RS2 rear brakes on Coupe

[Audi_CQ]

Posted this reply on another tread, but may be of interest to others too

Hi Rafael,

Here are a couple of photos of the modified hub. It's machined out to accept an RS2 wheelbearing, and have been added with a ring of metal so outside diameter is same as RS2 hub. It's also been machined to make a flat surface to attach the RS2 "backplate" to. Here you must measure the distance from bearing to surface on the RS2 hub and make the same distance from bearing to machined surface on the S2 hub. (Did that make sence to anybody but me ) A bit difficult to explain, but hope the pictures gives an idea of what have to be done.
NB! The calippers have to be in the S2 position and not as on the RS2. Because of this you have to move the bleeding to the other end of the calippers.

Cheers,
Roger

[The Spanish]

Looks like a very good job.

If instead of the RS2 rear calipers. Porsche Boxster S rear calipers are used (this are cheaper) there should be no problems and some advantages?

Same disc size (299x24mm) and built to be placed to the front of the car, so all seals will be on the correct position

Thank you for this info Roger

Rafael.

[The Spanish]

Hello, I need some help.

I have been talking to Roger about his setup (his car is not an S2)

He uses RS2 drivesafts (shortened), the machined bearing housing you can see on the pics, and then RS2 parking brake system, RS2 caliper carriers, RS2 rear calipers and rear discs.

My question is about the drivesafts.

Could I use the S2 drivesaft and swap the connection to the hub of the S2 with the RS2 connection so I don't need to buy and modify the whole drivesaft. Part number 15A on the picture 443 498 099C (Russian ETKA)

Help with this very much appreciated.

Cheers,
Rafael

[Audi_CQ]

The outer joint is not RS2 specific, but said to be the same as on other Audis with a 82mm bearing : 100/200 Q's , some 80 sedans and avants. Should make it easier to find and test

[The Spanish]

Also the diameter of the Front bearing is 82mm, so I could try using front one to try and see.

Does anybody know the answer for this?

[Jeffer]

Hi guys, I'm thinking about the same setup for my coupe. But I have some questions.

- If i machine my hubcarriers to the rs2 bearing size. can i use my s2
(5 x 112) hub? Or does the rs2 hub only fit (5 x 130)

- What disc do I need to use for that.

- Does the handbrake have to be converted to a hydrolic handbrake?

- Is my wheel offset going to change?

- do I need rs2 brake adaptor plates?

Hope I can get some awnsers.

thanks,
Jeffer

[Stick Insect]

Hi Rafael /Jeffer,

I would suggest getting a 4 stud hub from a Coupe Quattro ( like mine) machine the flange from it and weld on a new flange, this can be machined to suit the Porsche disks.

wilwood do a seperate caliper which is mechanical only this could go on a fabricated bracket with the RS2 or Porsche rear caliper.

http://www.adequatespeed.freeserve.c...and_brake.html

I would never suggest getting rid of a mechanical handbrake and using a hydraulic only. if you have a fluid loss then you can't stop. It would fail an MOT in this country. A club member had a fluid loss last year on his braking system. he was coming to a traffic crossing and the pipe ruptured. He ran over a small child and killed him, He was hauling on the handbrake which slowed him down and stopped him hitting 2 other children.

A hydraulic handbrake would not have slowed hin at all.

He has not been prosecuted as it was a mechanical failure. If the car had been modified illegaly he could have been liable.

Sorry for the sad but true story.

David

[The Spanish]

David, Jeffer

This setup works with the RS2 hand brake system that uses to small drums inside the rear brake rotors, so there allways will be a mechanic parking brake system fitted (of course).

Jeffer, front S2 hubs are 5x112 and uses a 82mm wheel bearing so you could use these for the back (theoretically)

You need RS2 brake adaptors plate for the use of the parking brake and to mount the calipers.

You should use RS2 rear disc brakes or some Porsche rear disc brakes because of the parking brake, as the drums must fit inside.

I don't know about the wheel offset, but the RS2 hubs are longer than the S2 hubs to habilitate espace for higher offset disk brakes wich can have the drums for the parking brake inside them. And also because the RS2 hubs are made to work with Porsche wheels wich have in the case of the RS2 wheels and offset of ET 55 if I remember from memory (anyway much bigger than standard S2 avus wheels.

Hope this helps.

Rafael

P.S. Still I need to know if the drivesaft outer joints could be swapped.

[Jeffer]

But if the hub is 5 x 112. its not possible to put the rs2 disk on there. because the rs2 disk has 5 x 130 mm?

greets.

[Stick Insect]

Understood Rafael,

I knew that Porsche used brake shoes inside the rear disk/drum. I was suggesting something simpler. The Vauxhall Vectra is similar at the rear.

The S2 has different front and rear hubs I'm afraid.

If the rear hub was modified to suit a Porsche disk which has a smaller offset. The Porsche wheels would then fit. it would be easier to fit a parking brake than sort the Porsche handbrake.

Just a suggestion!!

David

[The Spanish]

Jeffer,

Yes, if you install these setup you should use Porsche brakes front and rear with Porsche Hubs and Porsche wheels because of the peculiar hand brake system.

Theoretically you could have some new holes made on the Porsche disc for 5x112 PCD or talk to movit.de or other brake shops to see if they can deliver PORSCHE 299x24mm rear discs with a 5x112 PCD.

Rafael

[The Spanish]

David,

I appreciate very much your suggestion and I am thinking about it.

My initial plan is to use RS2 hardware. (Hubs, discs calipers, parking brake and wheels)
For these I need to modified the rear housing and drivesafts to accomodate RS2 hubs that are longer, have a 5x130mm PCD and a 82mm bearing.

Roger has sort all of these out but he uses Modified (shortened) RS2 drivesafts, as RS2 rear track is 1471 mm and S2 is 1437mm.

I would like to use standard parts so I need to find out if the outer joints of the RS2 drivesafts can be fitted to the standard S2 drivesafts.

Rafael

[Stick Insect]

Raphael, I feel that having 'off the shelf' items is a good idea. I want to do that with my Porsche caliper brake conversion.

S2avant ( Ben) is probably one of the best people for that, I suggest sending him a PM.

I will show my S2 rear hub to an engineering friend and see if he has any suggestions about the modification.

You could use an Audi Coupe Quattro rear hub, same dimensions as the S2 apart from the studs/PCD. ( easier to find than S2 hubs)

I don't like the idea of adapters at all. I would suggest that a good CNC shop could make a complete hub which would be best. However a ring properly welded to the hud and then machined to the correct dimensions would be more than strong enough.

This conversion would use standard Porsche components apart from maybe modified Porsche handbrake mounting components.

I realise that Roger had done a lot of work on the rear hub but I am worried about the strength of the rear hub carrier now that it has been bored out. The ring put round it will help but I am still wary as I don't think it will be driven gently!

There was a picture on the URS4 web site which shows the original caliper ( used as a handbrake only) and a Porsche 4 pot as well on the rear wheel. I can't find it now though.

David

[Audi_CQ]

Originally posted by Stick Insect
I realise that Roger had done a lot of work on the rear hub but I am worried about the strength of the rear hub carrier now that it has been bored out. The ring put round it will help but I am still wary as I don't think it will be driven gently!

David

Hi David,

I've used it for a couple of years, inkl track sessions and the carriers have survived On one track day I hit a bump real hard and made a big bump in one back wheel (1-1.5cm deep on inside of rim ). Carrier OK
The ring is pressfitted and total amount of metal is as thick(or even thicker) then the original housing. Don't think there will be a problem, but can't be 100% sure.

Cheers,
Roger

[The Spanish]

Roger,

Just to be on the safe side. The "backplate" or caliper carrier is what I can see on the third picture you posted. Part number 8A0 615 411 and 8A0 615 412.

Cheers,
Rafael