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Unread 05-18-2010, 03:29 PM   #1
pspradlin2
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gearing problem

i am deploying in june and with the extra money i want to regear my amc 20 and dana 30. i want to put lockers in there also. i want to keep running 35s. what ratio does everyone think is best. now i have 3.56 gears and i cant even use fifth gear. i want to be able to drive on the highway and still have alot of guts on the trails.

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Unread 05-18-2010, 03:41 PM   #2
kickingprop
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4.56 if you have OD. 4.10 if you dont
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1985 CJ7 Project
Phase One : 5.3L Vortec/4L60E, Moser axles for AMC20, Twin Stick'd Dana300 - Completed
Phase Two: Bedliner, Rollcage, Seats, BESRK Rear Bumper w/ tire swing, Soft Top, and a few other goodies - Mostly Complete
Phase Three: Waggy 44 front, Scout D44 Rear, 4.56's, ARB's (F/R) SOA with YJ Springs, 35x12.50x15 BFG MT - Not Even Close to beginning

Also a mostly rust-free 1970 Scout 800A That I'll get to start working on someday...

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Chrome won't get you home...BUT Rattle Can Black may just get you back"
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Unread 05-18-2010, 03:44 PM   #3
pspradlin2
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what do you mean by od? i have a t-5 trans. you mean od as in 5th gear?
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Unread 05-18-2010, 04:06 PM   #4
foggybottombob
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I would say 4.88 with a T-5. OD just means your highest gear ratio in the tranny is lower than 1:1. In the T-5 it will be either 0.86 or 0.76 in 5th. I have the 0.76 5th and I will be putting 4.88s in mine when I get 35s in the next month or so. 4.10s with 35s is gonna be a dog with an AMC 258 no matter what tranny you have.
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Unread 05-18-2010, 04:44 PM   #5
pspradlin2
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i thought the t-5 was .86 in 5th. how can you tell the difference between a .86 and .76. i did not know about od being less than 1:1. do you have a tach in your jeep? i am wondering about the rpm. what would be the best rpm with a 258 to cruz on the highway
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Unread 05-18-2010, 04:57 PM   #6
crzdmnky
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I would look on your local craigslist and see if you can score a deal on axles that already have the upgrade that you want. You usually can pick them up for cheaper, and not have to worry about all the labor that goes with re-gearing and putting lockers in...
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Unread 05-18-2010, 06:09 PM   #7
foggybottombob
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Quote:
Originally Posted by pspradlin2 View Post
i thought the t-5 was .86 in 5th. how can you tell the difference between a .86 and .76. i did not know about od being less than 1:1. do you have a tach in your jeep? i am wondering about the rpm. what would be the best rpm with a 258 to cruz on the highway
When I said less than 1:1 I just mean 0.76 or something. Just run at some speed in 4th (which is 1:1) then run at the same speed in 5th and see how much the rpms drop. I like to cruise the 258 around 2500 to 2800 rpm. Some people run them at 3000 and up but that seems a bit much to me for this engine.

If you were running 2500 rpm in 4th and then 5th at the same speed drops rpms to 2150 then you have a 0.86 5th. If rpms drop to 1900 you have a 0.76 5th gear. Just multiply the 4th gear by 0.76 or 0.86 to see what 5th gear rpms would be at the same ground speed.
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Unread 05-19-2010, 10:35 AM   #8
pspradlin2
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what axle should i look for? direct replacement or upgrade? what all goes into an axle swap. i know i could do it all but what the difference between the pinion yokesand what not for an amc 20/ dana 30 vs. a dana 44.
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Unread 05-19-2010, 01:23 PM   #9
foggybottombob
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You won't find any gears lower than 4.10's in a junkyard axle. So to go lower than that requires regearing. So can you get 1 piece AMC 20 shafts for less than you can buy a Scout rear Dana 44 axle? I don't know. The 72-80 Scout rear Dana 44 is an easy swap to a CJ7. It has the same 5 on 5.5" wheel bolt pattern and the ones after 74 have 11" x 2.25" brake shoes. Older ones have 11" brakes with more narrow shoes. You have to move the spring perches and set the pinion angle for your particular lift and that is it. I have no experience with AMC 20 axles. The scout rear axle is 2" wider than the stock late model CJ7 axles. It is 58" vs the stock 56".
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Unread 05-19-2010, 01:32 PM   #10
pspradlin2
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well i have one peice axles already in my amc 20. superior one peice chromoly. how strong is this set up. do you think it will handle 35s and 4.56s with a locker when it gets in a bind. i was thinking the amc 20 would be fine but not so sure about the dana 30 up front. i found a set of axles from a 79 f-150. Dana 44 front and 9" rear. they are already geared with 4.56 but not locked. i am haveing a little trouble finding the width though. i dont think i should put axles wider than 60" on there.
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Unread 05-19-2010, 01:47 PM   #11
CSP
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The AMC 20 with one piece axles is fine with 35s, even locked.

Those F150 axles will be in the 65-67" wide range. The front axle has the differential on the wrong side for a CJ anyhow.

A '74-79 Wagoneer axle narrowed 4" is a good match in width to your rear axle. Lotsa info on the web on this subject.
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Unread 05-19-2010, 01:54 PM   #12
pspradlin2
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well i dont think i would really want any axle that has been narrowed or that would need to be just so i dont have to go through all the trouble when i break something.
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Unread 05-19-2010, 01:57 PM   #13
CSP
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Then your choices are basically zero. There are no D44's that are of the same width as your Dana 30.
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Unread 05-19-2010, 02:07 PM   #14
pspradlin2
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thats what i was thinking. well i guess the next question is what lockers should i go with if i am going to keep stock axles? and should i even do the front?
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Unread 05-19-2010, 02:09 PM   #15
kickingprop
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I wouldnt waste any money on the dana 30 beyond maybe a lunchbox locker...the phrase "a Polished Turd is still just a turd" has been thrown around on here in regards to beefing up a D30. I'd go selectable in the rear if you've got the money. That way you can turn it off and maintain streetability
__________________
1985 CJ7 Project
Phase One : 5.3L Vortec/4L60E, Moser axles for AMC20, Twin Stick'd Dana300 - Completed
Phase Two: Bedliner, Rollcage, Seats, BESRK Rear Bumper w/ tire swing, Soft Top, and a few other goodies - Mostly Complete
Phase Three: Waggy 44 front, Scout D44 Rear, 4.56's, ARB's (F/R) SOA with YJ Springs, 35x12.50x15 BFG MT - Not Even Close to beginning

Also a mostly rust-free 1970 Scout 800A That I'll get to start working on someday...

Quote:
Chrome won't get you home...BUT Rattle Can Black may just get you back"
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