Try this one .Add all the info you can .Then push the button .It works out everything .

http://www.f-body.org/gears/

Lon

yblocksdownunder

There is a great article on this subject in the Rod & Custom magazine Feb. 2009 issue ... Hitting the Sweet Spot ... Calculating the optimum performance combination for your drive train .... it covers the tires, transmission and rearend ... it is not one thing but the combination of all of them. Great read ..... Greg 

  Greg

Well , i finally crowled under the vic today  to check  out the switch.....Its wired up .  I couldnt remember , but i think its wired to the on position on the ignition  switch..............When driving i can  feel it shift ,  so ireckon its working ok  .................a big thanks for all the help ,  had me worried for a while , been a couple of years ago when we rewired the whole car and a didnt remember if we had wired  the switch or not ......been working on other projects since ,  and sometimes they sort of blend ............!!.....................Sam.................West Central   Florida

56 victoria

Another way to do it for any tire, any rear axle and transmission... (that you can measure yourself) is as follows.





20168 divided by the (rear) tire dia[inches] 20168/dia=tire RPM @ 60mph



Once you know the rear tire rpm, you can multiply by the rear axle ratio to get ENGINE RPM at 60 mph.



If you have an OD transmission, then you also have to multiply by the OD ratio (0.71 for my E4OD for example) to get the rpm (at 60mph) ..............Direct drive is a multiplication of exactly 1.0 btw.





This is completely based on the rolling radius of the tire so it's not perfectly exact because the rolling radius of any tire is dependent on the pressure, load, etc.



For our purposes it's going to be "close enough" to predict what the engine rpm will be at 60 mph. (5280 ft/min)





By the way, if you have a lot of "squish" in your rear tire, it'll even be more accurate to measure the actual radius of the tire from the (center of the) axle to the ground if you do it that way then simply use 10084/radius=rear wheel rpm@60



I have 9.00-20 tires on my F-600. I measured them at 40" diameter. I have a 5.83:1 2 speed rear axle.



20168/40= 504 rear wheel RPM @60mph.



With the 5.83:1 axle, 5.83 x 504 = 2940rpm and in OD, 2940 x 0.71 = approx 2100 RPM









Happy New Year everyone!




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1955 F-600/272/E4OD// Disclaimer: No animals were injured while test driving my F-600 except the ones I ran over intentionally!

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This post was created using OpenSuSE Linux x64 and Firefox

GPS unit will tell the MPH very accurately.

You gotta have the right tools and know how to use 'em.

TC - Austin, Texas

Sam,

       Find a road with mileage signs. At 60 you will cover one mile in one minute. To be sure, try to cover three or four miles at a steady 60 indicated. If you time yourself and it takes longer than a minute your speedo is slow. Tell me the times you get and I'll tell you what the error is.   

Frank/Rebop

Bristol, In ( by Elkhart) 

Thsnks Pete and all,   Will check  the switch out.!            .....Sam

56 victoria

About your 700r4 transmission torque converter lock-up. The car it came out of had some means of "talking" to the torque converter and "telling it" to lock and unlock. Computer and/or a speed sensing unit that sent the signal. Since your 1956 is not equipped with this device a simple on/off switch is put in. You "tell" it to lock/unlock via this switch. Google 700R4 switch for more info. Or ask the place you bought the transmission. Pete

You might search the net for rpm calculators and tire size calcuators.  Know they helped me.  Below are links to both.

http://wahiduddin.net/calc/calc_speed_rpm.htm

http://www.discounttiredirect.com/direct/brochure/info/tmpInfoTireMath.jsp

Warsaw, IN

Pete,    I have no idea what the stll speed is   !!   This is a stock 700R4 trans.   Shifts well at the right speeds...there is no switch  to lock the converter.   It may be me , but it seems to me the RPM s are alittle high ,  and wanted some opinions  from other  y-blockers...........Sam.......................West Central     Florida

56 victoria