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Discussion Starter · #1 ·
Guys,

I am planning on some new gears this summer after my Dana 44 swap and SOA. I have an 84 CJ7 with a V8 304, t-5, and Dana300 Tcase. I think the stock gears are 3 somethings...lol

What would be the best gear ratio to get? I only use the Jeep for wheeling. Will 4:56's be to much? 4:18s? your opinions? Thanks.

1997 TJ w/ 33's & 1984 CJ7 V8/35's
http://members.aol.com/a4x4jeeper/
 

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I run 4.56's, 4.2, and 33's and like it allot on the trail. On the fwy lets just say I get
more of a chance to enjoy the countryside. 3000 rpm x 4.56 x 33 = slow lane.
Like yours its only a trail Jeep so go as low as you can, if you don't like it you can
always get bigger tires.

My first Jeep was a CH-47 "Chinook"
83 CJ5 4.2 t176 300 4.56 33s
 

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4.56 gears are great off road gears and they still arent to bad on the Hwy. In 4th gear at 1.1 ratio 4.56 R&P and 33" tires, you should be turning about 3025 RPMs at 65/ 35" tires about about 2850 RPMs. To get your gearing even lower for the trail you could also later go to a Tera Low 4.0:1 gearing change for your D300 T case this will give you about a 75:1 ratio at the hubs in low range first gear,but not affect your high range.

 
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Discussion Starter · #4 ·
One thing to consider if your Jeep is trail only, so low range is the most useful t-case mode. In a 84, your gears are probably 3.31.
Figure it out, stock t-case, t-4 trans and 4.56s will give you a crawl ratio of 50:1. BUT, Tera Low 4:1 t-case, 3.31s, and t-4 trans
gives you a crawl ratio of better than 53:1. So, if you can only afford the one, you are going to get a better crawl ratio with the
Tera Low. Plus, an 84 is probably going to need the t-case gone thru anyway.

Brad
ORC Land Use Section Editor
Get involved or lose it all, the choice is yours!
 

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One thing to consider though is the extra strain placed on your drive shafts yokes,axle shafts, etc. by staying with the higher 3.31 ratio. It can really start to take its toll on older running gear leading to frequent failure on the trail.
Jeff
89 Wrangler

 
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Discussion Starter · #6 ·
Please help me with the math that would get 50 to 1 ratio with these components. I must be missing something.
Thanks

80 CJ5, 52M38
 

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Here what they must have been talking about when they said someday math would help me in real life,(although I dont think they were counting on calculators,back then).
4.03:1(4.0)1st gear / 2.67(2.7) low range / 3.73 R&P = 40:1 ( or -)
with 4.56 gears = 49:1
with 4.56 gears and Tera Low 4:1 = 73.5:1
your gears with TeraLow 4:1 = 53.3:1
There you have it.
The Tera Low kits are nice set ups and give you very good low range, just remember as your building your Jeep with these lower gears, the relenless force of gravity and the torque needed to overcome it constantly seek out and destroy any weak link in the drive train.You start out to build up one component, you can end up building them all.
Jeff
89 Wrangler

 
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Discussion Starter · #9 ·
One other thing to toss out, the 4.10s are stronger than the 4.56s. I think Randy Lyman has an article on this on his site,
http://www.ring-pinion.com in the tech section. Oh, one other thing to cause even more thought, like was mentioned above,
the strain on components due to lower gears. We went around and around about this a while back, if something is gonna break,
and it will, make it something easy to fix. That's why stuff like full floaters be nice, axle change/removal a snap. Also, that's why
with all the money I dumped into my Jeep, I kept stock hubs up front. "Upgrades" aren't that expensive, under a hundred bucks,
but if something breaks let it be a 5 minute fix it hub, not an axle or u-joint. Hubs don't take up much room in the box, either, and
stockers can be found cheap because of all the people "upgrading".

Brad
ORC Land Use Section Editor
Get involved or lose it all, the choice is yours!
 
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Discussion Starter · #10 ·
FYI...I have 4.10's with 32" and the T5. The overdrive makes freeway driving pleasant, and starting off in 1st gear is much nicer. The Tera low is great for rock crawling, however, it won't solve the on street problem...33's with 3.31 gears is rough on the clutch. I wouldn't go with 4.56 unless I was going to run 35" tires or larger.

One other point...If you ever decide to replace the T5 with an automatic, say the GM 700R which has overdrive, you will now have a very good combination of transmission, gears and tires for both off and on road driving.

John......southern CA
84CJ7, 3"lift, 32"BFG, 4.10's, ARB Locker, Solid Axle's, Durabak
 
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Discussion Starter · #11 ·
But, the original post said this is a trail machine ONLY. So, low range is the key. Like I said, 4:1 low range gives better crawl ratio than 4.56 gears.

Brad
ORC Land Use Section Editor
Get involved or lose it all, the choice is yours!
 
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