I am at 38,000 miles. Has anyone else had a brief chirp-like squeak when accelerating a little harder than mild up-shifting between lower gears?

It's is easy to hear with the top down, but not that loud with the top up. It lasts for a fraction of a second, exactly at gear change. It sounds like its coming from the rear underside or possibly from the middle underside of the car, but its hard to pin down from the cabin. It can be recreated when accelerating a little harder than comfortable and up-shifting, but I think I heard it once when twisting the suspension over a rut with no gear shift.

Things I've tried

• Added dreaded belt dressing to the serpentine belt just to see if the sound changed - nope
• Lubricated the rear suspension - no change
• Re-torqued the wheel lugs and spacers too 100 ft-lbs, usually I tighten to 92 ft-lbs - no change

Remaining suspects

• Could still be serpentine belt jolt, but I think the sound is more central to the car
• eDiff or fluid - no leaks, looks brand new from the outside, no other issues
• Drive shaft?
• ZF8?
• Brake pads - which do squeal intermittently
• Suspension bushings - all look fine

I still have CPO left for 10 months, but it only covers drive-train and electrical failures AFAIK so this might not be covered or entertained. I have a little time to see if it goes away or gets worse. I was hoping someone might know of a similar issue/solution? Any thoughts or recommendations?

 

I had this on my previous XF. It was the gearbox. It went away after i had the fluid changed. The box in that car was the 6 speed version of the zf 8 speed we have in the F Type.

 

I think the "chirp" was a known issue some years back with ZF auto boxes. Seemed to be cured, or at least mitigated, with a fluid change. I'm surprised if you need a fluid change at 36k (I think ZF say 60k), but I don't know how or where you drive.

 

Thanks all, I ordered ZF's HP70 fluid change kit including the pan, filter, and magnets for under a little under $300. Looks like ZF's change interval is 50K miles or 8 years under normal driving, so its not far from due.

 

Your description also sounds like a squeaky exhaust valve, though mine make more of a squeaky grindy noise.

 

But Fuse 43 is in my glove box.

 

@RacerX PM sent

 

Ah yes.

I get this from time to time on hard acceleration around 6,000 rpm in low gears (1-3). Not sure if it's related, but it only seems to happen when it's a bit colder out. Sounds like a bit of belt squeal.

It's on my "please investigate" list for the next big dealer visit.

 

I drained my ZF8, refilled, ran the car a bit to mix the fluid in the torque converter​​​, drained again, changed the pan which included a new filter and magnetics, and refilled IAW the two step up to temp method as prescribed. All is good now, no squeak.

​​​​​​I decided to go with Amsoil's Signature Series ZF8HP700 fluid, since the OEM fluid didn't even last 40K miles. Hopefully it performs better. The shifts feel a little better already, but a little time will tell.

https://www.amsoil.com/lookup/auto-a...l-l/us-volume/