For those that are too far away from Cartek that does a full C5 conversion for the terrible strength C6 for the 2005 model year, I personally saw a different set-up using a C5 rear diff today. On a car done by Corvettes of Westchester, the center section (the 700 dollar core part), had been used with the side-arms of a C6 unit. While there is some question as to the strength supplied from deleting the side arms which may supply a wishbone type shearing force to the case, the middle of the C5 diff's case is beefed up by the additional metal that bolts up to the C5 mounting system. This additional metal is where the 2005 C6 unit splits up the center.

In other words the C6 side covers can bolt up to the center section of the C5 case which has more metal where the C6 case splits right up the middle. While I beleive that one bolt is deleted in the side cover bolt pattern, if it isnt needed for the C6 then it must not be so detrimantal that it is deleted on the C6/C5 hybrid case.

In any event, the car was a fairly well powered and tuned car with the usual bolt-ons and pulled very well. It had 4.10 gears and was quiet without whine and as far as I could tell, had no detrimantal effect to the car's performance.

A big advantage in such a s swap even if there wasnt a strength difference (but there is) is that the core, if destroyed will only be $700 instead of the silly $2200 of the weak C6 case. Call local tuners if they will do it or give COW a call to see what a build-up would cost for a core swap. Keep in mind your stock C6 core will fit a A4 and therefore has a good resale value (I sold mine for 1100). It will off-set the cost of a custom C5 rear with C6 side-arm covers.

 

Sounds promising!

 

Is the C5 center section the only part to change and rest of C6 parts will fit? I have upgraded C6 diff but still worry.

 

I was told today that the C6 internals will fit the C5 case. While at Cartek I was shownt the differences of the end covers (C5 and C6). The thing that puzzles me is how the o-ring is used with the C5 center section with the lack of an 0-ring groove in the C6 side covers. The C5 covers have a channel where the o-ring fits and the C6 one doesnt. Maybe Chuck from CoW can expalin how it was accomplished. I see that a sealant was used. There were no leaks on the car I saw the rear on and it had no noises in operation which included abuse.

 

They actually have a special red sealant used to seal alum cases and other engine and tranny parts together where no gasket is used. I have also seen some techs use normal RTV silicone in place of this sealant, I bet they just used one of these in place of the o-ring.

 

100% correct guess for this Diff. I could see a fair (and even) amount of black RTV seeping out all around the perimeter. I would still bet the o-ring is there too just quished into the corner.

I have seen the red RTV on the transmissions.