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Triumph TR3 FAQ page

TR3/4 Oil pumps

Does anyone have a supplier, who can actually supply 'good/high' quality oil pump, spindle & rotor assemblies? (504862) I fitted a new assembly 1,500 miles ago, and the spindle journal, closest to the rotor, is severely scored and has worn down about 0.002" in diameter! The shaft material looks awfully soft to me as well which, obviously wouldn't help! Yet I have some original pump assemblies that don't have a mark on the spindles? Anyone else come across this drama before me?

Thanks in advance
Kind Regards
Peter Vucinic

There was a rash of true stories out of England about 1993 where TR drivers suddenly lost all oil pressure. They all found that the lobe piece that is attached to the pump drive spindle was not pinned as on the original pumps were and as we see in the exploded view in the parts catalogs. It was only held on by some knurling that had been done on the shaft to save pinning it. The knurling failed and the drive spindle was still turning - but not the lobe part at the bottom. Hence no oil pressure.

In 1987, I had bought a new pump while in England and so about 1995, I took off my oil pan to check. There was no pin. I bought a new pump with the assurance from a major TR parts supplier in eastern US that it had a pin. When it came, it had no pin.

So I took things apart. The knurling was about 0.0015" deep on both the drive spindles. The shaft where it is supported by the bushing was worn about 0.002". The bushing was not worn so it went back in. If you think about it, you can't knurl a hardened steel shaft. So they use soft shafting and leave it soft. I checked the hardness and couldn't even get a reading on the Rockwell "C" scale. It was only on the "B" scale that I got a reading. So it was ordinary mild steel shafting.

Where to these chips from the wear go ????? I checked the babbitt on the bearing shells and they were scored so I replaced them.

Next, I bought a 12" length of 1/2" diameter hardened and centerless ground steel bar stock from a bearing supply shop for about $10.00. I checked it for hardness and it was Rockwell 60-62 on the "C" scale. I cut it to the correct length with a grinder cut-off wheel, used a grinder wheel that was thicker and ground in the off-set slot into the top end where it gets driven, ground through the hard outer shell on two opposite sides just where I wanted to put a pin through, pushed the lobe part on and drilled a hole through both parts in one shot and pressed a new hardened pin through both pieces. I peaned both ends of this pin with a center punch to make sure it wouldn't move.

And it's been fine for the last 8 years and over 50,000 miles of high speed highway touring. I have checked it again and there was no wear on the hardened shaft that I used. And I still have 8" of this hard shafting left to make 2 more.

Or find a reliable supplier who makes and sells the oil pump that has the original design with the hardened shaft and the cross pin. With wear on the soft drive spindle, the lobes will also wear because things are no longer parallel. With this wear, the oil pressure will drop somewhat with time. It did on mine. With the new hard shaft I put in, the oil pressure hasn't dropped any noticeable amount in 8 years.

Don Elliott, Original Owner, 1958 TR3A, Montreal, Canada

Because the manufacturers of the oil pump gears sets, (I believe they are marketed in the US as "county" brand) found the inner gears coming loose from the shaft was a problem, they began to install a pin though the rotor and the shaft about 6 or 8 years ago. We had one of those pins work loose and come out during engine operation and it consequently jammed the pump, which immediately sheared the slotted upper end of the drive shaft. The pump stopped turning completely at this point. The engine kept on running until it ran the bearings.

Previously, using original Triumph supplied pump rotors, two times I experienced the slot ears shearing off when there was no reason for them to fail except normal stresses of operation. This always stops the pump from turning. These shaft failures, I believe were cause by the shafts being too hard and consequently somewhat brittle. They were, and the new repro parts are also, machined with sharp corners to the drive slot in the top of the shaft. These sharp corners are stress risers that will help induce the beginning of cracks. We remachine the slots so that there is a full radius in the bottom, then glass peen the inside of the slot to remove the machine tooling marks.

As for the pin that is designed to keep the rotor from turning on the shaft, We found that the pin on the original gear is VERY hard to drive out, while the pins in the new gears are very easy to drive out. So we now remove all of the pins, tap the hole through the rotor and the shaft, and then loctite in a 3/16 allen set screw as a new "pin". Being loctited in with maximum strength retaining compound and screwed into place, it is NOT going to come out. With gears modified in this manner, we have experienced no failures, even in race engines turning over 7,000 rpm and pumping over 90 psi oil pressure.

Greg Solow

Hose size for external oil coolers.  This one is too small for its own page and this is the closest asociation I currently have:

-10 oil hoses are the size to use. The longer the hoses the larger in diameter they need to be. For a TR-4, -10 is large enough for most applications. You do not want the hoses to be a restriction to the flow.

Greg Solow

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