Need a little help.

[true blue]

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

[Mr70Monte]

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

[72MC]

These are the guys I have been using for info. http://www.wallaceracing.com/Calculators.htm Hope it helps. _ Dave

[true blue]

 

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

[monte70car]

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.

[Mr70Monte]

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)

 

[true blue]

 

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