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Discussion Starter · #1 ·
I am a rookie. I got my first off-road vehicle in November. It is a 1991 Dodge Ramcharger 4x4. It has a 318 V8 and an automatic transmission. It had a small lift and 33" tires when I bought it. I ran the bald 33's until last month when I purchased 35" Mud Trac Steel Radials. Now my gear ratio is out-of-whack. I need lower gears in my rear axle. How do I figure out what my current gears are and where can I find lower ones? I like my 35's, but I think the weird ratio helped to ruin my old transmission. I just spent almost $1,600 on an entirely different transmission and I don't want to go through that again. Any help would be greatly appreciated.
 

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WEl lmore than likely ui got 3:23 gears . U need to go up to a 4:10 ratio and it will be ok or a 3:70 will work . get a locker if u can afford it
 

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Discussion Starter · #3 ·
I would like to get a locker, but since it's my daily driver, I'm probably going to try to live without one.
 

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more than likely they are 3.55s since its a 91 and had OD from the factory. if u still have the OD, u can go up to 4.56 gears. if not, go with 4.10s. and i agree, get a locker, DD or not.

Duane
 

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To determine your axle ratio:

1) See if the tag is still on one of the diff bolts. If it is, the gear ratio should be stamped on it. If not,
2) For an open diff. Jack one tire off the ground. Make a chalk mark on the driveshaft and the rear tire that is in the air. Put trans in neutral, make sure the front tires are blocked. Spin the rear tire two complete revolutions, counting the turns of the dirveshaft. Number of driveshaft turns = gear ratio (3 1/2 turns = 3.55:1, 3 1/4 turns = 3.23, etc)
3)For a posi rear end. Same as above, except both rear tires need to be off the ground, and you will need to spin BOTH rear tires ONE revolution (If your posi is still working you shouldn't be able to spin only one tire). Number of drivershaft turns = gear ratio.

I can email you a speed vs rpm calculator I made in MS Excel if you like. It will plot your speed at 500 rpm intervals for common MOPAR gear ratios. All you need to do is input tire diameter and final drive ratio (1:1 for non-OD, 0.7:1 for OD)

-SM
 

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Discussion Starter · #6 ·
CLRracer, I was thinking about 4.10s but 4.56s were a thought also. Thanks for the information.

Slanter_Mind, Thanks for the information about determining axle ratios. I will try that. I would like to try that calculator you made. My e-mail address is [email protected]

Thanks for all of the infomation.

Luke
 

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Discussion Starter · #7 ·
Sorry about my last post, Slanted_Mind. I can't type very well.
 

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Hi I too would really like to try out your calculator it would be great for ordering my parts at home at the computer.

Mike.
email:

[email protected]

 

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If you have an overdrive trans I would go with 4.56's otherwise 4.10s
 

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BrianT said:
WEl lmore than likely ui got 3:23 gears . U need to go up to a 4:10 ratio and it will be ok or a 3:70 will work . get a locker if u can afford it
Hey Brian who's making a 3.7 ratio for the 9.25 rear end? :)
 

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i always thought the 3:70 ratio was available forthe 9.25 dodge axle . well to find out for sure we need to get ahold of Randy's Ring and Pinion and se eif they have it or not be nice to know for sure .
 

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well i wi'll bea mokey's uncle . ford and chebbies have that ratio . strange but a 3: 90 is probably better anyhow i thnk cuz dodge made the 3:55 3:70 gears would a been stupid to use isuppose .
 

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I agree 4.10's for non OD and 4.56's with OD tranny
 

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Firechicken and RingGold....you have mail. Sorry it took this long, I missed the new posts! Let me know if the calculator is any help/any improvements that would make it better.

-SM
 
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