Help! 1981 Datsun 720 King Cab Transmission

[Mulch]

I became the new owner of a 81 king cab 4x4 that has a 0 mile rebuilt z22 engine but no transmission. Are there any 5 speed transmissions that are direct bolt ons and if so what vehicles are they from? I have access to a 4 speed 720 transmission, would that fit and if so would I even want to put in a 4 speed when it should have a 5 speed?

[]2eDeYe]

Welcome :)
 

Is the transfer case there?

[datzenmike]

1/ the 720 had three different series of engines.The L20B the Z20/Z22/Z24 and the SD22/25 diesel.

L20B........................... '80

Z22............................. '81-'82

Z20 and Z24.............. '83-'86.5

SD 22 and SD25........ '81-'86.5

 

2/ As they are*, the L20B and the SD (diesel) transmissions won't bolt to your Z22 but the Z20 and Z24 ones will.

 

3/ You are lucky as a 2wd transmission will work in a 4x4 but not so well the other way round. This is because there is no speedometer drive in a 4x4 transmission, it's in the transfer case.

 

4/There were two 5 speeds, identical, but for their length. If buying one, it would be best that it match yours for length. They were 26." and a 31.5" long. So find out.

 

 5/ Four and 5 speeds. (this applies to 4x4s as well) Five speeds were an option on L20B and Z22 engines but there were no 4 speeds on the Z20, Z24 and the SD diesels, in fact there were no 4 speeds after the '82 model year. There's nothing wrong with a 4 speed and it will bolt to your Z22 if.... 3/ is the same length. If you do a lot of highway driving a 5 speed would be nice, but not required. It's really meant to lower highway RPMs and save a little gas. It does NOT make you go faster.

 

6/ Other Z series transmissions are the '80-'83 S110 200sx car. These are all 31.5" long.

 

7/* What makes a transmission fit your Z22 is the front case with the engine bolt pattern. So if you have a 4 or 5 speed front case you can swap it onto an entire host of other 71B transmissions and 'convert' it to a Z series. Say you find an old destroyed 4 speed for nothing. You remove the front case and save it. Later you find an '85 S12 CA20E transmission. You put the Z series front case on and now it fits your Z22. Doner vehicles with the 71B transmission are...

 

31.5" long

'78-'80 810

'81-'84 Maxima

'80-'83 S110 200sx

'84-'86.5 S12 200sx

'77-'78 280z

'79-'83 280zx

'77-79 620 truck

 

Could be 31.5" or 26"

'80 720 truck L20B engine

'81-82 720 truck Z22 engine

'83-'86.5 720 truck with Z20 or Z24 engine.

'81-'86.5 720 truck SD22 or 25 diesel

 

 

 

[Mulch]

3 hours ago, datzenmike said:

1/ the 720 had three different series of engines.The L20B the Z20/Z22/Z24 and the SD22/25 diesel.

L20B........................... '80

Z22............................. '81-'82

Z20 and Z24.............. '83-'86.5

SD 22 and SD25........ '81-'86.5

 

2/ As they are*, the L20B and the SD (diesel) transmissions won't bolt to your Z22 but the Z20 and Z24 ones will.

 

3/ You are lucky as a 2wd transmission will work in a 4x4 but not so well the other way round. This is because there is no speedometer drive in a 4x4 transmission, it's in the transfer case.

 

4/There were two 5 speeds, identical, but for their length. If buying one, it would be best that it match yours for length. They were 26." and a 31.5" long. So find out.

 

 5/ Four and 5 speeds. (this applies to 4x4s as well) Five speeds were an option on L20B and Z22 engines but there were no 4 speeds on the Z20, Z24 and the SD diesels, in fact there were no 4 speeds after the '82 model year. There's nothing wrong with a 4 speed and it will bolt to your Z22 if.... 3/ is the same length. If you do a lot of highway driving a 5 speed would be nice, but not required. It's really meant to lower highway RPMs and save a little gas. It does NOT make you go faster.

 

6/ Other Z series transmissions are the '80-'83 S110 200sx car. These are all 31.5" long.

 

7/* What makes a transmission fit your Z22 is the front case with the engine bolt pattern. So if you have a 4 or 5 speed front case you can swap it onto an entire host of other 71B transmissions and 'convert' it to a Z series. Say you find an old destroyed 4 speed for nothing. You remove the front case and save it. Later you find an '85 S12 CA20E transmission. You put the Z series front case on and now it fits your Z22. Doner vehicles with the 71B transmission are...

 

31.5" long

'78-'80 810

'81-'84 Maxima

'80-'83 S110 200sx

'84-'86.5 S12 200sx

'77-'78 280z

'79-'83 280zx

'77-79 620 truck

 

Could be 31.5" or 26"

'80 720 truck L20B engine

'81-82 720 truck Z22 engine

'83-'86.5 720 truck with Z20 or Z24 engine.

'81-'86.5 720 truck SD22 or 25 diesel

 

 

 

 

Great information. Thank you. I purchased a 4 speed transmission from a 81 4wd 720 off of Ebay before I realized that a 5 speed is what is supposed to be in the truck. Since the donor truck is the same year and also a 4wd it should just bolt right in correct? I have the engine, divorced transfer case, and both drive shafts but none of them are installed on the truck. Without them in place is there any way to find out what length transmission (26 or 31.5) that I am supposed to have? 

[datzenmike]

The truck might have had a 5 speed but it doesn't have to have one. It was an option.

 

The 4 speed will work if the lengths are correct. I think only the 5 speeds could come in the 26" length so it will be 31.5" long.

 

 

This short driveshaft to the transfer case would work with the longer 31.5" transmission.

 

 

 

 

This longer driveshaft to the transfer case works with the shorter 26" transmission.

 

 

Sorry I can't say what 720 got the short or long transmissions or why.

[datzenmike]

Have a look at the VIN or maybe the driver's door plate or the engine plate on the inner fender under the passenger side hood hinge. Look for his grouping of letters...  KMLY 720 FU

 

This would be a king cab Z22 engine left hand drive 4x4 720 DX (long wheelbase) and the F would denote a five speed installed when built, (a T is for 4 speed)... U is federal emissions.

[Mulch]

I just went out and checked and I have the shorter drive shaft. I also ran out and checked the truck but its raining and wasnt able to be too thorough. The only plate I could find was the one with my vin number JN6MD06Y8BW

[datzenmike]

Before '82 manufacturers made up their own VIN and there was no standardization. From around '82 on there was the 17 digit VIN.

 

J..... made in Japan

N.... Nissan?

6........truck

M......... Z22

D......... truck

0......... model change.

6........... king cab

Y............ 4x4

8........... check digit

B........... 1981

W........... Kyushu plant

[Mulch]

Do you know if all the 4 speed transmission were standard lengths and if so were they 31.5 inches or 26? I know the truck is a 81 4x4 DX and thats about all I know. I now own 9 vehicles but I'm mainly a vw guy. This is my first datsun so apologies for any amateur questions. To be honest until last week I didnt even know what a datsun 720 was. A kid from oriellys saw that I had some motorcycles and the truck is what he had to trade. So I traded 3 not running motorcycles and a not working winch for the truck. I paid $280 for the motorcycles and he was trying to sell the truck for $800 so I traded. 

[datzenmike]

I've never heard of a shorty 4 speed. Not that there aren't any just I don't think there are.

[Mulch]

So i need a 31.5 inch transmission and the 4 speed ebay transmission I bought that didnt list a length is more than likely 31.5 inches and should bolt right in? The only difference Inbetween my truck and the ebay parts truck that I see is that mine is a king cab and the ebay one is a standard. Thanks again for all the information.

[hensleyd13]

On 1/11/2019 at 8:57 PM, datzenmike said:

The truck might have had a 5 speed but it doesn't have to have one. It was an option.

 

The 4 speed will work if the lengths are correct. I think only the 5 speeds could come in the 26" length so it will be 31.5" long.

 

 

This short driveshaft to the transfer case would work with the longer 31.5" transmission.

 

 

 

 

This longer driveshaft to the transfer case works with the shorter 26" transmission.

 

 

Sorry I can't say what 720 got the short or long transmissions or why.

Is there a part number on the shorter shaft.

 

[datzenmike]

Early or late? The early were smaller diameter, '83s and on were larger diameter tube.

[hensleyd13]

6 minutes ago, datzenmike said:

Early or late? The early were smaller diameter, '83s and on were larger diameter tube.

Early 81

[datzenmike]

37100-41W00 about $650 at dealer. Better check for one in a wrecking yard.

 

Is yours missing? Only thing that wears on them are the two U joints and they are replaceable. 37124-P3000 take ths number with you and go to NAPA or any auto supply store and they can look it up. Probably around $30 each. Good ones have grease fittings.

[hensleyd13]

Problem is no availability on a 26in bought it with a countershaft blown out in the 26 went to wrench yard they had a 78 620 with the 31.5 so I snagged it for cheap with 620 drive line drive line is to short other to long

[Crashtd420]

16 hours ago, hensleyd13 said:

Problem is no availability on a 26in bought it with a countershaft blown out in the 26 went to wrench yard they had a 78 620 with the 31.5 so I snagged it for cheap with 620 drive line drive line is to short other to long

I dont think it's a lot to have them lengthened or shortened....

Take some measurements and see what a local driveshaft shop says.... 

[powderfinger]

19 hours ago, hensleyd13 said:

Problem is no availability on a 26in bought it with a countershaft blown out in the 26

 

Are you saying you have a short shaft transmission with a bad countershaft bearing? If so, just fix it. It's an easy repair. It would likely be easier to find the longer intermediate driveshaft to match the short transmission since most later model 4x4 trucks I have seen have the short transmission.

Edited September 6, 2023 by powderfinger

[datzenmike]

Every gear but fourth transmits power through the counter shaft bearing so they are the first to get growley. It's the bottom front ball bearing. All that's needed is a 12mm ratchet, snap ring pliers, gear puller and some Permatex Blue sealer. 

 

 

 

The pre '85 bearing is 56mm and part number 32219-E9000. The '85 and '86 bearing is a larger 62mm and is part 32219-V5201. If not sure measure the bearing hole on the front transsmision case.

 

[Stoffregen Motorsports]

Any driveline shop can build a new shaft from parts, and they are usually around $250-$300 each, if you are just using U-joints (not a double cardan CV).

 

Most metro and even some rural areas have driveline shops. If you're in an agricultural area, there is definitely one nearby.

[hensleyd13]

So to fill anyone that's been reading and replying I got the drive line built for100$ at the only local shop in Okanagan that does drive lines used 620 trans works great with only a little modification to the shifter and trans mount. I currently still need to order a bearing kit and synchro kit for the original trans for later use. I custom cut d21 jumper seats to fit. With help from you guys it runs it drives thank you guys it still has quite a bit to do 4×4 still not hooked up the driver cv is broken at the outer joint I've fully come to terms I bought a toy that I want to daily drive any leads on that cv ?

[hensleyd13]

Oh as for the original trans it's the 62mm bearing

[datzenmike]

Only available from '85 in the 720 with Z series transmission (the SD25 diesel also used it) and the S12 with CA series engines. These were the only two vehicles in '85 to have a 71B transmission.

 

The 71B started in '71 on the 240Z and progressed to a 5 speed in '76. It's been around and it's been improved as well over the years. Lots of changes in '80 and the change from 56mm to 62mm counter was one of the last things done. The 71C kept the 62mm bearings and was very much different inside than the 71B. The earliest 71C was in the '84 300zx.  

[hensleyd13]

So I'm pretty sure it's a 71c and the bearing cover was blown up the counter main blew up and on further removal found the center bearing along with a blown out synchro I'll post a pic of that tomorrow it's the same as previous just more broken.

[datzenmike]

 

The 71C has a totally different shifter mechanism.