Let's talk GEARS!!!

[cellz]

I have an '81 W/T cherokee laredo, and I have begun the restoration project. I want to use the truck for off-road use only. I have a 4" body lift, headers, dual exhaust, and replaced all hoses and wires under the hood so the truck would be MORE realiable. Does anyone have any suggestions or knowledge about what gears I have now, what I need, how much, and where to buy them? Also, is it worth it to put a new carb. on the jeep or anything else Thanks

LEEDOG

[joe]

Your gears are either the stock 2.72's or the optional 3.31's. Look at the boss on the pass side of the rear AMC20 differential, next to the big dowel hole. You'll see an axle code stamped in. "D" is 2.72 gears w/o Trac-Loc, "DD" 2.72 w/TL, "B" is 3.31's w/o TL and "CC" is 3.31's w/TL.
For stricktly offroad I would go with 4.56 gears. Look in the back of any 4x4 mag for vendors. There are prolly a dozen vendors. Randy's, WCD, Reider etc. Shop around for best price. For just offroad running I'd go with 4.56's or even lower(higher numerically) if you plan on huge tires. You'll need new carriers too and since it's just an offroad rig I'd considered lockers at both end also.
If your stock carb is in good shape and working I'd leave it alone. It's a pretty good carb for off-camber work. Unless you're mud bogging or dune running you don't need a 4v carb.

[jeepbob]

Well it will depend on the kind of wheeling you want to do, the amount of HP you have, and the size tires you want to run.
For sand light weight and HP are king. Wheel speed is your friend so good HP and middle range gears work well. For 33's I would run 3.73's in a FSJ of moderate hp (285 to 325 hp)with an auto tranny.
For mud (and I may catch some flack here, but it works for me) High hp and mid to low range in the gearing but not too low as once again wheel speed is your friend. Once again with 33's and a moderate motor, using an automatic I would (and do) 4.10's as with the extra weight of a full size vs a CJ in heavy goo you will need extra gearing to spin the tires. In my 304 manual trannied CJ I run 35's and 3.54's.
For mild trail riding run what you would for highway driving and leave every thing else alone. Just use low range.

With a 270/280 (adv) cam, an Edelbrock intake and 600 cfm carb, using the headers and duals you will have around 300 to 325 hp and that is enough to use in the sand dunes and deep, heavy goo with the proper gearing and tires.
BTW these are my opinions based on what has worked (and sometimes no worked) for me. Personally when the new motor goes in my Wag I will have a big cam (295/305 with about .5 lift) as I do most of my wheeling in low range. In low range first gear, I have a 20 to 1 gear ratio and in 3rd it is 8.25 to 1 so who needs low end torque? Give me revs and power! On the street with the 4.10's, I still do not need low end torque as the 360 makes plenty. These are not Chevies or Toyotas.
PS. once you put a 4V carb on a 360 you will wonder why you did not do it long ago.

[scotty]

jeepbob summed it up pretty well. for deep,sticky mud and sand you want to be able to spin the wheels fast to keep em clean,so more power will be neccessary. keep in mind that you will also likely need bigger,more durable axles with bigger tires and lots of power,unless youre gonna be careful and not ever put your foot on the floor.

for trail running,hill climbing,rock crawling,more power is not neccessarily better. i have a more or less stock 258(cept for a q jet carb) and it moves moe around just fine.i ran an auto with various new process cases and a dana 300( 2.61 low range) and now run a t18 and spicer 18 transfer case. i ran 3.31s for a lng time,and now have 3.54s. when i swap axles again i will be upgrading to 4.56s. you dont need lots of power for "technical" wheeling. you actually will have lots more control with low gears.

i personally prefer a manual trans. with an auto you do not have any comression braking to speak of,unless you have a reaaaally low final drive(from an ultra low low range in the xfer,and/or very low axle gears).also an auto is a more complex piece of equipment.hydraulic pressures and valves must function perfectly fot it to work. at slow speeds an auto builds up alot of heat,which can drastically shorten its lifespan,so plan on cluttering up you engine bay with an aux tranny cooler,and possibly a remote filter.if you plan on fording lots of deep water,defiantely stay away from the auto,as water and autos do not mix. if you do runan auto,id also consider a pan with a drain plug and a convertor with a drain plug are both mandatory.unless all youre gonna do is drive around in the desert smile.gif

people chose diffferent engines for lots of different reasons. i love my 258,cause ive put it thru all kinds of abuse and it keeps right on tickin.as i mentioned,for all but hardcore mud boggin or dune runnin,idont think you need lots of power.ive wheeled with lots of people with small blocks,big blocks,amc v8s,ford v8s,etc.i have never been left behind on a hill or mud hole cause i lacked power.on occasion i lack traction,but never power. so for me the 258 is perfect.its durable and easy to work on.

there are many ways to skin the cat smile.gif

[64Trvlr]

<BLOCKQUOTE>quote:</font><HR>Originally posted by cellz:
I want to use the truck for off-road use only.
<HR></BLOCKQUOTE>

For off road use only I'd go to 4:56 or 4:88's. They will do fine with what ever tires you wind up with.
I would also put in a locker or spool too.
:cool:

[Joe J-Truck]

Jeepbob has a good point re. axle strength. Before you dump a bunch of cash into regearing and installing lockers, etc. in the stock axles, I'd consider swapping in some burlier axles. If you're planning to thrash hard with big tires (35" or bigger) and big power you need stronger axles, otherwise you'll be out of luck on the trail when you snap parts. A GM corporate 14 bolt rear makes alot of sense to me. They're readily available in salvage yards out of 3/4 ton Chevy trucks and suburbans and often with 4.10 gears. Score an open diff and a Detroit Locker will bolt right in. The 14 bolt axle is plentiful and cheap.
The Dana 60 front is harder to find and more $, and if you want to retain your same t-case, a ford model will be the best bet, because Ford uses driver's side pumpkins.

[littlechief]

so I might be hooped if I changed the gears in my Cherokee to 4.56's and went up to 36's?Am gonna either rebuild the 360 or swap a 350 in there but am not planning on big hp....just a little torqueier is all that Im really looking at. Guess what Im wondering is if I'll just be throwing my money into a mud hole with new gears.

[jeepbob]

The problem with deep gears and bigger than 35's on D44 axles is that (as Scotty and River Beast have found) is that the axle tubes will crush on the rear axles at the spring perches. If you go to a GM 14 bolt be aware that there are several different style 14 bolts and some are not the best to use. Stay away from the 3/4 ton and dually 14 bolts. The 1 ton are alright as long as they have the full floating hubs. While the 14 bolt has a bigger ring gear, the D60 is considered to be stronger due to better pinion bearing spacing.

[scotty]

jeepbob,you are still the only person ive ever heard claim the 60 is stronger than a 14 bolt.

the 14 bolt is bigger in every imagineable way-pinion,ring gear,even the housing itself is massive. also lets not forget 1.5 ich axleshafts.

the 14 bolts design requires the 3rd bearing on the pinion.ive never heard anyone else say that this design makes the pinion weaker.

a big plus for the 14 bolt is that it is way plentiful and cheap.i gave $50 for mine,and i routinely see em for $75 to $125. you will find them in most 3/4 and 1 ton 2 and 4wd chevy trucks,burbs,and vans. actually,the only cnahge in the 14 bolt was the crush sleve was changed in 88. there is a semifloating "14 bolt" with a smaller ring gear that is available in some newer(mid-late 80s) 3/4 ton rigs,but it is easily identified by the lack of a hub-just an 8 lug flanged axle. look under 3/4 or ton trucks/vans from 73 to present youll prolly see a big 14 bolt in the rear.any one will do,as long as its got the full floating rear hubs,and not dual wheeled.

gm did use a d60 from 67 to 72,with course spline axles until 71. ford and dodge did use rear d60 and d70s up into the 80s,so theyre not super hard to find either,but there will be alot more variance in parts like brakes and axleshaft widths.there also was a semifloating d60 used in early or mid 70s j trucks,id avoid that one,tho.i think one of the biggest reasons to mess with a 3/4 ton rear end is so you can have full floating rear axles.

a word n gears: just about all of the pre 1980 d60s ive looked at have been 4.10 equipped. it varies with the 14 bolt,i think a 4.10 must have been a special order,cause you dont see many of them.the most common ratio in a 4x4 is by far the 3.73. a 2wd will prolly have 3.21 or 3.42,maybe a 3.73.

some more "food for thot" anyway... smile.gif

[jeepbob]

MY mistake the D60 and 14 bolt are pretty close with the 14 bolt winning out. It is the D70 that is stronger than the 14 bolt. Thank you for making me getting out reference source and correcting my self. redface.gif ;)Sorry for the misinformation.