gear ratio. turned tire 1 rev and driveshaft went 5

gear ratio. turned tire 1 rev and driveshaft went 5
J

jwillys

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t14, v6 oddfire, stock. Late 60' cj5 (no title so haven't verified yet) late 40's Willy's jeep cab. Dana 44 rear and 30's front. 4.88 gears. Drum brakes. No power steering. Don't know much else yet. Haven't tore into it too much.
I know this is simple math to most of you, but I just read a thread in tech about this. I jacked up the rear, both tires turned the same direction when turning one wheel. I marked the driveshaft and the tire. I turned the tire one revolution and the driveshaft turned just shy of 5 turns. Is this for real? would that be like a 4:90 or something?? Seems wierd. It is a very early CJ5 with a late 40's willys body. It is the very start of a resto. Will start posting in the build forum soon. Thanks everyone.
 
My guess would be 5:38's
 
I'm guessing just shy of 5 turns would most likely be 4.88. Any ideas what axles? Can you pull the cover and check the ring gear stamp?
 
CJ said:
I'm guessing just shy of 5 turns would most likely be 4.88. Any ideas what axles? Can you pull the cover and check the ring gear stamp?
Click to expand...

That's my guess too.

39 ring teeth and 8 pinion teeth gives you 4.88
44 ring teeth and 9 pinion teeth gives you 4.89
49 ring teeth and 10 pinion teeth gives you 4.90

Depending on which axles you have, they'll run one of those two combinations. The bigger pinions will come on the heavier axles. The Dana 30 probably runs the 39/9.
 
I will pull it and check and post. What is the best way to tell what I have in the differential? Both wheels turn the same way. Probably just a Limited slip?
 
Post a couple pic's, someone will know what it is.:chug:
 
See you have an oddfire - 4.88s My buddy has that in his 72 w a Dana 44 rear.

More than likely it's a tracloc - it was a factory option then. Very Limited terrain and then it slips.
 
jwillys said:
Both wheels turn the same way. Probably just a Limited slip?
Click to expand...
Sounds like you have a locker.

As for the gear ratio. I think the others have answered that but we need a little more accuracy. No gear ratio is ever an even 4 to 1 or 5 to 1. The gears would never last.
Check again. When the tire turns exactly one rotation does the drive shaft turn slightly less or slightly more than 5 rotations?

Side note: fill out your profile. I see you have a T-18 and a V6. And from your member name I assume it's old. If you fill out your profile we will know what we are dealing with.
 
Early Cj5scame with D44s in the rear, Offset pumpkin correct?
4.88 would be a common ratio.
there should be a tag on an axle cover bolt with the ratio.
post pics of the axle cover so we can see what it is
and fill out hte profile fields about the jeep so we know what we are discussing please
 
yes to the oddfire. i am excited about that engine. It reminds me of what Chevy did with the 4.3. It is basically a 350 (5.7) minus 2 cylinders. The T-18 is a negative now that I looked. It looks more like a T-15 /T-14 . (not sure on those numbers.) I looked at the pix on another post. It does have the offset rear end, and also has the pto coming off the tranny. I don't think I'll keep that. I will probably list it in the classifieds. I will take some time maybe tomorrow and take some more pix. right now I just have an outside pic of the rear end. It is a 10 bolt that angles longer to the right side. flatter on the left side of the pumpkin. I guess I could google it and get an idea of what I have. Thanks for all the info guys.
 
Standard ratio for the V6 was 3.73, optional was 4.88
Standard ratio for the I4 was 4.27, optional was 5.38
 
here is a pix of the rear and front diff's on the outside. no time to take covers off tonight. Please help identify. Thanks a bunch.
 
I bet it's a 4.88. It was just shy of 5 turns. my guess was 4.9. Thanks. I just posted some pix. Is the rear a 44? What about the front? I definitely need to upgrade to power brakes and steering. I will have to search the forum for my options. I hope it's not too difficult to do. Steer me in the right direction if you would be so kind... anyone. thanks brothers...and sisters, maybe?? Never know.
 
so is there anyway to tell if I have the dana18 Transfer Case that's obvious? I found out it is not a T-18 tranny, but a T-14 probably by the pix on the sticky at the top of this forum, but it's hard to tell by the pix which Transfer Case it is.
 
derf said:
That's curious...

3 to 1
High performance Yukon ring & pinion gear set for Ford 9" in a 3.00 ratio. - YG F9-300

4 to 1
Ford Racing oval ring & pinion set for 9" Ford in a 4.00 ratio. - SVOM4209B400

5 to 1
High performance Yukon Ring & Pinion gear set for Ford 9" in a 5.00 ratio - YG F9-500

6 to 1
High performance Yukon Ring & Pinion gear set for Ford 9" in a 6.00 ratio - YG F9-600
Click to expand...
Those gears would never last. They are all made for racing. Racing gears may be strong but they wear out quick.

Never buy an even gear ratio such as 4:1 or 5:1 and put them into a street vehicle. The reason is if the gear ratio is 4 to 1 then every time the ring gear rotates each tooth will mate up with the same tooth on the pinion gear. A small nick on one tooth will quickly wear the tooth on the other gear. If the gear ratio is 4.11 then the gears will wear much more evenly and last much longer.

A racer wants much more selection of gear ratios. The 9 inch ford rear end has a removable third member. The team can quickly swap out the third member to get just the right gear ratio for that course. They never expect to get very high mileage out of thier gear sets.

A gear set for street use is very hard (for high mileage) but not very strong. A racer may break one of these teeth because they are slightly more brittle. Compare this to a tap that is much harder than a bolt but much easier to break if you turn too hard.
A gear set made for racing is very strong but not very hard. The teeth may flex to the slightest degree but they don't break. Instead they will wear quickly if put in any vehicle that puts on much mileage.
 
jwillys said:
so is there anyway to tell if I have the dana18 Transfer Case that's obvious? I found out it is not a T-18 tranny, but a T-14 probably by the pix on the sticky at the top of this forum, but it's hard to tell by the pix which Transfer Case it is.
Click to expand...

It will have both drive output shafts offset right, it will have a cover plate right behind the Transmission input for mounting pto or Overdrive units, the shift lever mounts are part of the case casting and allways twin sticked.
 
jwillys said:
I bet it's a 4.88. It was just shy of 5 turns. my guess was 4.9. Thanks. I just posted some pix. Is the rear a 44? What about the front? I definitely need to upgrade to power brakes and steering. I will have to search the forum for my options. I hope it's not too difficult to do. Steer me in the right direction if you would be so kind... anyone. thanks brothers...and sisters, maybe?? Never know.
Click to expand...
The front is probably a model 27 with closed knuckles, they have casting marks normally along the side near the pinion. Power steering not so easy to add but if you must have it it can be done with enough $ and/or time depending on your fab skills.
 
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