Brake Master Cylinder size

[LQQKatJon]

seems like I have been tossing brake parts at my coach for years.... 9 years ago, I installed a sensitized booster bought at the time from the GMC
Coop. few years ago, I went and replaced all rear brake shoes, springs and cylinders and up'd the size of the mid axle wheel cylinder.

Last fall, I changed out stock calipers up front for the 80mm calipers, and installed perfomance friction brake pads. We used a special tool to
really prep up the rotors, and those Pads "bedded" in real fast and really well. I bet I had less then $150 in doing that change. (I had probably 8
year old stock front brakes).

So with a 9 year old sensitized brake booster, a stock master cylinder, 80mm front calipers running performance friction pads, the larger mid wheel
cylinder and stock rear brakes. I have no concern at all about stopping. I have been driving my coach almost as a daily driver this spring, and
stop/go traffic, around town and it stops just as well as my honda crv.

I have recently driven some coaches that have no "sensitized" booster, and have an old stock one in the coach. And they stop fine, but I really would
not want to drive them around town like I do my coach. and would not want to ever try to stop them without wearing shoes.

so in my opinion, running a sensitized booster, stock master cylinder, 80mm brakes(only if you need to change bad 70mm), and a mid axle larger
cylinder(again- only if you are changing brakes there). makes for a really pleasant driving/stopping experience.

--
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/

 

[Jim Hupy]

I know that it seem like GMC brakes need a lot of maintenance. To be
honest, they do. It is a heavy vehicle, and old. Drums, linings, rotors and
pads are all items that, if they do their job well, wear as we use them.
Fact of life. But, they fail when the coach sits without being used. But
there, it is caliper seals, wheel cylinders, master cylinders, distribution
valves, brake lines. It is all part of owning a motorhome. You cannot fix
it once, and forget about it. Brake fluid loves to absorb water from the
air. Periodic fluid changes are mandatory, not just suggestions. I don't
like it much, either.
Jim Hupy
Salem, Oregon

On Mon, Jun 8, 2020, 1:17 PM Jon Roche via Gmclist
wrote:

> seems like I have been tossing brake parts at my coach for years.... 9
> years ago, I installed a sensitized booster bought at the time from the GMC
> Coop. few years ago, I went and replaced all rear brake shoes, springs
> and cylinders and up'd the size of the mid axle wheel cylinder.
>
> Last fall, I changed out stock calipers up front for the 80mm calipers,
> and installed perfomance friction brake pads. We used a special tool to
> really prep up the rotors, and those Pads "bedded" in real fast and really
> well. I bet I had less then $150 in doing that change. (I had probably 8
> year old stock front brakes).
>
> So with a 9 year old sensitized brake booster, a stock master cylinder,
> 80mm front calipers running performance friction pads, the larger mid wheel
> cylinder and stock rear brakes. I have no concern at all about stopping.
> I have been driving my coach almost as a daily driver this spring, and
> stop/go traffic, around town and it stops just as well as my honda crv.
>
>
> I have recently driven some coaches that have no "sensitized" booster, and
> have an old stock one in the coach. And they stop fine, but I really would
> not want to drive them around town like I do my coach. and would not
> want to ever try to stop them without wearing shoes.
>
> so in my opinion, running a sensitized booster, stock master cylinder,
> 80mm brakes(only if you need to change bad 70mm), and a mid axle larger
> cylinder(again- only if you are changing brakes there). makes for a
> really pleasant driving/stopping experience.
>
>
> --
> Jon Roche
> 75 palm beach
> EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
> St. Cloud, MN
> http://lqqkatjon.blogspot.com/
>
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