Another gearing question...
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Freshman User
Joined: Oct 2012
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From: mesa, az
Another gearing question...
I have s 2009 crew cab short bed with an 8" lift and 37" tires. Looking to rehear the truck to gain back some shift points and maybe a lil fuel mileage. Mostly drivability. I tow my 12' work trailer around town all day every day and just would like things to be close to stock. Anyone know or have done this? I have 4:10s now and was thinking 4:56? Does this sound right?
Elder User
Joined: Jul 2005
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If my math is correct (it's presently after midnight and I'm on beer number 3), when you went to 37s, your effective gear ratio decreased by almost 20 percent. Going from 4.10 to 4.56 is only going to gain back half of tthat. If I were you, considering how regularly you tow, I'd definitely be looking at 4.88s or maybe more.
FTE Leadership Emeritus
Joined: Jul 2002
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From: Long Island USA
Yep, divide your current tire diameter by the stock diameter (32 or so), and multiply by your current gearing. 37/32=1.15625 so 4.10*1.15625 gives you 4.74 to bring to back to stock gearing.
So 4.88's would give you around 4.43 gearing on stock tires. 4.43 is a little steeper than the available 4.30's, but that would help if you're pulling a trailer all the time.
So 4.88's would give you around 4.43 gearing on stock tires. 4.43 is a little steeper than the available 4.30's, but that would help if you're pulling a trailer all the time.
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Freshman User
Joined: Oct 2012
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From: mesa, az
Nice! Thanks guys! I obviously didn't pay attention in math class so that was all Portuguese to me but the end result is 4:88. I should for sure get a larger pan to keep those cool huh?
Moderator
Joined: Jul 2010
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From: Media PA
Larger trans pans and bigger diff covers don't really do anything to improve cooling. It may take a tiny bit longer to get up to normal operating temps but then the extra capacity also requires more time to cool back down if higher temps are reached. I actually have a rear diff temp monitor on my 4.88 geared EX with 35"s that pulls our 11,000 lb TT. My only additional cooling is from an OEM '08+ aluminum rear diff cover, rarely will the temp ever touch 200.
More Turbo
Joined: May 2014
Posts: 643
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From: Poway, CA
Definitely go with the 4.88s at a minimum for top performance. By my calculations that will leave you just shy of an effective ratio of 4.30. The impact to fuel economy will probably be minimal. I highly recommend adding an accurate transmission temp gauge at the same time. After burning up a transmission with virtually no warning, I invested in a ScanGage II. It puts a lot of interesting and valuable information at your fingertips.
Tuned
Joined: Nov 2011
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From: Trumbull CT
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More Turbo
Joined: May 2014
Posts: 643
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From: Poway, CA
2400 at 70
This set up was chosen for towing at 65 MPH @ 2200 on 35" (actual 35.4") tires. I feel like I could move up to 37" at some point without too much of a performance penalty.
This set up was chosen for towing at 65 MPH @ 2200 on 35" (actual 35.4") tires. I feel like I could move up to 37" at some point without too much of a performance penalty.
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