68Datsun510 Posted February 23, 2011 Report Share Posted February 23, 2011 Im running a 280zx 5 speed, and plan on running a 4.11 rear gear, however, ive heard of cruising RPM at 65 to be around 3500+ from some people!?!? I know the gear math calculators say that it wont be that bad, but reality seems to say otherwise. How do you like your 4.11 gears for daily driving? I run a 22" outer diam tire. Quote Link to comment
datzenmike Posted February 23, 2011 Report Share Posted February 23, 2011 The zx 5 speed (a true zx) has a 26% over drive ratio. Need you rear tire size and the RPMs at 645 in 5th can beworked out. I don't think it will be that high. Quote Link to comment
fivetenguy Posted February 23, 2011 Report Share Posted February 23, 2011 Someone posted this site here on the forum. You will just need to get the gear ratio for 5th gear on your tranny. http://www.wallaceracing.com/calcmph.php Quote Link to comment
datzenmike Posted February 23, 2011 Report Share Posted February 23, 2011 You mean you need the over drive ratio. Plus you still need the tire size you are running. Quote Link to comment
datsunaholic Posted February 23, 2011 Report Share Posted February 23, 2011 Well, with a true .745:1 overdrive, 4.11 rear gears, 175/60R14 tires (175/60R14 are 22.3" dia) that would put you just a hair over 3000RPM @ 65. 175/60R14 Tire = 906 revs/mile. x 4.11 gears, 3723.66 RPM (Driveshaft @60MPH) x 0.745 overdrive = 2774.13 ENGINE RPM @60. /60, *65, 3005.3 RPM @ 65. That's the math. Temperature, clutch slip, tire wear, and inflation all play a role as well. And any different components change things too. Quote Link to comment
john510 Posted February 23, 2011 Report Share Posted February 23, 2011 I recently put my 411 rear end in,it had the 371.I dont care for it too much.It feels like i need to keep shifting up to the next gear a lot sooner.On the freeway it feels like i need 2 more gears.Im running a roadster 5 speed,im not sure how different it would be compared to the Z 5 speed.Also my tires are 205 50 15 real close to 23",about stock heighth if i remember correctly,at 65 mph its running about 3700 rpms.The car feels faster from a dead stop with the 371 gears which doesnt make sense to me. Quote Link to comment
68Datsun510 Posted February 24, 2011 Author Report Share Posted February 24, 2011 Its the true ZX trans, tire size is 185/60-14, ok, that all doesnt sound so bad then. I have an L19 so good gears are a must. No torquey KA here. johns510, how much ya want for that 4.11? The gears and bearings ok? ;) Quote Link to comment
datzenmike Posted February 24, 2011 Report Share Posted February 24, 2011 185 R60 14 tires with 4.11 and with the 0.773 '80 zx tranny = 3,050 185 R60 14 tires with 4.11 and with the 0.745 '81-83 (non turbo) zx tranny = 2,940 above but with 3.90 diff ... 0.773 over drive......... 2,895 0.745 over drive......... 2,790 with 3.70... 0.773 over drive .......... 2,746 0.745 over drive .......... 2,647 Quote Link to comment
john510 Posted February 24, 2011 Report Share Posted February 24, 2011 Its the true ZX trans, tire size is 185/60-14, ok, that all doesnt sound so bad then. I have an L19 so good gears are a must. No torquey KA here. johns510, how much ya want for that 4.11? The gears and bearings ok? ;) Im keeping it for now. Quote Link to comment
ppeters914 Posted February 24, 2011 Report Share Posted February 24, 2011 I recently put my 411 rear end in,it had the 371.I dont care for it too much.It feels like i need to keep shifting up to the next gear a lot sooner.On the freeway it feels like i need 2 more gears. I'm running a roadster 5 speed,im not sure how different it would be compared to the Z 5 speed. 1st 2nd 3rd 4th 5th ------------------------------------------ R 2.957 1.858 1.311 1.000 0.852 Z1 3.321 2.077 1.308 1.000 0.864 Z2 3.062 1.858 1.308 1.000 0.773 Z3 3.062 1.858 1.308 1.000 0.745 R (FS5C71A): stock roadster (SRL-311) 5-speed Z1 (FS5W71B): 280ZX 8/78-7/79 Z2 (FS5W71B): 280ZX 8/79-6/80 Z3 (FS5W71B): 280ZX 7/80-6/83 I'll let y'all do the math. Pete Quote Link to comment
Jesse C. Posted February 25, 2011 Report Share Posted February 25, 2011 4:11 gears are great for short road courses and drag racing but lousy for an everyday car. Get some taller gears if you plan to do a lot of driving and save some grief and gas. Quote Link to comment
ggzilla Posted February 25, 2011 Report Share Posted February 25, 2011 That's still better than a stocker with a 4-speed. I got 4:11s in my truck -- with a 4-speed! Quote Link to comment
ariascarlos1990 Posted February 25, 2011 Report Share Posted February 25, 2011 So whats the lowest 5th ratio 5 speed that will bolt to a l motor? Quote Link to comment
datzenmike Posted February 25, 2011 Report Share Posted February 25, 2011 Do you mean the largest over drive 5th gear? That would be the '81-'83 280zx with 0.745. That's about 26% over drive. If you are used to 3000 RPMs in 4th at 60 this will reduce it to 2235. This is a big drop for the smaller L16 and it may have trouble pulling a car at that RPM out on the highway or on windy days. Best to have a lower rear end for performance and this over drive for mileage. Quote Link to comment
68Datsun510 Posted February 25, 2011 Author Report Share Posted February 25, 2011 Exactly what im shooting for, i have the 82 zx box, and am searching for a 4.11 to stick my LSD from the 3.7 into =) Quote Link to comment
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