My son has a 2018 Chevy Silverado with the 5.3 V8 and six speed automatic transmission. He's unhappy with its performance, says it's sick. Now he was an 82nd Airborne paratrooper used to hitting the ground maybe 20 seconds after jumping from 700 feet, so his idea of performance is a lot different from mine.
Anyway, he wants to change the rear differential to 3.73 to 1 from 3.42 to 1. I think the acceleration improvement will be minimal and he'll turn more RPM in every gear and at every speed. He says that the six-speed is so high in top gear that the RPM difference will be minimal, and the acceleration difference will be significant.
So, who's right?
The 3.73 should get him off the line quicker. ?ÿAnd pull harder. ?ÿOn the top end he will rev more rpms higher. The 3.42 will be more sluggish off the line but allow for less rpms at higher speed.?ÿ
I have a 4.30 rear end in my truck i use for towing. Same truck with a 3.55 has less towing ability. Hope this helps. He has it backwards I think. But I don??t know where the gears ratio is on the transmission either. That can make a difference.?ÿ
edit. He wants to move to a 3.73. ?ÿHe is correct I read it backwards lol. Now if he goes to changing tire size (height) he can either increase the final gear ratio or undo what he was trying to accomplish. 3.42 to 3.73 will change his mpg some and especially when the foot is heavy. Oh how I remember my youth days. ?ÿ1977 ford f150. Literally drug it out of a briar patch on an old farm. $100 worth of hornet and wasp spray I was finally able to get it into the barn. Removed the engine that was blown and built a 351w had heads pulled from a 67 ltd with big plugs. ?ÿStraight pipes to cherry bomb glass packs 8? echo tips headers low end mid range cam. Retarded timing I could set off car alarms in parking garages by snorting it as I drove by. Had all the body work done primer grey. Drove around on a 5 gallon bucket for first year as seat had been completely eating away by rats. ?ÿHelped my cousin re do another seat he did upholstery. Had new headliner put in. But by the time I had the money saved up and all mechanical and body work done I was on my own financially and real world budgets had to take priorities. ?ÿSold the truck to a man who had lost his son from a log truck crash and he was helping his grandson find his first ride. I told him if he removed the engine and sell it to a guy who drag raced he could have the truck. I didn??t want someone on my mind dying in a fast truck. It would top out at over a 100 mph. I had dome pistons and other goodies under the hood. When that 4bl carb opened up and she would get gone. She was way to fast and quick. The day I sold it my dad said my mom??s prayers had been answered. She knew I was going to kill myself acting a fool. ?ÿNow I drive around like a snail. ?ÿ
If you're talking to your son about his feelings, and asking us about who's right, then I don't know if anyone can help you.
Have him get a manual transmission for the truck, and then the only way it will feel sick is every time he has to buy new tires for it.
Anything less than a 4.10 is a car not a truck. The chariot has 4.56 and the wood truck has a 6.17 posi.
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If I found the correct specs and did the math right, he'd be turning about 150 more rpm at 70mph in 6th gear.
All of the stock wheel and tire combinations I could find for a 2018 ranged from 99.5" to 101" circumference so I went with 100" circumference for easy math.?ÿ The 6th gear ratio for the 6L80 transmission is 0.67:1.?ÿ Someone else will have to comment as to the perceived acceleration difference off the line.?ÿ
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Here's the table I found for the gear ratios in the transmission that I believe that truck came with.
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The kid is right. That little bit of a change will help it scoot a bit. Not a ton, not enough to warrant the cost and effort but it will. The higher rpm at highway speed will be negligible in terms of mpg.
I went the opposite in my personal truck. Stock 3.73s then I went to a 35in tire effectively taking me to that 3.42 range. Hurts my towing and acceleration, but a fair trade off to me to roll on 35s. Should go to a 4.56 for awesome towing on the 35s but the expense is not worth it.
He's unhappy with its performance, says it's sick.
Depending on his age, that might mean it's great.
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Some new computer calibrations might be needed with a gearing switch.
If it's a two wheel drive it should work fine to give slightly more power at take off (3.45 to 3.73 isn't much of a change).
I like the lower gears when I want to go slow, when I'm in 4 low range I want it to go walking speed and retard it going down steep hills.?ÿ
However, if it's a 4x4 truck a lot more will have to happen than switching out the rear end. Might as well trade it in at that point.?ÿ
It's a 4wd. What are the considerations there?
@mathteacher he will have to change the front diff gears as well. Again not worth the cost. I'd say about 1g per diff.
What Jon said, it would be a major undertaking and unless you have a really good mechanic that does this often, I'd avoid it.?ÿ
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You've got to remember that I'm older than dirt. My twin sons are 50. The ex-paratrooper has slowed down some, but he still likes machines that kick a little.
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But officer my gauge said I was only doing 54MPH.?ÿ?ÿ
