Sunday, May 11, 2008

Going backwards to go forwards

I got another surprise when I tried mounting my calipers on the '73 spindles. They don't fit! None of the calipers I have will fit, including the 320i ones. So I got my depth gauge and micrometer out and took several measurements, comparing the old spindle and rotor (1970-72) with the new one. Fortunately I didn't throw out the spindles that came with the car. And I still had the rotors I bought, with new bearings pressed in them. The newer parts measure 21.6 mm but the older ones 17.0 mm. The calipers fit on the old spindles. The Pelican website says to machine off .125", I calculated 4.6 mm or .181". I spent a few hours visiting machine shops and couldn't find anyone who could do it. After a few hours of this I went over to Part's Heaven. They wouldn't take the rotors and bearings I bought the previous week back and didn't know anyone who could machine the calipers. But the did give me a good price on some 1970 spindles. after painting them and putting in new shocks, it was time to start making some progress.

The car is a 1970 model so I might as well put 1970 parts on it, even if it burns a hole in my wallet. I sold the newer rotors a few days later. So I'm just left with 2 sets of spindles and several brake calipers I don't need. It's a good thing I didn't sell the rotors.

This rotor has been on the car twice now. Once with the 1973 spindle and now with the 1970 one. It doesn't seem to care. The dust shield needed to be convinced that the 320i calipers were the right ones. A bit of banging with a hammer then some grinding and filing did the trick.

I'm missing the clips for locking the pins in place. Anyway the drama is over. I finally have 4 calipers mounted on the car.

I bought some more brake line with the metric fittings. At $5 each it sure is lot easier than making the flares myself. Running the line straight doesn't work for me. Maybe on an airplane they'll do that but all I have to work with is a 12" length of brake line and my hands. If there is any sideways pressure on the fitting it will leak.

I found a 29" long stick to hold the brake pedal down so I can bleed the brake system. With just one bleed valve open I press the brake pedal and then use the stick to keep it down. Then I go and close the bleed valve. Remove the stick and let the pedal return. Open the bleed valve again and repeat until brake fluid comes out. Do this with all the bleed valves. Some rear calipers have 2. The next stage gets the air out. I used a short piece of 1/4" ID tubing taped to the strut so it stays vertical. When I bleed it this way the air stays out. After no more air comes out, I move to the next caliper. When I got done with this the pedal was still soft. I had to loosen the adjustments on the rear calipers and stomp on the brake pedal a few times. That got the rear pads against the disk. After that the pedal was hard if I pumped it a few times - still a bit of air in the system. And it slowly sank to the floor as I pushed down on it - leaks. I tightened up a few fittings but it still leaks; just not as fast. The emergency brake doesn't do anything yet. The brakes are there, just not good enough for driving, whenever I'll get to that stage. So now I've got a roller.

1 comment:

Joe said...

I wanted to follow up on this while I'm still getting to this step. It was my understanding that to upgrade to the 320i brakes, that you just had to get them milled then bolted them in.

Also upgrading the 17mm brake pump to 19mm (but I have no idea how to tell them apart) as well.