I bought an oil pump for my 1958 TR3A in UK in 1987 as I was starting my
restoration. I rebuilt the engine in 1990 but a few years later heard about
the repro pumps with no cross pin. They have very crude straight knurling
on the drive shaft to "secure" the lobed part. On many of these pumps, it
was reported that the knurling slips and you suddenly lose all oil
pressure - and you don't know why. So I dismantled mine to check it and
found it had no cross pin.
I checked the hardness on my original pump shaft and also on the repro. To
emboss the repro shaft with straight knurling, the shaft is only mild steel
and I couldn't even get a hardness reading on the Rockwell "C" scale, the
shaft was so soft. So I used my micrometer to measure the wear on the repro
shaft with about 20,000 miles of touring on it. The shaft had worn 0.003"
on one side of the OD where it is supported laterally by the bushing because
of the mild steel. The bushing ID was still fine so I reused it.
I went to my local bearing supply shop and bought a 12" length of
centerless-ground hardened bar stock (Rockwell C 60) with the correct OD for
about $12.00 and made a new drive shaft. I ground it to the correct length,
then ground a tang in the top end. Next, I ground through the surface
hardening on two opposite sides, cross-drilled it and put in my own cross
pin. Then I swaged the cross-pin in so it wouldn't come loose, and slide
sideways to score the other part of the pump.
I have driven my stock TR3A 80,000 touring miles with this pump and all I
had to do to the pump in 2006 when I rebuilt the engine again was to lap the
bottom cover plate of the pump to get the specified clearance. The
home-made shaft and cross-pin were still fine. I still have the original
bushing for the pump shaft with 181,000 miles on it from new.
I agree with Glen. I too believe all the original pumps were cross pinned.
You can see that in the S-T Parts Catalog.
Don Elliott, Original Owner, Montreal
----- Original Message -----
From: <fubog1@aol.com>
To: <N197TR4@cs.com>; <fot@autox.team.net>
Sent: Sunday, October 26, 2008 9:31 AM
Subject: Re: [Fot] Serious Question on TR3/4 Oil Pump Rotor Assembly
> Joe don't quote me but I'm pretty sure that they were all pinned.
> It's easy enough to pin the replacements. They also usually need to have
> the end float set, and a good edge-break on the tang end.
> Glen
>
> -----Original Message-----
> From: N197TR4@cs.com
> To: fot@autox.team.net
> Sent: Sat, 25 Oct 2008 7:09 pm
> Subject: [Fot] Serious Question on TR3/4 Oil Pump Rotor Assembly
>
> FoT
>
> There is a rotor assembly for sale on EBay and the claim is that is NOS.
>
> I asked, and it has no pin in the shaft & rotor.
>
> Is it not true that all OEM rotors were pinned?
>
> Recent aftermarket oil pump offerings may be the cause of recent
> catastophic
> failures. A little knowledge in this group may save others this grief.
>
> Joe A
> Fot mailing list
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