I don’t have any idea what your background is Fire, or what you’re working on, or what your shop capabilities are so it’s a little difficult to answer your question.
Let’s start out this way, if you try to assemble parts by thermal expansion i.e., freezing one heating t’other you better be real quick because as soon as they touch each other the temperatures begin to equalize and you only have a few seconds to get it right. That works pretty good when your trying to assemble a steel bearing into a magnesium or aluminum housing where all you have to do is drop it in and when it hits bottom, your home. An example of this would be axle bearings into the magnesium side covers of a Halibrand quick-change rear end. You also have the fact that these are two materials with very different coefficients of expansion, unlike steel to steel.
Next if you have a hydraulic press the job is easy and it is the way it would be done in a proper engine shop.
The pin slips freely or floats through the first side of the piston and can be press into the rod to make full engagement, just till it is flush with the bottom side of the rod. I would use a solid spacer, probably aluminum, between the rod and the boss on the second side of the piston just so you don’t nick the piston. I would also press against a soft material like aluminum, to support the piston on the press table to keep from nicking up the outside of the piston. All you are doing here is compressing the second side boss of the piston, which should not hurt anything. Next I would place a spacer under the rod to take up the side play. A slotted clearance hole in the spacer will allow you to press the pin in a little further through the rod, far enough to give you a pilot into the second piston boss. Remember that you have to pull the spacer out so it has to be U shaped, slotted spacer and again don’t nick the piston. At this point you can drop the exposed portion of the pin into the second side of the piston and press it home until it is even on both sides. I would turn up a stepped plug (similar to a Champaign cork) that would drop into the pin to press against. I made this one in the upper picture to press sleeves into wheel cylinders:
http://rides.webshots.com/photo/2623085370098611668ETUIML This all sound like lot but once you have all the pieces together the actual job only takes a few minutes.
If you’re not equipped to do this or don’t feel comfortable with it, any auto machine shop will press them in for a minimal amount and it should only takes a few minuets.
Hope this gives you some ideas.
Denny Graham
Sandwich, IL
