jagman Posted March 1, 2019 Report Share Posted March 1, 2019 Did Nissan use two different ratios? One for the automatic trans and another for the 5 speed manual? 1 Quote Link to comment
datzenmike Posted March 1, 2019 Report Share Posted March 1, 2019 All automatics were 3.70 on the 2wd '85 720 truck. None of the other 4 had that ratio... although one of those 4 never came with an automatic, so really there were 3 other ratios. Find the engine tag riveted to the passenger side inner fender just below the hood hinge. this is for a 5 speed.... Bottom line... TRANS / AXLE............... FS5W71B................ HF38 or HF43 or HF 35 38 is 3.889 ratio An automatic tag would say... TRANS / AXLE...............3N71B.................... HF37 37 WOULD BE 3.70 RATIO . 1 Quote Link to comment
Charlie69 Posted March 2, 2019 Report Share Posted March 2, 2019 Mike I ran across a 1980 720 king cab 2 wd L20B automatic that had a 4.11 gear ratio. This is the wiring harness I started with on my 66 520. Quote Link to comment
datzenmike Posted March 2, 2019 Report Share Posted March 2, 2019 My info is for the '83 and up 720 which is what he wanted. I had an '82 long bed automatic and it was also 4.11. The '80 L20B long wheelbase reg cab were 4.625!!! 1 Quote Link to comment
85"720 Posted March 2, 2019 Report Share Posted March 2, 2019 3 hours ago, datzenmike said: All automatics were 3.70 on the 2wd '85 720 truck. None of the other 4 had that ratio... although one of those 4 never came with an automatic, so really there were 3 other ratios. Find the engine tag riveted to the passenger side inner fender just below the hood hinge. this is for a 5 speed.... Bottom line... TRANS / AXLE............... FS5W71B................ HF38 or HF43 or HF 35 38 is 3.889 ratio An automatic tag would say... TRANS / AXLE...............3N71B.................... HF37 37 WOULD BE 3.70 RATIO . Mines an 85 auto and I got the 3.889 gears 1 Quote Link to comment
datzenmike Posted March 2, 2019 Report Share Posted March 2, 2019 The tag says 3N71B and HF38??? Well ultimately Nissan may have changed the published specs, ya never know. But 3.70 is what it's supposed to be. The other thing is that in 35 years maybe the differential was swapped. Any chance the speedometer is reading 5% high? That's only 2.5 MPH @ 50 MPH and may not be noticeable. 1 Quote Link to comment
85"720 Posted March 2, 2019 Report Share Posted March 2, 2019 (edited) 19 hours ago, datzenmike said: The tag says 3N71B and HF38??? Well ultimately Nissan may have changed the published specs, ya never know. But 3.70 is what it's supposed to be. The other thing is that in 35 years maybe the differential was swapped. Any chance the speedometer is reading 5% high? That's only 2.5 MPH @ 50 MPH and may not be noticeable. Mines a L3N71B HF38. Nope stock rearend. Grandpa brought the truck from the dealership with just 4 miles on it. Edited March 2, 2019 by 85"720 1 Quote Link to comment
datzenmike Posted March 2, 2019 Report Share Posted March 2, 2019 Well I'll try to keep track of that info. L 3N71B? L may be for locking torque converter. There were also E3N71Bs in the 280zx but not the 720. The E was a heavier duty transmission. 1 Quote Link to comment
85"720 Posted March 2, 2019 Report Share Posted March 2, 2019 50 minutes ago, datzenmike said: Well I'll try to keep track of that info. L 3N71B? L may be for locking torque converter. There were also E3N71Bs in the 280zx but not the 720. The E was a heavier duty transmission. Yea mine has a locking torque converter. I can feel it lock up at 40-45 mph. 1 Quote Link to comment
85"720 Posted March 2, 2019 Report Share Posted March 2, 2019 53 minutes ago, datzenmike said: Well I'll try to keep track of that info. L 3N71B? L may be for locking torque converter. There were also E3N71Bs in the 280zx but not the 720. The E was a heavier duty transmission. I believe the e stands for electronic if I'm not mistaking. Kinda like GM's 4l60e. 4=the amount of gears. L= longitude. 60 =the strength of the trans. E = electronic. 1 Quote Link to comment
datzenmike Posted March 2, 2019 Report Share Posted March 2, 2019 Nissan uses the E on engine codes to signify multi port EFI. D for dual OHC, i for throttle body injection, R for supercharged and so on. The 3N71B has no electronics. Well reverse light switch and ignition interlock. 1 Quote Link to comment
Charlie69 Posted March 2, 2019 Report Share Posted March 2, 2019 Mike I also ran across an 85 720 regular cab short bed that had a HF 35, 5 speed & Z24. I know the tag was correct as we pulled that set of gears for Shawn's 521 convertible. He has a Z24 5 speed out of a 84 720. Needed a colorful picture in this thread! LOL Quote Link to comment
jagman Posted March 3, 2019 Author Report Share Posted March 3, 2019 Well DatzenMike, I looked all over the firewall, inside the door panels, inside the dash, under and in the fenders and I can't find a plate like you show in the picture. When I have a chance I will look at the long bed and see if it has the plate affixed. Thanks for the info on what should be there and if the long bed has a lower ratio than 3.70 (like 4.11 can I swap rears? Will I have to change the speedometer cable as well? 1 Quote Link to comment
datzenmike Posted March 3, 2019 Report Share Posted March 3, 2019 On 3/1/2019 at 3:44 PM, datzenmike said: Find the engine tag riveted to the passenger side inner fender just below the hood hinge. . Charlie yes for the standard transmissions there was a 3.545 gear for the Z24 5 speed pick up. There was a 3.364 on the Mileage Option Z20S which only came with 5 speeds. There was a 4.375 on the 5 speed Cab/Chassis only with a 5 speed and 3.889 on the diesel trucks that were also 5 speeds. The question was what was used on the '85-'86 Z24 automatics and I say 3.70. My info shows only the 3.70 was used. But as suggested maybe the 3.889 was also used. 1 Quote Link to comment
jagman Posted March 14, 2019 Author Report Share Posted March 14, 2019 Well, I have looked and it must have been forgotten during the build cause there aren't any holes there either. Can you make a lightweight samurai sword from aluminium? 1 Quote Link to comment
Charlie69 Posted March 15, 2019 Report Share Posted March 15, 2019 What year is your 720. I am not sure if the 1979 and 1980 720s had the little aluminum information plate Quote Link to comment
jagman Posted March 15, 2019 Author Report Share Posted March 15, 2019 Charlie, I think this truck is about the same age as my long bed which is 85-86. I don't know what the run of years is for the 720 but based on the build number they have to be close. 1 Quote Link to comment
datzenmike Posted March 15, 2019 Report Share Posted March 15, 2019 June of the previous year is the usual change over for model years. June '79 was the first '80 model year 720. 1 Quote Link to comment
jagman Posted March 15, 2019 Author Report Share Posted March 15, 2019 I don't know how many 720's sell per year but the build numbers are 372089 for the long bed and 308468 for the junker. That's 63,621 units earlier than the long bed. Would that make it an 81-82 assuming they sold ~ 20,000 per year? 1 Quote Link to comment
datzenmike Posted March 15, 2019 Report Share Posted March 15, 2019 There were reg cab short wheelbase, reg cab long wheelbase and KC For 1980 there were 168,999 reg cab short wheelbase trucks made and the same number of King Cabs... then there were the Long beds and the Cab Chassis models and to further confuse there were two plants operating with even more on top of these. That's a lot of trucks. What truck do you have? 1 Quote Link to comment
jagman Posted March 16, 2019 Author Report Share Posted March 16, 2019 I have an 86 std cab long bed with a 5 speed tranny. The junker is a king cab short bed with an automatic tranny. 1 Quote Link to comment
datzenmike Posted March 16, 2019 Report Share Posted March 16, 2019 I've found a 372,89 made sometime between April and May '85???. The driver's door jam tag should have the build date on it. 1 Quote Link to comment
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