Nissan / Datsun close ratio race gear box
- 56A four speed.

Ratios are:
1st = 2.1690
2nd = 1.5927
3rd = 1.2328
4th = 1

Have been lead to believe this is on of the original "shell sport" coupe gear boxes, as designed/built by Reg Cook in NZ - probably the last one still in existence.

Rebuilt one race meeting ago.

Being sold to finance a gear box for my new project.

I think you may find that this is actually an 'Option 2', 56 series gearbox. I think that they discontinued the Option 1 & Option 2 four speed gearboxes with the introduction of the five speed 56A & its competition stablemate, the Option 1 five speed.
I say this because I can find no reference to a 56A competition gearbox in either of my Competition Manuals, but the 56 series box appears in my 1200 manual.

The 56 series gearbox is defined by a smaller hole where the clutch cable fits into the bellhousing, & a larger, ball bearing, supporting the front of the cluster. The 56A used a closed ended Torrington neddle roller race to support the front of the cluster.

Thr first gear ratio of 2.169 in this box is exactly the same as the second gear ratio in a standard gearbox, so it really is a competition gearbox. If anyone wants to see what this would be like in a street car, then spend a day in some traffic using only second gear for takeoffs. This usually gets real old real fast.

I have heard of these Option 2 four speeds refered to as the 'Ultra Close Ratio' four speed. Hopefully it will find a new home with a caring & carefull owner.

P.S.
One was sold on ebay a few months ago in the USA.

Would these boxes be rated to withstand the torque from a hot A15?

Chris you won't find any reference in either Jap or US manuals for this box..it is as Brent has described a "Cook" gearbox which had custom machined gearsets for Shellport competition in NZ. As for strength they don't like high torque engines and are marginal behind A14s...

OK, now underkastumble !
He has retained the Option 2 ratios & I jumped to a conclusion. I'll give myself an uppercut. [ouch]
As you say, the high torque engines tend to worry the 56 series boxes, but they just lurve the high revving 1200's
Thanks for the info.

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