Thanks for the update Emery.. I have been wondering what the final result
was. I would like to update the web page, but guess I will wait until you
get home and have a definite on the pushrod. When I got my booster from
Lamey, he cautioned me very carefully to keep the old pushrod since it was
longer than the ones shipped with new boosters..... I wonder if it is the
same ??
Hope the rest of your trip is going well
gene
>I had reported earlier that my Cinnabar master cylinder with less than
10,000
>miles on it failed here in Florida. Jim Bounds had a brake mechanic look at
>it and they indicated that the GMC original master cylinder just didn't have
>enough capacity to handle the four wheel calipers that I had put on with the
>StreetRod disk brake kits. They felt that most of my braking was from the
>front brakes (80 mm calipers).
>
>My thanks to several who posted that I should use the P-30 chassis master
>cylinder which has a 1-1/4" bore. I was told that Leigh Harrison uses this
>cylinder with his brake kits. The mechanic tried this and still wasn't
>satisfied with the amount of pedal. He then put on a 1-3/8" bore cylinder
>which was CarQuest part number 20-1583. I believe he said that it was
from a
>C-30 but I'm not sure. They said it was for a large motorhome chassis that
>used 17 or 17-1/2" wheels. I'm going to ask CarQuest to look it up for me
so
>that I'll know.
>
>They made a push rod pin that was just a little longer than the stock one.
>When I get home I plan to remove it and measure it and will let everyone
know
>the length. The other thing that they had to do was to put a washer on the
>left hinge of the driver's front access door so that the door would clear
the
>bail wire on the master cylinder when the door was closed. I believe that I
>can bend the bail slightly so that the door hinge shim can be eliminated;
>however, it is out so little now that one wouldn't notice it unless it were
>to be pointed out.
>
>The result is that the brakes, which I thought were great before, are now
>really great. I've got about 2-1/2" of pedal left (bottom of pedal to
floor)
>when I push hard on the brake pedal, whereas before I had less than an
inch.
>I am also using a Lamy sensitized booster which allows the pedal to go lower
>due to the increased pressure of the booster.
>
>I was told that the GM (Cinnabar) (Bendix) master cylinder plunger was
>bottoming out within the master cylinder and scuffing the bottom edge of the
>piston seal and that mine had failed due to this scuffing.
>
>I suggest that any of you who have put rear disk brake kits onto watch your
>master cylinders for possible failure and be prepared to put on a larger
>master cylinder before you have problems. I doubt that mine was an
>abnormality because I had tried two new NAPA master cylinders before buying
>the Cinnabar one and on both the pedal slowly sunk to the floor and the red
>light would come on. The Cinnabar one had lower pedal than before the disk
>brakes were installed but it did not sink all the way to the floor. When
>installing the kit I thought that it was not bled properly and my wire and I
>literally spend hours bleeding and rebleeding the brakes. When the Cinnabar
>master cylinder was put on they firmed up right away and when the CarQuest
>one was installed the mechanic said that there was no bleeding problem right
>from the start.
>
Genef -- 77PB/ore/ca
GMC MOTORHOME INFORMATION
mr.erf
http://www.california.com/~eagle/
was. I would like to update the web page, but guess I will wait until you
get home and have a definite on the pushrod. When I got my booster from
Lamey, he cautioned me very carefully to keep the old pushrod since it was
longer than the ones shipped with new boosters..... I wonder if it is the
same ??
Hope the rest of your trip is going well
gene
>I had reported earlier that my Cinnabar master cylinder with less than
10,000
>miles on it failed here in Florida. Jim Bounds had a brake mechanic look at
>it and they indicated that the GMC original master cylinder just didn't have
>enough capacity to handle the four wheel calipers that I had put on with the
>StreetRod disk brake kits. They felt that most of my braking was from the
>front brakes (80 mm calipers).
>
>My thanks to several who posted that I should use the P-30 chassis master
>cylinder which has a 1-1/4" bore. I was told that Leigh Harrison uses this
>cylinder with his brake kits. The mechanic tried this and still wasn't
>satisfied with the amount of pedal. He then put on a 1-3/8" bore cylinder
>which was CarQuest part number 20-1583. I believe he said that it was
from a
>C-30 but I'm not sure. They said it was for a large motorhome chassis that
>used 17 or 17-1/2" wheels. I'm going to ask CarQuest to look it up for me
so
>that I'll know.
>
>They made a push rod pin that was just a little longer than the stock one.
>When I get home I plan to remove it and measure it and will let everyone
know
>the length. The other thing that they had to do was to put a washer on the
>left hinge of the driver's front access door so that the door would clear
the
>bail wire on the master cylinder when the door was closed. I believe that I
>can bend the bail slightly so that the door hinge shim can be eliminated;
>however, it is out so little now that one wouldn't notice it unless it were
>to be pointed out.
>
>The result is that the brakes, which I thought were great before, are now
>really great. I've got about 2-1/2" of pedal left (bottom of pedal to
floor)
>when I push hard on the brake pedal, whereas before I had less than an
inch.
>I am also using a Lamy sensitized booster which allows the pedal to go lower
>due to the increased pressure of the booster.
>
>I was told that the GM (Cinnabar) (Bendix) master cylinder plunger was
>bottoming out within the master cylinder and scuffing the bottom edge of the
>piston seal and that mine had failed due to this scuffing.
>
>I suggest that any of you who have put rear disk brake kits onto watch your
>master cylinders for possible failure and be prepared to put on a larger
>master cylinder before you have problems. I doubt that mine was an
>abnormality because I had tried two new NAPA master cylinders before buying
>the Cinnabar one and on both the pedal slowly sunk to the floor and the red
>light would come on. The Cinnabar one had lower pedal than before the disk
>brakes were installed but it did not sink all the way to the floor. When
>installing the kit I thought that it was not bled properly and my wire and I
>literally spend hours bleeding and rebleeding the brakes. When the Cinnabar
>master cylinder was put on they firmed up right away and when the CarQuest
>one was installed the mechanic said that there was no bleeding problem right
>from the start.
>
Genef -- 77PB/ore/ca
GMC MOTORHOME INFORMATION
mr.erf
http://www.california.com/~eagle/
