From: John V. [john928@yahoo.com] Sent: Thursday, November 08, 2001 8:46 PM To: 928 Subject: [928] Re: [racing] Re: Master Cyl. question For anyone who is still interested. I finally have the information I was looking for to hook up the S4 brakes and S4 MC to my 80 EuroS track car. I took a careful look at the 928 Workshop Manual and found out the following information. Up to 1983 the 928 used a diagonal braking system with two bias valves and a single bore MC with a 23.81mm dia. Starting 1984 the system went to a conventional front/rear braking system. ABS was an option integrated into the conventional system. The MC changed to a dual bore. 23.81mm/19.05mm with a single bias valve screwed into the front port for the rear brakes. Starting with S4 brakes and also with GTS brakes - a MC with a dual bore of 23.81mm/20.64mm with ABS standard from 87 on. So the correct hook up will be to install the S4 MC and hook both front calipers to the rear port of the MC which is 23.81mm. Hook both rear brake calipers along with a bias valve to the front port which is 20.64mm ===== John Veninger 1990 928GT 1980 EuroS (losing weight!) 928OC From: Kevin Kwasniewski [mailto:k.t.kwasniewski@na.modine.com] Sent: Thursday, June 20, 2002 1:20 PM To: 928 Subject: [928] Early 928 S4 brake conversion (long) I posted this on the forum, but I figured I would also post in to the list. Well I just completed my conversion to S4 brakes on my 85 Euro S. Previously the only way to convert to S4 brakes was to replace the front control arms with the S4 control arms. I did not want to go this route due to the added cost and headache of the alignment. Well fortunatly for me a local 928er (thanks again Mark) developed adaptors to mount S4 brakes on the front of an early 928. The adaptors are now being sold through 2 of the big three, but I will give you my 2 cents of how the conversion went. The rear was the easy end. All you need are 2 calipers from either an S4 or 951 (must reverse bleeders and crossover from 951), 2 rear S4 rotors (or 86 951 rotors), 1 set of pads, and 2 spacers (available from the retailers of the kit). Basically you just unbolt your rear calipers, remove your old rotors and install the S4 rotors and calipers with the spacers. The hoses are the same and the pad sensors are the same. Very easy. Now the fun part the front. If you are like me and have an S you will need spindles from an early model. Mine came off a 79. Then you will need 2 S4 calipers (or 993, 951S), 1 set of pads, 1 set of S4 brake lines, 1 set of adaptors and bolts, and one set of 993 front rotors (yes 993 not S4 front rotors). The reason the S models need the early spindles is because Porsche changed the mount points for the caliper and made it impossible to create an adaptor without floating rotors. I got my set of spindles from a local wrecker for $100. Early spindles don't command a lot of money. The installation: First you have to remove the old calipers, rotors and dust shields (can actually be cut off). Simple and straight forward. If you have an early model you can skip this next step. Now you have to change the spindles, so remove the dust cover on the hub and remove the hub. Save your old hubs if they are in good shape and use them on the new spindles (my spindles came with hubs, but they were pretty beat up and the bearings were shot.) Remove the dust shield. Now you have to seperate the ball joints. The best method for the upper is the 2 hammer method described on the Nichols site by Wally. Then seperate the lower ball joint with the self seperating bolt. Very easy! Last remove the tie rod arm. If yours are like mine they still had the tamper gue in them and I couldn't get it out. I ended up grinding off the tops of those bolts and replacing them with new regular hardware. You now have the spindle free. Reassemble without the dust shield. Make sure you clean and repack you bearing on the hub. Early owners can now start from here. Intall the caliper adaptors. Install the new rotors (making sure you have the correct side). Remove the old calipers and lines. Install the new lines, pad sensors, and calipers/pads. Bleed the heck out of the entire system. So that is it. For the S owners there is one kind of painful step, but you don't have to realign the car and it shouldn't take more than about 2 hours per side (Front) and 1.5 hour for the rears. For non S owners you should be able to complete the entire process in about under 3 hours. The only thing I did not cover was master cylinders. My car has a master cylinder close to the size of the S4 and the 33lb rear valve. Safe to leave alone. The pre 83 S models have a slightly smaller master cylinder with the 33 lb valve. Should be OK for street use. The non S models depending on year may need both a new master cylinder and rear valve. Best thing to do is ask the guys from the place you buy the adaptor kit. Last is clearance on the front wheels. I have 968 wheels and they actually rubbed very slightly on the raised letters on the calipers. Solution I ground off the raised letters and replaced them with high temp vinyl decals found on the web. I now have 1/8" clearance in the front. Fine for street, but if I were to track the car I would either put on spacers or get different wheels. So depending on you front wheels you may have to put in a 1/8-1/4" spacer or grind off the raised letters. (the 993 calipers of this size actually have the raised letters gone for this reason) Total cost was about $1100 for everything for me. I got some used parts and some new. A little time on ebay and looking at local PCA classifieds goes a long way. Good luck! -------------------- Kevin Kwasniewski (Quaz) 1985 Euro S 5-Speed