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I just bought my first 4x4 this weekend, a 1990 Ram W150, 7+" lift, 38" SS. It's in great shape with exception of the steering shaft which has a lot of play so I ordered a Borgeson Universal shaft for it. The engine is a bone stock fuel injected 318 in fair shape and gears are the stock 3.23's. I'm a muscle car guy and I run 3.91's in my Challenger so I KNOW that the 318 has got to be struggling to get the 38's rolling with 3.23's. If I upgraded to 4.10's the engine should not have to work as hard but how will it affect highway driving? My car 3K rpm at 55 mph with 3.91's but with such large tires will the truck be around 2K rpm at highway speeds???? I plan to get the truck set up correctly right now to enjoy and build a stronger 360 a year or so down the road. Any suggestions are appreciated. THIS IS A DAILY DRIVER SO I DON'T WANT TO GO SO RADICAL IT MAKES IT UNDRIVABLE.
Bryan
 

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i would say running the 4.10 ratio would almost be a bare minimum for gearing down to get your power back. But mathematically compared to stock it is almost perfect. If you have an overdrive transmission, or dont drive on the freeway much I would jump on 4.56 gears.
 

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well I would go for the power, go with 4.88 gears. the little extra gearing will make up for the extra weight of the tires.
 

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With a O/D trannny I'd run 4.88, or 5.13 even. Go to the Reider Racing webpage, under tech there is a gear ratio/vs RPM calculator. That will help you out.

I run 4.10s on my truck with 35s and that's with ~ 285hp and 500ft/lbs torque :thumb:
 

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Discussion Starter · #7 ·
Doing a web search I believe I should have the A-518 OD which final drive ratio is 0.69. 4.56's should be enough. On another note, what kind of problems can I expect with a lifted truck? How many miles can I expect out of a set of 38" Super Swampers? Should I look into any brake upgrades? The kid who owned it before took it to an offroad shop and it appears to done right (no half-azz contraptions) :drive:
 

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Are they radials or Bias Ply? I got about 25,000 out of a set of Radial 38" Swampers on my old truck.

Your MPG is going to be pretty bad no matter what. :thumb:



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Do you even want to throw money at gears for 1/2 ton axles??? The recommendations are correct for the gear ratios, but that would be a waste of time and money for 38's on a rig that weighs that much rolling 1/2 ton running gear. I suppose on the streets it would survive, and I would take the 4.88 recommendation for sure, but offroad, there are bigger fish to fry.
 

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True. What did Dodge use those years, D44 front and a 9.25 rear?

Personally I wouldn't daily drive a truck on 38" Swampers, but that's me.
 

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The 4.56s would probably work pretty good. As far as half ton axles that Dodge 9.25 is a pretty tough bugger but around here we can get used dodge Dana 60s rear ends for like 75 bucks already geared to 4.10 you would have to change your front axle to at least 8 lug outers. If you are building a 360 for it you could change to 3/4 ton stuff ( D 60 rear D44 front) and leave the 4.10s I ran 4.10s and 38" radials for a while and liked it. If you don't want to change the axles then just stuff the 4.56s in there and your good especailly with a 360
 

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I would definetely choose the lower of the gear options...I have 4.10s in mine running 37s and I still feel like im geared too high. My transmission can never make up its mind between 3rd and OD. I figure yours would likely do the same unless you geared low enough.
 
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