E21 Brake Upgrade

From: Greg Padberg, zundfolge@oanet.com CC: william.boyd@UAlberta.CA From: zundfolge@oanet.com (Greg Padberg) Reply-to: zundfolge@oanet.com (Greg Padberg) To: E21Digest@aol.com (E21Digest@aol.com) CC: william.boyd@UAlberta.CA (William Boyd)

For those of you thinking about a front brakes upgrade for '78-83 320i, here are my experiences based on (almost) completing this upgrade, I still have the grease beneath my fingernails as I type this: The stock E21 320i models from '78 onwards had solid-rotor front brakes, the '77 320i (and all E21 323?) had the same vented-rotor front brakes setup. The vented rotor front brakes setup is more desirable especially in extreme usage (e.g. racing and driver's schools) because it allows better brakes cooling. You need both the rotors and the calipers in this upgrade because the vented rotors are thicker than the solid rotors (the calipers for vented rotors are also wider spaced to accommodate the thicker rotors). Here's the required parts ('77 320i) and how much they cost me in Canadian Dollars (~.73 USD): $ 5.00 brake caliper (self-serve wrecking yard) $ 5.00 brake caliper (same) $ 15.00 brake rotor (self-serve wrecking yard) $ 15.00 brake rotor (same) $ 0.00 re-surface rotors (a friend did them) $ 33.60 brake pads (Repco Deluxe, they DO have an asbestos warning on package) $ 30.00 caliper rebuild kits (seals only, for 2 calipers) BMW P/N (?) 34 11 1 116 618 Optional parts: Tube of grease, suitable for wheel bearings (if you're re-packing the wheel bearings / hub) Front hub grease seals Front wheel bearings 34 11 1 118 711 Anti-squeal shims 34 11 1 150 542 Pin & Spring Kit (brake pad retaining hardware) 34 35 1 180 780 Brake Sensor Here are the major tools you will need: 17mm socket (wheel studs) 19mm socket (caliper bolts) 11mm 6-sided flare wrench (brake lines) 7mm wrench (caliper bleeder valve) 5mm hex key (rotor retaining screw) 22mm? socket (castellated nut on front hub) hammer (y'never know) brake fluid as required, DOT4 I drove my BMW quite enthusiastically for 3 summers and 1 driver's school and still had plenty of brake pad material and rotor left (although the rotors were slightly warped). I recommend you re-use your old hubs if they worked fine up to this point (also re-pack them with new grease as a minimum). Note that models through '79 have different (beefier) front hub / spindle / bearings than '80 onwards but for purposes of this brakes swap the upgraded rotors and calipers should fit either type of hubs just fine. I re-used my '82 hubs and re-packed the bearings (might as well if you're this far in at this point). Also remember to apply anti-seize on the rotor retaining screw. I drive my Bimmer only in summer so it's not bad but you all-season folks in the snow belt oughtta pay heed to this one. The vented rotors and calipers bolt straight in, you can keep the old backing plates in place (like I did) or remove them completely for even more cooling as required (I probably won't remove the backing plates unless there's some really serious driver's school action within the next few years). Anybody else out there with vented rotors that aren't running with backing plates, how about you E21bob, what's your setup? I tried (unsuccessfully, whoops it broke) to remove the brake sensor from the old pads but no big loss. The way I see it, if you do your own wrenching then you shouldn't need a light to tell you when to change brake pads. So I re-attached the connector to the wiring harness and cut off the sensor-end.

To better understand the next few points, think of the rotor as a top hat with a brim. Upon examination of the vented vs. solid rotors, they appeared to have very similar or same dimension from inside friction surface (bottom of brim) to where the wheel fits up (top of hat). Therefore given this same dimension for both types of rotors and the thicker 'brim' of the vented rotor, the vented rotor has a shorter 'top'. All this leads to why the wheels are now significantly more difficult to fit on to the hub. My first thoughts on fitting the first wheel: @#*&$, this wheel should be on by now! The wheel just refused to go on as easily as before. The grease cap got knocked off, and it was difficult to line up the stud / hub / wheel. I lined up the remaining un-installed vented rotor with the inner wheel surface, clearance should be OK. Before the brakes upgrade, the wheel used to be able to rest on the 'top of the hat' while you could line up the studs through wheel into hub and bolt it all together. I found it much easier to remove the wheel center cap and eyeball the hub through the wheel while fitting the wheel and then install the wheel center cap later. The larger calipers also contribute to more difficult wheel fitment. After completing one side and installing the wheel, I compared caliper / wheel distance with 'upgraded' vs. 'stock' (quick check using a finger as reference). I could manage to insert a finger between wheel and caliper on the 'stock' side but the 'upgraded' side had less room. I have the stock cross-spoke alloy wheels that came with the sport package and assume that the 'fan-jet' style alloys would have a similar fit (I can verify if you really really have to know, my mom's car has these wheels). So by now you are probably expecting driving experiences with the new setup, I haven't got any! I forgot to stock up on DOT4 brake fluid so I have yet to fill the reservoir and bleed the brake lines and calipers. Any better braking would probably be due to different friction pad material because the rotors and pad area are very similar (same?). I'm interested to see how little (or how much) the Repco Deluxes dust the wheels. Greg '82 BMW 320iS '86 VW Jetta "Jokeswagen" ____________________________________________________________________ BMW CCA #112616 Team OS/2, Warped since OS/2 v2.0 pre-SPG! Greg Padberg FAX:(403)987-2529 zundfolge@oanet.com ____________________________________________________________________ This

Ed: If you can't find 1977 calipers, Korman sells a spacer which allows you to reuse your 78-83 calipers with the vented rotors.

Back