Need help figuring out a driveline noise

[cheeky14]

[cheeky14]

I have a 97 base model S14 It has 40k original miles at the moment.
it has the stock KA engine; for the past year i have been working on it, on & off.

I started with upgrades by installing nismo engine mounts & Peak perf. trans urethane mount as well as nismo clutch & nissan motorsport lightened flywheel. after doing this everything was cool; no weird noises.

Then i took the suspension apart & replaced all the rear subframe & diff. mounts with the nismo mounts & converted my rear knuckles with z32 units as well as, all new o.e. hubs & bearings.

While i was working on the subframe I also installed a Ishihara crank scraper & verified the engine ran as normal with no abnormal noises.

I also sent my diff. out to have it, regeared with nissan motorsports 4.364 ring & pinion & a new quaife diff. with all new bearings it was proffesionally installed by an X-Nissan motorsport rear end mechanic.

After i installed everything i torqued every bolt & nut to spec. I drove the car & noticed & rattling, almost dog gear resonant sound when deccelerating from any gear between 2k & 3k r.p.m.; while the car is in gear only. I raised the car on a lift & verified everything is to spec. I removed the driveshaft & ran the car in the air to see if the noise is comming from the engine or trans. all good.

I inspected the driveshaft joints & found them to be worn out. Had the driveshaft rebuilt & balanced.

The noise is still there. I am running out of ideas. My next step is to disconnect the halfshafts & run the car in the air to simulate driving; in order to narrow it down to maybe an issue with the diff. setup.

Or maybe thats just how it is, due to the harder subframe & diff. bushings.

Has anybody experienced this???

Please help

[Bumnah]

If the noise only happens when it's in gear, then obviously it's in the drive train. I'd put my $ on the diff. rebuild.

[98koukile]

I have the same thing from when I did my 5 speed swap... think it the clutch. How stiff is yours? My transmission guy said the springs in mine are either too stiff or too soft... poor R&D skills if you ask me

[ecugrad]

I'd put my $ on the diff. rebuild.

Right now, I would too.

[clutchguy]

If you can make the noise happen in the air, with everything connected, use a mechanics stethoscope to narrow down the noise. But just hearing what you have said, I would put my money on the diff as well.

[DuckyD]

Did you change to a short-shifter along the process? May sound stupid, but my B&M short shifter RATTLES like crazy on decel. Could be something simple?

[ecugrad]

Did you change to a short-shifter along the process? May sound stupid, but my B&M short shifter RATTLES like crazy on decel. Could be something simple?

Damn, didn't think of that. Mine is noisy as hell on decel as well.

[jmauld]

Can you feel the noise? Did you replace the carrier bearing for the Driveshaft?

[Bumnah]

The B&M rattle is a pretty unique sound, plus you can actually hear it coming from the shifter area.

[Def]

Harmonic vibration of the diff caused by the springs in the clutch disk being the wrong stiffness. Between 2-3k RPM on decel hits the diff's natural frequency, and you hear/feel it.

[98koukile]

Harmonic vibration of the diff caused by the springs in the clutch disk being the wrong stiffness. Between 2-3k RPM on decel hits the diff's natural frequency, and you hear/feel it.

Who called it? Just in the wrong location haha

[cheeky14]

Thanks for the replies

when i was still driving the car i installed a B&M short shifter & noticed the rattly sound you guys are referring to; i replaced it due to the noise & also synchro grinding it creates; i used it for about a couple hundred miles. I installed a nismo shifter which is basically like the stock unit except it has harder rubber in the lever.

yes i replaced the center bearing on the driveshaft with an o.e. bearing.

its hard to say if i can feel it, especially having the harder bushings & you know how these ka engines tend to produce certain resonances
but definitelly i can tell its coming from behind me.

also i understand that the noise gets transmitted thoughout the driveline.

[Def]

Who called it? Just in the wrong location haha

I've been preaching this for over 3 years now. I even proved it by changing out my unsprung ACT 6 puck disk to a stock SR clutch disk with everything else in the car the same. Noise almost completely went away, where as before people would ask if I needed to call a tow truck as soon as I lifted off the throttle. Now you can just barely pick up a hint of it in 4th gear(the worse one since it's 1:1).

[cheeky14]

hey guys i wanted to mention that originally when the diff. was out & i was having the ring & pinion installed i had a new nismo lsd installed along with it, i pulled the diff out so i could have the diff. guy check the setup because of the noise in question then decided to go with a quaife & here i am with the same noise