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gear ratio; finding and understanding
Topic Started: Oct 27 2012, 10:21 AM (816 Views)
JROD CJ53
Member
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Other than taking off the cover and counting the gears is there another way to find the gear ratio? Is it stamped on the housing somewhere? I thought I had read that in one of the posts. I have been known to be wrong tho.
The PO had run large tires on the jeep at one point( picture included) but I have smaller tires on it now. Still bigger than the stock tires, but nothing over the top. I plan to be doing daily driving with it, around town. No highway speeds. and occasionally doing some trail driving here and there.

Posted Image


(2nd picture with the tires on there now)
http://sphotos-a.xx.fbcdn.net/hphotos-snc7...909229257_n.jpg
1953 CJ3B/F134 rebuilt with 6000 miles/ Dana 25 front, 44 rear/ T90, Spicer18/ YF 938SD/12V conversion . Tarpon Springs FL
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oldtime
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Originally there were tags located under one of the carrier cover bolts to identify the gear ratio.
Prior to the CJ's, all military LRV's were standard with 4.88 final drive.
All original CJ's from 1946-1962 will have 5.38 gears.
No optional final drive ratios were available for CJ's from 1946-1962.
The ratio tag will read 43/ 8.
43 ring teeth divided by 8 pinion teeth = 5.375 reduction ratio.

In my opinion the 5.38 ratio is the optimum choice for stock standard 134 engines.
If driven on road the Warn 25% O.D. becomes a huge advantage with 5.38 final drive.
I drive a lot on the interstate with my 1962 Hurricane powered 3B ( 5.38 gears plus O.D.)
5.38 x .75 (25% OD.) = compounded 4.03 final drive.
That's as high geared as is practicle for a Hurricane powered jeep.
When climbing the steepest interstate grades here my jeep can barely maintain 60 MPH at wide open throttle (WOT).
A higher combined final drive ratio would be a problem for the meager torque output of the engine.
Other engines like D-225 can accept higher final drive ratios but not the F-134.
The post November 1962 standard for all Hurricane CJ's is 4.27 final drive ratio.
That ratio alone is fine for the Hurricane but will not work well on high speed inclines with an O.D. engaged.
In September of 1964 Kaiser approved the Warn O.D. for use only with 5.38 or 4.88 final drive.

Also realize that tire diameter can effect the driven speed by about 10%.
Currently building my final F-134 powered 3B .
Rock Crawler using factory parts from the Willys Motors era (1953-1963)

http://s4.zetaboards.com/CJ3B_Bulletin_Board/topic/30228766/1/#new
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Bruce W
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If there are no tags, jack up one rear wheel with transmission in neutral. Get underneath and make a reference mark on the wheel and brake drum, and one on the driveshaft and rear-end housing. Turn either the shaft or the wheel while counting turns of the driveshaft until the wheel makes two revolutions. The shaft should turn 5 3/8 revolutions if the 5:38 gears are present, a little over 4 3/4 turns for 4:88's, and 4 1/4 turns for 4:27's. you have to go two turns of the wheel because the differential action of the rear-end doubles the speed of the non-stationary wheel. BW
Bruce Walker
Northeast Colorado
'53 CJ3B "Nellybelle", '48 CJ2A "Uncle Lyndon", '47 CJ2A "Teddy", '47 CJ2A "Rusty", '47 CJ2A "Zak", '43 GPW "Sarge", '88 XJ "Pluto"
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Lawrence
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Lawrence
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Originally there were tags located under one of the carrier cover bolts to identify the gear ratio.
Posted Image

Lawrence
1955 CJ3B
Family Tradition
Decatur, AL
~~"Seen it all, done it all, can't remember most of it"~~
~~"We cannot direct the winds but we can adjust our sails"~~
http://cj3b.info/Owners/Wade.html
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