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[Datsun 1200 encyclopedia]

Stumpy

Revision as of 21:30, 7 October 2017; view current revision
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Category: Transmission Modifications

Gearbox Swaps
 Types: 56 | 60 | 63 | 71 | 90 | R30 
 Transmission Swaps
 5-Speeds
 6-speed
 Stumpy
 Toyota 5-speed
 Manual/Auto conversion
 more: Transmission Modifications

A stumpy transmission is 26.3 inches overall length -- the same length as a Datsun 1200 transmission. The classic 'stumpy' is the 71B transmission from a Skyline, although there is a 63-series version commonly called a 'shorty'. These are the right length for a 1200, and the shifter comes up in the stock location, though obviously they are much larger around. There are 4-speed and 5-Speeds in this length.

Contents

71-Series

You can modify a "stumpy" gearbox to fit the CA, Z or L series front case. Then it bolts right in, shifter in the stock location for a 1200, and stock 1200 automatic driveshaft works too.

Also see main article: 71-Series Transmission

The stumpy Skyline gearbox commonly refers to the R30 Skyline Australia version with the L24 (six-cylinder) engine.

Stumpy Sources
* Skyline DR30 (FJ20 engine with 71B)
* Skyline HR30 (L24 engine with 71B)
* Datsun 720 pickup USA some models (71B)

Most Datsun transmissions are longer than a Datsun 1200 gearbox, so the shifter comes up 3 to 4 inches aft of normal.

5689.jpgAlbum click to view

The good news is you can use an L-series "stumpy" gearbox. It bolts right into the 1200, shifter in the stock location for a 1200, and stock 1200 automatic driveshaft works too. It will also fit other engines by swapping the front case with a CA or Z front case.

2118.jpgAlbum click to view

Stumpy Transmission

Plus: fits stock shifter hole and uses stock 1200 driveshaft (automatic driveshaft)

Minus: The 71B stumpy uses the same cluster as the 280Z 5spd, and while those are known for their durability, if the synchros are slight worn may not shift shift easily above 5,000 RPM. Solution if to replace the synchro rings AND the matching surface of the gears.

You need a CA20 or CA18 gearbox to get the front case which will bolt to a CA18.

To use the gearbox on a CA18, you must switch out the front section of the gearbox from a longer S13 gearbox, or a more common CA20 (e.g. 910 Bluebird Series 3) gearbox. There are conflicting reports about some of the swaps needing a different sized bearing to make this 'gearbox surgery' a success.

Beware: if the bearing doesn't fit right, the box will not last a long time. If the bearing is spot-on it can last for years behind a CA18DET.

  • 71B front case does not require a bearing swap
  • 71C front case needs the bearing modification
  • CA20E front case on a stumpy box doesn't require a different bearing
  • CA18DET front case on a stumpy box requires a spacer (or bearing change)

Bearing of 71B is smaller than hole of 71C case
2382.jpgAlbum click to view

Once modified, the "stumpy" transmission bolts right into the 1200, and the gearshift lever comes up in the right place. Other CA transmissions will require you to cut a new hole in the tunnel farther back.

See: Ca18DET and skyline 5speed install

If you wonder why people go for the stumpy 5 speed - here is a comparison photo between (from right to left) a 56 series (A12 gearbox) a 60 series (A14/A15 gearbox) and the stumpy 5 speed.
th_100_2710.jpg

Skyline DR30 transmission
th_ipodphotos243.jpg 22930.jpgAlbum click to view

North America

NOTE: custom "stubby" FS5W71B can be made from 26.3" FS5W71B. It can fit a variety of engine families by removing and swapping the front case

* Z-series - 1983 Datsun 720 4x4 with Z24 engine 
* SD-series - 720 with diesel engine
* L-series
* the rear case has no speedometer gear
th_83FS5W71Bshorttail001Large.jpg

Stumpy Transmission

Plus: fits stock shifter hole and uses stock 1200 driveshaft (automatic driveshaft)

Minus: The stumpy uses the same cluster as the 280z 5spd, and while those are known for their durability, they don't shift as nicely and don't shift easilty above 5,000 RPM.

The stumpy Skyline gearbox refers to the R30 Skylines with the L24 (six-cylinder) engines. The R30 came in sedan and hatchback styles.

You need a CA20 or CA18 gearbox to get the front case so that it will bolt to a CA18.

To use the gearbox on a CA18, you must switch out the front section of the gearbox from a longer S13 gearbox, or a more common CA20 (e.g. 910 Bluebird Series 3) gearbox. There are conflicting reports about some of the swaps needing a different sized bearing to make this 'gearbox surgery' a success.

Beware: if the bearing doesn't fit right, the box will not last a long time. If the bearing is spot-on it can last for years behind a CA18DET.

  • CA20E front case (71B) on a stumpy box doesn't require a different bearing
  • CA18DET front case (71C) on a stumpy box requires a spacer (or bearing change)

Once modified, the "stumpy" transmission bolts right into the 1200, and the gearshift lever comes up in the right place. Other CA transmissions will require you to cut a new hole in the tunnel farther back.

See: Ca18DET and skyline 5speed install

If you wonder why people go for the stumpy 5 speed - here is a comparison photo between (from right to left) a 56 series (A12 gearbox) a 60 series (A14/A15 gearbox) and the stumpy 5 speed.
th_100_2710.jpg

There is also a bearing swap that may need to be made when fitting a 71C front case. See photo below.

71C vs 71B front bearing
2382.jpgAlbum click to view

63-Series

Also see: 63-Series Transmission
* FS5C63A: Mid-close ratio for Z-series engines
* FS5W63A: Wide ratio for L-series and A-series engines

The 5-speed is commonly called the 'dogleg' box because it has a dogleg shift pattern. However, this is not a great identifier as several other Datsun transmissions have a doglog shift pattern -- like the 56A 5-speed which is the same length.

NOTE: 63-series 5-speeds came in both short and long lengths. Measure to be sure which one you are getting. The long version is 31.5 inches long.

  • 63-series 4-speeds can be identified by the removable pan on the bottom of the gearbox.
  • 63-series 5-speeds appeared starting 1976-1/2.
A-series Engine
* 1976-1978 HB210 (A14 powered B210) FS5W63A
L-series Engine
* 1977-1979 Datsun S10 (Silvia/200SX) 5-speed
* 1978-1979 Datsun A10 (Stanza/Violet/510) 4-speed
* 1978-1979 Datsun A10 (Stanza/Violet/510) OPTION 5-speed
* 1968-1973 Datsun 510 4-speed F4W63
* 1977-1978 Datsun 610 5-speed
* 1972-1973 Datsun 620 USA (early with L16 engine) F4W63
* Datsun 710 4-speed F4W63
* Datsun 521 with L16 engine has a shorty F4W63
  with flanged output shaft
Z-series Engine
* 1980-1981 Datsun A10 (Stanza/Violet/510) 4-speed
* 1980-1981 Datsun A10 (Stanza/Violet/510) 5-speed
Other
* J-series and R-series engines used F4W63, length unknown
  Bell pattern differs from L-series.
F4W63L (1976-1985)
* 1978-up A10 (510/Stanza)
* Bolt-on bottom pan but smooth main gear case 
  instead of the previous ribbed design

A14 FS5W63A comparo L20B FS5W63A
th_DoglegFS5W63AB-210and200sx002.jpg

Z20 5-speed
th_transNAPSdoglegmaybe80-81hl510three.jpg

S10 L20B 5-speeed (wide ratio)
1st 3.382
2nd 2.013
3rd 1.3121
4th 1.000
5th 0.854 
S110 Z20S engine (mid-close ratio)
1st 3.170
2nd 1.921
3rd 1.312
4th 1.000
5th 0.854

Do not confuse the shorty with a long-tail 63-series 5-speed:
th_transphatdaveunknownZtransmaybeMaxi.jpg

Interchangeability

71 to 71 front cases interchange. For example, an L-series 71-series front case can be used on a CA-series 71 series transmission.

63-series 5-speed transmission parts swap to other 63-series 5-speeds
* 63- 4-speed to 5-speed: Complete unit swaps. Parts do not.
* 63- L-series to Z-series: Front case swaps
* 63- A-series: Use JDM A14 front case
  or cut-n-shut