4.6 5-speed question
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Senior User
Joined: Apr 2006
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From: northern michigan
4.6 5-speed question
What is your speed at 2K RPM's? My GPS says that im running around 65 MPH! Is this correct? I have 3.55 gears and 33 inch tires. shouldnt my RPM's be lower? Do i have 4.10 gears or something? Could I run 35's to lower my RPM's?
Thread Starter
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Senior User
Joined: Apr 2006
Posts: 435
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From: northern michigan
My speedo reads 60 MPH. It reads slower because of the larger tires. I know my GPS is somewhat correct because i have to add about 5 mph to my speedo and add about 5% to my mileage due to the 5% increase in tire size. My mom drove beside me on the highway and her tahoe read 65 MPH. Are the 5-speeds geared lower?
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Joined: May 2003
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From: Maryland
Hello,
Sorry it took me a while to respond. I have a 2003 4.6 4x4 3.55 LS with the stock 16 inch tires (265 70's if I remember correctly with 35 pounds of air) 5 speed. I put the tac directly on 2k and the speedo read 62 MPH exactly.
Hope this helps.
Chip
Sorry it took me a while to respond. I have a 2003 4.6 4x4 3.55 LS with the stock 16 inch tires (265 70's if I remember correctly with 35 pounds of air) 5 speed. I put the tac directly on 2k and the speedo read 62 MPH exactly.
Hope this helps.
Chip
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Check your axle ratio. Should be a tag on it. Or in the VIN.
Find out your 5th gear ratio. .78? .80? I'm not sure.
Check the loaded radius of your tires and double it for the height.
Go here and enter the info and see what you should be running for any given rpm.
http://www.novak-adapt.com/knowledge/gearing.htm
Scroll down to the third place to enter info, under "MPH".
Find out your 5th gear ratio. .78? .80? I'm not sure.
Check the loaded radius of your tires and double it for the height.
Go here and enter the info and see what you should be running for any given rpm.
http://www.novak-adapt.com/knowledge/gearing.htm
Scroll down to the third place to enter info, under "MPH".
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From: Trussville, Alabama
I used to have a 2000 with 3.55 rear end and 5 speed.
In OD (5th gear) it was 32 rpm / mph.
So 65 mph X 32 rpm = 2080 rpm.
About what you are seeing.
Sounds right to me.
FWIW, 2K rpm is not really high rpm. You can run there (and higher) with no ill effect.
At least I did, for 170,000 miles before I sold the truck.
Drive on!
In OD (5th gear) it was 32 rpm / mph.
So 65 mph X 32 rpm = 2080 rpm.
About what you are seeing.
Sounds right to me.
FWIW, 2K rpm is not really high rpm. You can run there (and higher) with no ill effect.
At least I did, for 170,000 miles before I sold the truck.
Drive on!
