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What parts to replace when replacing gearbox?

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  • What parts to replace when replacing gearbox?

    Howdy folks,
    I am after some advice on what other parts to replace when having the gearbox in my ABY coupe replaced (something I’ve been getting around to doing for a while).
    The 1st gear is shagged and I have an (apparently) good condition 2nd hand box, also a CGR from an S2.

    The work will be by a mechanic in a workshop, ideally with the engine in (per the sticky guide in the transmission section of the forum).
    My S2 has done 135k km and as far as know the engine and gearbox has never been out.

    The mechanic has recommended at a minimum:
    - clutch
    - clutch release bearing; and
    - slave cylinder
    I am also thinking subframe mounts..

    What else is worth doing, without replacing everything that doesn’t need to be touched?
    Are there any gaskets required for the cats or elsewhere?

  • #2
    I would do the rear crank oil seal while there. No gasket on the cats, just a metal ring which you can 're use if its good. There is a gasket on the top end of the downpipe if you remove that. Gearbox mounts are worth replacing as well as the engine mounts. Don't buy cheap ones as they fail quickly. Go OE or the Porsche ones adapted (thread here somewhere). Take care of your linkage as they are like hens teeth. Error 404 (alex) sells replacement bushes for the linkage on his site, Ultra. Performance Engineering. All his stuff is really good
    Nothelle S2 Avant
    Wr Ur Quattro in restoration
    S2 Coupe getting a tidy up


    • #3
      You may as well replace the easy to get at gearbox oil seals, so input shaft, front output flanges, rear output flange, very simple and cheap to do.


      • #4
        All the above plus the spigot bearing in the flywheel, really cheap and easy to change. Changing the rear crank seal really is a no brainer given how old it now is, so you'll have to have the flywheel removed anyway and it's really simple to pop a new one in whilst it's off. Make sure new flywheel bolts are used.

        Just re-read your first post, if the car's only done 135K kilometres not 135K miles as my aging brain read it, then you could probably leave the spigot bearing alone. But for the sake of $20 Aus I'd still do it anyway as I guess you don't plan on parting with the car anytime soon.
        Last edited by K Simmonds; 16 November 2021, 09:57.
        1992 C4 100 2.8 Avant quattro, daily driver.
        1995 RS2, MTM K26/7, 380 BHP conversion.
        1996 C4 2.8 30V quattro, future project car...


        • #5
          Great suggestions from everyone above. I'd even add that it would make sense to change the valley pan gasket as well since you'll be dropping the subframe a bit and the rear bolts will have very easy access.

          It stings to even think that I did not replace the rear main seal when I swapped my gear box several years ago. I have since replaced all engine seals and a small leak, undoubtedly from the rear main, remains.

          The amount of effort involved to now replace that $25 dollar seal makes me sick.


          • #6
            I’d also have a good look at the hydraulic clutch pipe


            • #7
              Thanks all for the responses.
              Dave what gearbox mounts do you consider ‘OE’? Sourced from Audi only or others (eg Febi/Bilstein)?


              • #8
                I think the OE were Boge. Try your Audi dealer maybe?
                Porsche ones are for 912.
                Nothelle S2 Avant
                Wr Ur Quattro in restoration
                S2 Coupe getting a tidy up


                • #9
                  Originally posted by simons2 View Post
                  I’d also have a good look at the hydraulic clutch pipe
                  I can second this, this one came off my Avant!