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3.07 versus 4.56 - not your standard debate?

Kevin

NAXJA Forum User
Location
Richmond, VA
I’m currently running 33s on an open/open D30/D35 (27 spline) set up with 3.07 gears in my 95. While it is well known that the D30 and D35 are not that great for running lockers with the larger tires, I was wondering if there was any benefit (read that as less chance of breakage) to keeping the 3.07 gears if/when I lock these axles. The 3.07s and 33s are brutal on the highway but this is not my DD and I don’t drive it too much. Only long drives are to get to my wheeling spots, say a couple times a year. Rest of the time is the once a week trip into work, to the store, etc. I want to lock the rig, but also don’t want to spend a bunch of money since I don't get to wheel it much. So I was thinking about dropping in 2 lunchbox lockers (Powertrax no slip in the rear and a LockRite in the front) and maybe upgrading the rear shafts.

So, can anyone tell me if the 3.07 gearing would be more or less likely to cause problems over say 4.56 if I decide that I want 5th gear on the interstate? Or is gearing irrelevant in this scenario?

Thanks.
 
In theory yes you will less available maximum torque to be sent to the axles. On the other side there is a fairly big difference in gearing going from 3.07 to 4.56. You have more control with the lower gears which could also mean less wheel spin and more low speed control which is better on axles then trying to bump over everything.

I say irrelevant. Proper gears are good.
 
gears and carrier, master install kit, etc: $250-300 even with NAXJA discount
labor to get them installed (unless you do it yourself): $100-500 depending on friend rates etc

getting a different axle to put them in and not worrying about it being a d35 and breaking because of the new gears: $100 at the junkyard

My suggestion is to just add the extra 100 bucks to the cost and consider it done.
 
You will have more probability of braking parts with the bad gears than with the good gears. The good gears will let you crawl stuff and will give you much better throttle control, which will help keep down on breakage. The good gears will also let your transmission live longer with less stress and heat from the torque converter, and will put much less stress on the drivelines and the gears themselves because of more revolutions per wheel revolution.

I know you're making an attempt to justify not spending money on gears and a D44 rear axle, but sorry, there's no way to justify it. Save a few more pennies and do it right. A D44 with stock axles is the same or less than better shafts for the D35.
 
I had the same problem, 3.07 and 33s. If you like your clutch you will want 4.56. I found I needed a lot of throttle to keep the jeep from stalling while wheeling with 3.07 gears, with 4.56 gears there is less shock on the drivetrain, I can do 75 on the highway with no issues. If I where you I would get a new rear axle(29 spline 8.25, XJ D44) and lock it while its getting geared. My RPMs at 65 are about 2500-2650 so its definetly livable.
 
Thanks for the input. I can get an 8.25 for the rear, so maybe I'll start looking at that option and always keep my eyes open for a D44.
 
Another thing to think about if you stay with the 3.07's and the D30 locked is the money you will be spending on shafts for the front. Ask me how I know:doh:, not on the XJ but on my YJ. Upgrade the gears and get a D44 for the front. Just my .02.
 
You deffinitly have my sympathy and admiration if you are running 33's on 3.07. I had factory 3.55's on 32's and thought they were pretty bad. Made the gear swap to 4.88's and 35's and all of the above is true, better control and a lot less throttle needed.
 
As the others have already said, with those tires and that gearing you will have to put a strain on the drivetrain just getting going from a stop.

You will be getting on the skinny pedal more when offroad as you try and get more torque to the ground through HP instead of gearing.

Get some decent gears, or you will break something the way you are running now.
 
The only thing better about 3:07's is the driveshaft spins slower for a given speed reducing high frequency vibrations. Other than that the better gears are desirable in every way except for cost.
 
4.56's would be best in your case, but in theory if you could find a 4cyl XJ to pull axles from, most of them had 4.10s. If you can find one cheap enough thats a decent route to go.
 
If you decide to go the 4.10 route, you can pick up for 8.8's with 4.10 gears sets factory installed for about the price of a gear set and install kit. With a little fab work you get a much stronger axle and disk brakes.
 
WAY less than the price of a gearset and install kit... I paid 100 for my 8.8 with 4.10s. Needed brake hardware (rotors/pads/shoes) but so did my old axle. To compare, 4.10s for my new d30, with carrier and install kit, cost me $260 or so from the cheapest place I could find (even as a full member with discount.)

Still haven't installed it, but I've got it entirely stripped down and ready to go in, just need to weld the perches on.
 
i'd see it not a big issue for the axles themselves but the engine and tranny will not like it.

Regear will be good, but not a must.
 
I run 34" LTBs with 3.73 gears. Ford 8.8 in the rear. Both are welded. Have been running this setup for about 3 years now with some pretty intence wheeling. Lots of skinny pedal. Upgraded to the 760x shafts and spicer U-Joints. Have not had a single problem out of the R&P or the shafts. Used to spit the caps out of the smaller shafts but never broke one. Have not broken any of the larger shafts. It all depends. Been wanting to regear but worry about having a smaller pinion in the D30 and breaking it. I'd say lock it, wheel it and see what happens. If you start breaking, sell the locker and upgrade. Ditch the D35 and either put in an 8.25 or find an 8.8. I got mine for bout $70 with the flange to mate it to a stock rear drive shaft.

Mike
 
...,I was wondering if there was any benefit (read that as less chance of breakage) to keeping the 3.07 gears if/when I lock these axles. The 3.07s and 33s are brutal on the highway but this is not my DD and I don’t drive it too much,...
...,So, can anyone tell me if the 3.07 gearing would be more or less likely to cause problems over say 4.56 if I decide that I want 5th gear on the interstate? Or is gearing irrelevant in this scenario?
From an axle damage standpoint, gearing is pretty much irrelevant on the highway. Regardless of gear ratio, the engine is operating at a low speed/low power setting(17-2500RPM, part throttle).
Lockers make a difference, because except for driving in a straight line, all the engine torque goes to one axle shaft only.

I understand you want to save money, but look at it this way, in anyone's book 35" tires are at the limit of what you can safely push on the Jeep axle set. To regear, you have to buy new dif. carriers.(3.07 is above the carrier "break" for both axles)If you get a Chrysler 8.25, all the gearing in Jeeps is below the "break", so any carrier in any Jeep axle is good for any gear set you buy. The difference in price between a D-35 low carrier and a junk yard 8.25 is all the money you "waste"(or invest, your call)
 
Thanks again for all the input. It is time to start looking at some beefier axles and doing this right.

Or I could go back down to 30s instead of the 33s (lol).
 
I dont know what you budget is for this project, but unless you know someone who knows how to do gears super cheap & correct the price to regear is substancially higher. The price of the parts of 2 lockers and new gear sets are close, but thats about it. I would rather be locked, locked on 31's than on 35s on 3.07s.
If regearing is not a option, just swap axles for ones from a automatic at least & have 3.55's & just lock the rear which should be a Chry 8.25, and you would still be within a reasonable budget & have a real rear axle.
 
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