2wd or 4wd Raider? A 2WD gear swap would be pretty reasonable.

Not much more power to be had from the 3.7. It's old tech now, 2 valves, no VVT. At least it's got coil-on-plug, and the oil is easy to change. Also known to be quite reliable motors.

 

Im gonna check to see what rearend i have. It is a 2wd. The motor itself has been pretty good so far. I really need to replace the plugs in it. I can feel it not idling smoothly now. I have about 37K miles on it now so it is due. I dont understand why dodge couldnt make a motor that can keep plugs in it 100k miles like others do. Oh well. I ordered the plugs today and they will be in tomorrow so get to play with that tomorrow afternoon. Is there an actual programmer for the 3.7 out there? I would prefer to get one instead of the chip but i havent found one yet.

Has anyone tried any of these upgrades on their 3.7's? If so is there any noticeable difference in the truck?

 

NGK Iridium plugs p/n 6441

What gears would be better 3.90 or 4.11's? How many splines is our rear ends 27 or 29? Also, if i find a rebuild kit for a Jeep with the same rear end it should work on mine right? Last question, would my speedometer be off if I change the gears?

 

60 MPH , stock 245/70 R16 tires in overdrive (0.69:1)

3.92 = 1850 RPM
4.10 = 1940 RPM
4.56 = 2150 RPM

80 MPH:

3.92 = 2470 RPM
4.10 = 2580 RPM
4.56 = 2870 RPM

I'd say 4.56's. Alot of Ram guys do it, and love it. Better city fuel MPG, since the trans can get to direct or even OD very quickly. MPG above about 65 will suffer, but if you're pulling it's best to keep it at 60 anyway. Plus the truck will rip off the line.

Remember, going a given speed requires the same horsepower regardless of gearing. The gas pedal is your means to request more *torque* from the engine. Deeper gears = less torque required at the crank = less right foot. You loose a few MPG due to the higher losses in the cooling, lubrication, valvetrain, accessories and transmission due to the higher RPM's, but the 3.7 is much happier and more responsive when whirring away at 3,000, than lugging around at 2,000, with the 4 speed wearing itself out on constant downshifts.

 

I live in the country so very little city driving. I also drive around 150 miles a day to work in my truck. I gotta keep that in mind while looking at upgrades. Probably the highest I would go is 4.10. Will the kits for Jeeps work on the rear end of my truck?

 

Chrysler Corporate 8.25 or 9.25 is pretty widely supported; if you find gears and a rebuild kit for those axles, it should work. They've been in fullsize Dodge cars, vans, and trucks forever.

 

what about the 27 and 29 splines? I read that 29 splines is for the new axles but its harder to find rebuild kits for them.

 

I changed the spark plugs today. Don't know if it is just me but it seems better. Maybe running around 50 RPMs lower maybe a little less. Hopefully it will improve gas mileage a little. I was shocked today when I got 20 mpg. Recently i've been averaging around 17 to 19. I cleaned my K&N filter in my stock box earlier in the week so maybe that did it. I am still researching everything but hopefully soon I will talk my wife into fixing my truck up.