RB26 Oil Pump Info

[Allan74]

Here are outer diameter Gear Sizes for all common 2pc gerotor RB26 Oil Pumps:

N1..............77mm x 11mm (sintered metal)
STD............81mm x 11mm (sintered metal)
Nismo..........77mm x 11mm (hardened steel)
Greddy/Jun...81mm x 12mm (hardened steel)
Reimax........85mm x 12mm (hardened steel)
HKS............88mm x 12.4mm (hardened steel)
Tomei - Large 3pc gear set, not comparable to other pumps (hardened steel).


Replacement Gears, using your old housing (N1 or STD)

1) Build your own Nismo-like Pump set (you replace gears). $550 USD
http://www.rhdjapan.com/reimax-oil-pump-gear-kit-skyline-gt-r-rb26dett-54021
77mm or 81mm x 11mm

2) Build your own Greddy/Jun-like Pump set (you have to send pump to them for machining/fitting of 12mm gearset). $675 USD
http://www.rhdjapan.com/reimax-reinforced-and-capacity-up-oil-pump-gear-kit-skyline-gt-r-rb26dett-59391
77mm or 81mm x 12mm


***I specified RB26 in this post, because I am not sure of the measurements of STD RB20 and RB25 Pumps.

[Terrh]

so with the reimax gears you have to use the N1 or Nismo pump to start with? because the outer gear diameter is smaller.

[Allan74]

so with the reimax gears you have to use the N1 or Nismo pump to start with? because the outer gear diameter is smaller.

NO. The Reimax gears are meant to raplace EITHER the 77mm Gears from an N1 pump, or the 81mm Gears from a STD Pump.

Reimax offers 2 sizes, as above. 77mm or 81mm depending on the size you need.

[M13]

Hmm... Allan you make a good point.

I want to refresh my bottom end this summer, and wondering if I should just order reimax gears and re-use my housing (kinda iffy about it because it's old and dirty) or just order, STD and Reimax. It'd cost me 300-400 more the second route but I'd be using a new/fresh part, while I don't think I've ever seen an oil pump housing crack/break. Are the crank seals separate from the pump or built in?

[Allan74]

Dirty on the outside is fine. I bet you will be pleasantly surprised to see how well it looks inside, once you open it up. Crank seal is a replacement part on the front of the pump housing.....cheap....

I have a STD pump here that at first glance, looks like shit, but it's shiny on the inside. Looks can be decieving (on the outside).

[M13]

Dirty on the outside is fine. I bet you will be pleasantly surprised to see how well it looks inside, once you open it up. Crank seal is a replacement part on the front of the pump housing.....cheap....

I have a STD pump here that at first glance, looks like shit, but it's shiny on the inside. Looks can be decieving (on the outside).

True, and I can always just clean the exterior. I was just more concerned about internal gumming up/varnish coating, etc. Reimax it is. You can always sell the gear down the road too. mmmmm


If it were 79mm VS 81mm, I would have gone with N1, but 77 mm O.D vs 81 is just too much metal thickness difference to skimp over.

[Allan74]

....and find a 0.5mm washer to shim the relief spring with ;) VOILA !

The Tomei shims I have for my pump are about 0.5mm each.....so maybe 1mm is a bit much for a STD pump, but .5 would be perfect.

[M13]

....and find a 0.5mm washer to shim the relief spring with ;) VOILA !

The Tomei shims I have for my pump are about 0.5mm each.....so maybe 1mm is a bit much for a STD pump, but .5 would be perfect.

Do you want to take a pic and some measurements? I want to put .5 or .75 for my newly refreshed pump.

[Allan74]

I can try.....but I can't promise clarity. No decent cam yet. Not a high priority yet.

[M13]

I can try.....but I can't promise clarity. No decent cam yet. Not a high priority yet.

just a rough pic, dimensions should be fine. I'm getting SS anyways.

[Allan74]

wait...what is it you want pics and measurements of ?

[mcfly]

what pump casing flows better, n1 or oem

[Allan74]

what pump casing flows better, n1 or oem

I deduce......

Nismo pump uses an N1 housing. Nismo list itself as NO IMPROVEMENT over STD Volume.

Therefore:

I would say it's up in the air.

[M13]

wait...what is it you want pics and measurements of ?

teh washer.