knocking from drivetrain under hard acceleration
 

Hi All,

I have a loud rapid knocking sound from the drivetrain (sounds like from the front) under full throttle from a standing start. its short - maybe 4 or 5 solid knocks as the car moves from a stationary position.

No noise at all during rolling acceleration.

This occurs with no steering lock on and there's no noises from any of the the CVs when turning - both fronts are refurb items and are in good condition.

My indie says he's never heard the sound before.

I have just had the following replaced: front caster bushes, diff bush, RHF control arm and had a wheel alignment done. Indie says the suspension is in good shape.

I have searched the site as well as I could, and the only things I could find was transfer case chain slipping or a drive shaft bearing failing.

Do either of these sound right in my case? has anyone had anything similar?

Car is a 2003 4.4i E53 X5 with 143000kms (approx 90,000 miles)

cheers

David

I just heard a noise as you described too. Transmission?, transfercase? It sounds expensive to me....

Im getting the same noise... Going crazy and losing a lot of $$$ trying to figure out the reason. 4-5 rapid knocks when coming out of 1st / 2nd gear then its gone... Please Please Please let me know what you learn from this.

PS: I was also informed that it may be the integral link. #4 http://www.realoem.com/bmw/showparts.do?model=FA53&mospid=47745&btnr=33_1029& hg=33&fg=30

Well the problem turned out to be the transfer case chain slipping and jumping teeth. Apparently it had stretched enough for this to happen. this is a very heavy duty chain and takes a pounding from full throttle standing starts as you can imagine.

BMW's cure is a complete new transfer case at A$5000 as it's a non serviceable item.

I bought a triplex chain from Automatic, Standard Transmission and Transfer Case Rebuild Kits, Cobra Transmission Parts 1-800-293-1848 in Florida for $300 and had my indie fit it. all up cost was $800.00. just be aware that splitting the casing open means very careful resealing during reassembly as there's no gaskets - just crosshatching on the metal to metal surface. get it wrong and it leaks.

Incidentally, the same transfer case is used in Range Rovers and some Jeeps.