8E0 Rear Brake Upgrade

[Keeper of The Kitten]

Good effort Paul, keep us posted!

__MDC__

[Greg_S]

keep us posted on this paul, piccy's are always good

[90quattrocoupe]

If anybody still cares...Paul

I do. I always find someone taking the plunge and trying to find an alternative, to be productive. In the end, I may feel it may be more trouble than the gain, I still appreciate the attempt. No attempt, no new ways.

Thank you Paul,

Greg W.

[S2central.net]

If anybody still cares...

I have an update on the 8E0 rear brakes conversion. Essentially the calipers fit up a treat with no clearance on 16" Avus rims - thats not as simple as it sounds when you see how bulky the handbrake mechanism is.

The hydraulic connection is long enough to reach the factory fitted hard line union with similar slack to the original hose for suspension movement. I can only assume that the brake union will be identical but I didn't have the inclination to fight with that just yet. I'll order up some fresh onions and clips before changing the lines over.

Getting back to the handbrake - there are some fitment issues as expected. I'll post photographs over the weekend. Essentially I need to fabricate a small adapter bracket so that the S2 style handrake cable can be used without modifying the expensive new caliper.

Reason for the handbrake issue is that the s2 cable end has a diameter of ~14mm whilst the hole in the 8E0 caliper is only ~12.5mm. That and the 8E0 bracket ain't as thick as stock caliper - meaning the spring clip doesn't hold as neatly. A simple bracket should solve this.

The other handrake issue is that the original cable isn't anything like as long as it needs to be to reach the 8E0 application. I'm going to order up S2 Avant handbrake cables to try. These should have identical ends but are a whopping 40cm longer which could cause issues. I'm searching for others but hopeful that a machine shop can trim the longer ones down to a sensible size.

Its getting there slowly but surely. A local toolmaker can make me the brackets for test fitting.


Paul

[S2central.net]

By way of quick update... The weather has been shocking here all weekend so I couldn't dry fit the 8E0 calipers as planned.

I can tell you that the 8E0 calipers use a funky banjo style fitting for the brake line. This might cause another little hurdle as I doubt the 8E0 brake lines will be long enough.

I also think some sort of adapter will be needed for the handbrake mechanism so that it can accomodate the S2 cable end (assuming the length is OK).

Hope to have a dry fit over the next couple of days - weather permitting.

Paul

[Sweeper]

Interesting if there exist cross drilled S4 300mm rotor version(maybe aftermarket, they sometimes are even cheaper) =] , so it will look kewl with 332mm cross drilled front brakes =]

[S2central.net]

Oh go on - here's todays pics...

http://homepage.mac.com/nugentp/PhotoAlbum13.html

Just realised I never measured the hole for the handbrake cable yet !

Watch this space for news on the next dry fit.

Paul

[S2central.net]

As of today, I now have the mysterious 8E0 calipers and pads in my hands. Initial photos to follow and a dry fit over the next few days, but here's the lowdown.

- Calipers have same silver finish as the carriers.

- Single piston rear caliper - appears to be same size piston as UrS4/S6 at 43mm.

- The handbrake cable mechanism is similar in principle to S2 setup. Only real difference is that the cable pull is at bottom of caliper - not from the inboard side of the caliper so a longer HB cable might be needed.

- Brake hose fitting on 8E0 caliper is bigger than UrS4/S6 rear caliper. I was comparing them on a bench. Pretty sure S2 rear caliper has same size hydraulic connection as UrS6. So looks like custom lines or an adapter of some sort is required. No big deal if that is the case.

- Pads have strange looking clips that I can't fathom right now as there is nout to compare with. The pads seem to be common with an A6/S6 (1997 onwards) application so I'm hoping I have manuals for that here somewhere for reference.


Paul

[S2central.net]

any time you move a caliper outward and add a larger rotor, you are moving changing the bias because the same caliper will now have more torque. Now, assuming that a B6 S4 is a heavier and more powerfull car from the factory, I would venture to guess that the piston size will be larger and really change the F/R bias. I would only set this up on a car with large front brakes...and even then, you might need to add a Titlon or Wilwood brake bias adjuster to the rear line.

Totally agree with that... But I will be a bit naughty and hope to complete the rear conversion before I upgrade the fronts (have 996 monoblocks and RS2 carriers ready). I want to see how much the bias shifts before I upgrade the fronts.

I should really get a g-meter for before and after stopping tests on all of this upgrade related stuff. T'would be nice to quantify some 60mph to stop info. I suppose there is always a stopwatch and some simple maths and unit conversions.

Paul (Already scouring the family album for handbrake cable solutions)

[NoNonsense]

Nice work, Paul! I'm impressed! ;-) Guess I have to buy myself a Coupe so I can play with this!

[NoNonsense]

will this drag any of the (i think) current 70/30 brake bias towards the back? or is that regulated purely by the brake bias valve thingy???

This is looking really interesting - i need something to fill out the 18's at the back!!!

any time you move a caliper outward and add a larger rotor, you are moving changing the bias because the same caliper will now have more torque. Now, assuming that a B6 S4 is a heavier and more powerfull car from the factory, I would venture to guess that the piston size will be larger and really change the F/R bias. I would only set this up on a car with large front brakes...and even then, you might need to add a Titlon or Wilwood brake bias adjuster to the rear line.

[S2central.net]

Do you have a measurement from the inner mounting face to the inner face of the braking surface of the 8E0 disc?

Other mods are not a problem but it would be nice to just bolt on.

@Corey -

Total height of 8E0 300x22 disc is 35mm (maybe 36 - I don't have the most accurate ruler here). Subtract 22mm disc width for a 13mm 'hat' height. I measured ~7mm thickness of the disc where it mounts to hub surface...

Giving you ~6mm for the dimension in question.

Paul

[Ross]

Looking through my receipts today, it seems the rear calips have been replaced twice already on the car! Not had any probs since the regreasing, but it was sticky and once. And the handbrake still seems to go uber-floppy in the cold, and hardly works anyway.

Soooo, just tell me that I'm best to replace the rear brake setup and it'll all be working for my June MOT and I'll be convinced. Please, convice me

Personally I expected to be dissapointed with a £500+ figure, so that's not all that bad. Besides, I don't count the car costs in £££ anymore, I measure it in "days of overtime".

But would you be suggesting it's worth ordering brake parts before the end of the month? Or can these 'deals' be done every month, if you speak to the right person? :mischeif:

Cheers
Ross

[s2driveruk]

will this drag any of the (i think) current 70/30 brake bias towards the back? or is that regulated purely by the brake bias valve thingy???

This is looking really interesting - i need something to fill out the 18's at the back!!!

[S2central.net]

Looks really good Paul! Just as I thought I had all the projects ever in line, you go and add another to my 'wish list'

Sod the handbrake, mine hardly works anyway seriously, if the caliper fits like everything else this is going to be a mighty rear brake set-up with bolt-on parts right?

What's the costs looking like for a full rear set-up with this conversion, assuming it all works once fitted?

Ross

Nnnggg uuuhhhhh about £400 I think - there are mighty discounts available on brake parts from Audi this month. Probably wouldn't be much more expensive than replacing stock carriers, discs, carrier and pads with brand new parts. My calipers were shagged anyway and I had to eat new discs for MOT. Its a no brainer - IF and I stress *IF* it all works.