Thursday, December 31, 2009

Hydroboost measurements

-----------------------------94 Astro ------------99 Astro ----------------Dodge

Input rod -------------------.595 -----------------.595-------------------- .545

Power piston ---------------1.56 -----------------1.56-------------------- 1.56

Lever ratio------------------- .62------------------ .62 -----------------------.73

Stock pedal ratio ---------dunno ----------------5.2:1------------------- 4.2:1

All of these had the bigger power piston. The Dodge unit had the smaller input rod for more gain and the 73% lever for more relative motion of the valve spool.

Here is a pic of the Dodge pieces on the left compared to the 94 Astro. You can see the difference in the lever pivots. I can't tell any difference between the valve spools.

The GMC steering pump is supposed to be set at 1,400 psi. If I did the calculations right this would be 2,675 lbs of force to the master cylinder with a power piston 1.56" diameter and 1.911 square inches in area. This would be with an input rod force of 326 lbs with a rod dimeter of .545" and an area of .233 square inches. The force at the pedal with the GMC's stock 4:1 pedal ratio would be 82 lbs. All of this would make 2180 psi brake line pressure with a 1.25 diameter master cylinder. Way more than the vacuum booster.

Tuesday, December 29, 2009

Hydroboost kit and input rod seal installer

Got a hydroboost repair kit from Restoration Perfomance Center in Arizona. They had the best price.
These input rod seals have to stretch over the threaded rod and piston and not get torn up. They have to stretch a bunch... I made a two part tool with a sleeve and taper piece. The sleeve slides over the threads and end of the piston keeping the seal protected.
Sleeve and taper tool parts.
Got them on OK. Old seal on the sleeve.
The old seals tore stretching them to get them off.

Sunday, December 27, 2009

Snow and a John Blue pump

We got a blizzard Christmas day.
This John Blue pump was made in the 50's for LPG or anhydrous ammonia transfer. It has a piston motor that operates off of the difference between tank pressure and atmospheric and drives an attached piston pump that moves gas from one tank to the other creating a pressure difference. The transfer is done by a separate liquid line between the tanks. Some gas is lost to the atmosphere from the motor end in normal operation. The motor valve shifter had broken and it took a while to figure out how it went back together and what the parts were supposed to look like. Originally they were used to transfer anhydrous from a bigger nurse tank to a tractor mounted tank when tractors could not carry so much weight.

Tuesday, December 22, 2009

Snow blower fixit

They don't make them like this any more, 4 stroke chain drive and very little plastic. The starter recoil spring had come unhooked because one fastener loosened up. Put in a new plug, changed oil, lubed the chains and it's good for the big snow in the forecast and for more years to come. Below is a short movie of it starting and running...almost gets away from me in the back of the truck.


Monday, December 21, 2009

Accumulators on the hydroboost

I'm using the caveman c-clamp method of compressing the accumulator so the lock ring can be removed. There is an official tool for this but I don't have one. The pin punch fits in a hole that pushes the lock ring in enough to fish it out with a seal pick. The accumulator goes in about 1/8 inch against the stop in the housing. If the nitrogen is gone the accumulator will wiggle in the housing as there is no pressure pushing it test for a bad accumulator.
There is an O ring that seals the housing to the accumulator. The lock ring is at the bottom of the picture.
The blue accumulator is for disc/disc brakes charged to 450 psi and the gold for disc/drum brakes at 350 psi. Gold is the type needed for our GMC with original brakes. There are other types of these, some remote mount types and at least one using a spring instead of nitrogen for pressure.
A view of the housing with the accumulator removed.

Tuesday, December 15, 2009

Hydroboost Heaven, a tale of three boosters

Scrounged up three Bendix hydraulic brake boosters to maybe make one like I want. The top one is from a 99 Astro van, center Dodge flatbed and he bottom from a 94 Astro. Don't know what year the Dodge was as it was pretty much stripped. It was a gasser and had a long frame. Notice the angle of the 99 Astro mount plate and master cylinder. Maybe it will work better for the GMC. The blue and gold cylinders are accumulators with a nitrogen charge. Gold is for disc/ drum brakes charged to 350 lbs and blue for all disc brakes charged to 450 lbs. I'm looking to assemble a booster with a 1.56 power piston, .545 input rod and a .72 ratio lever. This will make a booster gain of a little more than 8 to 1.
The Dodge had a goofy angle adapter on the master cylinder end.
Angle adapter removed, now it has a pattern like GM uses.
Custom caveman square tube wrench used to remove the mount plate on the pedal end.

As Geico says a caveman can do it.
The input rod has to be cut in order to get it apart.
One solution is to thread the rod so any length extension can be fitted with whatever needs to be on the end to connect the pedal.

Sunday, December 6, 2009

Propane QCC connector

There was a 20 lb propane bottle I could not get to fill so I decided to cut the valve apart and do an autopsy.

The "new style" bottle connections have a valve in them that won't let gas out unless there is a fitting screwed in. This one was corroded enough that it would not move. Here is what he pieces look like.
The new style valves have an acme right hand external thread as compared to the POL left hand internal thread. This valve is not one of the OPD valves with a float deal to keep the tank from being filled past 80%.
Toyota bottle holder
Here is the other side of the QCC connector. Notice the round pin that is supposed to open the check valve. These have plastic knobs that are supposed to melt and release in a fire closing the valve. They come in different BTU ratings which is probably the size of the orifice.
3 HP lpg pump