gear ratio?
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Freshman User
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gear ratio?
Well i posted a while ago about getting new gears and some of the info confused me, i was told that i should be at 1900 rpms at 60 miles an hour and that if i had 35,s and 3:73 it would be lower than that but its at 2100-2200 rpms right now does this mean i have a lower gear than i thought or do i have 3:73
Posting Guru
Joined: Jun 2005
Posts: 1,268
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From: central Louisiana
1) look on your diff covers, if they are factory there will be a little metal tab that will have the gear ratio on it.
2) open your diff up (take cover off) and count the ring teeth, and pinion teeth and then devide them (ring gear / pinion gear = ratio)
those are the best ways. w/ my factory tires (31.5's), 4.56 gears i was running 21-2200 rpm's w/ an auto trans!! if that gives you any idea of where you might be at!
Jason
Team Mudd Pres.
415cid, 6.5" lift, 39.5's, YEA that's right 39.5's!
2) open your diff up (take cover off) and count the ring teeth, and pinion teeth and then devide them (ring gear / pinion gear = ratio)
those are the best ways. w/ my factory tires (31.5's), 4.56 gears i was running 21-2200 rpm's w/ an auto trans!! if that gives you any idea of where you might be at!
Jason
Team Mudd Pres.
415cid, 6.5" lift, 39.5's, YEA that's right 39.5's!
Lead Driver
Joined: Sep 2003
Posts: 5,844
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From: Albuquerque
If you have 35" tires and run above 2100rpm, then you absolutely do not have 3.73s. If anything...you should have less rpm's with larger tires and 3.73s...not more.
I read you post before going home today from work...so I paid extra attention to my speedo while at 60mph. I was running at about 1750-1800 +/- rpm at that speed with stock LT265 tires.
So...first, unless you re-programmed your PCM for the newer tire size, your speedo is not marking correctly anyway. It will be off about 6-8mph +/-.
You need to re-program the the PCM. Then get back to us about the rpm issue.
biz
_____________________________
2003 F250 SD SC 142" XLT FX4 V10 Auto 4x4 3.73s
I read you post before going home today from work...so I paid extra attention to my speedo while at 60mph. I was running at about 1750-1800 +/- rpm at that speed with stock LT265 tires.
So...first, unless you re-programmed your PCM for the newer tire size, your speedo is not marking correctly anyway. It will be off about 6-8mph +/-.
You need to re-program the the PCM. Then get back to us about the rpm issue.
biz
_____________________________
2003 F250 SD SC 142" XLT FX4 V10 Auto 4x4 3.73s
Post Fiend
Joined: May 2006
Posts: 10,007
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From: Central Florida
also is the tc locked when you see your RPMS?
Another way to get close on ratios, raise the rear tires and mark the drive shaft. Turn the tires a full revolution and count how many times the DS goes around. It's not exact, but it will either rotate less than 4 times or more than 4 times.
Another way to get close on ratios, raise the rear tires and mark the drive shaft. Turn the tires a full revolution and count how many times the DS goes around. It's not exact, but it will either rotate less than 4 times or more than 4 times.
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Freshman User
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sorry i could not respond ive been doing some military training. i have the 4r100 trans and should be in fourth because im going 65 in drive, ill count the shifts next time, also i dont think i have TC i just have the normal OD witch is always on unless im going up some strrp passes. my speedo is pretty accurate off maybe a couple mph, im thinking of cahnging my diff fluid and take out all the guess work and count the teeth while im at it.
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Posting Guru
Joined: Jun 2005
Posts: 1,268
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From: central Louisiana
the "torque lock" is when the clutches inguage after you have a set speed, or you set ups a switch to "manually inguage them (as i did). you have one. you should notice a drop in RPM's after you hit 4th (od) of about 2-300. at least that's what it is on mine!
let us know what you come up w/ on the gear count!
Jason
Team Mudd Pres.
let us know what you come up w/ on the gear count!
Jason
Team Mudd Pres.
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Freshman User
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yes i notice this is locks in arround 40-45 mph if i understand you correct, ill pay more attention next time im on the freeway to get an exact rpm at 60 mph. ill post tomorrow about my results.
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Freshman User
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ok i found out the exact rpm at 60 and 65 it 1900 at 60 and 2050 at 65 so not as high as i thought but it still should be lower because of tire size so i assume that i have 4:10s but ill check the calculator and it hit all 4 gears so no problem there.
Sit. Stay.
Joined: Oct 2001
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From: Washington State
Originally Posted by TeamMudd
or you set ups a switch to "manually engage them (as i did).
Junior User
Joined: Jul 2006
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well im not jason but here is the link to guzzles mod page with the tourque lockup switch..
http://guzzle.rbmicro.com/tclock.html
http://guzzle.rbmicro.com/tclock.html
