5.7 / 8 speed with 3.21 gears need info

[Prairegreen]

anybody running this combo? I am looking at a new truck with this combo and wondering if it correct for me. I don't pull a lot and when I do it is a medium sized boat or smaller trailers. I just don't want to make a mistake on this, I am thinking the 3.55 gears is what I need?

 

[toofart]

Won't have any problems with small trailers. How heavy is the boat?

The 8 speed will definitely make up for the 3.21's during take-offs since it has a steeper 1st gear (and more gears) but the final drive is the same as the 5 (and 6) speed trans.

 

[Diller]

I have 2013 with the 5.7, 8 speed, and 3.21s. I tow an open car trailer and have towed a full weight 2003 Mustang a couple of time with it. The super low gearing in the 8 speed make it feel like you have a lot steeper rear gear than you do. I have total towing confidence with the combination. I average 21mpg interstate, 16.5 mixed, and 14 loaded up (6000#). I don't feel like I am missing anything by having the 3.21s.

Keep in mind, this is coming from a guy that traded in his 2005 F250 diesel with 3.73s. That says a lot about the new Rams.

 

[Prairegreen]

The boat is not very heavy at all nor are most of the loads I haul. I had a 5.3 chevy years back with 3.42s in it and I hated it. It was always down shifting on hills and head winds even without a load. I want to make sure I don't get myself into that same situation again with the 3.21s is my reason for asking. I have driven a 2013 5.7 6spd with 3.55s for a few days and there is no issues with that truck for what I do I really liked it. Just wondering if the 8 spd with 3.21s will act about that same as that.

 

[Chewy]

I have the 3.92's and wish I'd have gotten a higher gear. There's just no need for the lower gear for me and my usage and with the 8 speed. That being said, the 3.92 "****'s and gets" from the light!

I pulled our boat which weighs about 5200 lbs and you can barely tell it's back there.

 

[Batram]

In my opinion, if you are considering doing any towing at all, then go with 3.55's at least. 3.21's are not the best for towing & moving up to 3.55's increases your trailer towing by an additional 2000lbs. Having the 8spd transmission only increases towing by 50lbs. 3.55's will still give you decent fuel economy with that extra pulling needed if you ever pull something bigger than a small utility trailer.

 

[Diller]

In my opinion, if you are considering doing any towing at all, then go with 3.55's at least. 3.21's are not the best for towing & moving up to 3.55's increases your trailer towing by an additional 2000lbs. Having the 8spd transmission only increases towing by 50lbs. 3.55's will still give you decent fuel economy with that extra pulling needed if you ever pull something bigger than a small utility trailer.

As a guy that came from the thought process of "buy the most capable truck you can afford", I can say that mentality doesn't make a whole lot of sense for most people.

I tow a race car 10-15 times a year and bought my last truck thinking that I needed a 15,000 pound tow capacity to tow 6,000 pounds. That cost me a ton of comfort, higher cost of entry (diesel engine), higher fuel cost, and much higher maintenance cost. I know that does not come along with just a slight increase in gear ratio but my point is that you should spec out a truck for what you actually use it for. No need to have the higher gears if you will never ever use them. The 3.21s really don't hurt the average tower unless they are towing a big car hauler or a travel trailer.

Just my personal opinion but I would rather have the truck be suited for what I use it for on a regular basis than what I MIGHT need it for once in a while.

 

[hemi8lonestar]

Opt for the 17" tires. The cost savings will pay for the 8 speed and the "final drive ratio" will be very close to the 3.55's and 20's. Thats what i did and it pulls my 19ft bass boat fine.

 

[Batram]

As a guy that came from the thought process of "buy the most capable truck you can afford", I can say that mentality doesn't make a whole lot of sense for most people.

I tow a race car 10-15 times a year and bought my last truck thinking that I needed a 15,000 pound tow capacity to tow 6,000 pounds. That cost me a ton of comfort, higher cost of entry (diesel engine), higher fuel cost, and much higher maintenance cost. I know that does not come along with just a slight increase in gear ratio but my point is that you should spec out a truck for what you actually use it for. No need to have the higher gears if you will never ever use them. The 3.21s really don't hurt the average tower unless they are towing a big car hauler or a travel trailer.

Just my personal opinion but I would rather have the truck be suited for what I use it for on a regular basis than what I MIGHT need it for once in a while.

I definitely agree with you to a point but thinking you need a truck capable of towing 15000lbs & moving up to a diesel is a lot different than what I'm saying. Moving up to the next gear ratio is about $100 option whereas moving to the 8-spd transmission is considerably more. I use my truck as a daily driver on a regular basis & I do need it to tow a toy hauler several times a year. Better to be prepared than be posting on here in a few months asking about gear swaps.
Again, the poster asked about our thoughts & opinions so we're just providing them.

 

[Diller]

Opt for the 17" tires. The cost savings will pay for the 8 speed and the "final drive ratio" will be very close to the 3.55's and 20's. Thats what i did and it pulls my 19ft bass boat fine.

I'm not going through all the math right now to figure out the gear ratios of tire sizes but to go off of your point, the 20" wheel option has a total tire height of 33" and the 17" wheels have a total tire height of 31.6".

 

[Pentastar]

I have this combo (except with pentatar 3.6). You'll be fine with the eight speed. In my opinion, the 8 speed transmission makes the final drive ratio less relavant than it used to be. I've towed a 18 foot (inboard/outboard) boat with 6 six people in the cab. Engine runs around 4K rpms up hills but didn't seem to struggle in terms of getting to or maintaining speed.