I have '78 928 & would like to upgrade the brakes. I've read some articles about it & understand that the S4 is the best way to go for performance. Would it be worth it to upgrade to the S brakes rather than the S4? I ask because it seems like you have to swap out everything for the S4 & am thinking the S upgrade may be fewer parts & cost less. If it's similar work & cost, then it's a no brainer - go with the S4. Thank you.

 

The S brakes are pretty decent. Going from S to S4 basically gets you fancier 4 piston calipers. Not sure if the caliper is compatible with your knuckle. I'm sure someone will chime in on that.

 

When I did my son's '83, I used S-4 brakes. Works great!

I changed the "A" arms, the spindles, etc. to be able to have the brakes bolts on, correctly.

 

AFAIK OB to S conversion cannot be done without changing knuckles. Its easier to jump directly to S4 setup.

 

To upgrade to S:
To change from early OB to S you need to change the spindles to allow you to bolt the S calipers on. Going to S brakes will give you better stopping power, but in my opinion still pathetic braking for a car of this calibre.

To go to S4 calipers, and rotors to fit, using your existing suspension setup:
Using your spindles you can fit a caliper adapter that most vendors sell which will allow you to fit S4 calipers at the front, and you can fit S4 calipers at the rear using a 5mm spacer washer to get the caliper at the correct centre. With this setup you use standard S4 rotors at the rear, and 993TT rotors at the front to fit the changed caliper center offset and to clear the lower ball joints.

To go to full S4 setup
Transplant full S4 front suspension onto your car, and fit S4 calipers and rotors to the rear with the 5mm spacers to the calipers.


I guess that the way you go will depend on what you want to achieve in stopping power, your budget, and secondhand S4 brake/suspension parts availability and price.

If you want any more specific information on any of these setups let me know ... I can post pics of the parts for the conversion using your existing suspension if you want to visualise the setup.

 

Thank you. That helps a bunch.

 

Scott,

Upgrading the brakes on a pre 82 US car or a pre Euro S ROW car is pretty easy. There are adaptors from several suppliers that allow you to use 993 front rotors (the same size as the S4 front rotor, but a different spacing that allows them to clear the lower balljoint) and the four pistion S4 Brembo rotors. IIRC they were $200's or so when I puchased mine. The calipers are available used from suppliers. It is actually easier to up grade to S4 fronts than to upgrade to the less capable S brakes. To do an upgrade to S brakes it requires relpacing your front spindles with the spindles from a US 82/86 car due to different caliper mounting bolt spacing, which is a whole bunch more work. The rears are even easier, all you need to mount S4 rear calpers is 4 washers to get the spacing correct, you can even get by without replacing the rotor. It is a little undersized 289 mm vs 304 mm and you get an odd wear pattern on the pads but it is livable untill you need to replace the rear rotors. As an aside if you upgrade the front brakes to S4 Brembos make sure the aluminum lower balljoits have been replaced with the steel ones. Second you will need new brake hoses on the front and actually for an OB new hoses all arround is a good idea. Finally the 304 mm S4 brakes fit inder 16" rims, the 322 mm GTS brakes require 17" rims.

Paul

1980 Euro S Red/Blk Lea