did not tighten up or maybe as you said. i will let you know. my goodness!

[desertg8]

preliminary diagnostics came back with a broken flange bolt in the cradle or a broken drive shaft bolt that goes to the cradle. i called my advisor and he had not walked back there to fully understand the situation himself.

[Rob@WretchedMS]

take pics if you can, i've never seen one of them break, not that they can't, but try to get pics.

[desertg8]

the dealer actually gave me pictures. one of the bolts in the drive shaft that attaches to the differential broke off. the back part of the bolt which still had the nut attached would go back on acceleration and hit the differential causing that fast paced thumping sound. it is not covered under warranty since the transmission was out when the stall converter was installed. the dealer claims over torquing the bolt caused it. no big deal. $100 and a grade A bolt.