what gear ratio?

[ford351w10]

any of you guys running 488's and 456's was wondering what rpm you were running at 65 in overdrive im trying to figure out what ratio to use ive got 33's the stock gears are 373's so im thinking 488s cause i might go 35's later anyway let me know what you guys got thanks

 

[Nedwreck]

Just curious, what's your RPM's with 33's at 65mph now? How about 55mph?

(There's a chart floating around here somewhere that has this info, but I expect a little varience with different brand tires, etc..)

Thanks!

 

[ford351w10]

yeah i dont belive those charts cause it says like 2250 or some thing like that with 33's and 373's and im running 1800 rpm in over drive at 65 thank you 65 cause thats the speed here in oregon on the freeway but most the time i run it 75 and in overdrive thats like 2250 so i just wana know ppls rpms of what they have dont trust the charts that some math egg head said they should be

 

[Nedwreck]

thanks for your note....

yeah the charts are off sometimes, but they do point in the right direction. usually anyway.
ya just about have to get out and measure your tires to dial in a closer to the chart, and little losses in automatic transmissions add up too. That and our tacho's aren't always spot on either. So yea, the chart is good.. but YMMV. heh

Also I just happened to wonder if the chart (I can't find it right off) is overdrive or not. The safe bet in charts is to use drive at 1:1 because not all cars/trucks have the same OD ratio.

 

[hunterdan]

Check this link, it assumes a 1:1 ratio at 65 MPH as it states on the site.
http://www.therangerstation.com/tech_library/gearandtirechart.html

Dan

 

[Nedwreck]

Thanks Dan!

So... IIRC an Explorer OD ratio is .75:1 ? So the chart gives 2469rpm in Drive (33's, with 3.73 @ 65mph), OD would be ~1850rpm at 65.

Neat.