8E0 Rear Brake Upgrade

[S2central.net]

Yep - I know the S8 280x22mm disc has very different 'hat height' than factory and 8E0 disc... Hence that aligns nicely with your idea to tweak the RS2 carriers (that we know fit a 996 caliper) - but I am still perplexed by the handbrake... unless you have hatched a mad scheme to copy something like the rear of RS2 with a drum style handbrake.

[Tommy200rs]

Just some side comments. A200 and S2 coupe both have side pull hand brake cable solution as original. Iḿ stubborn in having an easy cable solution because those parts need to be easy available and installable and therefore side pull solution.

If brake balance kept between front and rear (important when driving on sand roads and braking hard. A balancing valve can be fitted between front and rear brake circuits (Alcon, AP etc balancing valves = extra cost)

Earlier in this thread there were mentioned the S8 calipers:
(- there were also early model s8 calipers that were not alu ones )

These seem to be for sale and look kind of alu:
http://cgi.ebay.de/ws/eBayISAPI.dll?...=STRK:MEWAX:IT
- those have been for sale for long time allready

Quite BIG rears are available for the big engined A8 body and rs4 in etka. That big dimensioning would be nice for S2 360, 380 fronts..... Beware, those later series S8 calipers are crap because they are with servo motor (), but the carriers are old familiar design and compatible with older calipers from 100s4, v8, rs4 bit etc.

one other way to increase the caliper heightt / carrier disctance:
http://cgi.ebay.de/Bremsen-Adapter-h...14168005r26994

[John B]

Why the S8 disc?

Ok, well you'll know now that I selected the S8 (1st generation) and neu S4 rear discs to test. First I thought it was best to check the pad to disc interface to see if we would have a working solution.

Here is the S8 disc with the inside edge of the pad about 1mm from the disc circumference
tn_DSC01540.JPG
....looking good

Now let's see how the outside edge of the pad fits
tn_DSC01541.JPG
Well that is a surprise: how well it fits....about 1mm away although it's difficult to see (excuse the work tie!)

The acid test is the view across the face of the disc
tn_DSC01542.JPG
This view confirms the fact that we have a good fit for the pad to disc interface. Also the gap between the caliper body and the disc is sufficient. So we have a runner here.

In comparison, here is the same analysis for the Neu S4 disc
tn_DSC01543.JPG
with inside of pad aligned to the inside disc surface

....which leaves a gap of around 4mm on the outside
tn_DSC01544.JPG

...and here is the view across the disc surface
tn_DSC01545.JPG
and you can see the low hat height clearly here. This would actually make the caliper sit too far out board and would compromise the gap between the caliper body and my 17" wheel.

For the two reasons above (gap on the disc surface and hat height) the S4 disc was sidelined. Anyone want to buy them for an 8E0 conversion?

Next, after all good measurement sessions comes a little trial fit.....and yes we'll start to mention that pesky handbrake soon...thanks for your patience! More soon...

[Error404]

I'm impatient! We want more!!

[S2central.net]

Oh he really is keeping us all in suspense here... Exciting stuff !

[John B]

996 rear caliper test fit

Ok, I know I'm taking my time but I don't have too much at the moment and have not reached the end of this little conumdrum yet. I'm close to the solution but hoping for inspirational comments as the tale progresses ...please!

Anyway here is a quick blast through the test fit. This is the RS2 adapter bolted on

tn_DSC01355.jpg

Now, this adapter has 130mm bolt spacing for the caliper side, which is fine for the 996 Brembos (same as the front) but has 94mm bolt spacing for the strut side and 12mm threaded holes. Guess what? The strut has standard VAG spacing at the rear of 90mm and the hole is 10mm threaded. So I used some smaller 8mm coach bolts as a frig for the test fit. More on this subject later, when we decide on the adapter.

....and with the old spanner wedge trick, the disc looks like this: -

tn_DSC01356.jpg

Here is a view from the front...ignore the surplus length of bolt at this stage: -

tn_DSC01357.JPG

Now the final moment of truth.... here goes with the caliper: -

tn_DSC01358.jpg

That is reassuring of my measurements and here is the view from the front: -

tn_DSC01359.JPG

And finally the view from above. I have placed a nut there, which is 10mm high to show the gap from the inboard disc surface to the outboard strut mounting face.

Generally a successful test fit. Apart from the bolting differences, the only adjustment to be made is to move the whole caliper about 3mm radially outwards from the hub centre such that the pad centred on the disc surface, leaving about 1mm of excess disc to pad either side of the pad, which is acceptable IMO. This could be achieved using spacer washers between the caliper and the adapter but as we will see the standard RS2 adapter only has a cameo role in this story.....bye for now: my meter has run out!

[S2central.net]

That's all fine and lovely - great fit by just using off the shelf components - handbrake is the tricky bit though. What is the secret sauce for that ?

[John B]

Handbrake

Yeah, I know that is the difficulty but I have (or had) 3 solutions to that, which I will detail and will ultimately plump for one in a future instalment. As you can probably guess we will need a modified adapter but what I am trying to do is end up with an easy solution like the 8E0 upgrade that involves as many standard bits as possible, with one bespoke bit (the adapter). I can say that this solution has been done on an S4 by a very reputable brake manufacturer and I will share pictures / documents when I have time. Will really have to go now. Cheers, J B

[CliveH]

I can say that this solution has been done on an S4 by a very reputable brake manufacturer and I will share pictures / documents when I have time.

totally off-topic, I know, but are we talking urS4 or B5 S4 here John?

[John B]

S4 rear brake conversion

Hi, the documentation that I have gives the range of years 1992-2002, which covers both the Ur-S4 and the B5...will post it soon...I promise!

[S2central.net]

I'm more confused than ever now - why are we talking bout an S4 ?

[John B]

Confusion!

Just to clarify...I saw my intended end-solution on an S4, which was manufactured by a reputable brake manufacturer. A fellow forum member gave me this clue and I got the idea for a similar solution on the S2. All will be revealed and we are now firmly back on-topic!

[CliveH]

Thanks John

I'll PM you separately about the B5 S4 solution

[S2central.net]

Phew - OK - with you now John... You keeping us all in suspense here

[quattro]

Where did this end up?