Why does my 370Z clunk in the rear?

On a Z34, a thud or thunk on and off the throttle is most often the rear diff bushes. The factory bushes are rubber, and the diff puts a lot of load through them. Once the rubber cracks, the diff moves under power instead of staying planted — and you hear it. We confirm it on the hoist before quoting anything, because a similar clunk can come from diff mounts, driveshaft, or subframe.

Can I keep driving it like this?

It won't strand you, but it gets worse, not better. As the bushes break down the diff moves more, which puts extra load on the surrounding mounts and the driveshaft. Sorting it early is a smaller job than letting it take other parts with it.

Polyurethane or solid — which should I get?

Depends how you drive it. For a street car, polyurethane kills the clunk and stays comfortable. For a track or big-power car, solid or billet gives maximum precision at the cost of more noise and vibration through the body. Tell us how the car's used and we'll point you to the right one.

Will poly bushes make the car harsh?

You'll feel a little more of the driveline than you did on fresh factory rubber, but it's a long way from harsh. Most owners say the car feels tighter and more direct, and the clunk is gone.

How long is it off the road?

Usually a day. The factory bushes are pressed in, so the first replacement means dropping the rear subframe. We'll confirm timing when you book.

Do you do other 370Z diff work?

Yes. Diff fluid services, mount replacement, LSD work, and full driveline inspections. While the diff area's apart for bushes we check the fluid, mounts, and driveshaft so it all goes back together right.

KNOWN ISSUE Z34

370Z rear diff bushes

That thud or thunk on and off the throttle? On a hard-driven Z34 it's almost always the rear diff bushes. Here's how to tell, and how we sort it.

Get a Quote Call 03 9870 0540

After 370Z tuning or performance packages instead?

Nissan 370Z rear diff removed from the car in the Revzone workshop

The symptoms

Is your 370Z doing this?

Worn rear diff bushes give themselves away. The usual signs:

Thud or thunk on and off the throttle

The diff rocking in worn bushes as the load reverses. The classic tell.

Clunk shifting between drive and coast

Same play, felt at the moment the driveline loads and unloads.

A knock over bumps or mid-corner

The diff moving on its mounts when it should be staying put.

Oil weeping around the diff

Perished rubber letting go. You can usually see the stain from underneath.

Ticking a few of these? Worth getting it up on the hoist. A clunk can also come from the diff mounts, driveshaft, or subframe, so we confirm what's actually worn before quoting any work.

Book it in for a look

Worn factory 370Z rear diff bush, cracked and weeping gear oil

Why it happens

Factory rubber, a lot of load

The Z34's rear diff hangs off the subframe on rubber bushes. Every time you get on or off the throttle, the diff drives serious load through them.

Rubber perishes. It cracks, then starts to weep — that's the stain you'll spot from underneath. Once there's play in the bush, the diff physically moves under power instead of staying put. That movement is the clunk.

It doesn't fix itself, and it doesn't stay the same. The more the bush breaks down, the more the diff moves, and the more load it throws at the mounts and driveshaft around it.

The fix

Bushes that won't perish

We replace the factory rubber with bushes that hold the diff still and last. Two ways to go, depending on how you drive it.

Daily driver

Polyurethane

The street upgrade. Kills the clunk, holds the diff steady, and stays livable day to day. A bit more feel through the car than factory rubber, not harsh. This is what most 370Zs get.

Track & big power

Solid / billet

Maximum precision for hard-driven and high-power cars. The diff is locked down with no give at all. You'll feel and hear more through the body, which is the trade for the control.

1 hr vs 6 hr next time

Fit the aftermarket bushes once and the next change is about an hour. The factory rubber is pressed in, so the first job means dropping the rear subframe — closer to six. Supplied and fitted in-house.

While the diff's apart, we check

Diff fluid condition
Diff and subframe mounts
Driveshaft and CV joints

The job

Done in our Ringwood workshop

Out with the perished rubber, in with poly. Parts and fitting under one roof — tap any photo to look closer.

FAQ

Common questions

Why does my 370Z clunk in the rear?: On a Z34, a thud or thunk on and off the throttle is most often the rear diff bushes. The factory bushes are rubber, and the diff puts a lot of load through them. Once the rubber cracks, the diff moves under power instead of staying planted — and you hear it. We confirm it on the hoist before quoting anything, because a similar clunk can come from diff mounts, driveshaft, or subframe.
Can I keep driving it like this?: It won't strand you, but it gets worse, not better. As the bushes break down the diff moves more, which puts extra load on the surrounding mounts and the driveshaft. Sorting it early is a smaller job than letting it take other parts with it.
Polyurethane or solid — which should I get?: Depends how you drive it. For a street car, polyurethane kills the clunk and stays comfortable. For a track or big-power car, solid or billet gives maximum precision at the cost of more noise and vibration through the body. Tell us how the car's used and we'll point you to the right one.
Will poly bushes make the car harsh?: You'll feel a little more of the driveline than you did on fresh factory rubber, but it's a long way from harsh. Most owners say the car feels tighter and more direct, and the clunk is gone.
How long is it off the road?: Usually a day. The factory bushes are pressed in, so the first replacement means dropping the rear subframe. We'll confirm timing when you book.
Do you do other 370Z diff work?: Yes. Diff fluid services, mount replacement, LSD work, and full driveline inspections. While the diff area's apart for bushes we check the fluid, mounts, and driveshaft so it all goes back together right.

370Z clunking in the rear?

Tell us what it's doing. We'll get it on the hoist, find what's actually worn, and quote the fix. We reply within 24 hours.

Get a Quote Call 03 9870 0540