true blue Posted July 26, 2009 Share Posted July 26, 2009 Can someone tell me what RPM i will be at speed 60 MPH 700R4 Tranny with 3:36 gears and 245 60 R15 Tires = ______ RPM 700R4 Tranny with 3:90 gears and 245 60 R15 Tires = ______ RPM Thanks Bill Quote Link to comment Share on other sites More sharing options...
Mr70Monte Posted July 26, 2009 Share Posted July 26, 2009 if you are using a torque convertor that has a lockup & it is locked up when in OD, your rpms would be, 3.36-------1785 rpm @ 60 3.90-------2072 rpm @ 60 Quote Link to comment Share on other sites More sharing options...
72MC Posted July 26, 2009 Share Posted July 26, 2009 These are the guys I have been using for info. http://www.wallaceracing.com/Calculators.htm Hope it helps. _ Dave Quote Link to comment Share on other sites More sharing options...
true blue Posted July 26, 2009 Author Share Posted July 26, 2009 Mr70Monte Can you explain how you came up with those numbers??? because i have the first setup and according to my tach i'm showing 21-2200 and was thinking of going with the 3:90 setup but did'nt want to lose the gains i just got with the 700r4 O/D tranny. Thanks Bill Quote Link to comment Share on other sites More sharing options...
monte70car Posted July 26, 2009 Share Posted July 26, 2009 i came yup with the same rpm as mr70monte 1785rpm @60mph. Could you have been doing 70-75 mph as those are close to 21-2200. and thats withe 3.36 gear.Now the 3.90 gear will get you 2,072rpm at 60mph. Quote Link to comment Share on other sites More sharing options...
Mr70Monte Posted July 26, 2009 Share Posted July 26, 2009 Figure out how far your tire size rolls in 1 revolution... 24560R15---245 / 25.4 x .6 x 2 + 15 = 26.575" dia tire, x 3.1415926 = 83.488 / 12 = 6.96' per revolution 60mph x 5280'(feet in a mile) / 60 (minutes in an hour)/ 6.96 (distance that your tire rolls) = 758.62 (axle revolutions per minute) x 3.36 (axle ratio) x .7 (OD ratio for a 700r4) = 1784 (engine rpm) Quote Link to comment Share on other sites More sharing options...
true blue Posted July 27, 2009 Author Share Posted July 27, 2009 It"s a lock up as far as i know. When i reach 45 MPH it shifts into O/D and if i pull back into 3 it jumps the RPM back up again and another thing i notice is no matter how fast im going 70 - 80 MPH when i punch it it jumps back into 3 and when i let off a little it jumps back into O/D. One more question what is the stock rear end size for a 71 is it 8.2 or 8.5 ? Thanks Bill Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.