Audi TT RS Rear Diff noise on overun

2010 Audi TT RS Rear Diff Noise on Overun [ decceleration ]

This one had only done 55k miles!  The normal, is for the nut to loosen on the pinion and that allows for the pinion to run of axis [Unloaded]  wearing  the hardening off the pinion, and subsequently pitting. Cost wise if you go buy a unit from Audi,  complete with the troublesome Haldex unit you are looking at @ £3700 + vat ex fitting  We have seen some later ones that remove the nut from the equation and use a cir clip as a fastening method, which quite frankly is a little bizarre. [ It was a quick fix ] Both types operating without conventional squash tubes probably due to the double seal that separates the Diff oil from the Haldex oil. The nut on the conventional fastening pinion is left handed. The cir clip type mounts on a hardened non-sacrificial & machine ground 4.2 mm thick [assumed ] selective shim or at least it would be if Audi retailed the internal parts.  In terms of the diff it looks like they are constructed to last the dealer warranty and that’s about it.

This car also had substantial leaks around the engine and gearbox and a multitude of codes when we scanned it on VCDS [ Ross Tech ]

Rear Diff 950 Ml , Haldex 720 ML.  Don’t confuse the separate fill points.

[Quick advice to the trade, if you have noise on decel, remove the haldex unit and feel for end float on the pinion shaft]

Changing the oil wont fix it [ wallies in the forums ] [Picture shows nut type pinion look at the teeth to see pitting]

Call  National Gearboxes on 01502 586502 for advice or pricing.