Pulsing brakes fixed. 1989 765T with ABS and 135,000 miles.

I have not seen this solution discussed though there has been plenty of comment on the problem and other remedies. The symptoms were a pulsing of the brakes when light pressure was applied. I thought that it might be the over tightened wheel bolts or a warped rotor. So I jacked up the front and started investigating. Yes the wheel bolts were too tight but the rotor was true, they had been turned last June. What I found was a retainer locating pin was frozen in place. In replacing pads about 4 times on my wife's 744 or my previous 745 I had never realized that there might be other problems though if it had been a snake I'd have been bit.

In the Girling front brakes there is a retainer cage that fastens to two "ears" on the axle assembly. There are 2 hex socket bolts that hold this retainer on. Then in the retainer are two sockets that each receive a locating pin. The caliper is bolted to these pins so that it is free to move sideways a centimeter or so. In my case one of these pins on each side was frozen and not moving. Thus when the brakes were applied the pistons were able to push the inside pad out but the caliper was not able to move in and pull the outer pad into firm contact. This caused noise and pulsing.

One locating pin was free to move, I could push it in and the grease seal bellows would push it back out. However the other was stuck. With about a half of an hour of twisting and prying I was able to remove the pin without damaging the retainer though the pin was trash. At Volvo I found that you can only by a kit, 4 pins, 4 bellows, 4 caliper holding bolts and a tube of grease for $98. I objected but bought the kit.

Reassembly was simple though I did clean out the pin sockets and polish the ID with Scotchbrite on a stick on a hand drill. Reassembly was simple with a liberal supply of grease and properly fitting the bellows. Then locating the brake pads and slipping the caliper over the pads and fastening the caliper bolts to the locating pins. Since these pins are free to rotate a thin 13mm open end wrench comes in handy to restrain the pin while tightening the caliper bolts.

Since I had the pins I decided to check the other side. I was not so fortunate, one pin was stuck so hard it twisted off and I had to get a replacement retainer, $10.

My recommendation is that when replacing pads and or disks you check both retainers by pushing them to the outside of the car. If they do not move freely remove the retainer (2 hex socket bolts) and get to a vise where you can work the pins out. Replace the pins and bellows. Even if the retainer moves smoothly it might not be a bad idea to remove the pins, careful not do damage the bellows, clean the socket of old grease and any water and relube the pins. I suspect the grease isa silicone as it is water white (about like KY).

I hope this has not been too wordy and that it gives us a little insight in the inner workings of our Bricks.