I am planning to rebuild the ATE rear brake calipers on my son's 83 245. Will put on freshly bought rebuilt calipers and I plan to rebuild the old ones with a kit.
Brake literature demands that the rear caliper pistons be aligned at a certain angle. Has anyone made the tool for doing this? We need the dimensions posted on the "Special Tool" section of the FAQ 700.
GIA,
el Raidman.

I'm pretty sure I've got the Volvo tool somewhere. Both the angled wedge and the piston turner. If you want a piccy I can find them but frankly I haven't used them in years.



Regards



Pete

rhys is talking from experience... i made a "tool" out of a thin piece of cardboard..it's simple. the key is to have the piston at twenty degrees..don't worry, once you get it apart you will see how self-explanatory it is and you will ask yourself the same question I asked myself? what's the big fuss about? You do not need any special tool!

The angles are not as critical as the literature would make out. The relief on the edge of the piston provides a small amount of self-actuation of the pad into the disc surface. You may find the alignment out of spec on the calipers you remove.
Line them up by eye and be done with it - it will be close enough.

I have a slightly different experience to report. After trying the shims, the grease, the factory pads and rotors the squeal from the ATe rears would always return...until I tweaked the notch in the pistons.

The factory manual says 20 degrees +/- 2 and two degrees is not a lot and beyond my eyeball's abilities. It suggests the adjustment in persuit of quiet brakes. I used card stock and a protractor once, and another time the miter gauge from my table saw. 'Course you wanted to know how to turn it with the caliper in place, right? Now that's a nifty tool I could not imitate, so I was lurking to see if someone had a good idea. I won't even attempt to describe the combination of channel lock pliers and screwdriver that managed the rotation without mangling the piston; I got lucky.

Anyway net result, the car doesn't sound like a Volvo anymore, identified by the rear brake resonance. And if you have any thoughts that I elevate factory manuals to blind faith status, my torque spec for the caliper bolts is three whacks on the end of a combo wrench from a 2lb. drilling hammer. They's caliper-ated whacks.

Well, I guess you've seen a lot more of these than I have. Have you noticed a relation between the angle and the noise?
--
Art Benstein near Baltimore

Hi Art;
In my experience (trying to keep customers from complaining of brake noise....) I have found that the brake pad material ( or manufacturer ) is the single most important factor in reducing pad squeal. This includes other car makes like Mercedes and BMW which also use the Ate calipers. I set the piston alignment by eye, within a few degrees. I also use a square file to remove any burrs in the caliper mouth where the pad backing plate edges abutt. I clean the pins on a wire wheel, and them spray them with WD-40 and wipe them dry. No never-seeze on the pins. With the right pads, no squeal, happy customers.
For Volvos in particular, I find the PBR Metalmaster pad is the best - and I usually use a single shim with a bit of never-seeze between the shim and the pad backing plate. Sometimes two shims are needed, but only with a cheaper brand I also use on 240's only. One steel shim, one black rubber coated. The 740's seem to be even less tolerant of brake pad material. I use metal-master's or the factory pad on the rears. I have never known a factory pad (the very soft ones) to squeal, but they are terrible for dust and wear out in 18 months.
For front brakes on 240's, the Metal-master, but for some two piston 740 front brakes (88-89 in particular, with the rotor inner vents outboard), only the factory pad seems to give a good pedal feel, no "morning sickness", and quiet operation.
It can't hurt to align the pistons carefully - and I wouldn't dimiss anyone who does, but I have found the pads to be the culprit in almost every case.

Hi Rhys,

The noisy rear brakes became the third or fourth problem for me to solve after an engine harness and fpr introduction to volvo. I found a surprising wealth of stuff on line about tricks to correct volvo brake noise, some I mentioned. Four 240s later and a green book lists the notched piston alignment as a cause for brake noise, so I tried it. Now, Rhys, I found them maybe 10 or 15 degrees off, and I have no idea what forces make them become misaligned, but it was only that one car that persistently sang like a school bus-- until realigning those pistons.

I've looked at (eyeballed) others when replacing pads, but now that I think about it, they had no squeal to motivate me to adjust them.

Actually never bought Volvo branded pads except for the rear and only for that noisy car. You mention the steel and rubber coated shims? I still don't know how they are supposed to be used; I put the rubber one toward the piston and, some sil-glyde between the pad backing and the stainless shim. Never saw the rubber coated except that it came with the factory pads...

Yes, dust from those volvo pads. Everywhere else, I have been using Metal-masters. They have the familiar scrunch noise that sometimes set the rear springs to resonate as I try to creep or switch between drive and reverse without being firm on the brake pedal, which I like, and associate with well performing brakes.

The notch thing was such a successful event I just had to speak up and relate the anecdote. I have mucho respect for anyone doing this work all day professionally and then taking time to contribute to this forum.

5 240s and 3 captive "customers"
--
Art Benstein near Baltimore

Like they say Art, one should learn something every day - and I did. Just how such a carefull alignment should stop a squeal I don't know, but if it worked for you, it worked. I too have seen them out by many degrees - perhaps a previous overhaul or some kind of creeping in service.
I think both the rubber and steel shims originally came with Volvo pads - the rubber one is a later development (I think....) I use both when needed, but the extra squish does soften the pedal feel.
I too have noticed the low speed "graunch" of metalmaster pads.
Take care.