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?
15 speed double OD
Discussion in 'Trucks [ Eighteen Wheelers ]' started by Stroked F550, Nov 9, 2009.
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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
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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
Stroked F550 Thanks this. -
What would be the best rpm to upshift and downshift at?
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Trucker186 and Stroked F550 Thank this.
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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?Last edited: Nov 10, 2009
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The correct pattern is:
Low range
R 2 5
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1 3 4
Able to split all the gears in low
High range
R 7 10
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6 8 9Stroked F550 Thanks this. -
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.
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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.
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