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Revision as of 05:58, 7 January 2013

Datsun 1200s came with a traditional 3-speed fully automatic transmission. This was the JATCO 3N71B, as used in most Japanese cars in the 1970s. It is a very reliable transmission, typically not needing any service for 10 years or 100,000 miles. The car body is different in the tunnel area: Automatic-equipped cars had a significantly larger front tunnel area. The rear of the tunnel is the same.

Overview

Early Datsun 1000 was fitted with 3N71, and later 1000s were fitted with the revised 3N71A. Datsun 1200 was only fitted with 3N71B.

Cars with automatic weighed 75 pounds more than standard cars. All automatic 1200s have a small shift Console box.

Identification by ID plate: B110...A means an originally Automatic equipped car. Only sedans and coupes were fitted with autos. Wagons and Trucks (B120) never got them.

A side effect of this larger tunnel means an auto-equipped 1200 is the perfect donor for engine transplants. Larger transmissions fit more easily e.g. 63a B210 5-speed, L-series engine transmissions or CA18, SR20 transmissions.

See: Manual transmission conversion

JATCO stands for Japanese Automatic Transmission Company. JATCO was a joint venture between Nissan and Mazda, both owning 50%. The JATCO unit is very similar to a Ford C4 and almost bulletproof, the only thing that seems to go wrong with them is that (rarely) vacuum modulator diaphram ruptures and ATF gets sucked into the intake manifold, causing them to not shift right and the engine to billow clouds of oil smoke.

Apparently there never was a 4-speed auto available for the A series. 4 speed autos didn't show up until the mid 1980's, by then Nissan had stopped using the A series in any great numbers to make it profitable to do the design and engineering. See L4N71B Swap for more information.

The 3-speed automatic is less efficient than the 4-speed manual for two main reasons:

Some loss of power due to the fluid coupling (Torque convertor). This means top speed is a few mph less. Newer transmissions starting in the 80s overcome with with "lockup" gears
One less gear. 1st gear in the auto is fine, but there is a big RPM drop going into second. Just as with the manual 3-speed Transmission

Gas Station Information

The rotating torque converter drives the front pump in the trans & circulates oil through the trans & converter. Keep checking the oil level while idling & top up as per the book.

Lubricant: DEXRON ATF (automatic transmission fluid).

IMPORTANT: Check HOT. Not cold. This fluid expands a lot with heat.

Usage

1972 USA Owners manual (see pages 16-17):

[Use "D"] for most city and highway driving.

Fluid

Automatic T/M Fluid: Type DEXRON (3N71B A/T)

From Daily Care page of the Owners manual, these were recommended:

CHEVRON A.T.F.
ESSO A.T.F.
MOBIL A.T.F. 220
SHELL A.T.F. DEXRON
SUNOCO Transmission Fluid DEXRON Type
TEXACO Texamatic Fluid DEXRON

Any DEXRON compatible will work, including:

DEXRON 6
DEXRON III/MERCON

The bottle should say something like "Suitable for use in applications calling for DEXRON". Back in 1971 there was only one type. Now it has been superseded by Dexron VI (Dexron 6).

Badges

Auto-equipped 1200s came with a 'Nissan Full Automatic' badge:

See: Badges

Performance

You can use the same methods as with any automatic transmissions:

A specialty transmission shop can modify the converter to a higher stall, for faster acceleration. NOTE: if it's a khanacross/motorkhana car, you won't want ANY STALL at all. The stall means it won't move until the engine revs up, which is good for drag racing.
If you want to favor low-speed operation, fit 4.10 gears from the 1200 wagon or ute to your coupe or sedan
No lockup converters are available. This generally takes a different transmission design. It would only help high-speed running anyways, it wouldn't help to make the car accelerate faster

Discussion: Race cam 1 with an automatic?

Identification

Identification by Chassis ID plate: B110...A means an originally Automatic equipped car.

Identification by transmission ID tag: is bolted to the right side of the transmission, next to the shifter linkage.

First digit: Year 0=1970, 1=1971, etc.

Second digit: Month 1-9, X=October, Y=November, Z=December

Last five digits: Serial number for given month

Wiring

1200s with automatic transmissions have slightly different wiring than manual transmission cars.

Also see: Manual transmission conversion

places

photo

Inhibitor Switch

There is an Inhibitor Switch on the exterior of the transmission linkage.
Inhibitor Switch

Nissan 31918-X0185 Switch Inhibitor $76.67 USD
fits many including:
* Datsun B110 "1200"
* Datsun B210
* Datsun B310 "210"
* Datsun 510
* Datsun 720 Truck
* Datsun 910 "810/Maxima"
* Datsun S110 "200SX"
* Datsun S130 "280ZX"

AFTERMARKET Neutral Safety Switch
Duralast JA4084 $95 at autozone.com
Airtex/Wells 1S5497 replaces:
* 31918-X0101/31918-X0103, 31918-X0185/31918-X0187

The Inhibitor Switch:

prevents the starter from engaging unless the shifter is in Park or Nuetral.
engages backup light circuit when shifter is moved to Reverse

Reverse Lamp Wires
Red or Red/Black (R or RB)

Park/Nuetral Starter Inhibit Wires
Black with Yellow stripe or Black/Red (BY or BR)

Inhibitor Wires generic
* Starter circuit: two BY wires (black with yellow stripe)
  Should have continuity only in P and N position
* Reverse lamp circuit: two RB wires (red with black stripe)
  Should have continuity only in REV position

Inhibitor Wires 1972 USA
* Starter circuit: two BY wires (black with yellow stripe)
  Should have continuity only in P and N position
* Reverse lamp circuit: two R wires (Red)
  Should have continuity only in REV position

Inhibitor Wires 1973 USA With Nuetral Relay
* Starter circuit: two BR wires (black with red stripe)
  Should have continuity only in P and N position
* Reverse lamp circuit: two R wires (Red)
  Should have continuity only in REV position

Kickdown Switch

Kick-down Switch on the Accelerator Pedal, activates the Downshift Solenoid on the transmission. The latter is located on the left rear of the transmission case. This causes a shift down to the next lower gear (within certain vehicle speeds) when the pedal is push almost to the floor (7/8 or more pedal travel).

NOTE: this means Datsun 1200 does not have a mechanical kick-down rod from the carburetor like many cars.

Kickdown switch and striker plate in Red

3rd-2nd Kickdown is possible below 80-90 kph (50-56 mph)
3rd-1st or 2nd-1st Kickdown is possible below 40-50 kph (25-31 mph)
Nissan 31941-X0102 ASSY-SOLENOID,DOWN SHIFT $98.83 USD
- replaced 31941-X0101

NOTE: The speed is sensed by RPM of the input shaft, and is internally set to match a Datsun 1200 with stock gearing and tire diameter.

Shift Speeds

The speed is sensed by RPM of the input shaft, and is internally set to match a Datsun 1200 with stock gearing and tire diameter.

Shift specs are indicated below. RPM is of the propeller shaft (driveshaft): Kick Down (0 mm vacuum)

D1->D2 @ 1840-2340 RPM
D2->D3 @ 3340-3840 RPM
D3->D2 @ 3460-2960 RPM
D2->D1 @ 1790-1290 RPM

Half Throttle (200mg vacuum)

D1->D2 @ 330-830 RPM
D2->D3 @ 1720-2220 RPM
D3->D2 @ 1350-850 RPM
D3->D1 @ 1350-850 RPM
D2->D1 @ 700 Maximum RPM

Full Throttle

D1->L1 @ 1860-1360 RPM
Reduce speed by shifing from "D" position to "1" position (output shaft 2000 rpm)

Minimum Throttle (450 mm vacuum)

D1->L1 @ 1860-1360 RPM
Reduce speed by shifing from "D" position to "1" position (output shaft 2000 rpm)

Vacuum Diaphragm

The vacuum diaphragm (a.k.a modulator) is on the left center portion of the transmission case. Engine vacuum from the manifold is connected to this, and enables the JATCO to shift harder or softer depending on the engine load.

Be sure this is connected, and the hose is in good condition (still flexible). Inspect the ends of the hose carefully because this is the first place it will crack, thus creating a vacuum leak.

If it is not connected, shifts will always take place as if the throttle is floored (hard shifts).

If the diaphgram is leaking (won't hold vacuum) it will probably leak transmission fluid into the engine, creating smoke.
Modulator: Rockauto.com

AIRTEX Part # 7R1015 {#TM45}
STANDARD MOTOR PRODUCTS Part # TM34
Nissan 31931-H0101 ASSY-DIAPHRAGM,VACUUM $59.75 USD

Connection to intake manifold:
[http://datsun1200.com/uploads/newbb/thumbs/174_4e1162f307531.jpg]

Interchange

Datsun B10 & earlier B110 used the JATCO 3N71A trans while the later B110 & B210s used the Jatco 3N71B. This JATCO is a shared design used by Nissan, Mazda, Subaru, Isuzu, Suzuki, BMW, Volkswagen, and Land Rover.

Larger Datsuns earlier than the 1200 used Borg Warner 2-speed automatic transmission. For the 1971 model year, across the Datsun range a switch to the better JATCO 3-speed automatic was made.

A12 JATCOs are air-cooled and have a grille on the bottom of the bell housing. A14 and larger autos are water cooled, and require the radiator to have transmission fluid cooler fittings.

Differences includes:

Converter housing (bell housing) to suit the engine
Torque converter spec. to suit the torque curve of the engine
Output shaft
B310 auto is 5-3/8 inch longer than B210 auto

Nearly every year something about the JATCO changed, sometimes a small change, sometimes a more significant change. However, generally you can swap transmissions.

L3N71A

L: Light duty
3: Three forward speeds
N71: Series
A: First revision

Hollander USA

Strict Interchange: Hollander #932 is for Datsun 1200 1971-1973.

quote: Our #931 fits. The different parts are the converter & converter hsg & output shaft length.
- Auto Trans Assy 31020-X2402. Datsun 71-76 510 & 610. 73-79 620 pickup. 74-77 710. 77-79 200SX.

Torque Converter: 927
- Nissan PN 31100-X0100
  Datsun 71-73 B110
  Datsun to 2/74 B210

Converter Housing: 928
- Nissan PN 31300-X0104
- 71-73 B110

Front Pump: 926
- Nissan PN 31340-X0101
- Datsun 71-79 (and probably newer) most (if not all) models

Part Numbers

Input Shaft

National 99166 Redi-Sleeve
- 1.647" x 1.654" x .445"
- http://www.rockauto.com/catalog/x,carcode,1208483,parttype,10065

Extension Housing Seal

http://www.rockauto.com/catalog/x,carcode,1208483,parttype,8624
Timken 710324 $4.05
National 710324 $5.83
- Oil Seal: Nitrile
- Shaft Size=1.378"
- Housing Bore=1.969"
- Outer Diameter=1.976"
- Width=0.433"

Filter Kit

ATP B61

Master Repair Kit

ATP NM1 (includes Contains Friction and Steel Clutch Plates, Gaskets, Seals, O-Rings and Sealing Rings) $108.99

Modulator

http://www.rockauto.com/catalog/x,carcode,1208483,parttype,8500
Standard Motor Product TM34 $34.79
Airtex 7R1015 or TM45

Pan Gasket

ATP NG2 or D37Z7A191A (14-bolt gasket) $1.68
Fel-Pro TOS18644 $3.37

Oil pump Seal

SKF 16489 (0338-19-223A, 31344X0102, 90311A0005)

Rear Seal

SKF 13907
SKF 99139 $24.89

Torque Converter Seal

Timkin 2025 (Viton) $7.67
National 2025 $10.99
- Oil Seal: Fluoroelastomers
- Shaft Size=1.654"
- Housing Bore=2.362"
- Outer Diameter=2.379"
- Width=0.276

Also see: Gearbox Mount

Conversion

Fitting Automatic

Automatic-equipped cars had a significantly larger front tunnel area. The rear of the tunnel is the same. For this reason you can easily convert an Auto car to a Manual car. Do go to automatic you may need to modify the tunnel.

If you convert your originally automatic 1200 to a manual, you will notice that you have barely any room between the gas and brake pedals and you have to do tip-toe driving to make it work.

Replace the auto pedals with its larger brake pedal with the standard setup that has small brake pedal and clutch pedal.

Here's all the parts you need to gather to fit an Automatic in a car that currently has a manual transmission:

'Bridge' the start inhibit wires that go to the auto gearbox
Replace the spacer in pedal box with clutch pedal (requires removal of dash and pedal box)
Knock out the clutch firewall hole blanking plate
1. In manual cars there are nuts welded from factory on the inside but autos don't. You can either put bolts and nuts thru the holes or weld some
Install clutch cable
Mount: either weld new mounts in or make a new crossmember
Replace gearbox and auto tailshaft with manual versions

The speedo cable is the same.

Gearbox mounts are different, but is the shifter hole in the tunnel is in the same place (the rear portion of the tunnel is the same).

Also see: Manual transmission conversion

4-speed Auto Swap

A [wikipedia:Jatco_4N71_transmission|4-speed JATCO L4N71] was made during the 1980s. The top gear is an overdrive ratio, for reduced revs at highway speeds. It also has a lockup system (3rd and fourth gears are direct) for fuel-economy approaching that of a manual transmission.

See the main article: L4N71B Swap

Shifter

Shifter came with a console.

Driveshaft

The automatic has a larger spline. So use the auto driveshaft with auto transmission. Remember that B110 and B210 Driveshaft is the same. The B210 and B110 driveshafts are the same length. Only automatic vs manual lengths are different.

Rear Engine Mount

The rear engine mount, also called the "transmission crossmember" is mounted about six inches further back.

or you could make your own

Part Numbers

Rubber Mount

11321-H1000 ASSY-INSULATOR ENGINE MOUNTING REAR Manual trans
11321-H1020 ASSY-INSULATOR ENGINE MOUNTING REAR Manual trans

Crossmember

11322-H1002 MEMBER-ENGINE MOUNTING REAR Manual
11322-H1020 MEMBER-ENGINE MOUNTING REAR Automatic

NOTE: B210 parts number are different from B110, but reportedly fit the same.

Engine Differences

Carburetor

For emission controls, the carb differed. However you can use any carb with an automatic.

Distributor

Auto cars had a different distributor curve for emission control. However you can use any distributor with an automatic.

Clutch Fittings

Automatic cars don't have:

Clutch pedal
Clutch master cylinder (LHD models)
Clutch cable (RHD models)

These parts can be swapped from a manual car.

Flex Plate

Automatics don't use a flywheel, the torque convertor has enough mass to act as the flywheel. They use a thin "flex plate" with has the ring gear teeth for the starter.

flex plate

Also note the crankshaft adapter.

You can use the flywheel off the A14 on the A15. The thing to look at is the back of your A15's crankshaft -- make sure it has the hole for the trans pilot shaft bearing.

オートマミッションオートマチックトランスミッション

Retrieved from "http://datsun1200.com/modules/mediawiki/index.php?title=Automatic_Transmission"

Automatic Transmission

Revision as of 05:58, 7 January 2013

Contents

Overview

Gas Station Information

Usage

Fluid

Badges

Performance

Identification

Wiring

Inhibitor Switch

Kickdown Switch

Shift Speeds

Vacuum Diaphragm

Interchange

Hollander USA

Part Numbers

Conversion

Fitting Automatic

4-speed Auto Swap

Shifter

Driveshaft

Rear Engine Mount

Part Numbers

Engine Differences

Carburetor

Distributor

Clutch Fittings

Flex Plate