Zlich Posted November 5, 2012 Author Report Share Posted November 5, 2012 10 to 1 it doesn't match that ID plate.......possibly.....maybe. It does match the Id plate on the dash. Just checked it. Quote Link to comment
Sealik Posted November 5, 2012 Report Share Posted November 5, 2012 It does match the Id plate on the dash. Just checked it. I was referring to the gear ratio....after you determine what they are https://www.google.c...iw=1166&bih=653 Quote Link to comment
Zlich Posted November 6, 2012 Author Report Share Posted November 6, 2012 Oh well I will figure out what the gears are probably this weekend once I find the floor jack. Quote Link to comment
ggzilla Posted November 6, 2012 Report Share Posted November 6, 2012 The Z22 came in special fuel economy model -- hence the low ratio gears. The factory service manual is prepared ahead of time, so doesn't always show the actual configurations that ended up being marketed. The chassis ID plate is more accurate than factory service manual. Quote Link to comment
Zlich Posted November 6, 2012 Author Report Share Posted November 6, 2012 so more than likely my gearing is 3.89? Quote Link to comment
ggzilla Posted November 6, 2012 Report Share Posted November 6, 2012 Why would you believe otherwise? This chassis ID plate is for a 1891 Datsun 720 4x4 with Z22 engine and 3.889 final gearing. Quote Link to comment
ggzilla Posted November 6, 2012 Report Share Posted November 6, 2012 More on final drive gearing: High ratio/Low gearing (like 4.675) is good for: * quicker acceleration and better in-town fuel economy * heavier load hauling * allows use of taller tires High gearing (like 3.889) is good for: * slower acceleration but better Highway fuel economy * normal size tires * reduced noise due to reduced RPM while freeway cruising Either one can do 70 mph. Quote Link to comment
Sealik Posted November 6, 2012 Report Share Posted November 6, 2012 (edited) Why would you believe otherwise? This chassis ID plate is for a 1891 Datsun 720 4x4 with Z22 engine and 3.889 final gearing. ....." I'm normally going 5th gear 5k or so and just barely hitting 60."...... Revving a little high for 389s???? Only way to determine actual ratio is to.......calculate it. This will confirm or 'deny' the info on the ID plate EDIT Looking at your ID plate again...it has a "Y" (KMY720) in it....denotes 4x4 Sooooo...unless your speedo and or is out of whack.....gears have been swapped Edited November 6, 2012 by Sealik Quote Link to comment
ggzilla Posted November 6, 2012 Report Share Posted November 6, 2012 Is that correct -- you are doing 5000 RPM in 4th gear at 60mph? In that case, maybe your speedometer is way off. Maybe you are really doing 70 mph. Then in fifth you can do even higher speed. Z22 can do 70 mph regardless of the final gear unless you hit the redline first. Quote Link to comment
datzenmike Posted November 7, 2012 Report Share Posted November 7, 2012 This is interesting. I have no doubt that this is a 4X4 but have no info that any Nissan 4X4 ever had a 3.889. Quote Link to comment
Zlich Posted November 7, 2012 Author Report Share Posted November 7, 2012 5th gear and Im normally around 5k rpms and doing around 50 55 maybe. last time I actually drove it on the free way or somewhere I had to go 60 was in august so I cant remember the exact numbers. and yeah I ran the vin and everything told me it was a 4x4. but just to be sure I will check the gearing sometime this weekend. Also it has a z24 in it. I dont believe the speedometer is off cause I checked it to make sure cause the first drive it was ever on was from Bend Oregon up here to Hoodsport Washington. Im sure if it was wrong I would have gotten pulled over at some point along the trip. Quote Link to comment
ggzilla Posted November 7, 2012 Report Share Posted November 7, 2012 Well you have the proof now ... This is interesting. I have no doubt that this is a 4X4 but have no info that any Nissan 4X4 ever had a 3.889. Quote Link to comment
Zlich Posted November 7, 2012 Author Report Share Posted November 7, 2012 wait is the 3.89 gears why I cant hit 60? Quote Link to comment
ggzilla Posted November 7, 2012 Report Share Posted November 7, 2012 It is because of the 29 foot tires. have 29' tires on it ... 5th gear and Im normally around 5k rpms and doing around 50 55 maybe 3.389 gears should be able to go at least 80 mph with stock size tires. Quote Link to comment
Zlich Posted November 7, 2012 Author Report Share Posted November 7, 2012 ahh okay. so I ether need to get stock tires or regear my truck Quote Link to comment
ggzilla Posted November 7, 2012 Report Share Posted November 7, 2012 normal pickup tire size like 235/75R15 is 29.0" tall. For that to go 50-55 mph in fifth gear 0.83 ratio would mean the final drive gear ratio is ... Quote Link to comment
Zlich Posted November 7, 2012 Author Report Share Posted November 7, 2012 0.83 ratio would mean the final drive gear ratio is ... completely lost me there Quote Link to comment
ggzilla Posted November 7, 2012 Report Share Posted November 7, 2012 fifth gear ratio is 0.83 I think With 29 inch tall tires, at 55 mph in fifth it woiud be doing 2000 RPM with 3.889 gears. Even if you had monster 5.125 gears (which came in some Datsun pickups) you'd only be doing 2600 RPM. So this means your gear ratio is not the problem. Assuming you really are at 5000 rpm in fifth gear, you must have really really tiny tires. Like the ones on my car which are 19" tall. That does 5000 RPM at 70mph with 4.11 gears. What size are your tires? The optional 720 size was 235/75R15 Quote Link to comment
Zlich Posted November 7, 2012 Author Report Share Posted November 7, 2012 I believe 29 let me go check real fast. if anything Ill have to wait till I get it running and give better info. Quote Link to comment
datzenmike Posted November 7, 2012 Report Share Posted November 7, 2012 5k is impossible. Throw your tach away. At 55 MPH with a car tire (23") and a 4.625 rear end you would only be revving just a hair over 3,700 RPMs. Quote Link to comment
ggzilla Posted November 7, 2012 Report Share Posted November 7, 2012 I guarantee that your tires are not small enough to cause the numbers you are reporting -- with any gear ratio. Maybe the tachometer is probably reading incorrectly. Quote Link to comment
Zlich Posted November 7, 2012 Author Report Share Posted November 7, 2012 maybe the tires are 235/75r15 I have a after market tach now cause I didnt think mine was right anyways. I will post some more info once I can actually take it out and get it up to 60 or so. I know it can do 50 to 55 but I cant remember what my tach was saying. Quote Link to comment
datzenmike Posted November 7, 2012 Report Share Posted November 7, 2012 2wd were 205/75R14 4x4 were 215/75R15 so 26.11" 27.70" Yeah that's 28.88" diameter so only an inch above stock. Quote Link to comment
Zlich Posted November 7, 2012 Author Report Share Posted November 7, 2012 that shouldnt have anything to do with the truck not hitting 60mph Quote Link to comment
ggzilla Posted November 7, 2012 Report Share Posted November 7, 2012 it's not your tires that are the problem. If they were larger the RPMs wouldn't be that high. And if they are smaller, they wouldn't be that high either. Put your foot down and let the engine rev up to a real 5000 RPM. Quote Link to comment
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