GarageB

Getting a very concerning clunk / thunk feeling in the car when I stab the throttle in gear (lets say 3rd gear, 2000rpm, smack throttle) or if I lift off abruptly above 2-3k rpm.

Feels like the diff is moving, maybe subframe, maybe engine, motor mounts? Cant find a lot of people talking specifically about this.

When I used to mess around with 240sx's, the S14s all needed poly inserts on the subframe bushings as the factory ones wore out too quick, and you'd get a similar issue.

Don't want to keep driving it like this and break something.

2008 79k miles.

Thanks!


UPDATE: Issue is now SOLVED:


Diff bushings are worn out. Ordered a set from Figs, putting them in ASAP.

nks979

Im assuming you're certain its not an exhaust noise of any sort? Mine does something similar but its definitely the exhaust popping and crackling around 2-3k.

GarageB

100% no its not an exhaust pop or crackle. if it did that I would be happy.


Its like something large on the vehicle is shifting - like the subframe, driveshaft, differential, or engine. I dont have to listen for it, I feel it.

nks979

Seen quite a few threads on the rear axle lately, that might be worth a look.

GarageB

I isolated it (I believe) to the rear end.

If im rolling (2-3 mph) in neutral, and I quickly/smoothly engage the emergency brake to full stop, the car will stop and then I can feel the rear end rocking back and forth after its already stopped.

GarageB

Has anyone on this forum ever had to replace the rear subframe bushings? Diff bushings?

Do these driveshafts go bad?

Cant find much mention of rear end problems.

nks979

I haven't heard of any of those problems, I'm very certain that the driveshafts don't go bad. Yours could be but its definitely not a known or normal issue on these cars.

5280ISF

Maybe get a floor jack & jack stands under the rear end and do a visual inspection..Not sure what would cause the rocking feeling your describing.

lobuxracer

iTrader: (2)

There was a member who bought the orange IS F and the diff in it was really hashed. If this car is new to you and has these issues, it might have been severely abused by the previous owner and need some serious repairs.

GarageB

I don't doubt it could have been abused before I owned it.

If I drive the car normal or lightly sporty I do not notice a difference. I dont hear any noises when I do parking lot turns

Only when Im doing a harsh hit to the driveline (load/off load) do i feel/hear the thud from the rear end. To me it feels like something is shifting and hitting something. It reminds me of a 240sx with worn out diff bushings.


So, better question is: what are the symptoms of a worn out/broken differential vs worn out differential bushings vs worn out transmission mount etc.

Any tips to give my mechanic on inspection?

lobuxracer

iTrader: (2)

The first thing I would do is drain the diff fluid and inspect for metal content. After that, it's just methodical troubleshooting. Bad bushings are not at all common in these cars, so it will take some investigation.

GarageB

This is now solved, see the first post.

Action camera + hose clamp on the subframe brace.

nks979

Good to see it was a relatively easy fix, compared to a diff issue.

Sameer89

Did you replace the subframe bushings to remediate the problem?

GarageB

If you arent going to read the thread you arent going to learn anything from it.

Differential bushings need to be replaced.

There are 2 front bushings, called pinion bushings.

There are 2 rear bushings, called carrier bushings.

AFAIK I dont need to change the subframe bushings, but Ill know more after the differential stops slamming around..