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Sometime in the near future my 81 720 4x4 is going to need a transmission looking to get some information on nissan transmissions that bolt to z20/z22 engine I have a FS5W71B in it currently. Just looking to find a taller/steeper/lower/crawling gear ratio from 3.89 to like 4.11 just a example if any that will bolt to a z motor.

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If you are looking to rock crawl, it's not going to happen with the transmission, most them guys play with the rearend gears, and/or do a double the transfer case setup, like using a jeep transfer case as the primary, and bolt a Nissan 720 transfer case to the Jeep transfer case, and connect the drivelines to the Nissan case, in first gear, low range, low range, you can walk faster.

Sometime in the near future my 81 720 4x4 is going to need a transmission looking to get some information on nissan transmissions that bolt to z20/z22 engine I have a FS5W71B in it currently. Just looking to find a taller/steeper/lower/crawling gear ratio from 3.89 to like 4.11 just a example if any that will bolt to a z motor.

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Check your engine tag info located under the passenger side hood hinge on the inner fender...

 

720Large2.jpg

 

You will find the engine size Z22, The transmission, FS5W71B and the axle ratio, HF43 (short for H-190 4.375)  All early 4x4s were fitted with 4.375 not lower. In addition the transmission is a wide ratio with a low 3.592 first gear. (2wd were 3.321) You are as low as you can go at the moment.

 

With some looking around, if you find a 1980 Long Bed 4x4, the front and rear differentials are 4.625 and that's about it for factory parts.

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Check your engine tag info located under the passenger side hood hinge on the inner fender...

 

720Large2.jpg

 

You will find the engine size Z22, The transmission, FS5W71B and the axle ratio, HF43 (short for H-190 4.375) All early 4x4s were fitted with 4.375 not lower. In addition the transmission is a wide ratio with a low 3.592 first gear. (2wd were 3.321) You are as low as you can go at the moment.

 

With some looking around, if you find a 1980 Long Bed 4x4, the front and rear differentials are 4.625 and that's about it for factory parts.

I put s z20 in it not even 6 months ago. The tranny ks the original and that is FS5W71B engine tag says so and also HE38.

So pretty much the transmission I have is the one I want and I should look into my differential gears?

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4x4s did not come with 3.889 gears. So something is wrong with the tag (swapped) or the cab was swapped and the old tag left on.

 

Look at your 17 digit VIN code.

 

JN6MD06Y6BW004988

 

JN6.... (3 digit) made in Japan

M....... Z22 (engine)

D........ Nissan truck

0......... 0 to 9 (model change)

6......... i to 6 (6 is King Cab)

Y........ 8th digit designates 4x4.  S... standard 2wd, H... Heavy Duty. All 4x4s have a Y here

 

6........ check digit 0 to 9 or X)

B........ model year B is '81 C '82 D '83

W....... Kyushi plant, C... Smyrna Tennessee

004988 ....Vehicle serial number

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PB is the most common way. I use it, but there are others. Internet Explorer isn't the best for hand held devices.

The T-100 is simply a 2 to 1 gear reduction.

 

 

Yes any transmission will 'crawl' but I thought you said you want to 'rock crawl'. This would maximize engine RPMs and minimize vehicle speed MPH.

There are three 71B 5 speed gear ratio gear sets with these first ratios....

TRANS
Wide.... 3.592... some trucks and all 720 4x4s
Mid....... 3.321... most 2wd trucks and 280z and Maxima cars
Close... 3.062... 280zx

Lets assume you are crawling at 5 MPH, in lo range, Assumed 3.889 diff and first gear with stock tire. Your RPMs would be...

TRANS.
Wide.... 3.592.... 1,840 RPMs about 300 RPM above the zx transmission
Mid....... 3.321.... 1,699 RPMs
Close... 3.062.... 1,568 RPMs
 

If using a 4.375 differential the same 5 MPH above would increase the RPMs too...

 

TRANS.
Wide.... 3.592..... 2,070 RPMs
Mid....... 3.321 .... 1,914 RPMs
Close... 3.062 .... 1,765 RPMs

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PB is the most common way. I use it, but there are others. Internet Explorer isn't the best for hand held devices.

 

The T-100 is simply a 2 to 1 gear reduction.

 

 

Yes any transmission will 'crawl' but I thought you said you want to 'rock crawl'. This would maximize engine RPMs and minimize vehicle speed MPH.

 

There are three 71B 5 speed gear ratio gear sets with these first ratios....

 

TRANS

Wide.... 3.592... some trucks and all 720 4x4s

Mid....... 3.321... most 2wd trucks and 280z and Maxima cars

Close... 3.062... 280zx

 

Lets assume you are crawling at 5 MPH, in lo range, Assumed 3.889 diff and first gear with stock tire. Your RPMs would be...

 

TRANS.

Wide.... 3.592.... 1,840 RPMs about 300 RPM above the zx transmission

Mid....... 3.321.... 1,699 RPMs

Close... 3.062.... 1,568 RPMs

 

If using a 4.375 differential the same 5 MPH above would increase the RPMs too...

 

TRANS.

Wide.... 3.592..... 2,070 RPMs

Mid....... 3.321 .... 1,914 RPMs

Close... 3.062 .... 1,765 RPMs

Really still figuring out what type of offroading 4bying Im into but crawling through water over rocks but I also wouldn't mind hauiling ass in 2wd. I feel like I drive a gutless wonder on the road. Working on uploading some pictures to PB right now. Also it has 29" tires on it and I think chevy 6 lug 15" rim it could be a 16" they came off my old 1/2ton chevy with bald 31's when I bought new ones I went down to 29" tires cause they dont rub. Would like to go back to 31s some day
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29" is accepted as the largest on stock body height 720 without rub. Larger diameter lowers the ability to rock crawl. If you have a 3.889 differential going to 31s will be the same as lowering to 3.63... a terrible idea.

also been debating about regearing the differentials the 80s longbed 4x4 gears sound nice and allow for bigger tires. Would that explain why it was so easy for me to spin my bald 31s compared to my new 29s? I also think my torsion bars are maxed out. Not sure but everyone seems to think I have a lift on this thing. I'll post some pictures of the truck before and after the paint job I did.
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  • 2 weeks later...

PB is the most common way. I use it, but there are others. Internet Explorer isn't the best for hand held devices.

 

The T-100 is simply a 2 to 1 gear reduction.

 

 

Yes any transmission will 'crawl' but I thought you said you want to 'rock crawl'. This would maximize engine RPMs and minimize vehicle speed MPH.

 

There are three 71B 5 speed gear ratio gear sets with these first ratios....

 

TRANS

Wide.... 3.592... some trucks and all 720 4x4s

Mid....... 3.321... most 2wd trucks and 280z and Maxima cars

Close... 3.062... 280zx

 

Lets assume you are crawling at 5 MPH, in lo range, Assumed 3.889 diff and first gear with stock tire. Your RPMs would be...

 

TRANS.

Wide.... 3.592.... 1,840 RPMs about 300 RPM above the zx transmission

Mid....... 3.321.... 1,699 RPMs

Close... 3.062.... 1,568 RPMs

 

If using a 4.375 differential the same 5 MPH above would increase the RPMs too...

 

TRANS.

Wide.... 3.592..... 2,070 RPMs

Mid....... 3.321 .... 1,914 RPMs

Close... 3.062 .... 1,765 RPMs

Okay gear ratio out of the way because I'm working on a dual tcase setup what is a smaller tranny than thr FS5W71B? length wise that will bolt up to a z22 short and light but tough as hell. Any ideas? Not afriad to have to mix match parts.
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I think the simplest way to twin tcase a 720 is to get a d21 4x4 z24 transmission and bolt it to your engine. It has a married tx10 transfer case on it. Then relocate your stock divorced tcase a little bit. From there it's just driveshafts.

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Okay gear ratio out of the way because I'm working on a dual tcase setup what is a smaller tranny than thr FS5W71B? length wise that will bolt up to a z22 short and light but tough as hell. Any ideas? Not afriad to have to mix match parts.

The 82.5 and on KC (the 4x4 ones did for sure) with Z24 engine usually had the same FS5W71B transmission but only 26" long.

 

 

I think the simplest way to twin tcase a 720 is to get a d21 4x4 z24 transmission and bolt it to your engine. It has a married tx10 transfer case on it. Then relocate your stock divorced tcase a little bit. From there it's just driveshafts.

The D21 Hardbody 4x4 KA transmission/trans cases also had the same bolt pattern as the Z24i engine and should work.

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