Tow rig axle gear ratio

BigClay

Knower of useless ZJ things
Joined
Sep 24, 2008
Location
Winston-Salem
In my tow rig (dodge V10 with 5 speed manual) I currently have 3.54 gears. Tire size is slightly larger with 285/70/17s.

I use it like a truck, mainly towing and hauling. It is not a daily driver and sees very little unloaded drive time.

Would there be any benefit to swapping the 3.54s for 4.10s?
 

Stuntman Autoworks

Instigator of things
Joined
May 6, 2010
Location
Sanford NC 27330
As far as towing now, it makes it, just like it did when it was a SRW... I didn’t know any better until it was a DRW, now it goes better. I am just wondering if re gearing will make it any better
Yes lower gearing will help
 

Jody Treadway

Croc wearing fool
Moderator
Joined
Mar 20, 2005
Location
Hendersonville, NC
As far as towing now, it makes it, just like it did when it was a SRW... I didn’t know any better until it was a DRW, now it goes better. I am just wondering if re gearing will make it any better

See how it does in 4th compared to 5th. That will be a solid indicator of 3.54 vs 4.10 gearing.
 

RHSCTJ

Well-Known Member
Joined
Jul 1, 2008
Location
ROCK HILL, SC

BigClay

Knower of useless ZJ things
Joined
Sep 24, 2008
Location
Winston-Salem

shawn

running dog lackey of the oppressor class
Administrator
Joined
Mar 13, 2005
Location
Raleigh, NC
That is approximately $2,749 more than I want to put into an engine to replace a V10 with only 20k miles on it haha

You're going to spend half that regearing it, and it's not going to make any more power. It's just going to move the gears closer together.
 

marty79

Well-Known Member
Banned Twice Already
Joined
Dec 2, 2015
Location
Newton NC
For what it's worth I just regeared my suburban from 3:42 to 4:10 and pretty big difference unloaded. Never comes out of overdrive now, torque converter stays locked in always now, pulls hills in OD like butter compared to before (always hunting for gears) so I'd say do it. I've not lost any gas mileage cause I just slowed down to keep rpms close to where they used to be (2100). Thought it might help you out.
 

rodney eppes

Well-Known Member
Joined
Feb 3, 2010
Location
Mt.Holly NC 28120
Jody has a good answer! There's more to it than just changing a gear. RPMs are real important, as How many hills your trying to climb, & How many times will you tow. Might affect gas mileage, or might not be noticeable. Another option, from Marty, but for slightly different reason, Can, you slow down? I mean, are you towing 65 - 70 mph, or 60? My 98 gasser, auto, that had to tow in 3rd., had a Sweet spot around 60. And I seldom had to leave My lane to pass. I let all the Speeders Pass me! One more thing, no way to recoup the cost of re-gearing. Just may be more comfortable.
 

rodney eppes

Well-Known Member
Joined
Feb 3, 2010
Location
Mt.Holly NC 28120
I'll add a bit more. The Faster you go, the More wind resistance! My former truck, had 3.55 gears. I had a Deal on a new set of tires, but they were 1 size smaller. I went with the tires. The way I figured the difference, would be like if I had dropped to a 3.73 gear. I Really couldn't tell the slight difference, other than it threw the speedometer off!
 

marty79

Well-Known Member
Banned Twice Already
Joined
Dec 2, 2015
Location
Newton NC
Can, you slow down? I mean, are you towing 65 - 70 mph, or 60? My 98 gasser, auto, that had to tow in 3rd., had a Sweet spot around 60.
that is my case as well. I never tow above 65 max, usually set cruise at 60 in 3rd with all the 1500 tahoe/trucks we've towed with. My rpms have changed from 78 mph would be 2000 rpm and now I'm at 65 mph sitting at 2000rpm. So far all this week I've kept the same gas mileage keeping the rpms right at 2100 and still have gotten the great gas mileage that I get considering it's a suburban (around 18mph highway and driving like a grandma lol).

I do have a question since were on the topic of gear change and rpms? I'm running a 265/75 16 right now. With the lower gears, would stepping up to a 285 help at all or would I loose some of the extra umph that I gained...when towing would 285 with current gears help or would I loose a little on inclines and such. I need new tires soon and gotta make a decision. thanks
 

marty79

Well-Known Member
Banned Twice Already
Joined
Dec 2, 2015
Location
Newton NC

NCJeeplover

Well-Known Member
Joined
Jul 25, 2009
Location
Claremont, NC
My wife has a v10 Excursion (I know the power bands are a little different between the 6.8 liter ford and the 8 liter dodge but just giving my experience) with stock size 265/75-16 tires and 4.30 gears. It tows great. We've been looking at putting 35's on it and I will definitely regear to 4.88 or 5.13 if we do. I think gears are well worth the money on a tow rig.

If your currently towing in 4th, at 70mph you should be running 2553 rpm. If you regear to 4.10, in 5th you would be 2210rpm at 70. I believe I would go 4.56, that would put you 2459rpm at 70. Thats close to what you have now in 4th, like Jody said. I believe it would work well with your combo. I also doubt you will loose much fuel economy. (all the above info was found using grim jeepers calculator with your combo entered in).
 

Chris_Keziah

Joe Dirt @ Rev Limit Fab
Joined
Dec 1, 2010
Location
Winston-Salem
I'd have to run the numbers on it but I'd be going for 4.10s or 4.56s depending on what the rpms work out for 5th at 75ish.
 

CasterTroy

Motarded
Joined
Mar 21, 2005
Location
Wallburg
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