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996 rear calipers and Brembo handbrake for the coupe

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  • 996 rear calipers and Brembo handbrake for the coupe

    Introduction
    So, you’ve decided that the standard brakes of the S2 are, shall we say, very modest for its power and handling even in standard form! The RS2 had much better brakes with front calipers and rear brakes from the Porsche 968 CS including the drum handbrake within the rear discs. Front conversions have been covered many times elsewhere including some very large and powerful versions. It is probably fair to say that the most popular upgrade is to go beyond the RS2 and fit the later Porsche 996 “monobloc” calipers. Again it is fair to say that most owners are content to follow a similar style to the stock rear brakes and go for an upgrade of the combined rear and handbrake caliper such as that from the S4 or RS4.

    Well this guide looks purely at the rears and details an upgrade that is in the same vein as the 996 front upgrade over the RS2. The upgrade is not to be entered into lightly as it involves a significant bit of preparation in terms of drilling the hub assembly but once that is done, it is largely plug and play as I have done the awkward measuring and modification bits to build a custom handbrake bracket! I apologise in advance for any errors: I will endeavour to correct them as we go through. I've been asked several times about what to do so here goes - it has taken over 2 years in elapsed time to research and install it and what we've ended up with is (I think anyway) an elegant solution. Here goes.....
    Last edited by John B; 2nd January 2013, 23:23.
    2001 996 C4 - Being renovated
    1994 ABY Coupe - "Das Smaragd RS2+ Coupe" - Sold

  • #2
    Talk about being a tease
    Current-2004 Impreza PPP wagon

    Sold-92 3B coupe-RS2+, 996s, konis, rear torsen, forged rods........
    Sold ABY-stock

    Comment


    • #3
      Setup

      However before we start that it is worth summarising the standard setup, that of the RS2 and the Porsche 996, in the attached document: -

      S2 v RS2 v 996.pdf

      Other key braking components are: -

      3B v ABY v ADU brake components.pdf

      As can be seen the Master Cylinder is the same on the RS2 as the ABY S2 as is the ABS unit. The servo is different, which affects the ratio of pedal pressure to pad pressure i.e. the “push” that is exerted by the brake leg. The regulator is different which gives the balance between the front and rear brakes and this is to be expected as the S2 only has a single piston floating caliper versus the 4 piston fixed caliper of the RS2.
      Last edited by John B; 2nd January 2013, 23:50.
      2001 996 C4 - Being renovated
      1994 ABY Coupe - "Das Smaragd RS2+ Coupe" - Sold

      Comment


      • #4
        Parts

        The parts you will need are detailed in the attached.

        Part List v2.pdf

        I spent about £1k on this upgrade, which is a lot but when you compare it to the front upgrade, where I spent in the region of £700 and you consider that in effect there are two braking systems at the rear (hydraulic & mechanical) it didn't seem too bad. Please don't fault the logic....I've spent ages convincing myself it is worth it!
        Last edited by John B; 21st January 2013, 16:43.
        2001 996 C4 - Being renovated
        1994 ABY Coupe - "Das Smaragd RS2+ Coupe" - Sold

        Comment


        • #5
          Handbrake solution

          The handbrake caliper is the key to the solution and is used on the Lamborghini Gallardo and the Audi R8. It is faithful to the side-pull dynamic of the stock S2 coupe and uses a bolt-on pulley wheel arrangement to effect this: -

          Brembo hand brake caliper – disc side view

          Brembo hand brake caliper – disc side view.jpg

          Brembo hand brake caliper – hub side view

          Brembo hand brake caliper – hub side view.jpg
          2001 996 C4 - Being renovated
          1994 ABY Coupe - "Das Smaragd RS2+ Coupe" - Sold

          Comment


          • #6
            Excelent work!! Do you have anyphotos? This is what i have thought about doing to my quattro for some time, no doubt it will be different again!
            Angus

            (1984 ur quattro)

            Comment


            • #7
              Preparation

              The handbrake caliper adaptor needs to be mounted onto the hub assembly using two of the three splash shield holes and the holes need to be enlarged to take the strain of the handbrake caliper. In summary, this can only properly be done with the hub assembly off the vehicle and with the hubs removed from the wheel bearings. So if this upgrade is for you, then you might as well replace the wheel bearings while you are at it and replace the stretch bolts that hold the hubs onto the driveshafts.

              You will also need to: -
              1. Take hub assembly off
              2. Take the handbrake cable off
              3. Take the flexible rear brake line off


              The procedures for this are described elsewhere on this forum.

              With the hub assembly off, you need to: -
              • press out the hubs from the wheel bearings and (if you want to) replace the bearings
              • undo the 3 nuts holding the splash shield onto the hub assembly. On mine these were rusted on and I could only get the top one and the middle off intact. I had to then bend the splash shield, cut it off and leave the bottom nut in.
              • enlarge the threaded holes from M6 to M10 ensuring that there is at least 12mm depth to the holes. It has to be remembered that the standard S2 caliper carrier mounts to the hub using M12 bolts but the caliper itself mounts to the caliper carrier using only M8 bolts. Bearing in mind that the standard S2 rear brakes are for stopping as well as for the handbrake, the same M8 bolts should be sufficient for the handbrake. However, I have used M10 (originally I used M8 but then had reservations). In any case you will need to remove all of the swarf from the tapping (threading) operation.


              Since you have the hub assembly off you may want to then take the opportunity to have it blasted and powder coated or at least wire brush and paint with Hammerite or POR15.

              Here is a picture of the hub with M8 bolts in as marked by the arrows, that I later changed to M10. You will notice the caliper carrier is that of the RS2 front brake, which is what I was using to test in the early days of this solution (before I knew of Will's adaptor) when I was also looking at the S8 rear disc.

              Hub assembly with nuts.jpg
              2001 996 C4 - Being renovated
              1994 ABY Coupe - "Das Smaragd RS2+ Coupe" - Sold

              Comment


              • #8
                That is great, thank you for taking the time to document and list the parts!
                Current-2004 Impreza PPP wagon

                Sold-92 3B coupe-RS2+, 996s, konis, rear torsen, forged rods........
                Sold ABY-stock

                Comment


                • #9
                  Installation 1

                  Assuming that your brake calipers are in the condition that you desire (the handbrake caliper should be new but the 996 caliper will likely be second hand and need some refurbishment) and that you have the hub assembly mounted onto the car’s suspension and drive shaft, the installation of the 996 rear caliper and Brembo handbrake caliper can begin.

                  Mount the bespoke handbrake caliper adaptor to the hub with two bolts N 911 056 01 - they are M10 x 85 from the R8, cut to suit the depth of the holes drilled in your hub - you can of course use bolts of your choosing but I wanted to use Audi ones and ones that had done a similar job elsewhere (the bolts shown here are the original M8 bolts - 321 615 141 - I don't have pictures of the final set up, sorry). They are shown by the blue arrows and should be secured using your favourite thread lock compound.

                  It should look something like this: -

                  Installation 1.jpg

                  You'll notice that since I had the whole suspension off for bushes etc......I took the opportunity to have the struts and sub-frames powder-coated in aircraft grey
                  2001 996 C4 - Being renovated
                  1994 ABY Coupe - "Das Smaragd RS2+ Coupe" - Sold

                  Comment


                  • #10
                    Installation 2

                    Note that you will have to place 3 x 1mm M10 washers on the top bolt to give the correct spacing such that the plane of the bespoke handbrake caliper adaptor is parallel to that of the hub and disc, as indicated by the blue arrow. At this stage it is worth removing the small extension that holds the ABS cable, as this will foul the handbrake caliper, located by the green arrow. If you need to, you can tie wrap the ABS cable to the hub assembly but I found it not to be necessary.

                    It should look something like this: -

                    Installation 2.jpg

                    In this picture the handbrake adaptor is the prototype in mild steel but now my S2 wears a plated version. I daresay Kev will excel himself soon and produce some versions out of some really exotic material if the demand is there......like the caliper adaptors from Will.....
                    2001 996 C4 - Being renovated
                    1994 ABY Coupe - "Das Smaragd RS2+ Coupe" - Sold

                    Comment


                    • #11
                      Installation 3

                      Place your nice shiny 300x22 disc on the hub and use the trick of a wheel bolt through a large nut or ring spanner to keep the disc flat against the hub. In the picture below I used a cheap disc but have now gone for an EBC grooved and spotted one to match the fronts.

                      Mount the handbrake caliper onto the bespoke handbrake caliper adaptor using the M10 bolt (N 911 056 01 - M10 x 85), which is used on the R8 and Lamborghinis etc. as this caliper is used on those vehicles, on the top hole, with an M8 bolt on the bottom hole. Ensure that the calipers are on the correct side such that the side-pull handbrake cable pulley is at the bottom. You will need to trim the bolts so that they are flush with the disc side of the bespoke handbrake caliper adaptor, when tightened. I can’t remember the exact amount of trimming but you should do it to suit your vehicle and preference. These two bolts effectively hold metal tubes on which the handbrake caliper “floats”.

                      You should end up with this: -

                      Installation 3.jpg
                      2001 996 C4 - Being renovated
                      1994 ABY Coupe - "Das Smaragd RS2+ Coupe" - Sold

                      Comment


                      • #12
                        John,

                        Thanks for sharing. In the first .pdf is there a typo with the size of the RS2 rear disc, it states it as "290"mm, should it be "299"mm ?

                        I presume the main motivation was to have matching front and rear 996 calipers on S2 5 x 112 pcd hubs ?

                        I have the rear B5 kit from Quattro Corner, also sized at 300mm, while mine are silver, and don't colour match the front red Brembos, they did bolt straight on, with no wheel bearing, powder coating, or drilling and tapping issues.

                        I'm going to redo the fronts in silver, or do the front and the rear in matching black.

                        Another method is to change over to RS2 hubs and discs when doing the front brakes at the outset, although then new rims are needed, and the RS2 handbrake, ime, is never very satisfactory.

                        On reflection, only the first bit of my post is of any help.

                        Kind regards.
                        Last edited by macspring; 10th May 2014, 01:37.

                        Comment


                        • #13
                          Installation 4

                          If your chosen disc has a mounting screw hole, you may choose (as I did) to drill and tap a hole into the hub to take a screw that keeps the disc flat against the hub, such that when you take the wheel off in future the disc does not move.

                          Mount the VRS caliper adaptors http://www.s2forum.com/forum/showthread.php?t=60763 to the hub with the bolts (N 100 880 03 - M12 x 1.50 x 25 from the RS2 front brakes)
                          Last edited by John B; 3rd January 2013, 23:17.
                          2001 996 C4 - Being renovated
                          1994 ABY Coupe - "Das Smaragd RS2+ Coupe" - Sold

                          Comment


                          • #14
                            Originally posted by andy10v View Post
                            Talk about being a tease
                            I hope your itch is scratched!

                            Cheers


                            JB
                            2001 996 C4 - Being renovated
                            1994 ABY Coupe - "Das Smaragd RS2+ Coupe" - Sold

                            Comment


                            • #15
                              Originally posted by andy10v View Post
                              That is great, thank you for taking the time to document and list the parts!
                              No problem....i was surprised most about the Brembo handbrake caliper because if you ask for an Audi or a Lambo version, the price is astronomic

                              However, I saw some GT40 forum pictures of a handbrake solution and followed the trail to GD Cars who do GT40 replicas

                              Brembo Handbrake on GT40.jpg Brembo Handbrake on GT40 - 2.jpg Brembo Handbrake on GT40 - 3.jpg Brembo Handbrake on GT40 - 4.jpg Brembo Handbrake on GT40 - 5.jpg
                              Last edited by John B; 14th April 2013, 20:12. Reason: Pictures!
                              2001 996 C4 - Being renovated
                              1994 ABY Coupe - "Das Smaragd RS2+ Coupe" - Sold

                              Comment

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