Rear "whomp"!

[RPSN]

I was also experiencing a ‘Whomp’ or ‘Clunk’ noise which was coming from the rear of my car when engaging the transmission and applying the throttle. I have now had the issue rectified.

In the Jaguar F-Type workshop manual there is a section headed ‘Noise, Vibration and Harshness’. It states the following.......

“Symptom: Loud clunk in the driveline when shifting from reverse to forward.”

“Clunk is a metallic noise heard when the automatic transmission is engaged in REVERSE or DRIVE. The noise may also occur when the throttle is applied or released. Clunk is caused by transmission calibration, backlash in the driveline or loose suspension components and is felt or heard in the vicinity of the rear drive axle.”

There is a Jaguar technical bulletin JTB00498NAS1 which refers to 'Harsh Gear Engagement - park-to-drive and/or neutral-to-drive' (see attached file). This applies to the 2016-2017 Jaguar F-Type (X152) V6 S/C 3.0 petrol vehicles (VIN numbers K22185 - K38972) with 8HP70 8- Speed Automatic Transmission AWD / 8HP70 8- Speed Automatic Transmission RWD / 8HP45 8- Speed Automatic Transmission RWD. It says the Jaguar Land Rover-approved diagnostic tool with latest DVD and Calibration File is to be used and the fault is rectified by reprogramming the existing transmission control module.

I explained all this information to my Jaguar main dealership as the technical bulletin applies to my own vehicle. They ran a diagnostic on my car and found that a software update was available for the transmission control module. They downloaded the update and since doing so it has completely stopped the ‘Clunk’ that I was hearing/feeling through the car.

[gf15]

Fantastic info, Thank you.

[nurgle]

RSPN,

Thanks,

My VIN not included and the TCN software is up to date (the gooey brown diff oil suggesting something not right or being transmitted and becoming manifest in the diff, back there!)

regards,

Rob

[GARETH]

What is the oil specifications for the rear differential?

[RPSN]

RSPN,

Thanks,

My VIN not included and the TCN software is up to date (the gooey brown diff oil suggesting something not right or being transmitted and becoming manifest in the diff, back there!)

regards,

Rob

In your original post you mentioned........”Park up all day or overnight and the cycle repeats (the 'whomp' seemingly temp related).”

In the Jaguar technical bulletin that I posted, under the ‘Condition Summary’ it says:

“Situation: A harsh gear engagement -- park-to-drive and/or neutral-to-drive -- may be evident when the vehicle is cold (below 68ºF / 20ºC).”

“Cause: This may be caused by an engagement issue due to the current engagement strategy taking too long.”

“Action: Should a customer express this concern, refer to the Service Instruction outlined below.”

Although you've said that your vehicle isn’t within the VIN range on this bulletin it seems a coincidence that the ‘whomp’ issue you are having is also temp related?

Don't like the sound of the 'gooey brown diff oil' that you mention (especially after only doing a few thousand miles since it was last changed) so further analysis is needed there.

The Jaguar service schedule recommends the differential oil should be changed on the 64,000 miles / 48 months service and the automatic transmission oil should be changed on the 160,000 miles / 120 months service.

Also on the service schedule, Jaguar stipulate......."Please note that service intervals always represent the maximum time and distance that should exist between servicing. Driving style and conditions may necessitate earlier servicing as indicated by the notifications on your instrument panel."

See the Jaguar Service link below - input your VIN and select ‘Servicing Information’ then click on ‘Service Type’ dropdown arrow and ‘Submit’.

https://osh.jaguar.com/

Hope you get the issue sorted out

[RPSN]

What is the oil specifications for the rear differential?

I would have thought that the differential oil is the correct specification as it was replaced under warranty not so long ago.

Differential oil specifications can be found on the link below. Type in your vehicle registration and select ‘Axle Drive Oil’.

I think you'll find the recommendation is Motul GEAR 300 LS 75W-90 Fully Synthetic Car Limited Slip Differential Oil (LSD).

https://www.opieoils.co.uk/

[nurgle]

Hello again all and thanks for all the ideas,

The father and son technicians have spent some time driving the car cold.

The "whomp" noise is more prevalent at a certain speed, though still intermittent.

The Diff oil is grossly abnormal (should be honey coloured).

Given the diff is only a few 1000 miles old, the thinking is that something in the driveline is stressing the diff when it or something else is cold. Rear geometry looks OK.

Gear box service is to both renew the fluid (future proofing) but also minimize the possibility of this (as a key drive line component) affecting the diff.

Also had ICS updated, left door speaker rattle fixed, OBD port shifted to behind the right elephant's ear+ rattle behind there fixed, front bumper re-sprayed, all 4 alloys refurbished and a headlight (would be MOT fail) repaired!

Rob

[alpinaman]

Surely the diff is under warranty at only a 1000 miles since fitment ?

[nurgle]

The diff will still be under warranty hence beyond changing the oil doing nothing else with it. The question is whether this is a diff issue our that the diff is a symptom (other repairs wouldn't be under warranty). Once the gearbox has been serviced, planning a re-test then if still a problem back to the dealer who fitted the diff.

regards,

Rob

[01286p]

After much disbelief by my Garage and inspection of all the running gear etc., it was found that the oil level in the diff was low, probably from new as no signs of a leak. 8 speed auto v6s