Hi, I have a Sunny Wagon Diff fitted with 14" wheels. I think it is a 3.8 ratio. A15 engine 4 speed Gearbox about 4000rpm @ 100 k/ph.
Acceleration is O.K. but a little loud due to the revs when cruising.
Is this what every one else gets?
Also what are the other ratios that will fit this diff? And which cars do they come from?

On the firewall of your Sunny should be a tag like the one in the picture below.





































This tag will tell you all that you need to know about what was originally fitted to the car & I expect that your tag will have the same mechanical details as this one.
The engine should be an A15, with a single [S] carb & it displaces 1488cc

The gearbox is a [F] floorshift [4] four speed [W] wide ratio [60] sixty series gearbox with the [L] long extention housing.

The differential is an H150b [code HB] in 3.7 to 1 ratio [37]
The H150 diff was used in Australian 120Y & Sunny models, however the ratio was 3.9 to 1 when used behind A12 & A14 powered models. H150's also came in a 3.54 to 1 ratio as well, but this seems not to have been used in any Australian models.

Only the last of the Australian Sunny Sportswagons got the A15 engines & the 3.7 to 1 diff ratio.
I have an owners manual for one of these A15 powered models & it says that the original wheels were 13" x 4-1/2" [steel] or 13" x 5" [alloy] & they came with either 6.15S-13 Bias ply tyres, [582mm OD] or 155SR-13 radials. [580mm OD]
What is the size of your 14" tyres? If they are larger in OD then this will raise the overall gearing resulting in a slightly reduced performance & a slow reading speedo. [you would be traveling faster than you think.]
The amount of performance reduction & speedo error will be dependant on just how much larger the tyre OD is compared to standard.

Quote:Yes, that's how my car is.

For this scenario: acceleration is OK but too high revs when cruising, the solution is a 5-speed. It will let you keep your acceleration, but reduce revs dramatically on fifth. On the other hand if you move to a 3.54 diff acceleration will suffer.

See 5-speeds, Engines and Diffs for 1200s?.

THANKS DODGEMAN FOR YOUR VERY INFORMATIVE ANSWER, A GREAT HELP, BUT UNFORTUNATLY (FOR YOU NOT ME) MY A15 IS IN A MORRIS MINOR NOT A SUNNY SO THIS PLATE IS NOT AVAILABLE. THE REASON I AM ASKING IS A "BLOKE" TOLD ME THAT YOU CAN GET A 3.6 RATIO FROM A DATTO 1000 THAT WILL FIT AND IT IS LIKE HAVING OVERDRIVE AS THIS WILL CRUISE AT A NICE REV RANGE, BUT I WOULD THINK ACCELERATION WOULD SUFFER? ALSO ON THE SUBJECT OF OVERDRIVE/5 SPEED DATTO BOXES, I HAVE HEARD THAT THE 5 SPEED's TOP GEAR IS THE SAME RATIO AS THE 4 SPEED & IT ONLY GIVES YOU ANOTHER INTERMEDIATE GEAR. IS THIS TRUE?

Thanks ddgonzal, I am studying the links you have sent me.

I think that "bloke" might be mistaken.

Quote:The differentials that were used in Datsun 1000's were the H145 type & came in 4.11 to 1 ratio for sedans & coupes, & 4.375 to 1 for Vans & Utes. There was also an optional 4.625 to 1 ratio for Vans & Utes & all these differentials used an alloy carrier.

The Datsun 1200 passenger models, & utes up to 1973 also used the H145 type. [utes subject to confirmation] The standard ratio for the passenger models was 3.9 to 1 while the ute used a 4.11 to 1 ratio. There was a factory option of 4.11 to 1 ratio for Wagons & I suspect that this was the ute diff. When this ratio was used in Australian 1200 Wagons, it's the alloy carrier that has been reported, so these were probably dealer installed 1000 model items. The 'definitive' 1200 differential used an iron carrier, but is interchangeable with the earlier alloy H145's

These differentials will fit into the later H150 axle housings, however the axle centerline will be 2.5mm [measurement subject to confirmation] too far forward & the axles will not run true & there is no ready remedy for this.

As for this 'bloke' & his 3.6 to 1 ratio from a Datsun 1000, ... tell him he's dreaming.

The Datsun 1200 & 120Y GX five speed option gearbox is known as a 56 series box & this one has a direct drive in fifth, so it is a true five speed.
The A14 & A15 engined models used the larger 60 series gearboxes & these were available as a five speed in some countries. Earlier examples came as a dogleg shift pattern while later examples used a conventional shift pattern. Both of these are overdrive types, so the first four ratios will be the pretty much the same as the four speed.
There is rumored to be a 'direct-in-fifth' 60 series gearbox, but no verifiable examples seem to have surfaced to my knowledge.

Some overseas models used the 63 series gearbox which is even larger & heavier, & these too are a five speed overdrive type.
ALL of these will fit the A series engines

NONE of these gearboxes were used as a regular option in any Australian Datsun model, although it would seem that a small number of Sunny coupes were sold in Australia with a five speed. This seems to have come about more by accident than by design.