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67 411

1982 720 d22 trans rebuild need help please

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Hey guys I bought this truck about 4 years ago for 500 bucks it has been amazing all I have put into it was front brakes, clutch and 2 front tires. Not dad for a daily driver. Well receltly the trans started making noise, I pulled it and it looks like the bearings are bad. My issue now is I cannot get the cases split. They are only seperating lime 4-6 inches. It looks like a shift fork is getting caught on the gears. Any advice?

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It depends on which bearing went bad, if it is the lower front cluster gear bearing that went bad just replace it and put it back together, no need to remove the tailshaft housing.

If it messed up the lower bearing hole in that front diesel case then you will have to have the case turned out to the larger cluster gear bearing.

If it is another bearing then find another 5 speed transmission and put your front case onto that transmission and you are good to go.

 

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So the gas transmission tail shafts are the same as the diesel? I know the starter is on the other side. Are they the same length? Thanks for the help.

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There is a 1" adapter plate in the middle that holds everything. Then there is a front case that covers the first 4 gears and shift forks and a rear case that covers 5th and reverse and the shifter components. So which one?

 

 

4 minutes ago, 67 411 said:

So the gas transmission tail shafts are the same as the diesel? I know the starter is on the other side. Are they the same length? Thanks for the help.

 

Basically yes. I have an '85 diesel tail case on my '79 280zx 5 speed.

 

 

The 71B can be either a 26" 'shorty' or a regular full length 31.5" long tail.

 

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My trans bearing appear to all be bad. The input shaft and tail shaft have alot of play. 

 

datzenmike are you asking me what I cannot get apart?

  If that's is what you ment I cannot get the rear case to come off. There is what I belive is called a shift fork that was connected to the gearshift, it wont come off and it is getting stuck on the gears. 

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That top front bearing/input shaft always has a lot of play, if you turn the various bearings and they turn smooth and are completely intact with their cages I call them good.

It's that front lower bearing that goes bad on these transmissions 99 percent of the time, as far as I know all 720 diesels had longshafts, but I have never seen a 1985/86 regular cab/short box SD22/25 diesel truck either, they may have had a short shaft.

To get the tailshaft housing off easier you have to remove all the little doodads like the reverse lockout and such, it's a pain, try to move the shift lever mechanism around, but it will be just as hard or harder to get it back together if you remove the tailhousing.

Also getting all the bearings out and replacing them is a major task, not a job for the average Joe.

Edited by wayno
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I think the tail shaft is the worst really. That for that is getting stuck has a bold holding it on but I cannot get the bolt out. 

 

So if I find a napz motor with a 5 speed it should work with my diesel bellhouseing?

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Stand the transmission up on two pieces of 2x4. Hold the shifter over, hard to the driver's side while lifting the rear case and twisting it back and forth. 

 

I would only take the speedometer pinion out, and by out I mean pull straight out. It has a plastic gear that may be damaged. Everything in the tail (reverse check sleeve, pin stopper guide, striking rod/lever/guide) comes out with the tail. All it does is slide back off the mainshaft.

 

Any 71B transmission will work for the front case swap.

'77-'79 620

'77-'78 280z

'79 280zx  * the '80-'83zx have a too big overdrive you won't like it.

'78-'84 810/Maxima

'80-'86.5 720

'80-'83 S110 200sx

'84-'86.5 S12 200sx

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Thanks for all the help. I will try and. Get it apart tonight.

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1 hour ago, datzenmike said:

Stand the transmission up on two pieces of 2x4. Hold the shifter over, hard to the driver's side while lifting the rear case and twisting it back and forth. 

 

I would only take the speedometer pinion out, and by out I mean pull straight out. It has a plastic gear that may be damaged. Everything in the tail (reverse check sleeve, pin stopper guide, striking rod/lever/guide) comes out with the tail. All it does is slide back off the mainshaft.

 

Any 71B transmission will work for the front case swap.

'77-'79 620

'77-'78 280z

'79 280zx  * the '80-'83zx have a too big overdrive you won't like it.

'78-'84 810/Maxima

'80-'86.5 720

'80-'83 S110 200sx

'84-'86.5 S12 200sx

So I see the 620 on here but is there any other pickups that have the same trans? Like does the napz 5 speed work as well?

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Do not use anything made before 1980 on the truck transmissions for sure as the 620 5 speeds are geared differently and do not work well for a SD series diesel engine, I believe there is a 79 620 transmission that can be used also, but how do you tell which ones a re the good ones and which ones are not, my friend rebuilt a 620 5 speed and he was floored doing 60mph(high RPMs).

Yes a napZ transmission will work for you, as long as it is the same length as what you have right now, your diesel case will bolt right onto that transmission, but you will need a new small front cluster gear bearing if the transmission you get has the large cluster gear bearing.

I have 2 Datsun SD series diesel trucks right now, I have went thru this a few times as I used to find 720 diesel trucks for cheap with broken transmissions, bring them home and fix them and sell them or part them out.

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2 hours ago, datzenmike said:

 

'80-'86.5 720

 

 

Other that the gear ratios the 71B transmissions are all the same strength wise. They are suitable for the Z car's 6 cylinder.  Over about 10 years some small improvements were made (like the 62mm counter bearing)

 

Third up from the bottom. The 71B was used in all those vehicles, usually as an option. That's the L, Z, SD, CA series of engines. It's the front case bolt and starter position that allows this. Swap the case and you can use it on any of those. BUT... there is always a but... The 720 used a long 31.5" and in some cases a shory 26" length so watch for that. ALSO there's also and also... 71B after '84 came with a larger 62mm counter bearing up grade from the original 56mm. If you were to get an '85 and up 71B just swap the larger bearing from it for your smaller 56mm and your old case will fit.

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Thanks for all the great info. I was worried I might not be able to fix my truck. 

 

So I am still unable to get the tail end of the trans off. There is some kind of aluminium ring that has fallen out of place and is bunding up with the shift fork.  I'm not sure if I should try and break or cut it. I cannot get it back where it should go. Anyone have a pic of the inside of the tail end of a 71b. Thanks again for all the help.

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Just find another transmission and put your front diesel case on it, do not try to remove the tail shaft housing on it.

I have removed the tail housings on my transmissions in the past, but I removed the reverse lockout and speedo drive.

Where in Oregon are you?

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I don't see the piece I am talking about I will try and get a picture tomorrow. 

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