Auto-x and pounding noise under the hood

[Kobayashi]

Questions for everyone about a 2003.5 Mazdaspeed Protege...

Under acceleration through a fast, semi-tight turn (2nd gear-mid rpm), have you heard a pounding noise under the hood? I heard it twice yesterday in the same run and at first I thought it was the exhaust hitting the frame, but not sure. (It sounds like someone was hitting the bottom of my car with a sledge hammer.) It sounded like something that had some load and then just got loose and snapped back. It is similar, but not the same, to the hard pounding sound/feel if you launch too hard on the stock tires when it is cold out.

Another guy with an MSP described a similar noise and thought it was the front sway bar. Anyone experience this? Any ideas?

 

[Leigh]

My bet is something in the front suspension if its anything at all - I've noticed something similar too a few times - its a sort of crunching thud-thud-thud... but I can't decide if its just rough spots on the course (the suspension on these cars are really stiff - it is possible to hit places and get some wheels hopping), lingering ABS vibration or something hitting under there.... *shrug*

Anyone with more know-how? Something to worry about or normal?

I've just ignored it so far... It only seems to happen when I upset the car on exit...

 

[azian6er]

you have the stock motor mounts?

-B

 

[Kobayashi]

Leigh: I agree, it seems to happen when I upset the car exiting a corner - it does kind of feel like wheel hop but worse.

azian6er: Yes, I have the stock motor mounts. I'm running S-DS this year. Is that an STX legal mod? I'm thinking about that for next year.

 

[charles]

Isn't it the LSD?

 

[Kobayashi]

Isn't it the LSD?

Other people asked me the same thing, but it is way too loud for that.

 

[SciFiMan]

...Under acceleration through a fast, semi-tight turn (2nd gear-mid rpm), have you heard a pounding noise under the hood?

I don't have a MSP but have ridden a course in one, and there wasn't any noise; and it doesn't sound normal to me either. Does this happen anytime during daily driving? Possibly a motor mount or suspension is all I can think of. Have you made any recent changes? Probably needs to be put on the rack and gone over.

 

[charles]

Other people asked me the same thing, but it is way too loud for that.

What does your LSD sound like, then?

 

[Kobayashi]

What does your LSD sound like, then?

Even though some people say it will make noise on tight turns, I honestly haven't heard it make any.

 

[DistantTea]

The LSD will only make thunks at low speeds and really tight turns.

Is that noise coinciding with any wheel hop?

 

[Mike R]

Probably motor mounts.

 

[Kobayashi]

The LSD will only make thunks at low speeds and really tight turns.

Is that noise coinciding with any wheel hop?

It could be wheel hop - to the degree of when going around a tight turn at a decent speed (30-40mph) that the tire breaks loose for a fraction of a second.

 

[DistantTea]

Its most likely about three noises at once:

Your tires bouncing back from a hop +
Your engine coming back to center in the motor mounts +
Underpants Gnomes

 

[Kobayashi]

Its most likely about three noises at once:

Your tires bouncing back from a hop +
Your engine coming back to center in the motor mounts +
Underpants Gnomes

Yeah, well, it will be a couple week wait until the next auto-x to see of the
Underpants Ganomes return...

Seriously though, thanks for the input and I'll post if it happens again.