Hi! Newbie here. Read most of the posts on gear swaps and am wondering how those that have completed them like it? I am considering a gear swap in my 1994 ram 1500 3.9L V6 w/5spd manual. Currently the truck has 3.21 gears and is a dog, (V6) I know... Truck has 94,xxx miles on it...

I have done some playing with calculators online about gears and rpms. I like the 3.90 ratios mixed with the NUV3500 tranny but am a bit concerned about 5th gear. 5th gear ratio is .73, with 3.90's it will run 2000 rpm @60mph, will the 3.9L have enough torque to handle the load or it will bog down like it currently does? At 75 mph, it would run about 2500-2600rpm which seems like a good RPM for power and fuel economy... 4th gear runs about 2700rpm @ 60mph, seems like a mpg robber if it won't pull the truck in 5th gear. Probably wouldn't change then...

If I were to switch, how much would of a difference would I really notice? I plan to pull a light load <2000 lbs once to twice a month. A boat (2500 lbs) 5-8 times a summer... Otherwise just normal driving (empty load).... Trailering will be short distances (<30 miles round trip) ocassionally a longer trip about 200 miles round trip...

Any comments or thoughts on the idea are greatly appreciated!!

 

try a 3:55, that 3:90 is to low.

 

What size are your tires?

 

he prob has the stock ones on it that came with the truck. but he should have mentioned it in his thread

 

Thanks for the responses. They are stock size tires though not the originals. For the heck of it a few years ago, I put 15" tires instead of the 16" on it. Didn't seem to make a noticeable difference, however the 15" were a taller profile tire so the diameters were pretty close in size, the more I think about it.

 

okay, so you have 15 inch rims, alright what are the detentions of your tires? Like I said 3.90 is way too low. Get a 3.55 it would be perfect for almost anything your wanting to do with your 3.9L Mag

 

225/75, 245/75 or 265/75? Those are all stock sizes.
I say go for 3.55 gears if they are 225/75 and 3.92 gears if they are 245/75 or 265/75.

 

Hey Sheriff looks like the the dumb JD may know a little thing or two about gears? eh, i guess im learning haha!

 

if he doing a alot of highway driving the 3.55 would be better but if hes doing alot of city driving 3.92 would be better

 

The 15" rims are fords rims that fit the dodge hole pattern. We actually pulled the rims off a E-150. WE haven't really messed with it much since.

I like the 3.55 gear idea as we just want to improve overall drivability. We have a 7.3PSD F350 for any major pulling applications. (Learned there is no replacement for displacement in a hurry!!)

Would you go axle swap or just ring/pinion swap? Both routes sound like a somewhat DIY project.

If I do the ring and pinion route, I would take the axle off myself and take it in to a shop to have it switched out. I would estimate about $500-$600 parts and labor.

I have a lead on a 3.90 axle assembly (Wasn't looking at 3.55) for $350 bucks that I can swap out. The axle is from a 1996 truck, should I stick to a 1994 axle only? I am guessing that a 3.55 would be roughly the same or a bit cheaper since that is a popular axle. I worry about condition of axle coming from a junk yard as they won't guarantee miles on it. Would definitely want to have a shop examine, guessing total cost would be about the same as the ring/pinion set route.