Topic: Dana 44 build What gears?

[lax22]

i am getting ready to start building a pair of dana 44's to throw under my TJ hopefully this summer. I have a wagoneer front and an 8.8 right now but i may swap to an isuzu rear so i dont have to mess with spacers. My main question is what gears to get. I have 4.88's in the tj now and running a set of 35's. it does ok around town but get on the highway and you hit a wall at 65 and you might hit 70mph doing down hill, and forget staying up with traffiic on long inclines. I was thinking about a set if 5.13 gears but im not sure if they would be good for the highway. When i had 33's with the 4.88's i felt like i was running at 3,000 RPMs when crusing but my top speed was a little better than it is with the 35's im running now. I was also curious as to weatehr or not i will see better acceleration with the manual hubs up front since the axle will not be spinning all the time like with the unit berarings on the dana 30. I do daily drive this jeep as well as take it on a few trails now and again, I have another truck just for off roading, so i would like something that will give me a little more pedal on the street and if i decide to take a trip. Any help would be greatly apprechiated. I tried to figure it out with research but i figured i just ask. I know there is a member who built up a pair of 60's on his rig and kept the 2.5l. He was running 4.88's because i thing there was something about a future engine swap. I am also interested in  that but not sure if its worth the trouble. With my performance upgrades and a few more i plan to do i think with proper gearing i could keep my 4 banger, swap to an ax15 or 3550, and still have a pretty solid wheeler/driver. What do you guys think? 

[FourbangerYJ]

If the 5.13's are avail for the 8.8 or Isuzu D44 that's what I would go with.
I have 5.38's and 37's and love it! My milage improved when I switched from 35's and 4.88's. And it has better get up and go. Climbing the hills its able to stay in the powerband alot better.
As far as the lockout hubs giving you better milage, I don't think you will notice much improvement
Keep in mind the peak torque for the 2.5L is at 3200 RPM. I try and run between 3000-3200 RPM.

[lax22]

Wow thats good to know about the peak torque numbers. I never knew the 2.5l could run that high for extended periods of time. I also have never driven one stock so i have no real idea of where it should be when crusing as far as RPM's go. Mine sounds like it doesnt like being above 3 grand for too long, I want to switch to the 24# injectors and get the performance distributors ignition kit hoping that would help me a bit.

[TahoeYJ]

I blieve you're referring to Mozman's build-up with F&R Dana 60's. And I think he went with 4:56's, but could be wrong...

I'm surprised you have trouble pushing 35's with your gearing, I've got the same set-up and it pushes me around just fine. But, every rig seems to be different... Mileage actually went up a bit for me when I went from 33's to 35's, and around 70 I'm at about 2900 RPM's, a bit lower than I was running with 33's. I usually run 75+ when I'm on a trip though, so I'm right round the peak in the torque curve then.

If you don't take a lot of long trips, then 5:13's would probably be ideal for you. RPM's IMO might be a bit high on the highway, but the 4 bangers seem to handle higher rpm's just fine...

[lax22]

yeah i am am also running steel wheels with Mickey Thompson MTX's. All that rolling resistance may have something to do with it. I agree though i do think it pulls better with the 35's around town, its just on the highway where i see the problem. When i do my swap i'll have a set of eagle alloys that will go on so they should help lighten the load. I also have an arb bull bar with a 8,000lb winch so i think my weight is an issue. I run with no back seat and right now i have a duster on the back which cuts down on the weight but not much.

[TahoeYJ]

yeah i am am also running steel wheels with Mickey Thompson MTX's. All that rolling resistance may have something to do with it. I agree though i do think it pulls better with the 35's around town, its just on the highway where i see the problem. When i do my swap i'll have a set of eagle alloys that will go on so they should help lighten the load. I also have an arb bull bar with a 8,000lb winch so i think my weight is an issue. I run with no back seat and right now i have a duster on the back which cuts down on the weight but not much.

I had steel wheels originally too, 15X10's. When I switched to 15X8 alloys the weight saving made a significant difference. It stopped better, steering was a bit lighter, and it made a difference cruising on the highway as well. It made cruising 75 on the highway no problem. Swapping in a much, much lower mileage motor was the best thing I've done so far though. My old 4 banger has close to 200K on it and it was definitely tired. The motor in it now has about 55K on it.

[aw12345]

Rolling resistance of the tires makes a big difference for a 4 banger. I am happy with 35's they are the Baja MTZ's and those roll very well. I am not unhappy with 4.56 gears on my little 2.4l put put it will do 80 mph or better on the flat road. My biggest reason for changing to 4.88's would be a bot more crawl ratio for rocks for highway driving with the 6 speed this works pretty well. 4.88 or 5.13's would make 3 and 4 th gear to short for mountain driving. 4.56 gives really nice gearing for me in 4th and 5th and 6th is ideal for cruising at 65 and up

[FourbangerYJ]

Rolling resistance of the tires makes a big difference for a 4 banger. I am happy with 35's they are the Baja MTZ's and those roll very well. I am not unhappy with 4.56 gears on my little 2.4l put put it will do 80 mph or better on the flat road. My biggest reason for changing to 4.88's would be a bot more crawl ratio for rocks for highway driving with the 6 speed this works pretty well. 4.88 or 5.13's would make 3 and 4 th gear to short for mountain driving. 4.56 gives really nice gearing for me in 4th and 5th and 6th is ideal for cruising at 65 and up

Your 2.4L has more HP and TQ than the 2.5L. That might be the differance. I agree with the rolling resistance. I run my tires at 32 PSI for the street.
The steel wheels are heavier than the AL. Every little bit helps when it comes to getting the tires rolling and keeping them going.

[Jeffy]

If your TJ is a standard 5-speed then I'd go with 5.38's.  The extra gearing will help with any additions you may have added.  Weight, rolling resistance, aerodynamics, etc...  The extra RPM's from 5.38's will help.

[lax22]

I do have the standard 5-speed. I had thought about swapping in an 8 but i think that i would just keep the 4banger and swap to a heavier duty trans when the time comes. What would the 5.38's do to my gas milage?

[FourbangerYJ]

Well looking at a RPM calc. the differance between 5.38's and 5.13's is only about 150 RPM. Not as big as split as I thought it would be.
At 70MPH it would be just over 3000 RPM. That is figured with a .85 OD. If the OD is not .85 then I am wrong and need to refigure it. 35 inch tires.

With 5.13's 2900 and change. with 35's.

[Jeffy]

I do have the standard 5-speed. I had thought about swapping in an 8 but i think that i would just keep the 4banger and swap to a heavier duty trans when the time comes. What would the 5.38's do to my gas milage?

Well, you can't really calculate gas mileage when you start changing tires and gears.  If you kept the tires constant then theoretically, you would have better gas mileage with the higher gears BUT... What you're really doing is trying to get the engine to run in it's original powerband, since you have changed tires it throws off the overall gearing.

I think you're mileage will really depend on how you drive, how much weight you've added, how much lift and overall aerodynamics of the thing.

Also, when looking at gearing, you really want to set it up by looking at 1:1 and not OD.  OD is just that, you're cruising gear.  You'll want to have the engine running well into it's sweet spot in 4th so you have enough power for hills and what not.  Most gear charts are setup for 1:1.

You might want to go to jeeptech.com and look at the bottom.  There is a tire & gearing applet that will show you your speeds at specific RPM's.

[lax22]

Thanks I am going to check that out.

[lax22]

Revisiting this topic. Just wondering what the sweet spot is for these engines. Anyone still running stock and want to let me know where you run at crusing speeds. RPM wise. I found someone else selling a rear waggy 44 locally for cheap and i am going to start getting serious about this swap. I want to get the jeep running as close to stock as possible so i can cruse with it up and down the highway to the trails since i dont have a tailer or anything that can pull a trailer. I may be swapping between some 33's and my 35's for the summer and winter on the street. In that case should i stay 4.88 or go with the 5.13's. I would say 5.38's but i dont want to lock myself into a huge tire. I like to be able to swap between the two if i want.

[Mr_Random]

Revisiting this topic. Just wondering what the sweet spot is for these engines. Anyone still running stock and want to let me know where you run at crusing speeds. RPM wise. I found someone else selling a rear waggy 44 locally for cheap and i am going to start getting serious about this swap. I want to get the jeep running as close to stock as possible so i can cruse with it up and down the highway to the trails since i dont have a tailer or anything that can pull a trailer. I may be swapping between some 33's and my 35's for the summer and winter on the street. In that case should i stay 4.88 or go with the 5.13's. I would say 5.38's but i dont want to lock myself into a huge tire. I like to be able to swap between the two if i want.

I'm close to stock, but probably 1k lbs lighter than you guys. I see 4K in 3rd and 60, 3.5k in 4th and 65, then ~3.2K in 5th and 65. I'll confirm today, but my engine isn't quite stock, is only about 600 miles old, and it's an XJ, so less wind resistance, therefore I advise to take my numbers as at best a ball-park measurement.