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Ring and pinion

Ring and pinion

Germy

Full Time Jeeper
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Location
Cincinnati, Ohio
Vehicle(s)
1985 jeep cj7 360 20 rear and 30 front w/warn lockers 5 speed tranny,

1971 dodge dart built 318
This is oa rookie question
. Getting ready for regearing, do I have to do the front Dana 30 and the back model twenty. My insides are telling me both need gearing for 4 high. Any help appreciated!
Thanks!!!!
 
Use this chart to find the correct gears for your tire size.
Find you tires on the left and shoot for a gear that is in the green. That will get your gearing back to factory but compensated for your tire size.
_35422.jpg
 
Yes. You do need to have matching gear sets front and rear. If you change one, you need to change the other.

You can use my gear ratio calculator (link in my sig) to experiment with numbers to see what you like and don't like.

The AMC20 /Dana 30 have available ratios:

2.73, 3.08, 3.55, 3.73, 4.10, 4.56, 4.88

They may have 3.31. I know the AMC20 has it but I'm not sure about the Dana 30 .
 
they also have 4.27 for Dana 30 , not sure about 20 rear though...

What size tires are you running? I love the 4.27 for 33" tires. Really don't understand why its not a more popular ratio. It's a very well balanced freeway and off road ratio for me...

:chug:
 
they also have 4.27 for Dana 30 , not sure about 20 rear though...

What size tires are you running? I love the 4.27 for 33" tires. Really don't understand why its not a more popular ratio. It's a very well balanced freeway and off road ratio for me...

:chug:

No 4.27 for the AMC20 .
 
Was thinking 4.56. I want a little more get up and go, no highway, just cruising.
 
4:56's and 35's sound like a good combo since there's no big offroad plans for it.
YES you do need to regear both rears at the same time.
If you only did one and forgot and put it in 4wd you would have big problems.
 
I could imagine! Thanks all! Off to empty the pockets again!
 
I could imagine! Thanks all! Off to empty the pockets again!

Give Terry @ TKH fab a call, he might be able to save you a buck or two.
TKHFab
 
Was thinking 4.56. I want a little more get up and go, no highway, just cruising.


Thats what I run and its perfect for me, winds up some on highway. But I still can get freeway speeds to the trails.

And unless you get selectable lockers, you will be changing the carriers too. You won't need to change carrier if the AMC20 is over 2.73, that is the only one that won't work with higher gears. On the Dana 30 their are two breaking points. You will need the carrier for 3.73 and up.

Might want the one piece axles in the rear too if you don't already have. I did that first as most people do.

If you know someone to do them (experienced) then you can buy the kit for front and rear pretty cheap. Like $4-500. That doesn't include carriers, but does include rebuild kit. You can pick up carriers fairly cheap on EBay, forums or CL.
 
Thanks for the info! I'm pretty sure that I am running 2.73. Are replacing the axles something that a pro needs to do?
 
Are replacing the axles something that a pro needs to do?

not really, but you need to press the new bearings on the new axles.
You do want someone that knows what they are doing to do the gear set ups though.
 
not really, but you need to press the new bearings on.

x2

Not complicated like the gears. Need to remove rim, drum brake set up, bolts on the back to remove backing of brakes and disconnect brake line. Make sure you put it together in the right order like the instructions as I think the (brake) back plate slides over the axle before the bearing goes on (I may be wrong about order, this was some time ago). I just know I was concerned and thinking, glad I didn't "eff" that one up as you have to press the new bearing (or beat:D) down the shaft on and put new races in the axle.

I think I used grease, a rag around axle and a pipe wrench and tapped it down with a hammer. Wasn't too bad. I am sure I am missing stuff, but the instructions are pretty clear. Once the bearing is on and the races in, just slide the axle in and bolt up. Put brakes back on.

I had a the most difficult time getting that old hub bolt off and messing with drum brake springs. :mad:
 
Was thinking 4.56. I want a little more get up and go, no highway, just cruising.
That is how I'm set up,too. Running 33's, but I also have an Overdrive 5 speed tranny. Cruises good at highway speeds.
 
Thanks for the info! I'm pretty sure that I am running 2.73. Are replacing the axles something that a pro needs to do?
Not the axle isn't hard the hard part is set-up on the ring and pinion close isn't good enough it has to be prefect or you ring and pinion will not last long. I would sujest a one piece axle in the 20, at least. I also up graded the 30 axle with 4340 chromoly axles there about $658 for the set when I upgraded. It cost me about $800 in labor to replace the axles and set-up both ring and pinions. All the parts I put in cost about $2000. Do you have lockers or open diffs. Not sure but I think in your set-up it said you have warn lockers im not sure but I think you might be talking about your locking hubs and not the differantcal lockers. Which would be another thing to consiter while you in there regearing and put axles in.:chug:
 

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