JGT3

Thanks John for the recording. I'm afraid that it is not what I'm hearing. It is less loudy and occurs when decel or maintaining constant speed around 2000 rpm or little bit more (not too sure now).
996FLT : what means LSD? (other than well known substance)
I have to wait until next sunday to make a test and record this sound.

As Hiwind just said, maybe I'm too focused on those noises that are probably normal for a GT3. Just need some time to get familiar with. I will post some more pics soon.
Ciao tutti

996FLT6

Limited slip differential. A mechanical traction device for both accel/decel. If LSD has been rebuilt u'll notice rattling reversing and deceleration(it's doing it job). Fried LSD don't make any noise. mike

996FLT6

Also check exhaust couplers and exhaust tip if they are in tite. Could be catalytic converters too. Damn too many things can happen!!!! Hopefully nothing for u. Mike

HiWind

True Mike - I found one of my exhaust tips rattling this weekend. Had to remove bumper to fix tho but all good now. Must be first mention of The other LSD in the GT3 forum - although most in the OT know it well

JGT3

Thanks Mike. I'm building up a checlklist for the next week end. Today I spoke with the vendor of the car as I wanted to have its views on this noise. For him, " nothing to worry about" as it is due to the lifting chains which at low rev or decel are less tensioned because of dropping down oil pressure. How does it sounds to you guys ?

Burger

I had what sounded like mechanical rattles on deceleration. I thought it was from the driver's side muffler, as the welds can break internally and cause a lot of noise when vibrating. I put the muffler bypass pipes on and removed the mufflers... it could still be rattling somewhere, I can't hear it now. Compared to the insane noise my car makes now, the rattles were nothing.

joshd

I'd love to hear a video clip but what you're describing sounds exactly like what I'm hearing on my car on decel around 2-3K RPMs. Mine is at the shop for other routine maintenance and after much investigation the owner of the shop (Geoff @ ASG) seems to think it's internal to the driver's side muffler with something breaking loose ... pretty much exactly what Burger is saying above (although I hadn't heard of this particular failure before).

At this point I'm either looking to purchase a take-off muffler from someone that upgraded or replace the system with something like the FVD rally headers (larger version with RSR ring connector) + exhaust.

Burger

Here is a thread where you can see the insides of the stock mufflers. It's easy to imagine how a slight vibration in the muffler housing could come in contact with the internal components and create a lot of noise.

https://rennlist.com/forums/996-foru...al-repair.html

HiWind

Nice thanks! Meaning to open mine up soon and remove some impedences

JGT3

Hi guys,
Sounds bad to me I have done a sound record of what I hear when decelerating. In fact it occurs in 2nd gear, which seems to me that is due to something in the gearbox (bearing ?, synchro ?) The file starts when I'm shifting from 3rd to 2nd and then decel up to full stop, still in 2nd.
Any idea ?? I'm not very optimistic..
Ciao J

joshd

Yeah that sounds different than my drivers side muffler internal failure noise which is more of a metal on metal vibration/resonance. Definitely sounds more gearbox-like but I'm not an expert on that ...

996FLT6

Any noise if idling? Any issue rowing thru the gears? Cannot hear file on iPhone so will go back home and try on computer. Mike

JGT3

Mike, There is no (unusual ?) noise idling. During the first 10 minutes from cold start, its quiet difficult to change gears, and I must do slow shifts if I don't want to hear "krrr"... Then after it's better, but now than you ask, there is a kind of slight "step" that I can feel in the gear shift, when changing gears. Also when I hear this rattling noise in 2d gear, I can feel corresponding vibrations in the gear shift.
J

996FLT6

J- have u ever misshifted before on car. I blew my 3.8 rsr pp going from 5 to 2- got replaced. Lwf and clutch disk wasn't replaced- mechanic said good at the time. Noticed later on hearing rattling noise inside gearbox but very apparent at idle ESP reversing or slow speeds. Thought it was exhaust tips- titen those- didnt help. Same annoying rattling noise inside tranny. Told my mechanic mite as well change disc. Rattling gone after replacement. But never had issue with shifting though but sounds like yours does. U mentioned engine was rebuilt etc did that include tranny? Sounds more like your synchros are going bad and 2nd gear syncros mite be the culprit. Keep us updated. Mike

JGT3

Yeah. I don't think tranny has been revamp. Anyhow this thursday I'm going to the dealer to let him try the car. I will keep u posted.
J