Rich Atherton wrote:
> Yes I finally recevied your response....I will have to disagree with your
> assement of the thermal proporties of the metal used.
Disagree?
> When Heat is uniformally applied to the part with the hole,
> the dimension of the holes diameter "Will" increase. And when you freeze the
> shaft part, it's outside diameter will decrease.
>The "friction" fit (or intereference fit) is a standard industrial
>practice to join a shaft to a hole without resorting to woodruff keys, set
>screws,
>locking nuts, drive pins, and other more costly solutions. The shaft diameter
>gets smaller and the hole gets larger as a function of their themal expansion
>material properties. 0.005 to 0.007 interefernece is comon for light
torque>applictations.
Am I confused? How does this statement differ from yours? I said the same
thing!
> Different metals have different expansion rate of course. Aluminum being
> one of the most active in this property. The reassembly of the parts is Much
> easier when this is done, and they won't slip once their tempratures equalize.
Yes, of course. Again, how does this differ from:
> The shaft diameter gets smaller and the hole gets larger as a function of
>their
themal expansion coefficient.
> When I built my Last Drag Bike years ago---- I then put cylender block in
>the
> oven at 275
> degrees, and the sleeves in the freezer. --- Bike ran for 11 years with out
> breaking even once.
Good practice, and no disagreement.
> Just my thoughts. Sorry so long.
>
> Rich
My main point wan't a simple dissertation on thermal coeficients, anyway. It
was
in the dangers of rebuilt pumps by sloppy cheap shops.
> > A few rebuilds, or pump swaps later may
> >be a different story.
> >
> >Re-builders are known to use larger shafts for re-builds for the impeller
>fit.
> >Sometimes they are good enough to change the bearings and seals too match.
> >Sometimes they are not.
> >
> >I've experienced all variations on this theme, so make sure you know who you
>are
>
> >dealing with.
And some potential solutions:
> >A hard chrome plating on the shaft will increase it's diameter a few
> >thousandths, and make it almost impervious to wear on the sealing surfaces,
>and
> >bearing surfaces, as well as the hub.
And a Hi Performance, but expensive solution:
> >If you want increased flow performance, and can stand the cost, look at that
> >aluminum Hi-Po Edelbrock makes for the 289 "K" Hi-Po
> >motor. It is very close to the factory specs, and close enough to the TE/AE
> >numbers to make adjustment a simple matter. Using their hub and a new 6
>blade
> Ford
> >Canadian fan is a bolt on (with a diameter change for the steering rack), or
>you
>
> >can use your own hub pressed on by a pro (after measuring), or you can use
>the
> >lawnmower blade idea - very clever. I'm not so sure that the four bolts can't
> >center the fan accurately, with some post-assembly verification.
I am sorry if my message wasn't clear. Maybe I covered too many subjects. There
was no intent, whatsoever, to disagree with what you had said, or the
accomplishments you have made. I did feel, however, that those who rely on the
sevices of others may have some of the same unfortunate experiences I have had,
and
meant to suggest reasons for caution. My other intent was to observe the high
performance pumps used in racing, and how they could fit the Tiger. I am
distressed that your answer suggests you felt I was somehow disagreeing with
you.
Sorry about any confusion.
Steve
--
Steve Laifman < One first kiss, >
B9472289 < one first love, and >
< one first win, is all >
< you get in this life. >
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