From: bmw320i@earthlink.net Sent: Dienstag, 12. Mai 1998 12:12 To: Multiple recipients of BMW320i/323i-Digest Subject: Re: brake conversion Date: Mon, 11 May 1998 23:19:09 -0700 From: "Jack Roberts" Subject: Re: brake conversion Henrik, there are two brake upgrades scenarios that will work on an E21 that consists of used parts. The FIRST conversion is to use front calipers and vented rotors from a 323. These bolt to any E21 front strut but you might want to use 323 front struts as they are larger in diameter and therefore accommodate larger shock absorbers (dampers). The rear 323 calipers require the installation of 323 rear trailing arms for the conversion to rear disc brakes. Master cylinders are the same. The SECOND conversion is to use front calipers from 198x Volvo with vented disc brakes. These are usually only found on the Turbo and 6-cyl models. The Volvo calipers have the same 3-inch mounting center as E21s, a 4-piston design, are made by Girling, and use pads with about 50% larger surface area than E21. You will need to use a 1mm thick washer on each bolt to center them on the rotor and slot the mounting holes about 3mm so they will fit completely over the vented 323 rotor. The reason for the slotting is because they were designed to be used with 260mm rotors and the E21 rotors are only 255mm. The rear can be upgraded to E30 rear calipers which also use pads about 50% larger than 323 pads so the brake bias remains correct. These calipers bolt directly to 323 trailing arms but require custom flex hoses since they use a different style fitting. Any hose shop should be able to make these for you cheaply. If in doing this conversion you feel the need for less pedal pressure, use an E12 528i master cylinder. This also has the advantage of simplifying the front plumbing because it is already setup for 4-piston front calipers. So that's about it. You can chose from upgrading to stock 323 or something about 50% bigger. Unfortunately none of the 5-, 6-, or 7-series brakes will fit the E21 unless you convert to 5 lug bolt hub. And that involves a lot more work. Good luck and cheers, Jack 81 323 with 2.7L and stock brakes 78 Alpina B6 with Girling front and E30 rear brakes