Tow rig axle gear ratio

BigClay

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?
 
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
 
BigClay said:
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
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Yes lower gearing will help
 
BigClay said:
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
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See how it does in 4th compared to 5th. That will be a solid indicator of 3.54 vs 4.10 gearing.
 
BigClay said:
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
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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.
 
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.
 
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.
 
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!
 
rodney eppes said:
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.
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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
 
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).
 
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.
 
skyhighZJ said:
Facebook Marketplace: Cummins P-Pump 12 valve Diesel motor - Auto Parts - Van Wyck, South Carolina
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Both Joe (7.3 Ford) and myself (6.0 Ford) left Chris (cummings) like he was going backwards on the pulls coming back from Harlan. (I never downshifted from 6th)

But we were BOTH left in the dust by Adam in his 8.1 Chevy.

You don't need a diesel (especially towing to harlan) you just need an 8.1 :smokin:

besides...yours is the meanest looking Dodge evah!


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