One thing I forgot to mention - one of the mods that Jack made to the
stock style shaft is to radius the slot so that there are no sharp
corners or "stress risers" to help reduce tang breakage. I discussed
this with Steve and he pointed out that his slot is also designed
with a radius at the bottom of the slot in the oil pump shaft. It's
a pretty small radius so that's why I missed it, but it's there and
should be all that's needed.
- Tony
At 11:32 AM 1/19/2010, Tony Drews wrote:
>I was talking with a group of my Triumph racing buddies, and we were
>discussing a new oil pump design for the TRactor motor (TR-3 / TR-4)
>that came out of the Chicago area Triumph club. I realized that I
>may not have properly promoted this product. Steve Yott (aka
>"Drippy") has developed an oil pump design based on the stock pump,
>but with some important modifications. The rotor and shaft are NOT
>two separate parts, but are one piece - eliminating one of the
>failure modes of these pumps. Also, the end cap has been machined
>to accept a new shaft sticking out of the bottom of the rotor - so
>the rotor is supported on BOTH ends, rather than the stock single
>end support. The end plate is pinned to the main housing so that
>the location of this bore is consistent upon disassembly and
>reassembly. The rotor has oil passages in key places ensuring that
>all of the moving parts ride in an oil bath so there is no metal on
>metal contact.
>
>Steve Yott is at tr4@wi.rr.com . I believe the price for this was
>$225 with a core exchange.
>
>There are two primary failure modes of the stock oil pump. One mode
>is the tangs breaking off of either the oil pump shaft or the
>distributor drive, and the other mode is the rotor spinning on the
>shaft. They believe that the tang breakage is caused by "wobble" in
>the rotor due to it only being supported at one end. This causes
>binding and additional force on the tangs. The new pump eliminates
>this wobble with the shaft sticking out the bottom of the
>rotor. The second mode - the rotor spinning on the shaft - is
>eliminated by the rotor and shaft being made out of a single piece of steel.
>
>This is one of those parts that "just seems right". I ran one in my
>motor all last season and had excellent oil pressure the whole year.
>
>For some reason the newsletter detailing this part doesn't seem to
>come up from the links on their website, so I've taken the liberty
>of scanning an old beat up copy of that article to my website here:
>http://www.tonydrews.com/OilPump0001.pdf .
>
>- Tony Drews
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