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1G Noise in rear of the car when decelerating

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I havent turned the driveshaft to check for noise at the case. The driveshaft is completely rebuilt, all oem. The carrier bearings are all new oem. I am using the solid carrier bushing mounts to the body though. So basically front to back. Act 2600, act flywheel, rebuilt oem driveshaft, torque solution carrier bushings, jays racing toe kit, ingalls control arms, oem lower control arms. Rtm subframe bushings. All oem balljoints where needed. Bul fab mustache car. It sounds perfect except when decelerating. I attempted to change the angle of the driveshaft but that didnt work. I might try different combinations, it just takes forever. The car has 90k on it, owned by a doctor before me. Car wasnt abused. All oem fluids. Im running mt 90 in the tranny and mitsubishi lsd in the rear diff. The car was quiet as a mouse with 20 year old parts. The only variable i can see is the obvious change in material of the driveline components engineered to reduce harmonics and vibration. The car does have the balance shafts. It still seems like this is an issue that hasnt been figured out yet for most?
 
when you start using hard bushings or solid mounts you are going to get some feedback from the drivetrain .perfect example my sons 98 gsx with factory none filled motor mounts didn't make any noise on deceleration . my 98 gsx with filled motor mounts made noise . when i was trying to diagnose the problem i noticed that when pulled up on the e brake the noise would go away it went away because i was dampening the vibration . my noise isn't as loud as your but similar .
 
I plan on changing my exhaust housing to internally dumped on Saturday so I need to drop the exhaust anyway. Im going to make sure my exhaust isnt rattling against the downpipe first. Im considering installing the oem carrier bushing in place of the solid bushings to see if that help at all. Other than that im just gunna deal with it as its not my daily so who cares :applause:
 
I justed wanted to add since completely redoing my exhaust that the sounds had decreased substantially. It appears that as the car is decelerating alot of the vibration/harmonics from the transmission/ engine is not only transferred through the driveshaft but also the exhaust. Since both are technically moving/shaking. Maybe because the flywheel is lighter it's changes the resonance or potential energy being absorbed as its able to decelerate or accelerate faster. As the car decelerates the engine and drivetrain are vibrating when u press the clutch in you are removing that energy potential out of the drivetrain.... Vibration stops. Im half asleep....maybe I'm talking out of my ass
 
Any update on your final thoughts on this issue? I just put in DSS aluminum driveshaft, solid carrier bushings, bulfab mustache bar and polyurethane bushings everyone and I'm having drivetrain noise as well.
 
I have 2 extra sets of mustache bar bushings so I'm going to swap out the tubular solid bar for stock mustache w/poly and see what kind of difference that makes.
 
Its harmonics. I run a stage 3 trans act light fw and 6 puck u sprung clutch solid busing every where. Everything is tight and its just gonna make noise. Its bot a stock car anymore. U want it quite go back to stock. Just have to live with it and try not letting it do it. I just throw it in neutral and coast.. but mine bo longer street car its now street race car so i dont daily it
 
I tried to remedy this a while back.
After I did a lot of drivetrain work (carriers, rear subframe bushings, twin disk). I tried swapping out the rear end, carrier bearings, motor mounts, figuring something was wrong, but it didn't change.
The car has been making deceleration noises for the past 4 years without issues (related to this anyhow).
You need to embrace it from this point on.
 
The biggest change or reduction in noise came when I isolated my exhaust with better hangers, its 1/2 as bad now. I tried everything, different angles using shims blah blah blah. I removed the exhaust and replaced every isolator with a stiffer or better quality one. I believe some of the noise is resonating from the drive-train but id venture to guess alot of guys are hearing some of it from their exhaust. Its worth a try imo......cheap experiment
 
I have the same noise and my drivetrain is completely new. My car is stock save suspension and brakes and drivetrain. My car has 44k on it and it wasn't there with stock clutch/flywheel however I have the highest tier synchro trans build from TRE that was put in at the same time as the south bend clutch/chromoly flywheel. I put it on a lift at my shop and found it is horrible and super obvious from the endcase of the trans. Inside the car, me and 2 other techs all couldn't believe how it sounded like it was under the car and behind the driver. It ain't. I'm out of town but Jon from TRE is going to check the trans when I get back bc it's not even broken in yet. I used a stethoscope and the tcase, driveshaft, exhaust, and diff are near silent. When I say it's the trans, it was blatantly obvious. I wish I could find a stock flywheel to try while he inspects the trans but our trans tech said it seemed like a preload issue. I have dual synchros and it sounds like synchro rattle to me. We'll find out I guess.
 
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We were able to hold it at a speed that keeps the noise happening while on the lift. On the road I can only get it to do it while decelerating. Sorry if it's hard to hear and sorry for my stupid voice but it's really obvious under the car. Hope this helps.
 
This is remedied by getting a dogbox style trans. Herd from the guys who told me about the noise being normal
 
I have the same noise and my drivetrain is completely new. My car is stock save suspension and brakes and drivetrain. My car has 44k on it and it wasn't there with stock clutch/flywheel however I have the highest tier synchro trans build from TRE that was put in at the same time as the south bend clutch/chromoly flywheel. I put it on a lift at my shop and found it is horrible and super obvious from the endcase of the trans. Inside the car, me and 2 other techs all couldn't believe how it sounded like it was under the car and behind the driver. It ain't. I'm out of town but Jon from TRE is going to check the trans when I get back bc it's not even broken in yet. I used a stethoscope and the tcase, driveshaft, exhaust, and diff are near silent. When I say it's the trans, it was blatantly obvious. I wish I could find a stock flywheel to try while he inspects the trans but our trans tech said it seemed like a preload issue. I have dual synchros and it sounds like synchro rattle to me. We'll find out I guess.

Hey man, I've got a stock 6 bolt flywheel if you want to meet up to try it out, its been sitting for a while but you're welcome to borrow it if you wanna meet up at marketplace again sometime. Let me know!
 
I eliminated a lot of the noise by reinstalling the OEM rear upper control arms, those 3sX ones are not the best for the noise part of it, I did the original VFAQ mod. The mustache bar whether OEM or poly made 0 difference. Once I went twin disc that is when all bets were off. Its harmonics in the system. The only thing I haven't tried that you could might be to but the balance shafts back and see if that "might" help, but prol not. It is what it is...crappy.

Filling the carrier bearings vs OEM didn't matter either, I pretty much tried everything.
 
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