Help Me Obi-Wan: Clicking Noise Fades In And Out

[Scuderia86]

Hello, I just had a PDX day (car was great) and on the drive home I developed a clicking noise coming from the right (rear -- I'm 99% sure), which was synchronized with the wheel speed. At first I thought it might be a stone, but the sound fades in and out (and I checked the wheels carefully for evidence of a stone). Sometimes it comes in strongly, typically under braking. I don't hear the sound at all under acceleration and it can be loud enough that under mild acceleration I should hear it.

Questions:
--If it was a wheel bearing, would it fade in and out?
--Could it be a brake shoe dragging? If so, can I fix this at the track?
--Am I missing something critical?

Tomorrow I'm supposed to be out on track again. I'm guessing most likely I can't go out, but if it's possible that this is a minor problem that can be fixed during the morning, perhaps an afternoon session is possible. Advice?

Thanks.

Edit: Updates

First, the car pulls ever so slightly to the right just now. I mean, if I take my hands off the wheel it goes a considerable a few seconds before any noticeable direction change, so not a "real" pull.

Second, I have family near the racetrack and took my dad on a test drive. He described it as more of a "dragging sound." He did some independent Google-Fu to come up with a possible explanation: emergency brake has come apart in the rear rotor. I scratch my head at this: to avoid warping my rotors, I am really careful to not apply the handbrake after track sessions.

[Mr.ac]

If it's pulling to one side, check tire pressure. Could be just a tad low on one side.

If you suspect it's the inner brake shoes you could check that out if you have some hand tools.

My guess, it maybe one of the axle nuts came loose while playing around. Just needs a re torque.

[Ultramaroon]

No. Axle/hub splines click due to driveline torque only. They have nothing to do with braking.

[Scuderia86]

When I couldn't find anything obvious like a stone, re-torquing the lug nuts was the next thing I tried. None of them could be tightened any farther by hand. The actual axle nut seemed unlikely. Wouldn't the wheel be slightly wobbly when I jack the car up if that's loose?

I woke up early to go back to the track this morning. With luck someone there can help diagnose and solve the problem...

[ZionsWrath]

Tale off the wheels and have a look. If all looks good just drive the car

Clicking could be an axle wearing out but its not going to simply break in half suddenly. If the sound gets worse or you get vibrations or something feels sketch just put your fist out the window.

Cars are pretty resilient.

[CoolHandMoss]

I just had that experience yesterday and it turned out to be the rubber built up on the edges of the treads hitting the fender as it peeled off. It stopped after about 50 miles.

[ZionsWrath]

Originally Posted by CoolHandMoss

I just had that experience yesterday and it turned out to be the rubber built up on the edges of the treads hitting the fender as it peeled off. It stopped after about 50 miles.

lol, I had that before but it was a distinct slapping sound. I pulled over and found the marbles peeling off. Sounded so bad for something so insignificant

[Teseo]

On other car i had, the clicking sound was the brake pad pin loose and jumped inside of the wheel

[Scuderia86]

I'm alive and so is my car, although it's sitting in a Toyota Service Department parking lot right now.

I was positive it was coming from the rear. Had a look with my instructor for the PDX session, found nothing. After putting the rear wheels back on we did a street drive and it seemed fine. So then we did started the session at the back and went slow, and it was fine. After the session it was fine, no noises in the paddock. Drove it hard through the rest of the day and the car was great -- faster than yesterday and not making a peep.

Then I started driving home. As soon as I got on the brakes and thunk-thunk-thunk-thunk.

Huh.

Turned around, drove back to the track, found some of the old hats who are more mechanically inclined. Jacked the car up. Front wheel brake caliper bolt gone. Jesus. If that thing had swung forward into the wheel at 120 mph on the main straight, I would very likely be dead right now.

I must have had a guardian angel looking out for me today. Heed the warnings, you might not be quite so lucky.

[Spuds]

Originally Posted by Scuderia86

I'm alive and so is my car, although it's sitting in a Toyota Service Department parking lot right now.

I was positive it was coming from the rear. Had a look with my instructor for the PDX session, found nothing. After putting the rear wheels back on we did a street drive and it seemed fine. So then we did started the session at the back and went slow, and it was fine. After the session it was fine, no noises in the paddock. Drove it hard through the rest of the day and the car was great -- faster than yesterday and not making a peep.

Then I started driving home. As soon as I got on the brakes and thunk-thunk-thunk-thunk.

Huh.

Turned around, drove back to the track, found some of the old hats who are more mechanically inclined. Jacked the car up. Front wheel brake caliper bolt gone. Jesus. If that thing had swung forward into the wheel at 120 mph on the main straight, I would very likely be dead right now.

I must have had a guardian angel looking out for me today. Heed the warnings, you might not be quite so lucky.

Yep, definitely sounds like that time I forgot to tighten a rear brake caliper...