Parking Brake and Rear Caliper

Dave Bell · 07-08-1999, 05:47 PM

As I slowly go through stuff on the 914 I bought I have now come to the parking brake. The cable setup works fine. When I took off the driver side rear wheel to check out the operation, the actuating lever was moving fine but there was no "lock up" of the brake. After adjusting the venting clearance per Haynes, still no lock up. Normal braking operations with the pedal seems to work fine.

I have everything apart now. As it turns out the rotors are way below spec minimum so they are going to be changed. But while I have it all out I am wondering if there is anything I can do to fix the parking brake action... or maybe my venting adjustment was done improperly. Anybody else run across this problem?

Tom at Pelican and a local Porsche mechanic both agree that a rear caliper rebuild is an iffy proposition.

Also after I have everything back together I will want to bleed the back brakes. I notice that I have two bleeder valves on each caliper. Is bleeding through both necessary? What is the correct approach?

aporsche914 · 07-09-1999, 04:54 AM

umm...914 rear calipers only have one bleed nipple, right at the top of the caliper, its a 7mm size hex on the bleeder, im not sure what else youre looking at, but there should only be one, not 2..and check to make sure that all the handbrake connections are connected, as theres 3 in the cabin, and one on each caliper, if one is loose..the brakes wont lock, hope this helps. Ian, '72 1.9L

Dave Bell · 07-09-1999, 08:01 AM

You got me thinking maybe I was seeing double but after checking the caliper one more time and fishing around on the Pelican Site, I found one answer in the tech article, "Bleeding 914 brakes." "If your rear caliper has two bleed nipples (some have one, others have two), bleed the lower one first." There is also a picture of a two nipple rear caliper in the tech article, "Installing and Adjusting New 914 Brake Pads," (Figure 5).

Showing my ignorance, I am still not sure yet why two are used vs. one but I got two.

JP Noonan · 07-09-1999, 12:31 PM

Some have two, some have one. Why? Well maybe it's like the 911 and 930 rears, (from memory) the 911 has the caliper toward the rear of the car while 930 turbo's have (larger brakes also) the caliper in the front. So maybe whoever designed the caliper wanted it so that it could be mounted either way? Or the botom one is there so you can drain the system? I dunno, I think about things too much.

Anyway, bleed the top one. Air rises so the air is at the top. Pump the brake fast 3-4 times then push down and hold it. While holding it open the bleeder. When the pedal bottoms out tighten the bleeder and start again. I once only bled the bottom ones (1:00 a.m. after "bolting on" some 320i brakes) and the brakes were so bad I couldn't drive. I've also found that it pays to bleed the brakes when you first open up the system. Then let it sit for a day and do it again. Also bleed the proporsioning vavle.

Maybe the brake cable is streched? Try tightening it. BTW I've never had a great parking brake, just one that keeps the car from rolling (of coarse I live in Florida).

Dave Bell · 07-10-1999, 04:41 PM

Thanks aporsche and JP and thanks also to Pelican 914 tech articles. I picked up new discs last night and put them on today. After everything was re-assembled and adjusted even the parking brake works!... I like that.

On my first round of setting the venting clearance I did not realize I had to set the in board venting clearance also, duh!

With the calipers off and the inner pad adjustment cap removed, the little worm gear adjustment piece just fell out and I could see exactly what I had failed to adjust.

I'm back on the road.

- Dave