RPM's @ 70mph????
Elder User
Joined: Sep 2004
Posts: 824
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From: Helotes, Texas
My sppedo is pretty close to "dead nut". I see those signs all the time and always check it against my speedometer (I'm kinda **** that way, lol). I just don't understand how some guys with 4.10 gears are running 2500 rpms at 70, and others at 2000 rpms. I know tire size effects the speed, but unless the speedo has been recalibrated it should still read the same. Has there been a change in the final gear ratio in the transmissions between model years?
Max
Max
Posting Guru
Joined: Aug 2004
Posts: 2,417
Likes: 4
From: Braham MN
Max, are you using the code on the door, or did you actually figure the ratio??? cuz strange guys like me do axle swaps every other saturday on these things, based on our driving conditions coming up. 
I find it rather interesting the difference in these numbers too.
Motown Fire, you have 4:10s, based soley on the fact that I did an axle swap saturday and mine went from 2500 @ 70MPH to 2000 @ 70 MPH when I switched from 4:10's to 3:55's, which I calulated at the yard just to be sure.
one variable could be the TC not locking up right away. the final drive ratio should be the same for each tranny though all the years. I.E ZF5 one ratio, ZF6 another, E4OD yet one more.
I read in the general disscution forum that ford will let any vehicle out the door as long as the speedo is within +- 4 MPH. this could also be the other thing leading to odd numbers.
Diesel Rod
I find it rather interesting the difference in these numbers too.
Motown Fire, you have 4:10s, based soley on the fact that I did an axle swap saturday and mine went from 2500 @ 70MPH to 2000 @ 70 MPH when I switched from 4:10's to 3:55's, which I calulated at the yard just to be sure.
one variable could be the TC not locking up right away. the final drive ratio should be the same for each tranny though all the years. I.E ZF5 one ratio, ZF6 another, E4OD yet one more.
I read in the general disscution forum that ford will let any vehicle out the door as long as the speedo is within +- 4 MPH. this could also be the other thing leading to odd numbers.
Diesel Rod
Postmaster
Joined: Dec 2003
Posts: 2,864
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From: STEPHENVILLE,TX!!!!!
tires are the big differnce between all the rpm ##'s im at 2300rpm 70mph 5 speed 265/75-16 a handheld gps will work on finding the speed. i like seeing 100mph on thoose radar trailers.....
Posting Guru
Joined: Aug 2004
Posts: 2,417
Likes: 4
From: Braham MN
Haa. Never been able to get 100 MPH on one of those things. 
Heres a pic you'll get a kick out of jake, http://community.webshots.com/photo/327941690/327943338cGPpob
look at the one after it too.
Tires will make a diference, but only if the speedo is recalibrated, did you use a GPS to figure out your speed Jake????
my parents '93 IDI will run only 65 @ 2500, with the ZF5 I thought the ZF5's had a lil slower OD then the E4OD. there all different.
Diesel Rod
Heres a pic you'll get a kick out of jake, http://community.webshots.com/photo/327941690/327943338cGPpob
look at the one after it too.
Tires will make a diference, but only if the speedo is recalibrated, did you use a GPS to figure out your speed Jake????
my parents '93 IDI will run only 65 @ 2500, with the ZF5 I thought the ZF5's had a lil slower OD then the E4OD. there all different.
Diesel Rod
Last edited by 444dieselrod; Apr 21, 2005 at 11:01 PM.
Senior User
Joined: Jan 2005
Posts: 315
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From: West Texas
D rod, I know all to well about the ticket thingy LOL...Not had one in some time now and probably shouldn't even be talking about it LOL... Those pics are too funny dude... Brings back memorys that I laugh about now, but at the time was not so funny. Time has a way of making everything a good memory though.
Man that ticket you got would have been a smooth hundred dollars or more here in Texas. Heck the last one I got which has been a couple years ago now was 150 bucks and change, I know for a fact too that nothing like that has gone down in price either.
Yet these long stretches of good highway here in Texas, you have to drive a stick in the ground to make sure your moving at highways speeds LOL... You guys have a good weekend, its almost here!!!
Man that ticket you got would have been a smooth hundred dollars or more here in Texas. Heck the last one I got which has been a couple years ago now was 150 bucks and change, I know for a fact too that nothing like that has gone down in price either.
Yet these long stretches of good highway here in Texas, you have to drive a stick in the ground to make sure your moving at highways speeds LOL... You guys have a good weekend, its almost here!!!
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