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Unread 08-28-2011, 09:51 PM   #1
80cj
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CJ5 w 401, auto gearing

A friend has asked me to regear his Jeep for him. He has a 78 Cj5 with a glass body, AMC 401, Ford C6 auto trans running 35's in a rear D44 and D30 front. He is currently running 4.56 gears and probably getting about 6 or 7 MPG. Our gas prices here are still hanging in at well over $4/gallon. He wants to regear and we've been looking at 4.10's. The Jeep is 98% street driven and I was wondering if 3.92's would be too high considering the Jeep's weight and auto trans. Our hiway speed limit here is 50 mph. If the engine has a stock cam, do you guys think 3.92's would be too high. This calculator puts engine RPM at around 1882 at 50 MPH.

http://www.rocky-road.com/calculator.html

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Unread 08-29-2011, 04:41 AM   #2
Exposed
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80CJ, that must have a very short drive shaft
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Unread 08-29-2011, 07:37 AM   #3
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If your looking for mpg Id say 3.92s(I thought they were 3.91 in a D44) would be a better choice, its as tall as you can go with that carrier and a stock cam 401 should have plenty of torque to move a 5 at low RPM. That being said, throttle response from a 401 in low range with 4.56s has gotta be Wicked...keeper tween the ditches...OCG
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Unread 08-29-2011, 10:50 AM   #4
80cj
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Quote:
Originally Posted by Exposed View Post
80CJ, that must have a very short drive shaft
Yeah. He has a short CV shaft. Apparently he put a lot of money into the build up. The rearend is a Dynatrac D44 ... $3000.00. The paint job is really nice.
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