Topic: Gear Ratio

[mack90]

I was planning on going with 4.88 gears in my 98 tj se, but wanted to upgrade the rear axle for a little more durability.  Low and behold, I came across front and rear Rubicon axles with lockers for $2900 - the front has chromoly shafts too!  Now I guess I'm throwing in a dana 44 front too.  My final plan is to go with 33" tires, nothing bigger.  I will still use this jeep on the highway too.  Now that 5.38 gears are an option, are they too much for highway driving with 33"?

TIA,
Mack

[Mozman68]

If you are going 33", why not just go up to 35"  You know you want to....

[mack90]

33's are the magic number for me.  I would probably have gone 35's if I had a 6 cylinder.  I was actually hoping for better economy at the low speeds with this project.  My rubicon sucks gas when driving at idle speed.

[Jeffy]

I was planning on going with 4.88 gears in my 98 tj se, but wanted to upgrade the rear axle for a little more durability.  Low and behold, I came across front and rear Rubicon axles with lockers for $2900 - the front has chromoly shafts too!  Now I guess I'm throwing in a dana 44 front too.  My final plan is to go with 33" tires, nothing bigger.  I will still use this jeep on the highway too.  Now that 5.38 gears are an option, are they too much for highway driving with 33"?

TIA,
Mack

Are you going to be using the stock air lockers?  If you are then that will limit you to 5.13's.  5.38's are a bit low for 33's but would be fine for 35's.  5.13's would be good for 33's.

[mack90]

What would the fuel economy be at 65-70 mph between the two?  RPM's?  There really isn't much of a difference between the two.

[jfrabat]

What would the fuel economy be at 65-70 mph between the two?  RPM's?  There really isn't much of a difference between the two.

Anything over 55 mph and fuel economy goes down the drain regardless of axle; at that speed, it has to do more with aerodynamics!

[mack90]

Will 4.88 gears turn over 33" tires when locked up at lower speeds?

[aw12345]

Sure the 4 banger does better ofroad then on road power wise

[jfrabat]

Will 4.88 gears turn over 33" tires when locked up at lower speeds?

4.88'S should be about the same as stock with 33's...  You should not have any problems.

[bigchelis]

I have 4:88's with 33x10.5x15 mud Super Swampers and a 4in superlift kit.

At 65mph my RPM are 2800
at 70mph my RPM are 3000

With a bone stock engine I got 16.8mpg
With a cold air intake and spacer and fuel magnet I get 17mpg

I was under the impresion that a cold air, spacer, fuel magnet would net me at least 2-4mpg, but I was wrong.
At least the engine bay looks nicer.

[mack90]

I have a set of 33 12.5 swampers for offroad, and thinking about 33 10.5 bfg at's for the highway.  I think 4.88 will be best for the 33 10.5....may end up going that route.  Is that 17 mpg average or highway?


Thanks,
Mack

[jcsanders79]

I have 33x10.50 BFG AT/KO's and 4.88 gears.  Its ok.  I have a 4:1 TC in the garage but its not in yet.  I am considering 5.38's so I can stay in  4high in the mud and use the 4:1 for crawling.  With the 4.88's I do alright on hills and mud but could use a little more torque and even with the stock TC 4Low is to low for hills and mud.  I am thinking the small differnce in 4.88 and 5.38 will help.  On road I'll be fine but this is a toy not daily driver. 

Did you get those axles of the rubicon site?  I looked at them but only needed a front.  Also I don't think you can put 5.38 or even 4.88 on rubicon ARB's.  Aren't they thicker, is 4.10 the max?

[Jeffy]

Did you get those axles of the rubicon site?  I looked at them but only needed a front.  Also I don't think you can put 5.38 or even 4.88 on rubicon ARB's.  Aren't they thicker, is 4.10 the max?

If you take out the lockers you'll be able to run whatever gears that are available for a D44 in them.  The only thing stopping it now is that they use a 3.55 and under carrier.  This requires thick gears OR a shim to be made.  Currently you can get 5.13:1 in thick though.

[mack90]

You can do 4.88 or 5.13 with the rubicon axles with stock locker.  I actually only wanted the rear axle.  I'm willing to talk if you want the front.  The front has new alloy axles and in great shape from what I can tell from the pics.  I would expect more than half the cost I paid for the front because they go for more....also alloy shafts  The price on the rubicon forum was without the alloy shafts for the front.....

[bigchelis]

My 17mpg is average.  I live in the bay area, ca and traffic is bad going 101 northbound.  On weekends when I do not have traffic I try to stay around 70mph.  It is an overall average stop and go/some freeway. 

When I drive strickly on freeways(weekend trip), I get the same mileage.  I drive 80mph, and harder in the streets:its fun time.   Yet the same 16.8mpg