I did the S4 brake upgrade to my friend Bill's '85 euro 5 speed yesterday. It was not too clear what we needed to do the project when we started ordering parts a while back, and what was involved. This is my experience, for those of you wanting to do this to a pre-'86.5 car:

Front: a pair of non-"S" front spindles (steering knuckles) which would be euro '78-81 non-S or US '78-82 non-S. Note: ABS has no place to mount the sensor on the early spindle, so no more ABS.
The special billet aluminum adapters originally made by Mark Grasser, the big 2 sell them.
993 non-turbo front rotors.
S4 front calipers, pads, S4 brake lines, S4 front caliper bolts.
5mm spacer for clearance of wheel to caliper or not depending on what front wheel you are running.
Front dust shield from either spindle won't work, so no dust shield.

Rear: S4 rear calipers, pads, S4 rotors. The old brake line is OK for the S4 caliper.
Also about 3mm of washers to space the caliper inward between the calipers and mounts.
Dust shield: 2 of the 4 mounting bolts are in the way of the caliper, so again can't run the dust shield.

Sorry, no pics. The pics of this upgrade have been posted before. A day's work, and totally worth it as far as looks and performance. "S" brakes stink compared to S4 or GTS. Too bad the ABS is not retained.
Does anyone have anything to add?

 

Good JOB!

 

Nice,

I will be attemping this upgrade shortly with the emphasis on keeping the ABS on my early 86S.
Carl @928 Motorsports says the rear S4 caliper will work fine with 85/86S stock rotors. Washers/spacers are all that's needed with S4 brake lines and banjo bolts.
Carl also suggested drilling/tapping the front early spindles to accept the ABS sensor.
Has anyone attempted this?.

RDS

 

Really? What testing did you do? Other's have said they're better but have been less dramatic.

I'm running the S system with all re-built calipers and SS lines. (new lines every year.) The feel is rock solid and with Hawk Blues the stopping power is amazing. I'm consistently out stopping "better" cars (e.g., 930s, 993s) but maybe that's "style."

 

Glens right. Ive also competed at a level equal with some pro cars, as well as the older 993 factory race cars with the old "S" brake system. it was rock solid, and there is very little difference in stopping power. however I will say the ONLY real difference is the time between pad and rotor changes. with the S system, i would change rotors 2 x in a 10-12 race season. with the S4 system, i change rotors due to the drilled holes showing cracks just before the last couple of weekends. pads on the S4 last 4 weekends , while the "S" pads were disintgrated after 2.

other than wear, the "S" system is fantastic. in fact, with a set of paget orange pads, you have a system that was used by some of the top pro touring cars up until a couple of years ago. (many bmw racers still use the stock 928 S system today at a similar weight and hp ratio to the 928)

commit to a race season, i can see the need. If you like the looks of the S4 calipers better, that can be a reason as well. the "S" system doesnt "stink" by any stretch. in fact , its still a very powereful set up. (with the right pads)

great job on the conversion. if it can be done easily enough, its a good thing to do due to the bigger pads and larger rotor. But, loosing ABS. hmmm, may not be a good performance trade off.

Mk

 

Sorry Glen, I should have said that on THAT car, the S4 stuff is much stronger than the S stuff. He had new mintex pads (otherwise original) and they took a LOT of pedal effort to stop. The effort now is about 60% of before. I have strong stuff on my S4 so I am a bit spoiled- GTS calipers, SS lines and 33 bar valve. I'm spoiled now for sure.
Didn't mean to offend.
Mark: is that set up just as good for the street? As far as squeal, pedal effort, etc with race pads. You have lots of experience at the track, but most of us are going by the seat of our pants and not a stop watch.
RDS: the S4 rear rotor is wider and larger in diameter than the S rotor. If someone is going to the trouble of doing the change, I'd buy new rear rotors.

 

I was happy with S brakes on my 85; when it was converted to 5 spd the 86.5 donor car S4 brakes were also transplanted. I prefer the S4 brake pedal feel over the S brake pedal feel.

 

huge difference between mintex and paget pads. i used mintex in the early days, but when i discovered Pagid orange pads, it was night and day. i used the mintex on the rear to change the bias even further to the front.

racing both , you definitely have to be more concerned with brake fade with the S versions. with the S4 system, its a little more care free.

mk

 

I WAS PRESENT FOR THE UPGRADE. CARL'S THE MAN! GOOD FRIEND!

 

SO LUCKY!!!

 

Not a problem.

Just didn't want all the folks with "S" brakes to think it was essential or a car couldn't be tracked without it.

Also wondered if you were comparing a brake system with 20-year old components to one with new components, especially the brake lines. That obscures the real benefits of the change. Replacing the lines on the "S" brakes and getting a good bleed would make an old system perform much better. Those are $$ but the conversion is $$$.

Going from street pads to Hawk HP+ to Hawk Blues is a big change in stopping performance. As it is, if I could move the braking points closer to the corner, I'm not sure I'd want to!