15 speed double OD

a truck I am looking at has 22.5 tires and does 75 mph @1750 rpms(does that sound right?)

What would be the best rpm to upshift and downshift at?

 

also they are not double over, 14th gear is 1 to 1 derict drive 15th is .79 over drive. the old 13 speeds something like .87 and the 15's were faster with the .79 so people started calling them double overs

 

if you have lo pro you are about 342 rears, if they are 11Rs you about 3.55 shift so you stay in the power band for your engine

 

What would be the best rpm to upshift and downshift at?

 

on my 3406E I shift about 11 or 1200 on the low side and about 14 to1500 on the high side

 

for upshifting what rpm do you bring it up to, to pull the shifter out of gear?
( 1600-1700 rpms on the low side) ( 1900-2000 on the high side)

for downshifting what rpm do you rev up to, to pop the shifter back in gear?

 

You are correct I had a brain fart, sorry guys.

The correct pattern is:
Low range
R 2 5
|-|-|
1 3 4

Able to split all the gears in low
High range
R 7 10
|-|-|
6 8 9

 

The last truck I drove that had the 4 and 5 gears reversed was a deuce and a half and it was with the 3 and 4 on a 4 speed gear box. Haven't seen a 15 that split the lower gears and never drove a 15 that had the 4 and 5 reversed.

 

I guess some things never change, I drove an old Brockway cabover with a deep reduction 15, but the switch for the bottom range was on the dash. When it was loaded, that 238 Detroit needed it to get going! But it was the same pattern.

 

The RTO 15's were reversed, 9 over was reversed. 13 double over RTOO was reversed and also one of the fastest single box tranny's made. .60 over drive, like 118, 119 mph at 2100 with 3.70 rears. sometime in the 90's same tranny's called RTX, but had the stright shift pattern. The older one's with stright shift were RT's and 1 to 1 direct drive top gear