Looking for help/advice on truck purchase
01-30-2018, (Subject: Looking for help/advice on truck purchase ) 
Post: #28
RE: Looking for help/advice on truck purchase
After RStewarts dealings with that stealership, I wouldn't shop there.
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08-24-2019, (Subject: Looking for help/advice on truck purchase ) 
Post: #29
RE: Looking for help/advice on truck purchase
I know this gear ratio deal has been beat to death. My current truck has 3.55. This ratio is ok for states that have higher speed limits. 80k and 55 mph speed limit it is to high. Always on the lugging side. So I was playing around with a speed calculator trying to find a ratio to go with a 18 or 13 speed. Like say drive in 17th gear in California then 18th gear out of state. Or maybe 18th empty in California. So here is the pictures of the results. I guess it explains the logic in some of these new trucks with there gear ratios. So a truck with 3.36 in 17th gear is gonna have a better final drive ratio than my current truck with 3.55 and a 10 speed. So one thing I have never been able to get my mind around is the leverage at the rear end with these higher ratios. It’s like having less of a cheater pipe on your wrench when taking that rusty bolt loose. But a transmission ratio being lower gives you more power on that shorter lever. Seems like it should equal out. So if I want to pull a grade say.... 58 mph. In 17th gear. With 3.36 rear ratio. I’m doing that work with 1435 engine rpm. If I do it with current truck set up. 3.55 and a 10 speed final ratio on transmission of .74. Then I’m trying to do that work with only 1325 rpm. Real world driving that is a lot easier on the engine having high rear ratio and a low tranny ratio because it give my engine a extra 110 rpm. Less side load on cylinder walls...happier liners. Now let’s say I’m not lazy and I down shift the 10 speed. So to maintain 58mph I’m now turning 1775 rpm. So because of this situation in California I find myself not downshifting because the truck will pull the grade in high gear torturing the liners. But I don’t like to downshift to 1775 rpm every little hill. I know I’m lazy but where talking about setting a truck up for optimum real world driving for my lazy habits. I know I’m not the only person that does this. Most drivers don’t even know any better.
So after all this laying situation out. I believe I must have some of the physics wrong here. It’s widely understood that a lower gear ratio pulls better than a taller gear ratio. I had a truck with 2.88 gears once. Direct drive 10 speed. It pulled as good as any other 430 hp truck around I would just be in a lower gear but similar mph. Seemed more dependent on where the splits were at in the tranny. Did I just have a anomaly truck. I’m trying to get this figured out for future truck purchase.


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08-24-2019, (Subject: Looking for help/advice on truck purchase ) 
Post: #30
RE: Looking for help/advice on truck purchase
My peterbilt has 3:36 on 11r24.5 rubber, I drive between 100km and 105km in 17th and call 18th my "gettin home gear" reserved for speeds above 110km. I mostly only hit 18th when passing.


User's Signature: I'm no mechanic, I'm just a guy that breaks down enough to know a bit.
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08-24-2019, (Subject: Looking for help/advice on truck purchase ) 
Post: #31
RE: Looking for help/advice on truck purchase
Wow that’s some gears with that big of tires. I figured low pro 22.5. Super tall gears. I’m trying to cruise at round 1400-1500 rpm.
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05-16-2020, (Subject: Looking for help/advice on truck purchase ) 
Post: #32
RE: Looking for help/advice on truck purchase
I'm going to be planning or re- gearing on the future. I currently have 3.36 with a 10spd and I'm not crazy about it. I'd like to go to 3.70 or even 3.90 I run local ( 150 miles radius in & out of Chicago).
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