Rear calipers with big fronts

[Henka]

I'm thinking of going either 280mm NB/Golf front disc or a turned down R32 front disc (it's like 320-ish and that is too big) rears to match a future set of 314mm A8 discs with 996-calipers. So, with that choice of disks - what calipers do I go for? I mean, I need a parkingbrake so stock URS4 might work (with a relocation adapter!). But - I want to go bigger with a p-brake.. Anyone here use BMW 840CS rear calipers? Apperently they are non-float 2 piston with p-brake built in - I haven't been able to find a pic or in anyway verify this statement but maybe you guys know.

How about 928 rear calipers? They are floting so they should have p-brake - but then again, Porsche just love commonality so I guess they didn't change the p-brake when they started to build the 928.

EDIT: Well after some concideration and searchin the forum I've come to the conclusion that I'm almost sure I need/want 323mm disks fron. Also, I'm looking at 312mm disk at the rear.

[porkkis]

BuMWagen you mentioned has a drum for parking brake.

And there is no 840CS afaik, only 850CSi, 840 was i or Ci

[Greg_S]

Henka, do a few searches on the forum. Mark Halligan has audi A3 front discs on the back.

Greg

[Henka]

Henka, do a few searches on the forum. Mark Halligan has audi A3 front discs on the back.

Greg

OK, I thought I did search but I probably didn't do it enough... I just found that the TT has a good front disc to, 312mm. But the question is caliper..

Yeah, I was unsure if it was c, ci or csi or what ever... Well - anyone have a pic or comment on those calipers?

[RIX]

Henka, do a few searches on the forum. Mark Halligan has audi A3 front discs on the back.

Greg

a3 thats 5*100,the ones from a4 288*25 are 5*112,and a6 312*25 5*112,why not use them insted of drilling new holes,or are there something ihave mist.

Regards
RIX

[90quattrocoupe]

a3 thats 5*100,the ones from a4 288*25 are 5*112,and a6 312*25 5*112,why not use them insted of drilling new holes,or are there something ihave mist.
Regards
RIX

Rix,
All comes down to the hat offset and being able to work on the rear. Coupe has very short hat on the rear making it difficult to fit other Audi rotor. Two rotor are close on offsets, G60 VW front rotor and the A3/new Beetle both at 280X22.

I'm thinking of going either 280mm NB/Golf front disc or a turned down R32 front disc (it's like 320-ish and that is too big) rears to match a future set of 314mm A8 discs with 996-calipers. So, with that choice of disks - what calipers do I go for? I mean, I need a parkingbrake so stock URS4 might work (with a relocation adapter!). But - I want to go bigger with a p-brake.. Anyone here use BMW 840CS rear calipers? Apperently they are non-float 2 piston with p-brake built in - I haven't been able to find a pic or in anyway verify this statement but maybe you guys know.

How about 928 rear calipers? They are floting so they should have p-brake - but then again, Porsche just love commonality so I guess they didn't change the p-brake when they started to build the 928.

The UrS4/6 does not need a relocation adapter. You just flip the caliper and use it on the opposite side the it was on the S4. The ebrake cable fits right up with no problems. To use the 280 rotor though you need the carrier off an S8 and the carrier bolts up on the outside edge of the hub carrier instead of the stock location of the inside of the carrier.

Here is a small write up on some of the possiblilities for rear set up using Audi parts.

Below you will see two possible ideas for rear vented rotors. I tried a couple of different calipers and rotors, basically running with ideas I got from other original thinkers on other forums.

These are a couple of different combinations using two different rotors, two different calipers, both off the same carrier. The rotors are both 280X22mm. The g60 rotor weighs 11lbs and the New Beetle weighs 13 lbs.



These are the two rotors I used. CorradoG60 and a New Beetle. For the peoples in the old countries, all the G60 rotors should be the same as the Corrado. This was the only G60 imported to the states. The New Beetle rotor is the same as the A3, which we haven't gotten either.

Both rotors have had the center bore increased from 65mm to 68mm. The G60 rotor was redrilled from 4X100 to 5X112. The NewBeetle/A3 was slotted from 5X100 to 5X112.



I used the Corrado for the setup pictures. This is the aluminum A8 caliper on an S8 Carrier. This allows for the 280X22 vs the 269X22 on the normal A8. This caliper weighs slightly over 3lbs.



I got this idea from Stick Insect(David) on the S2forum. He mentioned using an easier to find caliper than the A8. I happened to have an S6 Rear caliper lying around, and fit it up to the S8 carrier. It fits just like the A8. It may be easier to use the parking brake cable on the this caliper as it is in the same place as the coupe rear. The A8 caliper has the parking brake mechanism in a slightly different location, but it stills pulls from the side and not the front. The S6 caliper weighs in at 6 lbs, but is definitely more available from a wrecker than the A8 caliper



This is the G60 rotor with just the S8 carrier.



As you can see from this picture, the G60 rotor comes a little close to the inboard edge of the carrier. It was even closer before I took the next step.



I took a look at the carrier and noticed that they had excess material on the inboard edge from the bolt on area. The least amount of excess material was 1.5mm. So I had an additional 1.3mm milled off each of the carriers. This allowed breathing room for the G60 rotor.



This picture shows the gap between the S8 carrier and the bolted up A3/New Beetle rotor. It is more centered, but as others did on this forum, you need to use 2mm spacers when bolting up the S8 brake carrier to the rear hub carrier. This moves the carrier outboard.

Now the brake carrier is bolted to the outside of the hub carrier, and not the inside like the coupe. Luckily for us the brake carrier is machined on both side of the mounting holes, just as the hub carrier is.

I am going to use the G60 rotor with the A8 carrier, and when they wear out, I will use the New Beetle rotor.

Remember, if you end up trying one of these combinations, the A8 caliper or the S6 caliper, they are used on the opposite side of the car, from where they were normally used. The right caliper goes on the left side of the Coupe and the left caliper goes on the right side of the coupe.

Greg

[S2 Ant]

Good write up!

[Henka]

Hmm

Yeah, guess which pictures inspired me a while ago...

Well, TT disks are 312mm and they are fitted toGolf as well so I guess that they should fit to. Now, machining to centerhole and to get correct PCD is needed.

About the URS4 calipers. What makes them different from the S2 unit? I actually thought they were the same but with a different carrier.

Brakes are for my S2 ABY Avant.

[90quattrocoupe]

Yeah, guess which pictures inspired me a while ago...

Well, TT disks are 312mm and they are fitted toGolf as well so I guess that they should fit to. Now, machining to centerhole and to get correct PCD is needed.

About the URS4 calipers. What makes them different from the S2 unit? I actually thought they were the same.

Brakes are for my S2 ABY Avant.

The brake design is similar, but the UrS4/6 caliper is wider so it will fit the vented rotor versus the sold disc of the S2/CoupeQ.

Greg

[porkkis]

Biturbo-S4 rear caliper should be quite easy to fit.

[Tommy200rs]

>>> Biturbo-S4 rear caliper should be quite easy to fit.

I used the S4 biturbo calipers for B4 80er sedan. Fits also Avant.
They do not fit to coupe S2 due to diferent handbrake cable routing.

S4 biturbo carrier is ok with modified 256x22 A3 disc for all S2
S8 carrier is ok with modified 280x22 A3 disc for all S2
Those carriers do not need machining because done for 22mm disc

+ mods shown in previous posts

For the S2 Coupe I recommend the urv8/S4/S6 rear calipers + above carriers + mods shown in previous posts.

Pic of that:
http://photos.groups.yahoo.com/group...+280mmx22m.jpg

These are modified rear brakes are no fancy ones,
but just far better than the original with 245x10mm discs...

[rotoryboy]

Is it possible to use the S8 caliper and carrier? with one of your choices of disc?

[Mark Halligan]

Is it possible to use the S8 caliper and carrier? with one of your choices of disc?

Mark,

Yes, I used the aluminium S8 calipers (VAG part no. W4D0 615 423 E and W4 615 424 E) with the S8 carriers (VAG part no.W4D0 615 425C) and had no problems with the handbrake cable fitment.

It was a while ago now, but the only problem I can remember having was the thread size for the hydraulic hose into the calipers was bigger than the S2, M12 as oppsed to M10...........I think.
So I had to make up some new hoses, which wasn't really too bad .

I used these with the machined A3 280mm discs.

Mark.

[90quattrocoupe]

Is it possible to use the S8 caliper and carrier? with one of your choices of disc?

Rotorboy,
A couple of things I found. The placement of the handbrake location is slightly different, they both pull from the side, but the A8 caliper has the pull at the top and the UrS4/6 has the pull at the bottom of the caliper.

The size of the hole for the cable stop on the A8 caliper is slightly smaller than the one for the Coupe rear caliper. This hole needs to be enlarger for the stop on the e-cable to fit. If you look closely, you can see the hole up next to the vise, under the red rag, in this picture. This is the hole that needs to be enlarged.



The throw for the ebrake cable, the distance from the cable stop to the lever arm, is slightly longer on the A8 caliper than on the UrS4/6 caliper. You may have to adjust the center pull above the drive shaft to get more length if needed.

Greg W.

[Mark Halligan]

The size of the hole for the cable stop on the A8 caliper is slightly smaller than the one for the Coupe rear caliper. This hole needs to be enlarger for the stop on the e-cable to fit.

Yes Greg is right about that hole being a touch too small, I just crawled under the car and snapped a pic.

Me being the bodger I am when I did the conversion, I just pushed the cable end into the bracket and fitted the clip, I didn't open up the hole and as can be seen in the photo the cable sleeve end is not fully seated (arrow).

Mind you in my defence it still works perfectly well.

Mark.