Nissan Oil Pump Replacement Solution for Skyline GTR Engine RB26DETT

Here is a novel solution to the Nissan Skyline Oil Pump Problem from Supertec Racing, based on the Spline drive oil pump from the Toyota Supra 2JZ-GTE motor, these guys have built a set of gears that will work with pretty much any RB oil pump out there. Including the Tomei, Jun, N1 77mm and OE Nissan 81mm oil pumps.
Spline Drive N1 Stock Jun and Tomei RB Oil Pumps
Supertec mentioned having supplied seven sets of these gears so far to customers that have been running them now for a few months, using them in drag racing engines like the RB26 and RB30 where some engines are producing in excess of 900 BHP and revving to 10k RPM as well as using launch control - zero issues have been reported yet.
Damaged Stock Nissan Oil Pump Drive
You'll recall the big killer of the stock oil pump on the Skyline is precisely hard rev limiter slams on the narrow contact patch - it's easy to see how a spline drive would solve this problem very effectively when considering, that with the splines you pretty much get contact of all splines equally distributing the force and you have the oil film between the splines as a damper as well. In most cases there are no issues with alignment during installation, you fit the pump to the block just like you would with an oem pump.
Supertec Racing is a registered trader on GTR.co.uk and has 100% positive feedback so far, you can reach them through register or on the Supertec Facebook page.
Jun Spline Drive fitted Oil Pump for RB Engine
Although they are not the first to try to solve this problem, Spool Imports has a Spline Drive Oil Pump solution as well, and the results of another forum members attempt to create a similar spline drive oil pump resulted in a number of issues discussed here - Supertec does seem to be having reported success with their solution so far.
Spline Drive Oil Pump on Nissan RB Crank Shaft
Below is the explanation of how this solution came to be, followed by the Splined Drive Gears Installation Manual from Supertec for the RB Engine.

"First of all I must say a big thank you, because if it wasn't for your article I would not have thought about the seriousness of the issue with the clearances on flat drives and tolerances between gears. I initially purchased a new R33/34 wide drive crank and some Reimax N1 gears and measured the clearances which were shocking 0.017 each side and very wobbly. Also the old OE Nissan pump which I took off and the narrow crank the actual contact points 3/16th looked very scary. Myself and a colleague took it upon ourselves to develop a spline drive solution based on what is used in a Toyota 2JZ-GTE engine a more robust solution."
RB26 Engine Rebuild Oil Pump Piston
1. Collar installation on to the crankshaft
Warning: before turning works, make sure the crankshaft lies in the workroom for at least 2 hours in order for it to be of the same temperature as the workroom. The collar and crankshaft measurement procedure must be performed at around 20°C temperature.

Grinding crank’s nose working order:
Grind RB26DETT Crank Nose
  1. Measure the diameter of splined collar’s hole using hole-gauge.
  2. Set the crank into lathe. Check the crank is fixed correctly between the front and rear turning spindle unit by the aligning of noses beating (whipping).
  3. Grind the crank’s nose (where oil pump mounts) for placing of splined collar, supplying pre-load of 0.08 mm. Make a fillet in the place of transition between crank’s nose and splined collar’s neck (Picture 1, figure I).
  4. Remove the chamfer in front part of alighting crank’s neck (Picture 1, figure II).
  5. Remove the chamfer on the inner side of the collar under the adjacent surface of the fillet.
For the correct and convenient installation of collar you must make a mandrel with inner hole diameter of 35mm. The installation of collar must be performed under the heating of 400°C temperature – visually the metal will start being red slightly.
Crank Grinding Nose Diagram Instructions
Picture 1
Sequence of collar installation
  1. Heat the collar in the high frequency current equipment (RF current). If you don’t have one you can use gas burner but the heating must be applied from all sides equally. Watch the collar going red cautiously, don’t let the drawback (softening) happen.
  2. Put the collar on the prepared crank’s nose (neck) using forceps. With the help of mandrel and hammer make sure the collar fitted correctly. Cool the crank.
    Warning: it is prohibited to cool the crank using water or oil.
  3. Inspect the collar’s work surface for seal and make sure there are no nicks or asperity, if necessary finish with sandpaper on a lathe.
RB Crank Collar Installation of Oil Pump Drive

RB Crank Oil Pump Drive Spline Installed
2. Installation of gears into the oil pump
Important: in order to have a minimal clearance between gears and case you have to buy a new oil pump case.
  1. Disassemble the oil pump case (in order to loose screws in the rear cover, a local heating of screws’ caps is required by using gas burner as they are fixed by clamp).
  2. Remove stock gears from pump.
  3. Lubricate installing gears with engine oil before putting them in the oil pump case.
  4. Install gears with markers to the rear cover of oil pump (Picture 2). The notch of the big gear (with sharp angle) must be directed counterclockwise (except Tomei pumps).
  5. Check the rotation of the gears inside case. There must be no sticking or biting of gears.
  6. Install the rear cover of the oil pump.
  7. Evenly torque screws in cover (preliminaryly apply the screw-thread fixator) with 3.7-5.0 Nm (0.4-0.5 kg/m).
  8. Check the gears are rotating in the case normally. There must be no sticking or biting of gears.
Spline Drive Oil Pump Gears
Picture 2
Alignment
Note: Before the final oil pump installation it is recommended to set it up on a cylinder block without seal and visually check clearances uniformity between the crank’s collar and small oil pump’s gear. If oil pump’s gear will be clamped in one side of the collar, you have to drill two guiding holes (7mm) in the oil pump case (holes guiding block/pump case). Also, you need to make a mandrel to align (center) the oil pump relatively to the crank. Install the oil pump with mandrel to the block and tighten the screws. Remove mandrel and set the seal.

Lastly, here's a couple of photos showing measurements on the crank and collar clearances for the Reimax Gear and Drive set on an RB26 crankshaft:
RB26 Crank Collar Clearance Gauge
RB26 Oil Pump Drive Dimensions 40.72
RB26 Oil Pump Gear Dimensions 41.38
RB26 Oil Pump Drive Gear and Crankshaft Clearance Chart