youngmonte71 Posted October 14, 2010 Share Posted October 14, 2010 I am wondering which is better posti track or limited slip? im building a 400 sbc for about 450lb and 420hp with a 700r4 with a lockup converter, and im planning on running 3.73 gears, so which would be better posti or limited slip? i drive it during the week and drag on the weekends. Quote Link to comment Share on other sites More sharing options...
Mike 57 Posted October 14, 2010 Share Posted October 14, 2010 Positrack, is just another name for limited slip. Limited slip: uses clutches to attempt to make both tires maintain traction in a straight line. The clutches will slip as the car goes around a corner. Locker: uses a ratchet type device to maintain traction in a straight line, while cornering the 'outside' tire ratchets ahead of the inside tire. There is some noise with a locker but not too bad. Powertrax makes a locker type of unit that fits in an open carrier. Spool: Spool both tires always move a the same speed. Quote Link to comment Share on other sites More sharing options...
DavidTX Posted October 15, 2010 Share Posted October 15, 2010 If you will be doing much daily driving I would highly recommend 3.55 gears or even numerically lower gears. Quote Link to comment Share on other sites More sharing options...
kc8oye Posted October 16, 2010 Share Posted October 16, 2010 DavidTx: with a 700r4 and over drive 3.55 is really the lowest you want to go. any lower and you run into issues with the engine wanting to turn Too slow. I run 2250rpm @ 70mph with 3.55's and 27.01" tall rear tires. (255/60-15) (with the torque converter clutch on) (toggle switch) i can only JUST use o.d @ 55mph and definitely not locked. and i have a mild 350 that makes excellent off-idle torque. Quote Link to comment Share on other sites More sharing options...
DavidTX Posted October 16, 2010 Share Posted October 16, 2010 DavidTx: with a 700r4 and over drive 3.55 is really the lowest you want to go. any lower and you run into issues with the engine wanting to turn Too slow. I run 2250rpm @ 70mph with 3.55's and 27.01" tall rear tires. (255/60-15) (with the torque converter clutch on) (toggle switch) i can only JUST use o.d @ 55mph and definitely not locked. and i have a mild 350 that makes excellent off-idle torque. The reason I recommended that is because I have a 350 (dynoed 421 HP) with 700R4 and 3.55 with stock tires. I thought the 400 would have additional torque to allow numerically lower gears if desired. I am very happy with the 3.55 gears. Quote Link to comment Share on other sites More sharing options...
kc8oye Posted October 16, 2010 Share Posted October 16, 2010 that's going to depend a lot on how the 400 is built. if it doesn't make a lot of off-idle torque, it might not be a good idea to go much lower on the gears. I LOVE my 700r4 / 3.55:1 combo. awesome off the line grunt and cruises down the freeway NICELY. Quote Link to comment Share on other sites More sharing options...
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