May 29, 2019 update to the BMW 318is project car

Project BMW 318is: It’s Time for Brakes

With the suspension finished and installed, it was time we looked at the brakes on our 318is. The brakes on an E30 BMW are quite simple four-wheel single piston disc units made, oddly enough, by Girling in England.

Even nasty brake calipers like these can be restored to new with a little elbow grease and a good bead blasting cabinet.

We went back and forth on just what we should do with the brakes. Any of the aftermarket brake kits from UUC, BimmerWorld and others would be a viable option—one we may explore in the future—but the experts we talked to told us that Spec E30 racers have made do with the stock brakes (with upgraded pads and brake fluid). With this in mind, we decided we would cheap out, at least initially, and see how adequately we could make our 318is stop with slightly modified stock brakes.

Now armed with a plan, we turned to our friends at FCP Euro. Thankfully, they had all the parts in stock to rebuild both front and rear brakes, including the brake pad wear sensors that are found at the left front and right rear of the car.

We did opt for some modifications from stock, ones that provide both improved brake feel and longer service life.

First, BimmerWorld has cleverly reproduced the stock brake pistons in stainless steel. And as anyone who has rebuilt disc brakes on an older car will tell you, standard mild steel brake pistons are quick to rust and jam up, especially if the car sits for any length of time. At about $100 (for all four corners) these improved pistons fit perfectly and provide a sensible, low-cost option when rebuilding E30 braking systems.

Second, we chose a 6-Line BimmerWorld V3 Stainless Steel Brake Line Kit. This kit is made from Teflon, stainless steel, and is DOT-approved. Priced at a modest $119 (again for all four corners of the car,) it was an easy decision to make. While braided steel lines do not improve braking performance, they do improve pedal feel and modulation. These lines tend to expand less under hard braking than conventional lines. They also—theoretically at least—offer more protection from cuts or abrasion due the improved materials from which they are constructed.

Our original brake lines at left and the set of new braided stainless brake lines we got from BimmerWorld at right. These lines don’t improve braking, but they do improve brake feel.

Happy with our modified parts, we set about rebuilding our BMW’s brakes. We’re can report that it is a rather simple task that can be done in less than a day by any competent mechanic.

With the brake pads removed, block the fluid and carefully media blast the caliper assembly, making sure you don’t get media on any mating surfaces or inside the caliper. The most difficult part of this job is getting the old pistons out of the calipers. We usually leave the calipers assembled (there is usually no reason to ever split the calipers,) and slide a loosely fitting block of wood into the area where the brake pads once resided. From there, a bit of air pressure from your compressor will normally cause the piston to come loose. Be very careful when doing this, as you don’t get brake fluid all over everything, especially in your eyes. The piston also moves with great force, so keep your hands out of the way of the path of the piston as it approaches the block of wood. We generally put a rag over the caliper when we do this to catch any remnants of old fluid. From there we clean, apply high-temp paint, and start to reassemble the calipers with new seals, and boots with the BimmerWorld brake pistons.

We use brake fluid to lubricate the new seals when sliding the pistons back in. And speaking of brake fluid, James Clay, founder of BimmerWorld, told us he races extensively in the ChampCar series with Red Line Oil’s new RL-600 brake fluid. He also informed us that he has had no fluid boiling issues with this DOT 4, full synthetic fluid. That was good enough for us and we ordered this fluid for our project. A silicon fluid has the added benefit of not attracting water like conventional fluid, thus causing fewer rust issues in brake components.

We topped things off with Akibono street pads and new stock rotors that we sourced from FCP Euro. Our buddy Rennie Bryant from Redline Bimmer Performance told us he has installed these low-cost, street pads on hundreds of cars and finds them to perform well on the street, with little or no dusting and squealing. We should state that street brake pads are okay for an autocross occasionally, but for any track use, you need real performance brake pads.

Our finished calipers with the Akibono street pads we got from FCP Euro are now ready to go back on our BMW.

And speaking of performance pads, we picked up a full set of Pagid RSL brake pads for track days. These pads are known for initial bite and long wear and should work for us, no matter how many laps we wish to run.

For track use we went with Pagid RSL race pads that should not wear out or overheat.

Anyone contemplating track use should consider separate brake pads, tires and wheels specifically for the track. While initially a bit more expensive, this is ultimately the cheapest way to enjoy this sport in the long run. And sure, it will be more time consuming, but pads, tires and wheels can easily be switched in less than an hour and then switched back at the end of the weekend. At the very least, you’ll become a pro at it in no time.

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Jerry From LA
Jerry From LA SuperDork
5/30/19 2:54 p.m.

Plus 1 on the Akebonos.  My brake pad change interval has changed significantly for the better since I started using them on all the family's street-driven cars.

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