8E0 Rear Brake Upgrade

[S2central.net]

Here's the latest after trial fitment of the S2 Avant handbrake cable to an S2 Coupe... Essentially its going to be a real PITA to change the handbrake cable cos the exhaust gets in the way and the propshaft doesn't help - plus all that sound insulation bolted on with gnarly looking nuts. I was trying to do this on the phooking driveway - sad state of affairs I know...

The Avant h'brake cable is a lot longer than the Coupe one but I think it can be accomodated although the following issues need resolved -

1. There are some fixings on the Avant cable which need to be removed as it makes the cable too rigid in a critical place for the Coupe application

2. The fixing of the lever end of the Avant cable is larger than the Coupe cable so the bracket on the Coupe *might* need modified to accomodate it - no way to do that with exhaust etc in place.

3. The Avant cable and Coupe cables are reinforced in slightly different areas so additional trimming of the cable armour is required to beef it up on the Coupe.

So, I'm back full circle again thinking about some other way to adapt the Coupe handbrake cable... as an awful lot of disassembly and messing around is required to fit the Avant cable. Ultimately - I'm very confident on that working - its just the sheer hassle and pain of doing all that.

I'm going to have a 'proper' mechanical engineer friend look at this problem to see if he can dream up a suitable handbrake adapter - I've kinda got an idea in my head but I don't have the skills or materials to implement it.

I'll compile a list of all the bits required - WITH the big caveat that I have not yet completed the work. Somebody with an Avant would need to perform a dry fit for any clearance issues there as I have not tried this on Avant yet. BIG advantage with the Avant is that the handbrake mechanism looks identical so I reckon that will be easy.

Paul

[s2avant]

Rest assured I will be trying this on my Avant soon.

Only thing I'm waiting for is the 2007 model year calipers to become available. As soon as the part numbers go live I'll be ordering them.

Ben

[S2central.net]

Show off

[Jon441cc]

Rest assured I will be trying this on my Avant soon.

Ben

i hope so

[S2central.net]

i hope so

Here's a picture of stock calipers from the rear of an S2 Avant that I was working on ages ago. They are pretty much identical format to the 8E0 caliper with regards handbrake. Only issue is if they have clearance issues with rear suspension leg on the Avant.

Compare the pic with those I published on my mac.com pages way back near the start of this thread. Rear avant calipers are trailing - same as these 8E0 jobs... Unlike the Coupe which has a leading caliper position.

Paul

[Ross]

Paul, you're a star doing all this work... seems like this one isn't as simple as hoped, but still very much interested here!

[S2central.net]

Had another hour or so tinkering in the garage with an assortment of 8E0 rear brakes and the S2 Avant handrake cables. These hook up to each other perfectly. Photos to come... There is just no way to run with the Coupe handbrake cable and the effort required to change the Coupe cable to Avant is just too much in the mindset of a simple bolt-on upgrade for me.

So here's the next bit of thinking - a hybrid rear setup as follows -

8E0 300x22mm rear discs (machined down to 280mm) - bolt straight on
S8 rear carriers for 280x22mm discs (a la MarkH) - bolt straight on I reckon
UrS4/S6 Avant rear calipers - bolts straight on and have correct h'brake for Coupe

Alternate calipers are the sexy light alloy ones from S8 or S6+ as dimensions and topology are otherwise the same.

Note if referring to MarkH's mighty work on this subject before that he needed spacers and longer carrier bolts because he was using 280x22mm discs from the front of an A3 (machined for correct bolt spacing and centre hole) which had a 3mm difference in height from the S2 disc. I'm fairly confident spacers and such won't be needed with the S8 brackets on the machined down 8E0 discs.

I'm going to sleep on this one cos it means spending more damn money - but it means there will be a set of 8E0 calipers, carriers and pads for anyone mad enough to prove my theory that this will bolt straight onto an S2 Avant. Ben would be the man of course except he is waiting for 2007 rear calipers to come available. Any takers ?

Paul

[S2central.net]

For the record here is the 8E0 part numbers I have been toying with on the Coupe. It all works a treat except that the Coupe handbrake cannot connect. Lots of disassembly is required to change the handbrake. Based on what I know (the Coupe and Avant use same rear discs and carriers), this conversion would work perfectly on the S2 Avant, but a dry fit is needed to be sure that there are no clearance issues.

Calipers 8E0 615 423C & 8E0 615 424C
Disc 2 x 8E0 615 601R
Carrier 2 x 8E0 615 425B
Pads 4B3 698 451
Hoses 2 x 8E0 611 775H

Note the calipers are trailing edge on the 8E application and the S2 Avant, whereas they are leading edge on the S2 Coupe.

New carrier to hub bolts are required (4 x N019 912 3 for the Coupe) but its 2 pairs of differnt bolts on the Avant as the rear knuckle is an odd shape.

Note also that when changing the brake lines that its a good idea to renew the union clip clamps (2 x 4D0 611 715B).

Note also the handbrake may require a fresh new lock clip (2 x N900 527 02).

These fit under 16" Avus rims (though I never tested that with the handbrake connected).

Paul

[90quattrocoupe]

Hi Paul,
I was thinking along the same lines as you. Turning down the NuS4 rotor to match up with my 280mm rear set up. Went to the stealer and measured the offset on the rotor. It is about the same as the S3/New Beetle rotor, so you will still need to use the spacers behind the carrier. Sorry, but at least it is only turning down the rotor instead of bored and slotted.

By the way, Mark H. is using the light weight A8 calipers, slightly larger piston. I am using the UrS4/S6 caliper. By the way, the sedan ones fit just fine, doesn't need the avant calipers.

Greg W.

[Chris5044]

has anyone not tried the rs2 rear brake setup? .. since it uses front and rear porsche brakes?...

any reason why this shouldnt work? interested to know

[S2central.net]

RS2 discs are sized for 5x130 PCD. The hub centre is wrong size and offsets are all different. That and the RS2 handbrake is notoriously bad - its a funky drum configuration that accompanies the caliper setup.

Paul

[twoqu]

Paul,

Would it not be possible to effectively loop the cables the other side of the suspension and then bring them back under to the calipers so that the radius of the cable isn't so tight. Guess you could also cross them over. Might need to find some longer cables!
I'm guessing the problem lies in the fact that you are trying to connect from the normal side and the angle in the bracket is too tight. Whereas if the approach was made from the other side it would be less acute and more in line with the OE fitment.
Just a thought!

[S2central.net]

I'm totally with you on that twoqu - I'm 99% certain the Avant cables will do just this - its just the sheer amount of work getting them onto the Coupe is really offputting. Its far from a bolt-on upgrade when it looks like the following is required -

Remove exhaust system
Remove heatshields in the handbrake lever area
Remove old cables
Enlarge the holes on the brackets under the car to accomodate the Avant cables
Modify each Avant cable by removing a stiffening sleeve (which limits bendiness)
Modify each Avant cable further to provide better physical protection under the Coupe
Then finally fit the Avant cables to get smooth routing to the caliper... without causing interference issues with moving suspension parts and driveshaft.

Sorry to sound like I'm going lame on this one - gawd knows I've thrown a lot of money and effort into this but the handbrake problem is a show stopper on the Coupe.

Only nice way round would be if we could get a custom made handbrake cable that had the correct length, fittings, reinforcement and whatnot to work on the Coupe. You'd still need a lot of disassembly to swap the cables over, but at least you wouldn't have the PITA of modifying brackets and bodging Avant cables along the way.

So - last call - does any of the assembled motor trade or 'proper engineers' on here know of a suppiler that we could entrust the manufacture of a custom handbrake to for this project ?

Paul

[twoqu]

Paul,
Undoubtedly you could get "correct" cables but you would need a Frankencable to recplicate. I guess someone like Speedy Cables (if they are still going!).
Obviously it would be great to get an oe cable. However if you could get/make a kit up of the relevant parts in the right places, then the cable length/ends would be the least of the problems.
I know it sounds like a lot of work but is it more involved than it would be if you were replacing cables as a maintenance issue?
If you were going to all the trouble and expense of upgrading it would be false economy not to replace the original cables. After all I doubt whether it would need doing again in the cars life!
Out of interest, does anyone know whether these funky electro/mechanical hanbrake calipers have a cable. A switch would be easier than a cable!

[S2 Ant]

Dunno how i missed this thread but all looks hugely interesting and one i will keep in mind for the future i think.... along with Ben's RS6 upgrade on the front!