Finding this thread very interesting.....
I have a copy of:
Datsun B110 Competition Tune-Up Manual
published by Nissan Motor Co in 1974 (120Y just released)
In the chassis section they mention 3 gearbox for competition use.
Option 1 is a 4spd with ratios of 3.757, 2.169, 1.404, 1.000
Option 2 is a 4spd with ratios of 2.169, 1.908, 1.350, 1.000
Option 3 is for race use and a 5spd with ratios of 2.676, 1.691,1.398, 1.182, and 1.000

Thanks for the reply b110sss

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Is there a chance you had the "normal" Gx5 56A 5spd gearbox? It has a first gear of 3.757 but still recommended for rally and sprints.Even so, Its not the close ratio 56a 5 speed.

I've seen it now on a couple of occassions the gx5 5spd gearbox being sold as a "close" ratio gearbox(as is evident on start of this thread)
While they look similar on the outside,the have very different internals.

Or do you consider the nismo F5C56A (Close ratio 56A 5speed) first gear of 2.676 as an "extremely long 1st"?

Below are the ratios of the 56A 5speeds,

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Also would it be possible to get the internal pics of your gearbox before its finished?

cheers mate

Looks like i also added to the confusion hehe,,,I just edited my previous post.The mid close and ultra close 56 4 speeds were F4W56L not F4W56A.
56a 4 speeds were revised to be "abit stronger".
Which kind of explains the reputation of the 56L 4speed close ratio gearboxes...
So there was no 56A 4 speed close ratio gearboxes from datsun competition??

quote from tech wiki

F4W56A is the 1973-1/2-revised version of the F4W56L that was mounted on the B110 series. Modifications have been made on the following points to strengthen the gears and bearings, and to improve lubrication performance as well as noise and vibration proof at high-speed driving.

Strengthened gears and bearings: Although there is no change in the gear ratio, each gear has an increased width by 0.039 to 0.079 (1 to 2 mm) and the countershaft, front bearing and main shaft bearing are strengthened.
Improved lubrication performance: To ensure proper lubrication in the rear extension bushing, an oil dam is installed in the center of the extension.
Reference: Service Bulletin Vol. 188 "Introduction of New Model Datsun B210 Series" page 69, July 1973, Nissan Motor Co., Ltd. Tokyo Japan Telex: NISMO.

Not sure if this will add much to what has already been covered but my Dad ran a 1200 rally car with a Reg Cook 1298cc A12 and a close ratio 56a 4 speed (not ultra close). There was one or two gears that were straight cut. At the time-mid 80s when he got it off Cook no one knew who did the gears for him apart from the fact that the mans nickname was Herman the German.

He told me that it was a 120y box and it was stronger that the 1200 4 speed - I didn't know there was a difference between the two 56a boxes but back then most things were word of mouth. It never let him down but he always said it was the weak point of the drive train.

Dave, I am quite surprised at how reasonably priced this kit is and look forward to hearing how it goes!

Hi A12 Grunt,
Thanks for your input which is news to me as I was always of the understanding that the ultra close 56a box was a 5 speed.
I can't really add to what I have previously said- that box was very, very close in the ratios and had an extremely long 1st. I would have thought that it made sense for a really close box to have a big long first then that gives to ability to close all the ratios up in the rest of the gears but then I'm a wool exporter- not a mechanical engineer...
The box to the very best of my knowledge was all Nissan and I ran either a 3.9 or a 4.1 ratio diff.
Bettanty's actually only made the gearkit for the 60A box for Re Cooke- one of 5 only ever made for him.
There are a number of other mods that Cooke did to this box including selector forks.
The box is presently out waiting for my mechanic to put it back together.
The cluster is all 1 piece with 2 helical gears at each end and 2 straight cut gears in the middle.
Hope this answers all you need to know.
Cheers
Dave

B110SSS,

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Just abit of clarification so not to add to the misinformation about the 56a 5speed gearboxes already..
There was never an "ultra" close ratio 56A 5spd offered from datsun competition/ nismo. However there was a mid close and ultra close 56L (F4W56L) 4spd gearboxes offered.

Did u mean a 56a 5speed with a custom ultra close gearset?

what were its gear ratios and what diff ratio did u run with it? Doesn't make sense for an "ultra" close gearbox to have a "huge first gear".

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is this bettany 60a gearbox already in your car or is it being reconditioned/built?

as for the 60a gearbox,that bettany gear info you gave is priceless.Might go down that route with my 60a gearbox. How much did the custom mainshaft gears cost? Im hoping helical gears will be cheaper as i wouldn't want to run straight cut gears on a street car.

I'm also eager to know if the cluster is a one piece machined item or custom gears welded onto the shaft.

Rallytwit,

If possible enquire if bettany gears can get the 60a gearbox to a direct fifth gear 1:1
Would be more efficient than an overdrive for your application.

cheers

I sent an email to Bettany, hopefully I will hear back shortly. The current plan of attack is to see about changing 2nd in the 60 series or if that's not possible going to a 4.60 rear gear will getting the fearing low enough to make the stock ratios work OK.

Tom

Hi Tom,
I believe that years ago Bettany's made a 4spd c/r 56 kit for Reg Cooke so you may be in luck.
Cheers
Dave

Yes, straight-cut gears are weaker than helical gears, but they stress the case less

The best ones are forged billet countershaft with integral gears. 2nd best is the splined countershaft. Gears keyed to the shaft is the weakest design

Dave thank you for the source; that price is around $1000 US. I found an email address for them so I will contact them straight away. The 60 series ratios are such that s the only thing to change I really needed would be 2nd gear. I assume he also did the mainshaft gears as well. Per chance did you check on simply having straight cut gears done up for the 56 series box, or are even those weak?

Tom