Regear 4.88 or 5.29

[knosack]

So, we're planning to build up our '99 for wheeling. We plan to run 315s. Was planning to run 4.88, but now am starting to think 5.29. Going to do a front ARB to increase the strength of the front diff, so while we're at it, going to regear. We plan to tow a camp trailer (~ 6000#) and live at 4500 feet, so I'm starting to lean towards the 5.29 even though the 4.88 gets me close to stock. Any idea what rpms would be at 60 mph (or 70)? Stock vs 4.88 vs 5.29 with 315s?

Reading this thread started me thinking 5.29. And the guy going to do the work questioned the cost for 13% improvement (4.3 -> 4.88).

Thanks in advance

 

[ShottsUZJ100]

Wow...will the gas mileage take a hit! It all depends on how many long trips you'll go on.

 

[Downey]

Unless there is something I'm missing, I can't understand why a guy running 10.50's would even go as low as 4.88's unless he just wanted low off road gears. 5.29's would just be out of the question. You said you would be towing, so I guess you are talking about highway use!!! I generally advise customers to lean toward the higher side on gears because the lower the ratio, the weaker the pinion shaft!!!

 

[hoser]

I can't understand why a guy running 10.50's would even go as low as 4.88's unless he just wanted low off road gears.

10.50?
Anyway, 4.88's and 35's is just the same as stock tires with stock (4.3) gearing. 5.29/4.88=8.5% so your RPM's would be roughly 8.5% more than stock gearing/tires.

If I could have it my way, I'd choose something in the middle, like 5.13's. Too bad that's not an option. If at high elevation, often towing AND you don't regularly go faster than 70 mph, I think 5.29's will be fine.

5.29's is roughly 210 rpm more than 4.88's at 70 mph.

 

[100 TD]

So you want to regear for highway use?
If you want ot regear for off road use, IIRC I think Marks 4wd adapters make a reduction gear for the transfer case that will lower your ratio by 25% in low range. This works by changing the gear in the transfer without touching the front or rear diffs. Something to consider for off road use.

 

[ginericLC]

How often do you tow? I'm at 315s with stock gears and I've towed a few times with my 100. I towed 4500lbs a few weeks ago a short distance. It wasn't bad. I'm at about 4k feet. Figure out how many miles you tow a year and figure out if it is worth the sucky gas mileage you'll get going low on the gears for the amount of time you actually tow. Buidling your rig for 90% of your use makes sense rather than building it for 3-4% of your use. I'm actually looking at going back to a 285. I don't feel that how I use my 100 the 315 is necessary. Unfortunately, these tires are going to last forever because I made that decision. That is something else you might consider.

 

[knosack]

Thanks for your input everyone. To explain a bit more, since it's a '99 I decided to add an ARB up front, to strengthen it and add a locker. Since that all is getting worked on, it's not much more in labor to regear. And since I want to tow a 6000# camp trailer several times a year and wheel with 315s, and we live around 4500 feet, and climb up to at least 8000' for camping, regearing seems to be advisable. Was planning on the 4.88, but read some threads on regearing and it got me thinking maybe 5.29 would be better, as long as highway use didn't suffer too much. You guys make it sound like mileage will go in the toilet, but hoser commented that it will only increase rpms 210 at 70 mph. That doesn't seem that much.

Since we'll be towing only occassionally, I'll probably just do 4.88s. I do wish there was something between 4.88 and 5.29. That would be ideal.

 

[Letsgomoreplaces]

gear ratio

Mileage would not "go to hell". What many dont understan is that tires have the same effect as gear ratio, but the other direction. By installing gears you are simply bringing the RPM's back where the should be. This can actually improve economy. I run 315's and 4.88 and overall it is a great combo, almost dead on with a stock vehicle rpm wise. I used to run 33's with the 4.88 which is pretty similar to 5.29 w/ 35's. You would be fine with 5.29, although I dont know if it is necessary. I have a lot of weight on my truck and drive mountain passes every week, as well as tow a 5500lb boat in the summer, and it works for me. I suspect with 5.29 the vehicle will be less smooth in general due to increased driveline speed, etc.

 

[ShottsUZJ100]

By installing gears you are simply bringing the RPM's back where the should be. This can actually improve economy.

Depending on the gearing. Back to stock...yes.

Lower than stock (as in this case)....mileage will suffer. My 4.88 LX on 35's is horrible on gas. 11-ish and it's a unloaded trail rig.

 

[e9999]

seems like that engine has plenty of grunt in reserve. Probably no need to go super low?

 

[sleeoffroad]

Kurt, fwiw, we have 5.29's in the BlueBerry. I would say, probably the only 100 in the US with 5.29's. We run 39's on it and it runs really good on the road. I am not sure if 35's is a little small for 5.29's.

 

[knosack]

Thanks again. I'm definitely going with 4.88s

 

[Letsgomoreplaces]

UPDATE: 100 series gears are now available

It is now possible to obtain direct fit gears for the 100 series diff. Slee is now stocking them. No longer is it required to change carrier or us hybrid ARB to regear the 100 series landcruiser!

http://www.nitro-gear.com/news/2009...ruiser-ring-pinions-another-industry-1st.html

 

[ShottsUZJ100]

It is now possible to obtain direct fit gears for the 100 series diff. Slee is now stocking them. No longer is it required to change carrier or us hybrid ARB to regear the 100 series landcruiser!

HOLY SHxx! Fricken....4856743 relgh0574ytthg rwtlrht 6gfhj 5udfgl....CRAP...I GO TO OURAY in a month. ARGHHHHHH! Too much stress!

 

[Letsgomoreplaces]

gears

I know, never say never

HOLY SHxx! Fricken....4856743 relgh0574ytthg rwtlrht 6gfhj 5udfgl....CRAP...I GO TO OURAY in a month. ARGHHHHHH! Too much stress!

 

[ShottsUZJ100]

I know, never say never

I never said never.

OK....I've always said I'd not 4.88 my 100 UNTIL I needed some work done in the pumps. Well, I'm close...I have U-joint rebuild kits so my shafts have to come out...maybe we'll pull pumpkins and swap out new ARB air o-rings and re-gear.

OK...question...the install I got years ago has been 100% trouble free. This includes many hopping and bouncing and clawing for traction...no failure so I know the stuff's in there right.

How much work is it to just change the gears? It requires just the right amount of preload and all that setup crap just like when adding lockers? Right? If so I hessitate to mess with what I have (though I already emailed Slee about price).

 

[jgray]

Thats good news! Too bad this wasn't an option last year... I'd have 4.88's now if it was...

 

[wildsmith]

I just ARB'd both my diffs, glad I didn't go to the trouble of a hybrid regear while they were out!

IMO it's setting up the pinion depth and pre-load that's tedious on a re-gear so more work than just lockers if you left the pinion bearings alone when you did the lockers.

 

[ShottsUZJ100]

IMO it's setting up the pinion depth and pre-load that's tedious on a re-gear so more work than just lockers if you left the pinion bearings alone when you did the lockers.

Arghhh! I hate to mess with this as my 5-year setup has been ultra-reliable. Hmmmmm.....