Adjustable Hydraulic Pushrod Design



[[ Taken from a post I sent to Milo Kral about fabricating 
   adjustable pushrods for his car ]]

Date: Tue, 1 Aug 1995 09:47:26 -0700 (PDT)
From: Greg Meboe   meboe@lestat.scs.wsu.edu
To: Milo Kral    
Subject: Design of an adjustable pushrod

Milo,
	I run one of the adjusters on each of the master cylinders in my
car, and on a few customer's cars.  They really make pedal optimization
easy. 
	I wouldn't worry about bottoming the master cylinder with a longer
rod.  The amount of length that you will adjust into the system won't be
that great, and on a Dual master type brake cylinder, the bottoming out
point is a metal to metal position, that is there should be no damage to
the internals.  Now the Single clutch master, depending on the year, will
have metal to plastic contact at full plunge, so I'd keep the adjustment
just short of that. 

Cheezy ASCII Art to follow:


   	--------TOP VIEW--------------

				    v-----------Adjustable Clevis block  
                             _   ___________|__
            /-|             | | |     ______:__|
           |  |-----------^^^^^^^^^^^^|     |
 Pushrod-> |  |-----------vvvvvvvvvvvv|_____:__
            \-|             |_| |___________|__|      
    					    :
		 Locknut ----^	            ^---- Clevis pin Hole  



	------------SIDE VIEW----------

				    v-----------Adjustable Clevis block  
                             _   ______________
            /-|             | | |          __  |
           |  |-----------^^^^^^^^^^^^    /  \ |
 Pushrod-> |  |-----------vvvvvvvvvvvv    \__/ |
            \-|             |_| |______________|      
    					    
		 Locknut ----^	            ^---- Clevis pin Hole  

I've just made these with a solid chunk of steel for the Adjustable 
Clevis Block.  The design is simple and can be made in 1/2 hour with a 
grinder, hacksaw, drill and tap.  Then run a die over your old pushrod 
after you've cut off the clevis portion, fit a locking nut, and you're 
finished.

I hope this helps,

		Greg
                            Greg Meboe     meboe@lestat.scs.wsu.edu
			    Dept. of Mechanical and Materials Engineering
			    Washington State University,  Pullman, Wa.
			    '85 XJ-12 H.E. (daily)  '67 Spit-6 '74 TR-6

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