Rattle on idle with clutch pedal not depressed

[Eskozki]

My 944 NA -87 started making a bearing type rattle when idling in neutral and clutch not depressed. When I depress the clutch the noise goes away. I'm almost convinced that the noise comes from the transaxle. I need to get a listening device to isolate the noise to be sure. I read that the reverse idler gear is the likely culprit? I quess the best way to be sure would be to decouple the tranny from the engine, but how easy it is to do?

[944 Ecology]

Reverse idler gear has enough looseness to rattle. $$$ to fix, nothing to learn to live with it.

[TheSecondChris]

My 87 does the same thing. My 84 doesn't.

[Eskozki]

crawled under the car, its definetly the transmission. Heard it a bit more clearly at the front of the transmission. I was planning a longer trip this weekend and its a relief I can do it with the old porsche.

[Monkey Wrench]

maybe just do a transaxle oil change , check for metal, If you see lots of metal it might be a bad thing. . Yod know best if its' been done or due.

[culture]

had this for YEARSSS since purchasing the car. turned out to be the torque tube bearings. it’s the only thing that spins in neutral. and stops when depressing the clutch

[ERAU944]

I'm with culture, my '84 has had this rattle in the torque tube since I bought it 50k miles ago in 2001, she soldiers on.

[944 Ecology]

Originally Posted by culture

had this for YEARSSS since purchasing the car. turned out to be the torque tube bearings. it’s the only thing that spins in neutral. and stops when depressing the clutch

Bzzzzt! Wrong... The input shaft of the transmission (since it is mechanically connected to the torque tube drive shaft) also spins in neutral, and stops when depressing the clutch.

[Eskozki]

Now I can hear it rattle on 4th and 5th gear when cruising or decelerating. While accelerating it might just get drowned by the engine noise. I found my rear main seal is leaking a bit so I'll be replacing that and with everything apart I wish I can Isolate the noise. The sound is more like gears clattering than anything else.

[walfreyydo]

Originally Posted by Eskozki

Now I can hear it rattle on 4th and 5th gear when cruising or decelerating. While accelerating it might just get drowned by the engine noise. I found my rear main seal is leaking a bit so I'll be replacing that and with everything apart I wish I can Isolate the noise. The sound is more like gears clattering than anything else.

Pretty common, especially at slower speeds - both my S2 transaxles made that same sort of noise, especially on decel. It becomes more pronounced if the rear carpet and sound deadening/padding is removed as well. Been running mine with that noise for years with no issues, fluid looks great as well, so not overly concerned about it (but I was at first).

Do note that this is different from the original issue (rattle at idle) which points to torque tube bearings as the first thing to check. Neither of the trans I had did this (but I did rebuild the torque tube).

[Monkey Wrench]

on cars with driveshafts , Ujoints and center bearings sometimes people take things apart and back together in a different orientation , this affecting bbalance and causeing driveline noise and vibration.

Im not familiar enough to knwo if a posche with a torque tube can be put to geter out of balance others may .

I did see an article where a german guy went into detail about synching the two 944 CV joint axles. I believe they can be put together so they work but are actually out of balance or "out of phase" with one another . I think there was a part where the phase of each side needed to be checked.. Ill often use paint and centerpunch marks to avoid changing orientation but it is possible it was already apart before and assembled different than it should be. it may be a case where all is normal until you hit higher road speeds.

in trqditinal rear axle cars the driveshaft speed relates directly to road speed but it is differeint in a 944 becaue of the transmission location. I guess then more related to RPM's than road speed.

[Eskozki]

I'm halfway through the clutch job. The bearings at the clutch were worn, but not anything too bad. Torque tube is fine, there is no issues there. I did remove some of the sound deadening last winter when I removed the rear carpet and found some corrosion under the factory material. I did put some aftermarket stuff in its place. But I quess I can hear it better now, and the noise might have been there.

Told my father atleast 3 times to put some tape on the hole of the clutch bellhousing during reassembly. First time he dropped a bolt, he got lucky and was able to pull the bolt with a magnet. Second time he dropped the bolt we had to remove the clutch and managed to get the bolt from behind the flywheel. I quess he learnt his lesson. Atleast I got to say "I told you so"

[Eskozki]

No more rattle on idle with or without clutch. But the 3rd and 4th gear rattling is still there. I took a video of the noise, you can hear it at the beginning of the clip the best. On the clip I'm driving about 40 - 50 km/h on 3rd gear. Is this normal transaxle rattle? Maybe the stripped soundproofing causes this issue, even though I tried to add some aftermarket sound deadening.

Is this an issue I should fix by adding volume to the radio or do I need to take the transaxle to be rebuilt?

https://photos.app.goo.gl/q3rZsRNVvWo82ZxJ8

[wwdwgs]

try the cheapest approach first - the radio volume.
I didn't hear any rattle in you video. You shot it with your cell phone, didn't you. Cell phone don't capture the sounds well, after all, they are radios, not recorders. I use a digital recorder for faint sound, which can't be captured by cell phone. I'm sure that there are some plug-in microphones suited for cell phones.

[Eskozki]

I can hear it on the video, but then again I know what to listen for. Its during the very first second you can hear it the best. Yes, it is a cell phone video.