Guest ZmeFly Posted December 12, 2000 Share Posted December 12, 2000 im really new to this forum but not to Zcar.com, but this is my first v8 Z and everyone tells me that this is the place to be. well ive already gotten some good advice on the carbs, now for the rear. i hae a stock 350, with the 3 speed auto, but the rear is an R200 3.7, stock 280 rear. i have what i belive is a 3.36 from a 260, but not sure it was a 4 speed. would that work or is there something better. its just that im going at like 5000 or better rpms when im doing 60 mph. really sucks. can someone enlighten me as to whether i should keep the rear i have and go with a 4 peed auto, or switch the rear. i can get one around here from a 82 280zx auto would that one be better, thanks for any info you could give james Quote Link to comment Share on other sites More sharing options...
BLKMGK Posted December 14, 2000 Share Posted December 14, 2000 I'd go with an overdriven transmission rather than switching out the rear. How short are your tires? Even with a 1:1 trans ratio 5K at 60mph sounds pretty high to me. If you go with an overdrive you'll be able to keep a nice launch off the line and changing from a 3.7 to a 3.336 doesn't sound liek much of a difference. Sit down and do the math using the ratios in an OD trans and see if it works out better. I'm not sure what the ratiios are but I have to believe it would work out better. I'd also take a long look at the tires you're running to see if their height is too low. Anyone got the formuals handy to run the numbers on say a 700R4? Would changing the tire height an inch or two be better? Might be cheaper and easier that's for sure... Quote Link to comment Share on other sites More sharing options...
Guest Anonymous Posted December 14, 2000 Share Posted December 14, 2000 Try the utility off the main page on this web site. Its off the links page, select Info and its the transmission/rear end ratio deal, looks like a java applet you'll see it. Lone [This message has been edited by lonehdrider (edited December 13, 2000).] Quote Link to comment Share on other sites More sharing options...
blueovalz Posted December 15, 2000 Share Posted December 15, 2000 When my engine was in my old '66 Stang, I had a 4.11 rear that drove about 3800 rpm at 60mph with a 1:1 4th gear and normal (205/60R14) tires. I cannot see how 5 grand at 60mph is happening with any Z rear end. Perhaps the torque converter is slipping more than ususal or the tach or speedo is off (wrong speedo gear in the transmission). My 4sp Z with a 3.54 rear never went past 4 grand at 60mph no matter how small the tires were. With a 22" tall tire, the rear wheel rotates at about 916 rpm. Multiply this by the diff ratio, and you get the engine rpm (provided you are in a 1:1 gear ration in your transmission). With this in mind you would have to have a 5.45 ratio rear gear at 5 grand at 60 mph. Something else is amiss. Terry Quote Link to comment Share on other sites More sharing options...
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