RE: 4.7 Speed
 

0.75*3.55=2.6625

70mph*2.6625*336/32.4=1933

I just don't know if I'm doing the equation right or what. AIR RAM, gimme a heads up as to what I'm doing wrong. When I'm traveling at 70mph, I have a reading of about 1750 rpms in OD.

OD ratio x axle ratio x mph x 336/tire diameter

My tires are LT265/70/17 and are 32.4" going by the tire's websire specs. My axle ratio is 3.55. I was in OD, hence the 0.75 x 3.55=2.6625 overall gear ratio. What is the 336 number?

Thanks guys,it has been bugging me all day[:@]


****Edit****

Perhaps I should have read the rest of the thread first. Not trying to be fasicious here. I just am trying to figure this equation out.

RE: 4.7 Speed
 

OK...


You have 3.55 gears and a .67 overdrive...
Transmission gear x Rear Gear = OVERALL GEAR RATIO
--------.67--------- x ----3.55---- = 2.37 <------------Your OVERALL GEAR RATIO


Now use your overall gear ratio to figure out your RPMs at speed:

SPEED x OVERALL GEAR RATIO x 336 / Tire hight = RPMs
70MPH x .............2.37..........x 336 / ....32.4...= 1726RPM <------ Your RPMs at 70MPH


I hope that helps, All you need to do is INPUT ANY rear gear ratio to ditermin your OVERALL GEAR RATIO and then use the OVERALL GEAR RATIO to figure your RPMs at speed.


SPEED SAFE, AIR RAM

RE: 4.7 Speed
 

I got a ticket when I was seeing how fast I can go, the cop clocked me doing 104 MPH when I was bouncing back and forth off the governor

RE: 4.7 Speed
 

ouch.... that must have been expensive.

SPEED SAFE, AIR RAM

RE: 4.7 Speed
 

It was about 290 i think. Then traffic school on top of that, the ticket itself was written up for 90 MPH. I guess I got a nice cop.

RE: 4.7 Speed
 

Thanks Air Ram, I was thinking the OD was 0.75, I forgot it was 0.67 Thanks again. I knew there had to be something I was missing;)

RE: 4.7 Speed
 

No problem, Im just glad I could help out... If you have any additional questions please feel free to contact me.

SPEED SAFE, AIR RAM

RE: 4.7 Speed
 

Last chance to calculate how many hp it would take to make a 2002 Ram go 145 MPH, AirRam.

This weblink will go into your 'AirRam Greatest Hits' album
that you will be seeing a lot in the future,

Sure you don't want to make some comment,
before the post that shows that the etrucker article
matches closely
what a stock Ford Lightning top speed is
or what a 3rd gen SRT10 Ram will do,
but shows how truthful you are about your 'magical' skills?

RE: 4.7 Speed
 

LOL hank... I was there.. "5200 RPMs in OVERDRIVE".... I could care less what YOU calculations where... Please prove my tachometer was WRONG and then I may say OK hank perhaps you are right... but untill you can prove my Tachometer is WRONG then no matter how you try to discredit me ... you will be WRONG.

I think it is you who shoud "Do the math" hank... Untll then SPEED SAFE!

Please notice how hank has added NOTHING to the subject on hand... Again hank "LAST CHANCE" how fast have you been in your 3rd Gen Ram? ... Thats a good question since thats what the subject is on...

SPEED SAFE, AIR RAM

RE: 4.7 Speed
 

airram i think u should get an aft. market speedo ;) sweet sounding truck. build a gallery i wanna see it