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Is it possible to put 4.55s in a D30?

dspilot

NAXJA Forum User
Location
Hickory Flat, MS
Just like the title says.....I was changing my front diff oil today, and when I got the cover off and cleaned up, the numbers 455 were written on the cover with something like chalk. It was obvious that the cover has been off recently (RTV in good shape), and I have only had the jeep for 3 months. Is this something a shop would do? Also, to me, the ring gear looked to really fill up the housing, but I am a complete novice in the gearing arena. Is it possible that the PO had these installed? If so, what advantage does it give in a crappy axle like a thirty, especially considering when I bought it, it was completely stock otherwise? Anything else I could look for as far as clues in this. I still have the cover off.

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Yes it is possible, I know a guy with a wrangler who had 4.55s, and now has 4.88s' on his front d30. If it is 4.55 gearing, check your back to see if its the same. Mismatched gears on front and rear axle will leave you without a driving jeep once you pop it into 4wheel drive, especially if you do so on pavement. I have seen it happen twice.
 
jack your front end up and spin the tire 1 revolution then count how many tire the drive shaft spins per revolution

example: your spin the tire 1 full revolution...and the drive shaft spun 3 and a half revolutions...you have 3.55s or somthing around there

do the same for the rear
 
who knows it might be a different cover from a 4.56 truck... but more likely that somewone had a brain fart and wrote 4.55 instead of 3.55 cause I dont think a shop would make a mistake like that, cause cherokees didnt come with 4.55s, it would be custom...
 
Some mechanics will mark the cover with the date of the most recent service. So maybe 455 means April 5, 2005.

What are the specs on your Jeep? For example, if you're running stock size tires, it's unlikely that someone would install that tall of a gear.

Best way to check is to count the revolutions, as stated above.
 
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Cherokees came with 4.56 gears back in the 80's. It's really rare, but the 4.56's were put under jeeps with the 4 cyl and automatic transmission.
 
could be anything. The mechanic coulda been on the phone booking a dentist appointment and that's all he had to write on ;) lol
 
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