Discussion in 'Early CJ-5 and CJ-6 Tech' started by tripilio, Jan 4, 2019.
Other than opening the pumpkin cover, how can I know the gearing on my dana 44? Thanks!
It's pretty easy if you've got an open differential. Jack up one tire off the ground. Put a piece of masking tape on the driveshaft. Put a piece of tape on the jacked-up wheel or use the valve stem as a marker. Rotate the tire one or more complete revolutions. At the same time, count the number of revolutions the driveshaft makes. Then divide the driveshaft revolutions by the number of tire revolutions. Obviously, the more tire revolutions you make, the more accurate your final answer will be. At the same time, if you know the possible gear ratios in advance, one tire revolution is usually accurate enough to determine which of those distinct values you've got.
If you're lucky, one of the bolts holding the cover on might still have the small metal tag that tells the ratio.
...IF the tag still matches what's actually inside.
Ah yes. I bought a 3B last summer and tested the 4wd on the grass on my back hill. When I drove off the grass onto the asphalt to my driveway, the jeep was a bucking bronco trying to drive up the road. I couldn't get the transfer case out of 4wd. My first thought was the axle ratios between the back and the front were different. I jacked up one side of the front to do the rotate wheel test to calculate the diff ratio and as soon as the wheel came off the ground, all the binding let loose and the wheel spun by itself. There was a tag on the axle that read 43/8, which equals 5.375, which equals 5.4. However, when I rotated the tire and counted the driveshaft revolutions, I computed an axle ratio of 4.27. Doing the same tire rotation test on the rear axle gave me a gear ratio of 5.4. I couldn't believe the front tag could be wrong. I removed the diff cover and manually counted the ring and pinon teeth. They were 47/11 = 4.27. So indeed, the front and rear axle ratios were different and the front tag was wrong. By the way, the story has a happy ending. The seller picked up the jeep and had 5.4 gears installed in the front and returned the jeep working fine in 4wd.
Unless that tag is still there you won't know. Even then it's an educated guess.
You'll have to crack it open and read the gearing stamped internally to know with absolute certainty.
Tag is great on an unmolested vehicle, but like jeepster says, you won't know without looking... I have an '86 K30 that someone had marked out on the SPID (parts identifier in the glovebox) 3.73 and penciled in 4.10. No tag on the rear Dana 70 but 3.73 tag on the front Dana 60. Pulled the covers to put LockRight in rear and Spartan in front and both had 4.10's as per the penciled in #.
Just my experience...I think counting the driveshaft revolutions when turning a tire by hand works quite well. Common jeep ratios would be 5.38, 4.88, 4.27 and 3.73.
Thanks! The main reason for my question is that I'm ready to rebuild my front dana25 and the idea of "what if they are different?" popped in my head. Now would be the time to re-gear. I have a 5.38 in the front. In case the gears are different, which would be the best ratio for city driving?
Best differential ratio depends on which engine and whether or not it has an O.D. unit.
Catastrophic failure would have happened with different axle ratios in the same vehicle
If your going to rebuild your dana 25, the just rebuild your 44 as well. In that case, just open the cover....
You probably should at least change the fluid and check the condition of things anyway.
I have an f134 withot od.
Either the 5.38 or 4.27 gears work fine with an F134 for street use without overdrive. The 5.38 gears were standard from the factory up through around 1963 when Kaiser changed the standard gears to 4.27 for '64 -newer. A change in transmission 1st and 2nd gears was made at this same time. With 5.38 gears, don't expect to run more than 55-60 mph unless you add an overdive. Just make sure that both front and rear axle ratios match each other!
I know that eventually I will have to get to the rear axle, but at this point, I am trying to stop the dismantling all over and start closing items I am working on. I think my best approach will be to open the rear cover anyways. If I have to move it it would be just a couple of feet, it would not hurt it to be moved while open. Right?
F-34 implies low power.
Go 4.27 ratio for better road speed if you don't use an overdrive.
5.38 was the CJ standard and only CJ ratio available from 1945 through 1962.
4.27 ratio was the CJ standard from 1963 through 1971.
The 1966-1971 Dauntless CJ was optional and has higher ratios due to increase of power.
With 4.27 your crawl ability will suffer by about 30%.
With 5.38 and no O.D. your road speed will suffer about 25%
5.38 with O.D. unit is most certainly the optimum set-up for any of the 134 engines.
Thanks, oldtime! I guess I can predict an OD purchase in the future!
The OD is easy - except on the wallet. Pop the rear cover off the Tcase, pull Main gear, replace with OD Bowel Setup, slip OD on back of Tcase, set shift levers - Done...
See, that wasn't so hard
I think you passed over a few hours worth of cursing, banged knuckles & oil in the eye.
But yup it's a worthwhile expense.
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