Here is a question I got over email from a customer I sold a custom Jeep Bumper Hoop too. I thought I would post the questions and answer here so other can see what I have to say and correct me if you think I am wrong.
Intro:
I am the guy with the Red Jeep who ordered the hoop from you last year with continuous plate and tow rope tabs. My Jeep pictures are posted on your website. With your profound knowledge on the Wranglers, I wonder if you can give me some insight on gear ratio. Beside my Red Rubicon, I have another 2004 Wrangler Sport TJ Manual 5 speed (25,000 miles) with:
2” Coil ProComp Lift
MX-6 Shocks
32x11.5x15 BFG Mud Tires
Dana 44 rear
Dana 30 front
3.73 gear ratio
ARB Snorkel
Gas mileage averaging 13.5 to 15 mpg
Freeway driving speed: no more than 75 mph
Power is okay on flat but once is on hills, it goes way down. I had to down shift to 4th and 3rd just to stay moving. I am thinking of changing the gears to 4:10 (Genuine or Superior ?) and add the $250 “LockRight” locker in the rear. This is my everyday vehicle. I don’t do any hardcore off roading but don’t want to get stuck on ski trip in the snow….. that is why I want to the add the locker in the rear. I have to stay under $1K budget for parts and labor.
Questions:
Q: Is changing gear ratio to 4:10 the right way to gain power?
A: The big power stealers are the tires. They have two bad effects, they are heavier and they go farther on a single rotation compared to the stock 30 inch tires. So changing to lower gear bring the number of engine rotations back in line with the factory specs. You will feel more torque and have better acceleration and be able to keep hills in 5th but 4th for sure.
Q: What are the down sides in changing to 4:10 ?
A: Lower gears multiply the torque at the wheels, so when you need more torque to turn big tire this puts more stress on all the u joints gear and axles. This is more of a technical engineering point, I have 4.56's a 4-1 transmission and 33's when I am hard core wheeling I can break axles and u joints, But with 4.10 and 32 inch tires you should be fine.
Your speedometer may be off, but getting it aligned is a simple 10 dollar part that is easy to change right on top of your t-case.
I think the Dana 30 has a carrier break at either 3.73 or 4.10. If you go past this you will need a new carrier which will add to the expense. Ask about this or look it up. I know my d-44 I had to get a new carrier for the 4.56's so I went with a Detroit.
I looked up Carrier breaks on Pirate 4x4 and you will be fine with the front but will need a new carrier for the rear end Dana 44
Dana Diffs Carrier Break
Dana 30 3.54 and down; 3.73 and up
Dana 44 3.73 and down; 3.92 and up
Dana 60 4.10 and down; 4.56 and up
The locker will make it drive a bit weirder on the street. Mine is fully locked and it gets jiggly some times.
Q: Will my gas mileage go down or up?
A: I don't know the tires are the big gas hog, but the gears will bring things back in line with the factory specs. I don't really even know what gas mileage I get on the freeway, maybe 15 with mine. I trailer it and then wheel it, and when wheeling I get about 10 or less mpgs. You may want to consider 4.56 gears if you are ever going to go with 33 or 35 inch tires.
Q: Can freeway driving go higher than 75 after this mod?
A: Yes, I am guessing, but my Jeep wobbles all over the place to I stay at 75 or below.
Future Mods. include:
Q: Electric Fan?
A: Everyone I talk to says a motor fan is a lot better than electric, unless the electric is an extra. Jut move you factory shroud up and jeep the factory fan.
Q: 1" body lift with 1/2" motor mount lift
A: This will help you clear the bigger tires, and make it look taller. an easy thing to do.
My Final Answer:
Good luck, let me know what you find out after making the changes.
Saturday, January 31, 2009
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