Sunday, December 20, 2015

40 mm master mods hydroboost adapter and changing stops

40 MM internals on top P30 below for size comparison.
Fabricated two piece spring retainer to allow more stroke on primary
   Recessed stop for more primary stroke, far as it could go without spring bind.
                               Before modification
                          Two piece retainer installed, original below.
                                       Two piece on the rod
            Primary spring not binding when on the stop.
   I wanted a 3.2 to 1 ratio but that would require new pistons. 3 to 1 worked OK.

 The bottom of the bore is not flat. Spacer makes up the difference that was put on the primary side.
               grooves go to the bottom to let any air out

Hydroboost being installed has an output stroke of 1.708"
 This is the 40mm master shown and it fits:

2001ChevroletC3500HDBase Cab & Chassis 4-Door8.1L 496Cu. In. V8 GAS OHV Naturally Aspirated
Doorman M630028

 Ours came from Rock Auto and I see them on Ebay too.

Sunday, December 6, 2015

Hydroboost gets a bore job

Opening up a hydroboost output end to accept a 40MM master cylinder. Going to use this in combination with a spacer. Not bored full depth so the spider that holds the output rod will still be usable.

Thursday, November 26, 2015

GMC brake booster output stroke measurements

 Original motorhome booster, a "metric" replacement and Hydroboost. These are output rod strokes.
I used these straps and a rod to hold the input rods all the way in.

Monday, November 23, 2015

Galaxy S4 screen replacement

Samsung phone fix. We found very good instructions on youtube here

Monday, September 21, 2015

Airboat rudder fix

 Airboat rudder with a bent and cracked control tab attachment
 After straightening we ground out both sides of the crack with a rotary file
 Tig with 4043 rod

Saturday, September 19, 2015

Coolant pump impeller R&R

The GMC came with a cast 4.25" water pump impeller. This can be swapped to a replacement water pump. Replacements mostly have a stamped open back impeller of a smaller diameter.

 Original 4.25" cast impeller compared to the generic 3.875" impeller
I set the clearance .015" minimum. Using a pump affinity calculator like-

Changing only the impeller diameter makes around a 12% difference in pressure.

              Jacket water pressure at road speed with OEM 4.25" impeller

Thursday, September 17, 2015


                                                 Watson Lake
                                  Alaska Highway
                                       By Watson lake...We picked up a mouse hitch hiker ha
                             Turn again bay

               Speedo gear gave out but I had a new one!
   Cruise control gave out in multiple ways... Foam filter deteriorated enough that the solenoid couldn't pull in, removed. Minimum speed switch went erratic so it got jumpered with a paper clip at the transducer. Stalk switch went out so it was replaced with a door bell button for engage and jumpered the hold part to always be on. Still turns off with the brake pedal. Love my auto throttle.
   Glacier by Denali
   On the way to Homer spit
        Fish at homer spit
     On the way to Stewart
   Fellow GMC at Stewart...This coach was Darren Paget's who did stainless countertops
Norm Alinson present owner
Ferry to Dawson
Attempted window repair  from rocks thrown by a nine axle truck. The window later cracked big and needed replaced
Lost a headlight too


Took a flight around Denali from K2

Around Denali

Transportation museum Whitehorse

Richardson Highway

Glacier view camp

                      Tunnel to Whittier, share with train and one way traffic
Going in