auzivision

Lately, a rather loud tapping noise occurs when driving out of the neighborhood. It appears to be related to vehicle speed more so than RPM. It’s a tapping noise more than a rattle and it's louder and much lower frequency than the ticking noise given off by the injectors or valves after a long respite.

I’m thinking it could be related to the front brake pads because it usually goes away when braking. Even thought it’s more of a tapping noise rather than a rattle, I was wondering if there some sort of rattle trap for the front pads that could go bad?

How can I rule out TT bearings… if they were failing, wouldn’t they make noise all the time and more pronounced at speed? It goes away a speed and after warm-up.

Any ideas on what to check?

RET

I had a strange intermittent clanking sound that would only happen at at about a fast walking speed. It did not occur at slower or faster speeds. It was very annoying, and somewhat embarrassing as it happened most often as I approached or drove away from my house.

After much aggravation and dismantling of brake and suspension parts, it turned out to be a nut rattling around in my rear tire. It was an extra nut normally used to secure the tire stem to the wheel (app 12 mm across the flats), apparently lost when the tires were installed. It is amazing how much noise this little nut made bouncing around in my tire and occasionally banging on the rim.

Good luck.

auzivision

Thanks RET,

Sounds remotely plausible, but the clanking noise is much louder than what I'd guess a loose nut inside a wheel would make. Plus, I've added sound proofing material to my interior and this tapping noise is very pronounced.

It sounds like its coming from a larger part like an A arm, but all the bushings and ball joints on the front are good. I might buy a heat shield on the exhaust clanking around, but I can’t find anything loose, plus it sounds like it coming from further up front.

It does goes away after driving a while and only occurs while rolling at low speeds. Also, for some reason while backing down my drive way in cold conditions, there is a strange shifting noise that can be both heard and felt. It’s like the transmission is shifting back a quarter inch or so. Hard to describe, but definitely not right.

I’ve read a little about transmission mounts and wonder if that is something I should check, but not sure how? That wouldn’t explain the tapping noise because that is emanating from up front.

Does any of this rambling ring a bell for someone?

chaadster

Kurt,

Since it's related to vehicle speed, you might try jacking the front and spinning the wheels by hand to rule out bearing failure (although this is not a typical symptom) or slop in the bearing.

I dunno...kinda perplexing. Good luck in the hunt.

auzivision

Thanks for the tip Chaadster... I've tried wiggling the wheels both North/South and East/West (with the steering locked) and there wasn't any play… so I don’t think it’s ball joints, tie rod ends, or wheel bearings.

Since it always goes away, I've never really worried about it, but it appears to be happening more often. I bought the greasible front sway bar bushings and will go through the front suspension again when installing these.

ew928

On a manual, you can declutch and take transmission out of gear to take the torque tube out of the equation. Not sure if there's an easy way to isolate the TT on an auto.

Are the front pads on tight? (wild guess)

SharkSkin

I had this exact same thing happen on a front wheel. It's a good match for your "tapping" symptom -- it sounded like it was much bigger than it was, and took me a while to track down. Get someone to stand on the sidewalk as you drive by under the conditions where it makes noise. Someone with a good ear will be able to help you localize which wheel is making the noise if this is the issue.
Could be something loose in the torque tube. Does it really go away after driving for a bit, or does it come back as soon as you slow down?

The large clunk sounds like the dampening weight is sliding on the shaft. The smaller noise could be a TT bearing that has popped out of its carrier.

bfellows

I've had this exact same problem twice! In my case it turned out to be a brake pad that wasn't returning squarely in the caliper. Much the same as your problem it was more noticeable at low speed - less road and engine noise, then disappeared if I pressed the brake pedal.

Might be worth jacking up the car to isolate which side is knocking, remove the wheel, remove the brake pads, clean out the caliper (the plates on which the pads slide) Clean up the pads themselves, file a slight chamfer on the leading edge of the pads and then refit.

Got to be worth a try? Nice and simple and might cure it (ever the optimist.......)

auzivision

Thanks guys.

First I’ll check over the brakes by cleaning them up the calipers and installing the new pads I have on hand even though there is a lot of meat left on the old ones. I’ll also roll the tire around in the garage to see if I hear anything bouncing around inside.

Since I still haven’t sorted out my transmission issues, I may be dropping that in the near future. If I do, I’ll just install a rebuilt TT along with Constantine’s flex plate clamp.

Even with Lucas Oil transmission treatment and the ATF level spot, the tranny still acts up. A couple people I’ve discussed this with suggested it sounds like fluid starvation and the weird thing is it usually acts up either during or just after a right hand turn.

I wonder if there is a valve, camber, cavity, pin or something that would be sensitive to centrifugal forces pulling the fluid to the left?

nosnow

Sounds strange but check your center caps. One of mine was seperating from the metal backing and would rattle. When the wheel warmed up enough the metal would expand and stop the rattle but after enough cooling time it always returned Drove me nuts and I took the stupid tire off 2-3 times to try and locate the source before I realized it was the center cap.

WallyP

A warped brake rotor will knock the pads back enough to get a tapping sound. Applying the brakes, even gently, will almost always stop the tapping. When you install the brake pads, check for warpage on the rotor.

A hard spot on the rotor will also sometimes do this, but it usually causes a very noticeable pulsing during brake application, wheras a warped rotor may not cause the pulsation.

If the brakes have no effect, the center cap would be a good thing to check...

Check the battery for looseness - a shifting battery can cause a heavy, soft clunk.

LT Texan

I had a rather large pebble lodged in between the tire grooves that made an annoying tap tap tap as I rolled down the road. Unbelievable that I could hear it over the pioneer supertuner under dash cassette player always cranked up to the max. Hey, you never know. This was 1979 in a 1969 Camaro. BTW, never happened to me again.

ew928

Bad flashback.
Last time I heard a low speed tap tap tap that varied with road speed came from my back tire.
As in there was a nice wood screw jammed into the tire tread.
That wasn't pleasant. (Only fortuitous thing is that I pulled over in about 2 blocks and that the rear tires were down to the wear bars anyways)

Hoping it's nothing like this in this case.

auzivision

It appears that the tapping noise has to be related to the brakes. It immediately goes away with even the slightest touch on the brakes. Maybe the rotors are warped but there is absolutely no pulsating under heavy, medium, or light braking. I’m not too worried about it for now… mostly just an annoyance and not TT related.

I also figured out the ‘thunking’ while backing down the driveway in cold weather. It’s actually the engine misfiring, coughing, spitting or whatever you want to call it. For some reason, in colder conditions (<40F) the engine now stumbles at idle. This used to be a rather rare occurrence on really cold days, but now it’s becoming much more prevalent even when not so cool.

This morning it kept stumbling at stop lights all the way to work… even after everything was up to temp. I think today has to be the first day I’ve ever driven my car by myself and didn’t experience any WOT BBRRRAAAAAAAAWWWW! Maybe that’s what’s wrong.

Not too long ago I had the plugs, wires and distributors all replaced with OEM stuff by a very well known (and expensive) local mechanic. I’ve also run a few cans of Techron through before each oil change and just put in a new Mahle air filter.

What are the most prevalent candidates for causing misfires at idle under colder conditions? I’m pretty sure after 100K it’s still has the original MAF, O2, crank, and knock sensors. To my knowledge the injectors have never been serviced either other than a couple leaky O rings/seals.

It’s a 1987 so I believe it’s just before the OBD stuff was incorporated so my car doesn’t have the chip to record fault codes. If it did have one of the chips which I believe can be added… would a Bosch Hammer or other similar devices be able to diagnose this stumble?

ew928

Is the ISV schticking under cooler conditions?
If not recently renewed would a nice WD-40 ISV bath help will cool idle?