gear change (5sp/with 33's)

[OILBURNER]

I think 4.10's with 32's and a 5 speed would be just fine

My PERCEPTION of 5 speed gearing options:

31's = 3.73 (3.55 nice highway gear but only 0.18:1 difference)
32's = 4.10
33's = 4.56

You can 'get away' with many other combinations, but I think these are pretty close for anything driven on the highway with regularity.

Anyone care to add/dispute these numbers?

 

[xj-grin]

I run an AX15 w/ 3.73's and BFG 32's and, while not bad, 4.10 would be better for a daily driver. I think 4.56 would be less than ideal, but not bad on the highway w/ 33's IMHO.

 

[Vug]

Here's my experience...

I went from 3.07's with 32" Swampers to 4.56's. I found this gear to be very good on the road with these tires. I have a stick but no tack so I don't know my on road RPM's but it sure doesn't sound like it's overreving. Also, Swampers run closer to nominal than other brands so they are more than likely closer to the same size as a non-Swamper 33".

Now here's my opinion...

When faced with a gear change, lean toward the gear ratio one steeper than you thought originally unless you have first hand driving experience with the setup you want. 2000 RPMs in overdrive is NOT your goal!

 

[David - Atlanta]

This rig is no longer my daily driver but I do have to drive a good 1.5 to 2 hours to hit the trails. Most of the trip are highway miles and I have no plans, or cash, to make this XJ a trailer queen.

 

[sredish]

[delete]

 

[Apanthropy]

Just as a reality check I figured I would point out that on the japanese side of things, stock mitsubishi monteros came with 4.62 gears and some stock 5-speed first-generation ones with 4.88 gears. Many of the owners who drive those trucks off-road are switching to 5.29 gears for 33 and 35" tires.

Stock isuzu troopers, came with 4.56 and 4.77 gears, depending on option - and more recent ones with 4.30 (after they started putting an engine with actual power in the trucks) . Mine has 4.77's and I tach under 3200rpm at 75mph "indicated on speedometer"

My girlfriend is going to run 31" tires on her XJ and might someday run 33's , so I have recommended 4.56 gears to her.

 

[Vug]

David,
If you got a good deal on 4.10 axles and you want the 32's, I say go for it. An axle change is no biggie compared to a gear swap. If you don't like it later, regear or drop to 31's. BTW, I loved my 32x9.5 Swampers but got the itch for 36's.

 

[David - Atlanta]

Wow, that was quite an itch. I'm going to try and keep my distance from that bug. Riiiiiight. Famous last words.

 

[Vug]

Yeah, my wife hopes the itch don't spread to 42's. She just if I even hint at it.

 

[h.curtis]

Thanks for all the imput on this. I think I want 4.10's. I have really good low end torque with the Borla exhaust and the HO I have. If I had an automatic or if I did a lot of rock crawling I would go with 4.56's. I am glad so many people gave there experiences. I was going for a 3.73 or I may have gone with 3.55's because they can be had in a d44. So, I am now searching for a d44 with whatever gears I can find due to me changing them anyway. It seems you can get a 3.07 for cheaper than a 3.55 for some reason. Not sure why.

Curt

 

[Eagle]

Apanthropy --

Although I think many people are too worried about this "engine will be screaming" bit, I think 4.56 gears with 31" tires is too much gear. Might not be so bad here in the east where many speed limits are 55, and the best we ever see is 65 -- out where y'all live the limits are 70 to 75 and I know you drive faster than that.

Work out the RPMs. IMHO what you should aim for is what the original versions of the engine were designed to run at, which was 24 MPH per 1000 RPM -- 60 MPH = 2500 RPM and 72 MPH = 3000 RPM.

That's the way AMC used to set their cars up before all the federal emissions and gas mileage mandates, and they ran well and delivered great gas mileage. Everything since then has been devolution.

 

[Scott Mac]

I for one wish I had listened to those who went before me and sugest 4.56 when I had my 32s. Now I'm hateing 4.10s even more with 33s. After some thought I'm now considering swaping in 4.88s and after looking at Jes's dash pic, I have realized that it's a realistic possibility I'm thinking that I can cruise at 70 mph and keep it around 3grand on the tach.

 

[red87cherokee]

I just regeared with the intention of going to 35's, but that will have to wait for a few weeks/months. So now, I am running 4.88's and 31's, and love it.

In essence, I have a 4 speed with a granny 1st gear. Before, with the 3.07's, I would have to use 4Lo far too often IMHO. On highway, I start out in 2nd gear (which is a fraction of a percent off of the stock 1st gear with stock gearing and stock sized tires).

The revs are a little high now, but with a 5th overdrive and the nearest freeway over 100 miles away I can live with it. Here are the revs I see (and the indicated speed on the speedo - approximately 50% higher than actual), versus actual ground speed:

ACTUAL . . GEAR . . . . . . RPM . . . . SPEEDO

. . . 20. . . . . .2 . . . . . . . 2506 . . . . 30
. . . 20. . . . . .3 . . . . . . . 1506 . . . . 30
--------
. . . 35. . . . . .3 . . . . . . . 2635 . . . . 52
. . . 35. . . . . .4 . . . . . . . 1882 . . . . 52
--------
. . . 45. . . . . .4 . . . . . . . 2420 . . . . 67
. . . 45. . . . . .5 . . . . . . . 1912 . . . . 67
--------
. . . 55. . . . . .4 . . . . . . . 2958 . . . . 82
. . . 55. . . . . .5 . . . . . . . 2337 . . . . 82
--------
. . . 65. . . . . .5 . . . . . . . 2762 . . . . 96