Wasn't throwing you under the bus there jpop, just noting his reference. Perhaps I should have stated it differently.

And the OD Off was my assumption when I ran the numbers in that thread, since I certainly could not see him running 37's with 3.73's and OD ON at freeway speeds. I specifically asked him to point out where my assumptions might be incorrect, and his only answer was something to the effect of I had no idea what his rpm's were. But most of us by now know that your charts are in fact pretty darn accurate.



There is a notation on the charts telling you that they use OD (4th) on autos, and 6th gear on manuals. Be sure to use actual measured tire height also. For auto's, once you get the OD On (4th gear) rpm, you divide that number by .69 to get OD Off (3rd).

ex
2000rpm at 70 with OD On
divide by .69 to get OD Off
= 2898 at 70 with OD Off

 

Yes, the numbers quoted are for OD.

The first thing is you will unlock the converter which will cause your rpms to spike 10-15%. A kick down or down shift from the .69 OD gear to the 1:1 3rd gear will spike your rpms another 40%.

One of the big things with having the appropriate gear set for your vehicle is having some level of power in reserve to deal with mild grades, headwinds and power to accelerate to pass someone without necessarily kicking down.

 

It's all good, didn't think you were throwing me under the bus. Just want to squash any thought of myself being a "self proclaimed expert". That is definitely not me and I have shied away from the term "expert" my entire career. I learn just as much about things on this forum as I espouse.

 

Don't forget you also unlock the converter which will spike the rpms 10-15% before the down shift.

 

Thanks I was just about to ask if anyone had this same setup and how they liked it. You the man

 

Thanks. I assumed there wouldn't be a need to downshift as much with proper gearing. After all, that is the reason I would regear; to have the engine powerband match your speed.
For the record, I always give your answers more weight in forum discussions as you seem to carry more wisdom and impartiality in your responses.

 

Thanks, it's appreciated. Wisdom just comes from already having made mistakes, and I've made my share of them.

 

Yeah, that's something that I don't know enough about to even bring it up. People would be asking me about the 5th gear I was referring to . But the numbers behind pushing the OD button in and out are easy for me to understand.

 

That's great info man, thanx!

 

In line with what's in the FAQ.