audi49

I occasionally hear what I would describe as a 'high frequency rattle-type' sound coming from the rear of the car around 1800rpm when slowly accelerating in 1st or 2nd gear. It's sort of a shrill like sound.
To me, it could be an exhaust rattle (best case scenario) or something in the transaxle (worst case scenario). I've read about some sort of rattle (5th gear?) in these transmissions... not sure if that could be it???
The sound seems to go away when I press the clutch pedal down, but I'm not sure if it's load related or rpm related since the rpm's change some when I depress the pedal.
Any insights? Thanks in advance. Tom

mytrplseven

Easy part: check the heat shield above the muffler and the exhaust pipe, take a rubber mallet and bang on the muffler and listen for rattle, also down the exhaust pipe towards the CAT. Ensure the rubber exhaust hangers are all there. Move the CV's by hand and see if you can feel a lot of play.

audi49

Thanks. I'll ck on those items. A better way for me to describe this noise is that it sounds like sheet metal dragging on rough pavement for a second or two at a time. As I mentioned, it's specific to ~1800rpm.

EJZero1

I've experienced three scenarios leading to the same types of sounds. Vibrations in a very narrow and specific RPM range. First incident was a bad CAT a few years ago. Rattled like hell. Just a few weeks back, the sound returned only worse. Turned out to be the muffler innards coming apart this time. After my muffler guy replaced it, he said the car still had a bit of a rattle, but he had already traced it to a loose heat shield. If you can duplicate the sounds with the car parked and in the affected RPM window, any of these will be likely suspects.

audi49

So I went under my car last night and banged away at the exhaust system. The only slight rattling I found was coming from the secondary muffler (the smaller muffler close to the cat). Hard to say the sound is the same but when driving I suppose it could be somewhat different or loader. I checked online for new mufflers and I only found replacements that did not have that secondary muffler... is that OK? Also, any recommendations for a cost-effect exhaust system... I'm OK with stock performance and sound. thanks.

EJZero1

Was someone else holding the throttle at your suspected rpm range to duplicate the issue while you were searching for the rattles? That's how we zeroed in on my cat and muffler issues.

mikey_audiogeek

This does sound like the infamous "5th gear rattle". Harmless.
Happens at 1800 rpm on my car, sound like I've hit a patch of gravel. Or thrown a steak on the barbie!

Info here: http://www.connact.com/~kgross/FAQ/944faq09.html

And here: http://www.clarks-garage.com/shop-manual/ts-05.htm

Cheers,
Mike

audi49

Mike - that definitely could be it. Those descriptions sound very similar. I was thinking this too, and then changed my transaxle fluid to Redline MT-90 fluid hoping that would make it go away, but it didn't. Anyway, i do think that this is it, and if so glad the hear that it's normal. Thanks.

mikey_audiogeek

No worries, happy to help!