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Part number for S3 rear differential?

Rip Jan 16, 2020

  1. Rip

    Rip Active Member

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    Can anyone please tell me what part number the rear differential assembly is on a 2014 S3? I'm assuming there might be several compatible part numbers including maybe VW?

    Mine has started whining at about 40mph and more so while coasting and it's annoying me now. As there doesn't seem to be any fix for it I'm going to have to gamble on a 2nd hand one and hope it's quiet.
     
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  3. pburv

    pburv Well-Known Member

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    Part number- Rear Diff main unit: OCQ525010K
    Part number- Rear Diff ECU : OCQ907554H


    Got this off a salvager's site on ebay. So not sure if 100% correct.
     
  4. JohnM100

    JohnM100 Well-Known Member Gold Supporter VCDS Map User

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  5. Rip

    Rip Active Member

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  6. Rip

    Rip Active Member

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    I've had my oils done recently and the diff did have oil in it.
     
  7. Rip

    Rip Active Member

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    I'm assuming I wouldn't need another diff ECU as my current one should be fine.
     
  8. HertS3

    HertS3 Well-Known Member

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    I'm the author of the above post - I know all about rear diffs! Mine is a late 2014 build (car delivered early 15) and I had the F variant on my car. You can get any 0CQ525010X where X is what you have or later; there were D, E, F, H, K, J, L and S I believe (S is the current version you get new from Audi if you fork out £3,800!!!)

    There are a few knocking about on eBay, what I would say is play the waiting game, not many of these sell, if you watch the items or message sellers they'll give you big discounts on the prices they ask on their listing. If you look at the thread above, I found one guy that was willing to sell for around £200. I'd be weary of West Yorkshire-based dealers, the one I got was from a Nottingham breaker and (touch wood) all fine so far
     
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  9. HertS3

    HertS3 Well-Known Member

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    Oh and you can keep the existing Haldex ECU, I did, otherwise you need to programme the new one to your car
     
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  10. Rip

    Rip Active Member

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    Legend, thank you, that's literally all I need to know then!
     
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  11. Rip

    Rip Active Member

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    Do you mind if I PM you if I have any queries before I buy one?
     
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  13. HertS3

    HertS3 Well-Known Member

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    Sure, no problem
     
  14. Rip

    Rip Active Member

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    Nice one. The electrical wire going in to my diff is all knackered (dry and flakey), is that the ECU wire?
     
  15. HertS3

    HertS3 Well-Known Member

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    Not sure about that, better asking a mechanic, but I would imagine that it is the electrics/comms for ECU
     
  16. Rip

    Rip Active Member

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    Thinking about it, new/used diff will have its own wire anyway regardless of what it is.
     
  17. HertS3

    HertS3 Well-Known Member

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    To me it's a no-brainer, you can pick up a used one (some with low mileage) for around £200 or a new one for £3,800. Problem is if you have a problem with it, extended warranty (if you have it, I do) will probably not pick it up, then again you could just buy another one.

    After my experience with the original rear diff I would say definitely get a mechanic to check the diff oil when you're servicing your car, my one seems to have gunked up for some reason which caused its eventual demise. Could be a design flaw, though I've not seen swathes of people complain about it so may only happen to several unlucky ones among us.
     
  18. Rip

    Rip Active Member

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    I didn't buy the car new so I guess warranty is out of the question. For the cost of a used one I'll gamble it. Hopefully the fitting cost won't be too much, not sure exactly what's involved to be honest, shouldn't be 'too' much work.
     
  19. HertS3

    HertS3 Well-Known Member

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    Yeah I bought mine at 3.5 years old too. I got an L rear diff for £370, but like I said can get it cheaper, look at the previous thread, that part was going very cheap from a low mileage car, may well still be for sale!

    I think it's an hour or two of labour, plug n play really (if keeping Haldex ECU), you'll need to get new Haldex and rear diff oils for it as it'll come drained, so those will set you back probably around £70.
     
  20. HertS3

    HertS3 Well-Known Member

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  21. Rip

    Rip Active Member

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  22. Rip

    Rip Active Member

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    I've made them an offer so hopefully I'll end up with it after some negotiation.
     
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  23. HertS3

    HertS3 Well-Known Member

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    Best of luck. Just check with them the variant, what car it came off and its mileage, I seem to recall it was a low mileage one and I think variant L which is pretty much as new as you're gonna get used (S is most likely from the new WLTP cars, doubt there's many around that have been written off already).
     
  24. Rip

    Rip Active Member

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    It's an L yes and under 10k miles. Thanks for the lead on that!
     
  25. HertS3

    HertS3 Well-Known Member

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    That's the best of the bunch, the one I got was similar but slightly higher mileage. You're welcome :)
     
  26. Rip

    Rip Active Member

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    Well hopefully I'll get it.
     
  27. HertS3

    HertS3 Well-Known Member

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    I'm sure you will, just a question of how much. He said to me at the time (it was advertised for £399) that he'd do it for £300 delivered, he'll probably take less as time ticks on!
     
  28. Rip

    Rip Active Member

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    My offer isn't far away from that so fingers crossed, I'll negotiate when he gets back to me.
     
  29. pburv

    pburv Well-Known Member

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    Here's a video of someone replacing their diff on a Mk7 Golf R. Without using a car lift!
     
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  30. Rip

    Rip Active Member

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    That actually doesn't look to bad.
     
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  31. pburv

    pburv Well-Known Member

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    Would be easier if you had access to a lift, but as you said not too difficult.
     
  32. Rip

    Rip Active Member

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    Well going by that video getting someone else to fit it on a ramp shouldn't cost too much. Luckily I know the owner of a reputable VW/Audi tuner who I trust and charges fair prices so all should be ok.
     
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  34. pburv

    pburv Well-Known Member

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    If it was me personally I would get a garage to do it. Only for the fact they have lifts . but if you had no option then doing it yourself is doable.
     
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  35. Rip

    Rip Active Member

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    Got it for £290 delivered, I'm happy with that :)
     
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  36. HertS3

    HertS3 Well-Known Member

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    That's a result! Mine was £370 delivered so you got a very good deal indeed
     
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  37. Rip

    Rip Active Member

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    Thanks to you yes!
     
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  38. HertS3

    HertS3 Well-Known Member

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    Glad to help :)
     
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