# Rear diff clunk



## Idrees (Apr 17, 2015)

Hi,

Since having a full fluid change on my MY09 GTR (44k miles) the rear diff clunks, mainly when reversing on full lock.

The best way I can describe is that it it sounds and feels like an aftermarket clutch type LSD.

I bought the car with 40k miles and the diff never once made a noise. I heard it on the first day I picked it up from having the fluids changed when doing a 3 point turn.

I use a specialist for all work carried out who have told me the noise is normal, however it was silent and smooth before changing the fluid so I want it just as it was.

Is there an alternative diff fluid I can use to reduce the clunking?

Cheers


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## 5star (Nov 17, 2014)

What fluid did your specialist use this time?


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## Idrees (Apr 17, 2015)

Motul Gearcomp 75w-140


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## Idrees (Apr 17, 2015)

Anyone?


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## 5star (Nov 17, 2014)

Can you find out who serviced it last and what oil was in there previously?


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## Idrees (Apr 17, 2015)

Unfortunately that's not an option as I bought it from a dealer and don't know the previous owner.


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## charles charlie (May 3, 2008)

Surely just take it back to the servicing specialist and ask them to check that the diff is filled correctly?


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## Idrees (Apr 17, 2015)

They've checked it and told me the clunk is normal.


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## Chronos (Dec 2, 2013)

Idrees said:


> They've checked it and told me the clunk is normal.


post a video clip with sound up


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## charles charlie (May 3, 2008)

Idrees said:


> They've checked it and told me the clunk is normal.


Have they specifically checked that the diff is filled correctly by opening the drain plug and seeing fluid dripping out, or just listened to it?


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## charles charlie (May 3, 2008)

To answer your question more specifically, the original fluid fill is Castrol Syntrax Limited Slip 75W 140 (Formerly SAF-XJ 75w-140, approx 1.75lt) so your supposed Motul fill should be fine. That isn't reason enough for noise issues -

1. Either the noise was always there (hard to see how you would have missed it before)

2. The diff is the source of the noise and something is amiss (low fluid?)

3. The noise isn't from the diff, could be trans fluid change being an issue also.

Certainly a decent video from inside and outside the car would help us check if it's considered normal.


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## terry lloyd (Feb 12, 2014)

I find it hard to believe the oil would cause a clunking noise also - have you checked the wheels are tight - really tight - this can cause a clunk if they were taken off and not torqued up correctly when put back on


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## Crafty_Blade (Jul 11, 2012)

Had a clunk from the rear same as you usually reversing on lock at low speed. Thought it was the diff or transmission, turned out to be play in a drop link. Was replaced during a routine service and never heard the noise since. May or may not be the same thing but worth a check


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## Paddygtr (Sep 10, 2020)

Crafty_Blade said:


> Had a clunk from the rear same as you usually reversing on lock at low speed. Thought it was the diff or transmission, turned out to be play in a drop link. Was replaced during a routine service and never heard the noise since. May or may not be the same thing but worth a check


How loud was the clunk? As im reversing its fine straight turn it on lock and wheels skip (read thats normal) but I get a clunk every maybe full rotation of the wheels only on lock tho and sounds to be coming from the rear passenger side


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