loud knock from back

[nitrosman1]

just been out in the ro and i keep getting a loud knock from the back when i accelerate and then again when i decelerate (if thats a word) sounds like its coming from the petrol tank area but could be underneith ,very annoying as my waranty has run out now

[ringram]

Twist the driveshaft in neutral. If you look at the diff you will see if its the diff gears which are loose/worn or the rear cv joints. In my case it was the cv joints. Got some secondhand from oz cheap.. except for the shipping!
I spoke to Roger about it at the time. He will be able to sort you out.

[nitrosman1]

worn out already its only done 17000 miles

[nitrosman1]

just found this on the gto site
GM has issued bulletin 04-03-09-003 to repair a knocking noise from the rear of the vehicle that may occur on a aggressive launch or acceleration. The repair is to install updated rear cross member insulators p/n90447991 and 2 new bolts p/n92038482 between the body and the rear crossmember. Art Spong, Brand Quality Manager for the GTO, has requested all dealers update the GTO's as a Customer Satisfaction Repair. Vehicles involved are built prior to Vin break 4L246712
sounds like it could be my issue

[Toprivetgun]

Sounds like diff issues.

[doleboy]

If you're lucky it's just the diff oil / friction modifer that needs topping up.

[ringram]

Is your car stock? If not then the extra driveline forces wont be helping longevity.

[nitrosman1]

hi just been under the car there seems to be a bit of both going on ,in the diff and the rear cv joints a bit dissapointed now the car has had a sports pac fitted but thats it till next week when im booked in for a sc to be fitted