LOUD CLUNK noise from rear when pulling off, any ideas?

Gibbo · 7 Apr 2016 at 18:16

Hi there

After yesterdays track day it seems something in the rear has come lose or even worse the differential is upset.

Here is a video (happens at 17s):

Only happens when pulling off and only sometimes, the noise of the clunk is always different volume, sometimes quiet, sometimes loud, of course letting the clutch out faster tends to make it louder.

However it does not feel like driveline thud/bang if makes sense, it actually feels more like something right in the back of the car at the rear, but diagnosing a noise is hard.

Any ideas?

Gonna drive home gently and get the rear in the air and double check everything.

Ricochet J · 7 Apr 2016 at 18:18

Does track daying the car void the warranty? If not, return it and don't worry. If it does, begin to worry.

scrivz69 · 7 Apr 2016 at 18:20

Not a loose brakepad, I would check that.

ttaskmaster · 7 Apr 2016 at 18:28

Loose caliper?

austinpowers · 7 Apr 2016 at 18:28

Does it do it when you try to move backwards and forwards with the handbrake applied, that way you should be able to rule out the brake pads as it does it just after you move off.

Exhaust not hitting anything?

Are you able to stop without applying the brakes then pull away and see if it's there still?

MarkLP · 7 Apr 2016 at 18:31

Sounds remotely diff/shafts related but so hard to tell. Can you not jack up the rear and try turning wheels by hand?

Dup · 7 Apr 2016 at 18:34

My MX5 made that noise when setting off from a stop, was the diff. Was quite normal for that though I believe. It still locked up when needed, so I wasn't bothered

pepsilol · 7 Apr 2016 at 18:37

My 911 had the same noise taking off like that, and also around town going on and off power suddenly could get it to knock like that, was some worn gears or something in the diff.

Clarkey · 7 Apr 2016 at 18:48

Check the rear subframe is secured tight. I've had this on both the BMW and the Nissan.

Diagro · 7 Apr 2016 at 18:58

Take it back and have them rwpair it. Hopefully you haven't told them.it's been on track?

Clarkey · 7 Apr 2016 at 19:06

Of course they know, it was a Ford invitational day!

Gibbo · 7 Apr 2016 at 19:06

Diagro said:
Take it back and have them rwpair it. Hopefully you haven't told them.it's been on track?

Track use is fine, does not void warranty especially as it was a Ford paid for track event as well.

Car drove home fine, hit pot holes, bumps, brakes hard no bangs or clunks. However do an aggressive downshift and rev match get it slight clunk/thud, but have to pull of quite harsh to make it do it.

Yes these cars do have some driveline thud standard is common on them and mine did this from new as they all do it but hardly noticeable. This is very noticeable but only when pulling off, but before track day no such clunk when pulling off, so something must be lose is my thought.

Wheel spinning under power, sideways, chuck car around no noise, just pulling off.

So as it drives essentially fine will just take it garage tomorrow and check all is tight and if nothing shows up then yeah Ford can fix it.

Gibbo · 7 Apr 2016 at 19:19

Another video from earlier I thought did not work.

Again clunk is at end of video but mucher quieter in this one.

paradigm · 7 Apr 2016 at 19:23

Prop donut?

Gibbo · 7 Apr 2016 at 19:25

paradigm said:
Prop donut?

These cars do have some backlash and prop noise as standard but generally not audible like this. As nothing is about to drop off not gonna bother messing tonight just will take it garage tomorrow.

Will · 7 Apr 2016 at 19:32

Subframe lose is my guess, like Clarkey says, my old Civic Type R (FN2) did similar, it was a common problem for those on the front, the bolts would need tightening, it manifested itself in exactly the same way, a single mechanical 'clink' sound when getting on the throttle.

Have you actually done anything to the rear subframe at all, locking collars or replacement bushes/inserts or anything? My thinking is something is now loose there if its been tinkered with, the higher loadings on track can make things move if they're not perfectly tightened.

Mal X · 7 Apr 2016 at 19:37

the above post is very interesting.

Clarkey · 7 Apr 2016 at 19:44

Worn? It's a brand new car!

Mal X · 7 Apr 2016 at 19:45

Clarkey said:
Worn? It's a brand new car!

yea that's why i edited it... my guess it's as you say

Gibbo · 7 Apr 2016 at 20:02

Will said:
Subframe lose is my guess, like Clarkey says, my old Civic Type R (FN2) did similar, it was a common problem for those on the front, the bolts would need tightening, it manifested itself in exactly the same way, a single mechanical 'clink' sound when getting on the throttle.

Have you actually done anything to the rear subframe at all, locking collars or replacement bushes/inserts or anything? My thinking is something is now loose there if its been tinkered with, the higher loadings on track can make things move if they're not perfectly tightened.

Yes all subframe bolts were removed to do CB005 over a month ago, so you and Clarkey could be right, gonna go through everything I've undone tomorrow and then re-torque with blue loctite.

I am thinking lose subframe bolt or lose differential bolt (bolts that secure rear diff into subframe.