A Strange Thunk (NA)

The POSIV has a odd thunk that sounds like it is coming from the passenger side rear of the car. I put "newer" upper control arm bushings in it this weekend thinking that might be the cause of the noise. But the wife I heard it on the way to Home Depot yesterday.

Strange thing is I can't replicate the noise consistently anywhere but at the kids school going over a speed bump. Anywhere else it is hit or miss if it will make the thunk.....

SO far I've checked the following.

1. Battery (Tight and secure)
2. Shocks (Everything it torqued to specs)
3. Rear Bearings (Checked out OK)
4. Upper Rear A-Arms - Replaced all bushings.
5. Lower A-Arm bushings (No unwanted play)
6. Alignment bolts (All tight)
7. Brake Calipers lubed and replaced pads
8. Took the spare, Jack, Tire Iron, and Jack handle out of the car.
9. Checked every nut and bolt I could find to see if I could locate anything loose......

I plan to swap the rear shocks tonight to see if the noise travels with the shock.

What am I missing?

Mine was thunking and it was one of my rear shocks. Did you check all 3 nuts on top of each shock? (In the trunk that is)

Perhaps it's a leprechaun... check for gold.

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Originally Posted by sammm

Mine was thunking and it was one of my rear shocks. Did you check all 3 nuts on top of each shock? (In the trunk that is)

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Yep checked all 3 even pulled the passenger rear shock an reinstalled when I did the bushings. The plastic isolator was even still with the car looked like new.

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Originally Posted by trickyrix

Perhaps it's a leprechaun... check for gold.

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I didn't see you near my car. ::Banana::

Did you torque the bushings on the ground, or while unloaded?

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Originally Posted by OZMDD

Did you torque the bushings on the ground, or while unloaded?

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On the ground. Keep in mind the thunk was also occurring prior to the bushing swap.

Swaybar loose or broken swaybar bracket?
Muffler loose, or missing exhaust hanger?

Jimmy Jan left a turd in your trunk?

I assume you checked the diff and all the bracing around it. How about the driveshaft? I had to replace mine recently. I would think it is probably the exhaust.

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Originally Posted by POS Racing

I didn't see you near my car. ::Banana::

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I was climbing trees in Mobile, AL...

http://www.youtube.com/watch?v=nda_OSWeyn8

Those people vote.

The resemblance in that amateur sketch is uncanny! ::Spit::

<---- So, um, that's my new avatar?




Well played... :rolleyes:

I like the black Irish guy with a steel pipe passed down from his grandparents thousands of years ago!

Great success... ::Banana::

http://img524.imageshack.us/img524/1831/threaddrift.jpg

I had the thunk noise twice - one was from a dead rear shock, and the other was due to the passenger side door - that thunk went away when I re-adjusted and tightened-down the rubber thing near the bottom rear of the passenger door opening.
Hope this helps.

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Originally Posted by trickyrix

Perhaps it's a leprechaun... check for gold.

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Wasn't me..... I swear....

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Originally Posted by miataspeedracer

Swaybar loose or broken swaybar bracket?
Muffler loose, or missing exhaust hanger?

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Pulled the rear swaybar a few weeks ago still had the noise. Checked everything when I reinstalled it looks good. But I'll look at it again.

Exhaust hangers is something I hadn't looked at! With it being intermitent this is something I'm going to look at closer!

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Originally Posted by motorollow

I assume you checked the diff and all the bracing around it. How about the driveshaft? I had to replace mine recently. I would think it is probably the exhaust.

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I checked every nut & bolt I could get a wrench on didn't find anything (yet).

Hmmmm second vote for exhaust hangers!

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Originally Posted by Walsted

I had the thunk noise twice - one was from a dead rear shock, and the other was due to the passenger side door - that thunk went away when I re-adjusted and tightened-down the rubber thing near the bottom rear of the passenger door opening.
Hope this helps.

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Plan to swith the shocks from side to side, didn't get a chance to do it tonight.

I'll definately take a peek at the door.

Thanks everyone (well everyone but trickyrix ;) )

My vote is for exhaust hangers as well as that is what was causing the noise on my NA. You can use a hose clamp around the hanger to stiffen it up and keep the exhaust from moving around so much.

Are you absolutely certain that you used the correct metal shank-pieces which go through the center of each bushing? I had to check mine with a micrometer because some are 1-3mm larger or smaller on the inner diameter which the bolt passes through. A deadblow tap will tell you the truth.

i think you are good enough at shock swapping to do mine in your sleep! keep us up to date. i have the same issue on the drivers side but i know my bilstien is shot.. it peed all over when lifted during a tech day

You still might check the driveshaft. Mine was making noises before I changed it.

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Originally Posted by motorollow

You still might check the driveshaft. Mine was making noises before I changed it.

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How do you check it?

Yeah! How do you check it? I think mine is making a different funny noise.

I was getting a clunking type noise while driving. I took mine over to TDR and Black Roadster made the diagnosis. When I went to install the replacement you could easily see the wear in the joint. Easy to install a new one, just 4 bolts.

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Originally Posted by onething

Yeah! How do you check it? I think mine is making a different funny noise.

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OK BR, how do you check the U joints?

With a BFH(Big Freaking hammer) ;)
...J/K

Usually, i have been able to tell by twisting the shaft and tail piece in opposite directions and seeing play in the joint.

The wear was very visible. Because of the play in the driveshaft, you could see fresh scrapes and torn metal in the joint. One look at the joint and you will know. All Black Roadster did was jack up the car on one side and looked.

OK finally had some free time tonight so I spent some time under the car.

• First of I looked for leprechauns didn't find any.
• Checked the drive-shaft checked out OK.
• Then I swapped the rear shocks side to side to see if the thunk noise might move.
• Flipped the end-links on the rear swaybar just for giggles and since miataspeedracer had mentioned it.

Took it for a run and so far no thunk I'm thinking it was either leprechauns or the end links. Plan to run the car around more tomorrow hopefully it stays thunk free!

Appreciate everyones input!

Update the noise has now moved to the other side of the car so it looks like one of my Bilstiens may have an issue. More disassembly required..... :(

arent those new?

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Originally Posted by patf

arent those new?

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Nope pulled them off a car at Mazda Heaven about this time last year.

Front were also used I found them on E-Bay!