Gearing choices with 35" MT/R's and overdrive tranny

[mbryson]

I felt like I was a little down on gear the other day and with my engine showing some miles, I'd like to see some better performance. Anyway, I'm wanting to regear and plan to stay with the 35" tires for the XJ (at most 36" as I'm not going bigger axles in the XJ chassis).

I think the 4.56 gears would be 'adequete', but I've been having bad thoughts about the 4.88. I'm running a D30/D44 combo and drive about 20K miles per year (i.e. gas mileage is a of a little concern).


My Opinions--the 4.56 should put me back where I want to be on the road, and would definitely help out off road, but I think the 4.88 would be really nice off-road, and would 'work-out' {I'm thinking gas mileage penalty here} on road. I tow our families little pop-up trailer 4-5 times per summer and I think the 4.88 would be awesome for that. For a rig that sees about 95% street duty, but likes to do Pritchett, Rusty Nail, Lower Helldorado-Proving Grounds and the like, it's kind of a toss-up.............


Your Opinions---??????

 

[Caleb]

I say 4.88s, but I always like to gear as low as I can...if you are towing(even just your pop-up) then I think you will be happy with 4.88s...the main drawback I see with this is the small pinion you get with 4.88s in the D30...

 

[mbryson]

Originally posted by supergper
I say 4.88s, but I always like to gear as low as I can...if you are towing(even just your pop-up) then I think you will be happy with 4.88s...the main drawback I see with this is the small pinion you get with 4.88s in the D30...

That would kind of be my next question. Who's sheared a pinion in a reverse D30 running 4.88's........Didn't SukaB run a D30 for a year or two in competition?

 

[muleskinner]

I put my 31-10.50's on today for street driving. With my 5.29 gears my speedo said I was going 92 mph. A loaded semi passed me...... guess I'll toss those tires. (feels like a V8 though I may buy a 5th wheel)

 

[Caleb]

I think you are right marc, I think suka ran a D30 in UROC the first year...and true, who has actually sheared one off...I know when I went 5.89s in my D44/9" combo people kept telling me to be careful...even though I only ran that for about a month or two I never had a problem with it...

 

[Greg]

How many Teeth are on a 4.88 pinion vs, a 4.56 or even 4.10 pinion? I think that would be the thing to consider. If they have the same amount of Teeth, then the contact area will be the same. The Strenght should be equal.


4.88's!

If you'd just drive under 90 MPH, you're mileage shouldn't be too bad.

 

[muleskinner]

If you'd just drive under 90 MPH, you're mileage shouldn't be too bad. [/B]

I think I was REALLY only going 65-70 I'll check it with the GPS.

 

[Hickey]

I had 4.88's in my old 30 and I absolutely loved them! The only draw back was that they were too low (no O.D.) and I broke a lot of joints and shafts too, go 4.88, trust me.

 

[EZRhino]

Go 4.88. As far as gas mileage goes, you're only talking about a couple hundred RPM's difference between the two.....there just isn't that great of a difference. Your starts off the line will be better/faster. I think that a lot of gas mileage seems to be how you drive (Mr. Leadfoot). The other thing to consider is when you drive a vehicle with the aerodynamics of a small barn gas mileage goes out the window anyway, you might as well make it more fun to drive by going lower (higher numerically). Towing will be better, and crawling obviously.

EZ (What the hell do I know, I don't listen to what anyone tells me. I can hear it now.......shuddup Carl!! )

 

[WJL]

4.88s
in the long run you will regret if you only get 4.56s.
and oll the coments above.

 

[ewander]

Marc,

As you know, I have run the superior 4.88's in my front 30 for years, and never had a problem. When I went from 4.10's to 4.88's I felt like I had an entire gear lower in 4 low.

Eri c

 

[Vonski]

4.88's man, and never look back!

 

[Herzog]

5.13's w/ 36" Good ratio!