REGEARING TO 4.11 FROM 3.07

I have posted this once today, but for some reason it did not post. If anyone finds it, sorry for the duplicate post.

Anyhoo, I definitely want to re-gear but I am not sure if the 3.73 or the 4.11 ratio would be better for me. I currently have 31" BFG All Terrain T/A KOs, but will definitely upgrade to a 33" tire of some sort in the future when these wear out. I will never upgrade to bigger than a 33" tire. As for off-roading, I do some light trail riding and the occasional hop in the mud puddle when I find one that looks fun. 80% of my driving is highway at approximately 70 miles round trip at a speed of anywhere from 60-70 mph. The other 20% is split between city driving (10%), and off-roading (10%). My main goal is to get my Jeep to drive as close as possible to the way it did bone stock (being able to use my 6th gear on the freeway) and to prevent excessive wear and tear on my clutch and engine parts. Someone please help! : D

'06 TJ (4.0L with I-6)

P.S. Would I also need to upgrade my Dana 30/35 to a bigger one (like

You are viewing this Usenet Newsgroup via Google groups. Sometimes they can take days to update their Usenet feed. I am on a dedicated Usenet server that updates almost instantly.

You get what you pay for....

I believe you will want at the 'highest', 4.11 gears. Others like even 'lower' gears like the 4.56 I think it is for 33's. The 3.73's are too high still and will make very little difference.

Because you aren't going to Baha it off road or run bigger than 33's, the D35 rear will be fine.

I doubt you will want a rear locker or even a limited slip due to your snow load. I am in Canada and have the same snow.

A locker or limited slip is called a 'Low side finder' and does not track in a straight line well in snow, especially with a short wheelbase Jeep. Some can't even run the trails in the winter, because they have to crabwalk up an off camber trail and the trails are too narrow for this. When you see a pickup or something crabbing it's way up a snowy hill sideways, that is due to a locked rear end or too much gas on a limited slip, not fun. If I was going to run a limited or locker, I would want it in the front.

It is a different story on dirt, where the limited slip or locker shines.

With an open diff, one wheel acts like a rudder and you track straight.

My $0.02,

Mike

Is it me or are the posts getting screwed up? I don't understand why two things I posted today (1 was a repeat) is not showing up in the main posts, but rather in the "Active Older Posts" column on the right side of the webpage. How can it be older? I JUST posted it. Then when you click on the link for the post, it comes up blank stating something to the effect of the messages have been deleted or are expired. Can anyone give some insight?

I have posted this once today, but for some reason it did not post. If anyone finds it, sorry for the duplicate post.

Anyhoo, I definitely want to re-gear but I am not sure if the 3.73 or the 4.11 ratio would be better for me. I currently have 31" BFG All Terrain T/A KOs, but will definitely upgrade to a 33" tire of some sort in the future when these wear out. I will never upgrade to bigger than a 33" tire. As for off-roading, I do some light trail riding and the occasional hop in the mud puddle when I find one that looks fun. 80% of my driving is highway at approximately 70 miles round trip at a speed of anywhere from 60-70 mph. The other 20% is split between city driving (10%), and off-roading (10%). My main goal is to get my Jeep to drive as close as possible to the way it did bone stock (being able to use my 6th gear on the freeway) and to prevent excessive wear and tear on my clutch and engine parts. Someone please help! : D

'06 TJ (4.0L with I-6)

P.S. Would I also need to upgrade my Dana 30/35 to a bigger one (like

Your first post showed up here, but I will reply to this one. Sixth gear in your transmission has a .84 gear ratio, meaning that it will reduce your RPM by 16% when you use it.

I'll assume your stock tires were 29". So with the 3.07 gears your RPM in 5th gear at 60MPH would have been approximately 1750

Assuming 60MPH at highway speed, your RPM will be as follows:

These won't be exact because of the tires. They rarely measure the same as their advertised size. Anyway, if you're definitely going to 33" tires, I would personally just go with the 4.11s. Even with the 31" tires your highway RPM wont be excessive, and the driveability in 5th gear will be a little better than with the 3.73s and much better than with the 3.07s.

There are a lot of articles out there about the D35 rear being too weak for off roading with big tires, but for your application you should be OK. The Dana 30 front is more than adequate.

One note about changing gears. Make sure you find a reputable shop that knows how to do this. It is not difficult with the right tools, but it is definitely not for the average home mechanic. You may also want to look into a locker for the rear axle, which will give you more traction off road, but some of them can make driving in the snow a little tricky unless you have one of the switchable lockers. Regearing can get expensive when you start upgrading to Dana 44s, lockers, etc. so be prepared to spend some pretty serious cash. You may want to keep your eyes open for a used D44 with the gear ratio you decide to use. They are out there.

Chris

You are viewing this Usenet Newsgroup via Google groups. Sometimes they can take 'days' to update their Usenet feed, though it sounds like you have got some settings messed up.

All your posts show here almost instantly.

I am on a dedicated Usenet server that updates almost instantly. You get what you pay for....

Having three or four threads going on by continuously reposting about the same thing is bad news for you usually. It can make for way too may things to confuse both you and others between the threads.

Mike

Hi Tracie

I currently have 33' Dunlop Mud Rovers with 3.73 gears on my YJ. When I went to 3.73 I was running 31" tires and the jeep performed well both on and off road. When I went to the 33's I found that I really needed 4:10/4.11. Best bet is to only do it once.

As far as axles go, your D30 in the front should be OK as long as you are careful. There are a couple of people in my club who run 33" tires on D35 rears (at 3.73) without any problems, but they are mostly experienced drivers who are very careful, don't spin tires, and avoid bouncing. I have had to help change axle shafts for other, less experienced folks in the club who have locked 33s on locked D35s.

Given this vehicle has OD axle ratios are not as scarey. A 4.10 would be a big improvement and might be want you want based on your driving. A 4.56 would play better here if you live in a hilly area or at a higher elevation too. One more note, 3.73 with 33's is about the same in effective gear ratio as stock 225's and 3.07 gears which is no barn burner either. So you really do not want to go 3.73 route unless you plan to go to smaller tires than 33's.

----------------- TheSnoMan.com

If you want it too run like it does now the ideal gear ration would be

Carl

Not necessarily. Her original tires were 225s I believe. If so her original tires should be about 29", which would be close to the same effective ratio as 3.55s with 33" tires. Going to 4.11s would result in approximately 15% more RPM to attain the same speed. You have to remember that going up in RPM doesn't cause a loss in fuel economy if the gearing was too high to begin with. Since her highway RPM is below the torque peak RPM of the engine, it is very possible she will see the same, or even slightly improved economy. Besides, she is having to use only 5th gear on the highway now, so obviously she needs more gear ratio.

Chris

Ok, that's true. To get close to stock you would need 3.07*33/28 =

Unfortunately the flying bricks we drive don't react the same as cars when it comes to low revs.

Once you get the axles 'into' the air stream by raising the body away from them with a suspension lift, it reacts 'strongly' to wind resistance.

On a lifted Jeep, anything much below 2000 rpm at highway speed will start the engine lugging so you need way too much gas pedal to keep up with wind twitches or slight hills.

Everyone I know and that has posted on the newsgroups that has 'dropped' the overdrive with large tires and tall gears gets better mileage at highway speeds.

My CJ7 came with overdrive (5th) and 3.31 gears or 'mileage' gears. When I lifted it 3" and put 33's on, my mileage dropped by about 8 mpg after calibrating the odometer when I drove it the same as before using all the gears. It just 'doesn't' like 1750 rpm at 65 mph...

As soon as I stopped using 5th so I stayed in the 2300-2400 rpm range at

Now I do have a manually 'tuned' carb engine with a 'hot' spark and timing curve that insists on 91+ octane with a super light fiberglass body (it only takes two people to 'easily' pick up the whole body tub 'with' the seats and roll bar in it) so the thing is basically an engine on wheels that goes like a scalded cat, but still.

Mike

Mike,

I=B4m going to start paying attention to my RPMs when I'm on the highway. Right now I'm running 30 inch tires with 4.56 gears (up from the original 4.10) and like it a lot. I plan to put 32 inch tires on it next year. It will be interesting to see how it runs then.

Sorry, but that is incorrect. Her original gear ratio is 3.07 and her tires were 29". It's s simple ratio between the tire diameter and gear ratio to maintain the same RPM. 29/3.07=9.45. If she maintains that same ratio between tire diameter and gear ratio, her RPM will remain the same. To calculate the gear ratio, she just needs to divide the tire diameter by 9.45 to get the proper gear ratio if she wants to achieve the same RPM as original.

for 31s it would be 3.26 for 33s it would be 3.49

Chris

Carl S wrote:

If it makes any difference, my original tires were the 215/75/15. I do not have a lift on now. Just thought about it in the future.

That is why I was thinking 4.11s to match or for the 'power feel', once lifted, 4.56's.

You can easily check your mileage as the modifications happen. You do enough highway driving that it can be figured easy which gear works the 'best' for 'you'.

You don't need to run full tanks for tests, you can fill up after each highway run or two, or each circuit of your normal daily 'route'.

Mike

I have a rubicon running 33x12.5 with 4.10. My auto tranny won't stay in over drive on a hill with a heavy load. Go 4.56 with 33's. Hands down.

Real Jeeps use 5.38s on a stock Dana 44. God Bless America, Bill O|||||||O mailto: snipped-for-privacy@aol.com