3.21 8speed and 37s

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Heucobob

Heucobob

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I looked first gear in the 8 speed 3.21 is like 4.71
 

MarshRam

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Ok thanks . I got a email from a guy who said he runs this set up and shuts the mds off . He said he sees some Change in power but he expected that . For me personally I drive around town and put less than 5000 miles a year on my truck so I'm going to give it a go and I will definitely come back on and give u my honest opinion.

Well, I have mds off. Looking forward to hearing about your experience!
 

PDXRam

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I was running 3.92 gears, 6" lift, 35's, cai, custom tune and my truck would give you a whiplash if you went from stop to pedal to the metal. On the freeway it had juice too. 37's would have probably slowed it down though, but I'm not sure how much more the 37s weigh compared to the 35's.


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Heucobob

Heucobob

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I drive one at a local custom 4x4 shop yesterday with 3.21 and 8 speed and 37s and it drove nice and had nice power still much like my buddies that has 35s so I'm not sure y all the guys on this forum are saying it's a big drop off from 35s
 

deangtp

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I have a 2014 hemi 8 spd. 3.21 gears with 37's. It does hunt on the highway a little bit. It looks awesome. It's not terrible, but you do have to drive a little different. I don't regret the decision to go 37's at all. It looks awesome. My wheel/tire combo weighs 119lbs a piece. I still pass people. It'll still do 100. Did I mention it looks awesome. I do have 3.92's I need to install, so I'll have a comparison at some point.

Mod list
Moes 87mm TB
S&B CAI
ATI balancer
Hemi tune
Pedal commander
 

Dirty from upstate NY

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The reason for my post was for people with first hand experience using this kind of set up . I appreciate all the feed back but most people that answer on this forum and other forums never really experienced this set up to give first hand experience .

I have a 2016 Ram 1500 with a pro comp 6" lift and a 1.5" body lift. Wheels are 20x10 XDs and 37x12.5 MTs. Truck drives just fine man! Has no issues with the acceleration or lack of it with the 3.21 gears! I average 17mpg with a 50/50 mix of express way and around the town driving. Just did minor add ons like the peddle commander, ported throttle body, intake and cat back exhaust. Just go with it, I'm super pleased with the setup and have NO issues with running 37s and 3.21 gears.
 
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Heucobob

Heucobob

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Thank for the replays Its good to hear from people that have first hand experience !
 
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Heucobob

Heucobob

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Finally got my 37s and I love it. the power is definitely still there gas mileage is a little different. Around town driving is great . Haven't did highway yet but over all I'm glad I went with it . Don't anyone shy away from doing it the truck has plenty of power !
 

Jameson

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il19DRq.jpg

37s on 24x14s with 8spd and 3.92s. Only mods are Greene Tune and Vararam. I want to swap 4.55s but the front is a pain in the ass. I average 14mpg and power is there. 4.56s and a Maggie would be ideal though lol.
 

Rzrman328

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Finally got my 37s and I love it. the power is definitely still there gas mileage is a little different. Around town driving is great . Haven't did highway yet but over all I'm glad I went with it . Don't anyone shy away from doing it the truck has plenty of power !

Well where the hell are the pics?
 

JB1

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Finally got my 37s and I love it. the power is definitely still there gas mileage is a little different. Around town driving is great . Haven't did highway yet but over all I'm glad I went with it . Don't anyone shy away from doing it the truck has plenty of power !

My lift plan was to get 37's, then a member here recently got 37x13.50's and complained he couldn't keep 8th gear on the hwy. and that was with 3.92's. That made me wonder if choosing 37's would ruin my truck from being driven on hwy and be stuck to only neighborhood city street driving.

I have the money in the bank right now for lift/tires/wheels etc and still cant decide on 35's or 37's :hmm:
 
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I don't do much highway driving to worry about 8th but for everyday driving around city and town it's perfect. . For some reason I can't upload me pics .
 

Dangulo

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My lift plan was to get 37's, then a member here recently got 37x13.50's and complained he couldn't keep 8th gear on the hwy. and that was with 3.92's. That made me wonder if choosing 37's would ruin my truck from being driven on hwy and be stuck to only neighborhood city street driving.

I have the money in the bank right now for lift/tires/wheels etc and still cant decide on 35's or 37's :hmm:

You can always swap to 4.56 gears
 

letsgonats

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Thread has been stale, but I have been running 37x13.5R18s since December on a '17 1500 w/ 3.21 and have no problems at all. I keep MDS off the entire time and while it does hunt between 7th and 8th over 55, I just drove to Florida from Virginia (and back), got 17mpg, and rather enjoyed the drive.
 

Lifted2wd

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Thread has been stale, but I have been running 37x13.5R18s since December on a '17 1500 w/ 3.21 and have no problems at all. I keep MDS off the entire time and while it does hunt between 7th and 8th over 55, I just drove to Florida from Virginia (and back), got 17mpg, and rather enjoyed the drive.

I've had my 37s on my 15 w/3.21 since Oct and had no power loss and love the ride. I don't really notice the gear hunt, and eco mode works perfect
 

Jared Zickowski

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I just lifted my truck 8" and 37x13.50r17 and 3.21 lost some power for sure. But still have plenty. I still want to regear just trying to figure out which gears to go with
 

2010 Infantry Vet

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My truck is a 2010 so i dont have the 8-speed. I have 3:92 gears, 6" lift, and 37's. At a dead stop, when i stomp on it, the truck wont even spin the tires...at all. Truck is a pig with 37's and 3:92 gears. I only get 12 mpg on the highway. Passing people on the highway is possible, but takes forever. Only cure is a blower. I cant imagine running 3:21 gears and 37's. There isnt that much of a difference between the 6 speed and 8 speed when your going above 55mph.
If i had 3:21 I wouldnt even think about 37's.
Also depends where in the US you live. If your down south, there are no hills and its all flat. Up north, you have long steep hills. I live in Pennsylvania, so i fight long steep hills daily.

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