Gearing? 4.56 or 4.88

[TEC3]

hey guys,

Working on getting the 100 build sheet together and budget. It's a 2006.

Need some info from guys running each. What are RPM's like when traveling on the HWY?

What tire size are you running. Current size is 265's that came on it.

Currently the truck is stock, but planning on going to 864's in the rear(fridge, rack, tent, tools, moody teen in 3rd row) we tow a 1000lb expo trailer on trips as well.

Was looking at 33's-35's. Need to see some pics of 100's at those heights as well.

Any help to make that decision would be great. Don't want to end up like my 80 series screaming down the Hwy to the trail.

 

[cmck]

Most agree that 33's don't require regear, 35's do, along with causing more steering rack stress in general. I have 33's (on 99 with 4 spd tranny) my rpm at 75mph is 2700. Your tranny setup is better than 99 in low and high ratios as I understand it.

I'm using ToughDog tourflex progressive rear springs and am realy liking them. There "RED" from TrailTailor here on mud.

Make sure you get comments from some 2006 guys, also. Moody teen is ultimately a ~7 year blip on the timeline so, keep the faith. Mine is now offering to help with mods.

 

[TEC3]

Thanks!

I am swapping everything from my 80 to the 100 that will swap. So my 3:1 tcase gears will come over as well.

I have OME 863's and 864's and was going to test both. I also have 315's (35's) from my 80 that can swap over.

My biggest concern is we tend to truely overland travel. Full family, full rig, trailer and then we wheel a bunch at the location. But we use interstate/ Hwy to get there. My 80 screamed at 2850 at 70ish and really wasn't good over 75. Most of the time due to the load I drove with O/D off and was like 3400-3500.

I want gearing for wheeling, we use it. But I don't want it to be so low that my interstate/ travel side suffers like the 80.

My moody teen is 1 of 4 kids... sadly I will be stuck in the "stupid" zone for a while

 

[juane]

My original build plan included 35 inch tires so I re-geared to 4.88s. Later realizing that 35s were overkill for my needs I went with 33s.
My concerns that the truck would be over geared with this combination (high revs and poor mpg on the highway) have proven to be unfounded. I could not be happier with the highway power, off road gearing, and, surprisingly the mileage. I've seen 17 mpg when religiously sticking to 65 mph on the highway. If I recall correctly the revs are like 2200 at 65 and the speedo is off by about 7 mph. The truck is heavy with typical build stuff including bumpers, sliders, winch, drawers full of stuff...

 

[DJCloz]

my 99 with a 4 speed is re geared to 4:88's, my tires are 295's which is a 34.5'' tall tire. I previously ran 33's without re gearing and it was ok, but definitely lacked power from a start off the line and when driving up steep grades it would downshift and just need more. I re geared when I broke my front diff gears rock crawling and once I did that, it felt really peppy off the line, but was running out of gear on the hiway. This made me make the jump to larger tires. The truck really felt balanced once I did this all around. @ 80 mph I am at about 2900 RPMs. 85-90 mph is about 3100 RPM. I try not to drive faster than that, but in some states like Utah the speed limit is 80 on the open hi ways and seems like everyone is doing 85-90. The truck is ok at 3000K RPM for an extended period of hi-way, but you will notice the gas really starts going fast. gears are a hefty cost at around $2600-3k, but if you can afford it, do it. But once you are working in the diffs, you might as well get lockers, add another $2500? I probably could have saved $700 in labor if I did it all at once, but I could afford to do it that way.

 

[TEC3]

So sounds like if I stay in the 295-315 that 4.88s will net me what I am wanting off road but not kill the truck on road. also with the 5spd trans I am probably looking at closer to 2400-2500 RPMS. It will be very similarly build to @juane cruiser pictured above. Just want to make sure I don't end up with no power and super high RPMs like my 80. I was climbing mountain passes in colorado doing 35-40 in 1st at 4800rpms... building the hundred to not have to deal with that strain.

 

[KC100series]

I'm running 295s with stock gearing on an 06. I was just up in Vail and had no issues at all running 60-65 up every pass I came to. Had the transmission drop into 3rd a couple times when passing a slower moving car uphills, but no struggle at all keeping speed in a 100 quite like an 80 would be

 

[jLB]

Be somewhat cautious in comparing the requirements for re-gearing between the 4spd 98-02 models, and 5spd 03-07 models

(Stolen from 4 sp vs 5 sp)

Our 06 w/ 32.6" tires, factory gears are fine.
Our 00 w/ 32.8" tires, feels like it could use a slightly lower gear.
(more than likely the difference is gearing, not the 0.2" of tire diameter)

 

[TEC3]

So what would put that final drive ratio on a 5spd in terms of RPMs? Looks like a .55 difference between 5th gear 4.10's and 4.88's

 

[jLB]

From memory, in my 06 (5spd) with 4.10 gears & 32.6" tires, I'm around 2200RPM @75MPH.
My math seems to indicate that 4.88 gears would add ~500RPM at 75MPH.

 

[TEC3]

Also, with the 3:1 tcase gearing what is the final low Rangel first? I am trying to figure that out.

 

[jLB]

Also, with the 3:1 gearing what is the final low Rangel first? I am trying to figure that out.

(In the chart above)

 

[TEC3]

Is that the low, first with marks?

 

[jLB]

Is that the low, first with marks?

Yep, I believe that is correct.

 

[OverLand Cruisers]

Expo built '04 (heavy) does great with 295 KO2s (34s) and stock R&P.
On the highway it has no problem pulling grades and off road I'm normally in low range manually shifting (2nd start).
I wouldn't change anything.

 

[LandCruiserPhil]

@TEC3 You are set and lucky having a 5sp and VVTi IMO. I have the same year and pull 5000# all summer long with no issue using stock gears and 34's.

I have also been known to pull stupid stuff also using stock gears.

 

[TEC3]

Nice,
Good info all the way around. I think I am going to be in good shape.
@LandCruiserPhil when are you going to do 100 series flip up windows... the wife is already asking