Deeper than 5.13 for 14 Bolt

[Abugarcia]

I know that 4.10's are going to be needed. I am only going to drive it this summer and then I am going to swap pretty much everything bolted to the Unibody. I seriously don't think it is that bad. Yeah deeper gears would be better, but I am not having any problems. Plus I don't care about the cluch because I am swapping to an auto. I don't really see a point in swapping gears and such when I am replacing the axles. I don't drive it daily either.

 

[What Rd]

I know that 4.10's are going to be needed. I am only going to drive it this summer and then I am going to swap pretty much everything bolted to the Unibody. I seriously don't think it is that bad. Yeah deeper gears would be better, but I am not having any problems. Plus I don't care about the cluch because I am swapping to an auto. I don't really see a point in swapping gears and such when I am replacing the axles. I don't drive it daily either.

Well it sounds to me like you hear us but aren't listening. It may not be worth regearing if you plan to scrap your tranny, axles, etc. in short order. But don't fool yourslef into believing that you're not having problems, because you are. It's just that you're betting you'll replace everything before the damage manifests itself.

 

[Abugarcia]

Enlighten me, What kind of problems am I having?

 

[csudman]

Your engine, tranny and t-case are getting ragged. There way more costly to replace than gears. And your right they might be fine till you put gears in. But how much life did you suck out of them.

 

[Abugarcia]

I'm not saying your wrong, but could you explain the damage to the Engine, Tranny, and t-case? I know it is hard on the cluch, but I didn't figure the engine cared how fast it was spinning in relation to engauging the tranny. I didn't figure the tranny cared as long as the cluch engauged it. I really didn't think the t-case would care about the input from the tranny. Maybe there are issues with temperatures, I don't know. Thanks

 

[BrettM]

with a 5 speed you are mostly killing your clutch, but the engine is also not operating at proper RPMs and you will be lugging it which is not good for it.

when you swap an auto tranny, things get worse; the whole tranny will heat up and damage the whole thing. also, autos came with 3.55 gears, your 3.07s are a step in the wrong direction, even with stock tires you would be killing your tranny, let alone 33s.

 

[Jared]

are you serious!?!? i couldn't STAND 3.07s and 31s, I can't imagine 33s. you may think it's fine because you keep telling yourself that, but it is killing your clutch and gas mileage (assuming it's a 5 speed b/c of the 3.07s). Get some 4.10s or deeper and you WILL thank yourself. Right now I have 33s and 4.10s with a 5 speed and it's perfect on the street, but I will soon have auto,4.88s,35s

I ran 3.07's for quite a while. They really aren't that bad, I even flat towed another 4x4 with mine. The towed vehicle was heavier than the XJ. In 4th (manual trans) the engine was cruising at about 2700 RPM on the freeway. This was perfect, as this is right in the engine's peak torque range. I got an honest 22 MPG with this setup. Now I run 4.10's and can't tow as fast because my RPM's get up too high for me to be comfortable with. I also get about 15 MPG now. If you ask me, the deeper gears kill your mileage, not vice versa. Do I like the 4.10's off road? Of course, but I'd rather run 3.55's on the highway. I currently run 31's on the road mostly, but sometimes end up running my 33x13.50x15 TSL LTB's.

Jared

 

[Jared]

maXJ, you will only heat up your (auto) transmission if you are pressing the pedal down enough to unlock the torque converter. This happens when the intake manifold vacuum drops sharply, typically caused by low RPM and a lot of throttle. If the converter stays locked in, which it likely would on flat ground with no trailer, the trans will be fine. If it does unlock often while being driven, simply put the trans in 3rd gear and it WILL stay locked in.

No, your drivetrain will not explode because you have higher gears. Just make sure they are low enough that your engine is up in the 2400+ RPM range or you will get poor performance out of it (low horsepower). Just be nice to your clutch when you begin from a stop, you shouldn't have any problems with it.

Geez guys, his jeep is a little hungry for gears. Don't make a mountain out of a mole hill...

Jared

 

[BrettM]

I ran 3.07's for quite a while. They really aren't that bad, I even flat towed another 4x4 with mine. The towed vehicle was heavier than the XJ. In 4th (manual trans) the engine was cruising at about 2700 RPM on the freeway. This was perfect, as this is right in the engine's peak torque range. I got an honest 22 MPG with this setup. Now I run 4.10's and can't tow as fast because my RPM's get up too high for me to be comfortable with. I also get about 15 MPG now. If you ask me, the deeper gears kill your mileage, not vice versa. Do I like the 4.10's off road? Of course, but I'd rather run 3.55's on the highway. I currently run 31's on the road mostly, but sometimes end up running my 33x13.50x15 TSL LTB's.

Jared

4.10s in 5th gear give about 100 more RPMs than 3.07s and 4th gear, definitely not too high for the 4.0, plus it gives you an extra gear in between which will save your clutch.

I had an XJ with 31s and 3.07s, then an MJ with 31s and 3.07s and both sucked big time in first gear, I can't even imagine trying to get a trailer moving as well. sure, once you're up to speed and stay in a gear it doesn't matter, but getting there is not nice on the drivetrain


wasn't this thread about 14bolts?

 

[csudman]

Well mine will be a 13 bolt when I'm done, so maybe i need to start a whole nother thread.

 

[Jared]

Towing in overdrive is a bad idea. 4th is the only gear in the trans with no gear reduction whatsoever. The input shaft locks to the output shaft for a gear ratio of 1:1. Therefore, there is no side load on the bearings in the trans and therefore, very little wear and very little internal resistance. The whole idea is that you want to AVOID overdrive while towing. 4.10's put me in the 3,400 RPM range at freeway speeds, which is above the 4.0's peak torque range, and higher than I want to run mine for extended periods.

As far as clutch life goes, I disagree with the idea that 3.07's will wear them out prematurely. With higher gears, you actually do LESS shifting while driving in town. Less shifts = less clutch wear and also less wear on the synchros in your trans. Yes, it takes a bit more clutch to get moving, but I doubt this causes enough additional wear to be overly concerned with.

Run what you want to run. Just don't act like it's your way or the highway. 3.07's worked great for me, and apparently they work great for him. If you are any good with a stick and have a little patience, they work great. Better mileage and longer transmission life will be your reward. Yes, if you run HUGE SWAMPERS you will need more power and gears. But maybe the gear ratio isn't the problem, the horsepower is. Instead of throwing out 500-600 bucks on a new set of gears, turbo the 4.0L. Get a little Chrysler turbo at a junkyard, read some books, and fab! Build a stroker! Get smaller tires! Gears aren't always the answer. I now step down from my soapbox.

BTW - once I had a 14 bolt sitting in my driveway.

Jared

 

[1986xj]

I got an honest 22 MPG with this setup. Now I run 4.10's and can't tow as fast because my RPM's get up too high for me to be comfortable with. I also get about 15 MPG now. If you ask me, the deeper gears kill your mileage, not vice versa.

Jared

Just a thought.... did you change the speedo gear to match the gear change or the tire size change? Do you change it to match tires when you change between the 31' & 33's? If not you have no idea what kind of MPG's you get... unless you adjust for the difference when doing the math to figure the MPG's.
Mike B.

 

[What Rd]

Yes, if you run HUGE SWAMPERS you will need more power and gears. But maybe the gear ratio isn't the problem, the horsepower is. Instead of throwing out 500-600 bucks on a new set of gears, turbo the 4.0L.
BTW - once I had a 14 bolt sitting in my driveway.

Jared

We're in the presence of genius, ladies.
Can I get some pics of what's left of your main bearings after you "turbo" your already-prone-to-running-warm 4.0 with taller tires and stock gears?
That'll be fun.
And there's a 14 bolt sitting in my driveway at this very moment - and that means absolutely nothing.

 

[vintagespeed]

Enlighten me, What kind of problems am I having?

Some kind of Newb-eyesight tied to a hearing problem. Maybe "thickskullitis?"

You're fine, and maybe you'll win wheeler of the year too. See ya in JV!



-jb

 

[Jes]

LOL, I'll bet this thread is over 5 pages long when I get back from my trip.

Jes

 

[What Rd]

LOL, I'll bet this thread is over 5 pages long when I get back from my trip.

Jes

Jes is gonna make it to Winterfest! Finally a west-coaster who isn't afraid to wheel on frozen midwest mud (or in this case wet mud over frozen mud).
:clap: :sunshine:


wait . . . what thread?

 

[Jared]

Run what you want to run. Just don't act like it's your way or the highway...

Got it? I'm just saying that maybe we shouldn't flame a guy because he's happy with a setup that you don't like.

The 14-bolt comment was just an attempt at humor, given the title of this thread and where it has gone. I'm signing off this thread before I have to see it degrade any further.

Jared