Gears and stress

if you increase the gear ratio in the diff. does it put more, less, or the same stress on the axles shafts??

say your running 3.73 and you up grade to 4.56

if you drive the same (not too much hammering, mostly crawling as slow as possible with my setup) would it put less stress on the axle shafts??

the way i'm thinking is if i have lower gears then i should be able to keep the engine where it likes to run at, then the engine runs fine and i move forward with more ease than having to give it more gas to get up and over something... without putting more stress on them in rotation... slower the better right?

am i right or wrong??

stock axle shafts, and i dont want to break them... but want more crawling ability... gears help or not?

Gears always help! You mentioned upgrading to 4.56, but with what size tires? No matter what, you want to match the gearing to the tire size.
The lower gears will transfer more power to the shafts, so technically it will increase stress on the shafts, but it will decrease it on the rest of the drivetrain.
However, you are correct in your line of thinking. You only need X amount of tourque to turn a tire, so as long as you don't get in a bind, you can apply less throttle to achieve the power needed at the wheels. Slow and steady

Tire size is important, driving style off-road, and regular maintenance. I've driven with 4:56's dana HP 30 and a 35 for about a year. Very easy on the gas off road, and ran 32" tires, BFG at KO's no problems. I switched to 34" LTB's and drove for a few months off-road with narry a prbblem. Then I broke the rear ring gear on a steep rocky hill climb (Cherokee Hill at Wheelin' In The Country, TN.) after giving it a little more gas than I normally do.

I switched to a 4:56'ed Chryco 8.25 with 29 spline stock shafts. Never had a problem. I eventually ran for about 4 years with 35's and many trail rides without ever breaking.

I also had an AW-4 Auto Tranny. The autos are much easier on the d-trane than a stick.

On the road, the Jeep was much happier with the 4:56's.

With a reasonable amount of knowledge driving off-road. n 8.25 29 spline, and an HP Dana 30, will last with 35's. No bumping obstacles with out complete stop in motion, we call it "bouncing" when you back and forth the vehicle on ledges to bump over.

I live in an area with plenty of rocks, but they are slippery. Out west they're idea of "slick Rock" is very grippy stuff. I could see problems with breakage there if your getting on it with 35's and same axle set-up.

Use your head off road. Winch out or get pulled is better than breaking on the trail. Your Jeep will survive many years if your smart about driving, and you take care of it.

One more thing. Get under there after every ride, tighten and check drive-line components. I would venture to say that many front shaft breaks are do to bad axle u-joints. These are easy to check. Watch you d-shafts too for signs of u-joint wear.

This is a hobby that requires vigilance with maintenance. Especially if you dd the thing, as a wreck could injure yourself, or worse, some innocent driver you run into.

One more thing... Your steering is also very important when you run bigger tires and lifts. They should include upgrades with all lift kits over 3 inches. I ran Curries with 7"es of lift, and 35's. Worked very well.

first off thanks for answering my question... i didnt realize the lower the gears the more torque it put on the shafts...

and some background info:

33 12.5 R15 ProComp MT

4" lift

SYE kit and tom woods rear driveshaft

stock D35 and D30 (with disco) (trying to eliminate that though)

D35 has lockright locker

stock 3.73 gears

so im guessing by your replies that i need to upgrade to 4.56 to keep with my 33's ??
so far i havent had too much trouble and no shaft breakage

Re-gear after you get the 8.25 in there or a Ford 8.8. The 8.8 will be more expensive ofcourse. I would just look for a good 29 spline 8.25.

Lower gears by themselves do not put more stress on the shafts. Stress is a result of load either static or dynamic. Dynamic means accelleration. If you accellerate more quickly, you use more torque and have more stress.

It takes exactly the same amount of torque to go up a hill if you do it at the same speed (static load).

Lower gears give you the option to apply more torque, but that is your option.

YJ rear in xj

Hey guys, Im trying to chane my gear ratio from 3.55 to 4.10 to compensate for 32" tires. Does anyone know if the rear out of a 4 cyl. yj will directly bolt in to an xj?

Re: YJ rear in xj

Stefan Spencer said:

Hey guys, Im trying to chane my gear ratio from 3.55 to 4.10 to compensate for 32" tires. Does anyone know if the rear out of a 4 cyl. yj will directly bolt in to an xj?

Click to expand...

Doubtful that it will work as a direct bolt-in. The YJ's are spring-under and also the leaf springs perches are a few inches inboard of the XJ spring pads. (Some cutting, grinding, and welding and it will bolt right in.)

find one from a 4 cylinder xj
I know a friend that has factory 4.10's in his

Ive tried to find axles out of a 4 cyl. XJ but apparently 1 out of every 1000 were 4 cyl. because Im striking out everywhere. Anybody use the Jet Accu-Speed by any chance? I dont mind the decrease in performance so much as my trans overheating from up/down shifting too much

Jimbo 1321, arent the stock gears in the dana 44 4.10s? If they are how much do you want for it?

4cyls almost always have a dana 35 rear end regardless of what Jeep its comming out of. YJs are spring under and irc spring pads are 2" wider, MJs are spring under and 2" wider for sure and do some times come w/ rear 44s and 4.10 gears.
Just get a 8.25 and regear it. Go through a member here and it will be cheap.

I got an 8.25 form a junkyard but it has the 27 spline axles and the 3.55 gear ratio (they told me it was a 4.10). The reason Im swapping axles is because the lowest price of a gear swap I found is about $1000 plus parts so I dont want to do that on the 8.25 either. I just dont want to destroy my AW4 by having 32" tires w/ 3.55 gears but I cant find and 4 cyl. xj's out there at all

There are a couple 4:10 XJ's at Widewater Salvage just south of Quantico. Not sure what rears are in them, could be D35, could be 8.25. One of them is a HPD30 front. I paid $75 for a front axle less discs and rotors there a couple of weeks ago.

Have you thoroughly walked the north lot at the huge yard just outside Cavetown MD, are you sure there are no 4cyl xj's there? Pricier than Widewater but its 100 miles close to you.

John

I have never heard of Cavetown. There was a 4-banger xj(obd1) and a 4-banger mj at crazy rays off rt 1 a month ago, fyi.

Do you mean the one on 64 with cars on one side of the road and trucks on the other? If thats the one youre talking about they have 3 but theyre all from the 80's and Im trying to find something a little bit newer (no axle rebuild is good news for me).

Is there anybody in Hagerstown or the surrounding areas who knows how to do the swap (the correct way) and would either want to do it or help me do it at least (I would prefer to just be guided through it so I can learn how)?

anybody have the number to widewater by any chance? I tried to find it but got nothing

Is this them....
http://www.superpages.com/bp/Stafford-VA/Widewater-Auto-Parts-L0088401146.htm?SRC=dogpile&C=auto+salvage&L=Quantico+VA&lbp=1

stefan spencer,

Yep thats the one. I am surprised they dont have any newer XJ's or more of them. I have never seen an XJ on the main (car) side. Were you over on the truck side? I have seen several on the truck side, its huge. I pulled some parts for my Rambler off of a couple (the AMC heritage runs deep).

John