Re-Gearing with larger tires? (2 Viewers)

[enox]

Also depends on your load. I've got full drawer system, tailgate storage, front & rear bumpers w/ winch, roof rack, sliders...I noticed a difference going from 33" to 35" on stock gearing.

The ratio with 33" and stock gearing loaded was okay...still shifting a lot on inclines.

I also fixed the speedo with a yellow box, it's back to spot on and I'm sure I'll have to do it again after the 4.88 are done.

If I still feel like I need more low or a higher o/d then I can tear into the T-Case and change the final drive...

 

[COYS]

Opposite experience here. I had 35s/4.88s on my last truck and while it was a huge improvement, it still felt like I could've used slightly more gear. Looked hard at 5.29s/35s this go around but that just felt a little too aggressive.

Apt for someone named ‘dozer

 

[96bruizer]

It’s not a conclusion, it’s a fact. Engineers had the gearing correct, we messed it up when we installed larger tires. Re gearing is us trying to make the engine and transmission work how it was originally supposed to. Get on your mountain bike and climb a hill. Takes way more power and energy to turn this tires in a higher gear. Wears you out more. Lower gears make it much easier, the same laws of physics apply to lower gearing in our rigs after we’ve altered the tire size. Much easier on our engine and transmission.

 

[OffRoadScott]

This topic and been beaten to death.

People have sworn 5.29 is best for 37 and some will swear that 4.88 is the best. But for now, I would recommend changing out the gears in your transfer case. There are gears that will change in theory your drive ratio to 4.56 and if you plan on going to 37s just upgrade to a 4.56 in the 3rds would put you around 5.00, going with a smaller gear like the 4.56 or 4.88 gives you a little more reliability.

I personally am planning on running 4.88 and with the 10% overdrive which would give me just over 5.29. But as with all plans they tend to change.

 

[Feldrian]

Yes, lower gearing gives you more torque or more load on the drivetrain. @96bruizer is saying the opposite, so I’m asking what his reasoning is.

Depends on how you look at it since there are two factors at work. Lower gearing reduces torque upstream of the crown and pinion. Larger tires increases the torque requirements on the whole system, so lower gearing and larger tires will give you similar load on the driveshafts, T-case and transmission to factory (assuming you pick a suitable ratio and ignoring the effects of driveline angle), however the load on your axles, birfs and hubs will still remain increased. Increased mass of a larger tire will also increase overall shock load on the system, but this will be lessened (but not eliminated) by a taller crown and pinion upstream of the third member.

If you had a hypothetical option to install hub reduction (like a portal or planetary axle), the torque would also be reduced on the axles and birfs, with the brunt of increased torque requirements from larger tires borne by the hub outbound of its reduction gear.

 

[leonard_nemoy]

I think location should be a big factor in these decisions. If I lived somewhere flat and close to sea level like Georgia or Florida for instance, than I would take a different route for gearing than I would out here in the west.

 

[93yotasr5]

315s id go 488 and for anything over go 529.

 

[Lowbudgetlc100]

Didn't know you could re-gear the transfer case. Is re-gearing the transfer case easier and cheaper that doing both axles? Would that put more strain on the driveshaft u-joints?

Specializing in Toyota Land Cruisers

Full service shop providing all your offroad parts, and fabrication and Mechanical needs. Ozark Overland Outfitters, 80 series, 100 series, 200 series.

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they have the tc gears in stock last week. give them a ring

 

[Box Rocket]

Personal opinion with maybe a fact or two thrown in........

First off, I don't think a diff regear is even worth considering until you get to at least 35" tires. I think location is a factor in the decision to regear or not. I'm going to base the rest of my opinion on a 35" tire size so the rest of my comments will reflect that. If you live somewhere in the midwest that is mostly flat then a diff regear isn't really worth the cost in my opinion unless you are spending most of your time on technical trails. If you live somewhere that has a lot of change in elevation where you're driving long, steep canyon roads then you'll have noticeable slowdown on hills with stock gearing. Whether or not that is acceptable is up to the individual. My '93 on 35's never had a gearing change and I drove it that way in Utah with lots of hills and highway climbs for 15 years. You just have to be ok moving into the slow lane when climbing hills. Wasn't a big deal to me.

That said, I got a set of new Nitro 4.88 gears for a great price and installed them in my current '95 on 35's about 5 years ago. I do like the improved torque and ability to get up to speed and maintain speed better than with stock gears. The truck would still slow down on some of the big highway climbs in my area but the truck maintained an overall higher speed than before and wouldn't have to downshift and hunt for gears as frequently during long climbs.

You will be "overgeared" (effectively lower gearing than stock setup) with 4.88's and 35's. Many people prefer the "feel" of being overgeared because it feels like the truck has a bit more power. Obviously torque is increased with lower gearing. One of the effects of being overgeared with 4.88's and 35's is that your speedometer will not be accurate. There are a few solutions to this. There is a speedo correction box that will adjust for different tire size. I didn't bother with any correction. In my case my speedometer was about 8-10mph slower at highway speed with stock 4.11 gears and 35's. After changing to 4.88's my speedo was reading about 5mph fast at highway speed. I used a GPS calibrated Ultragauge to get an accurate speed reading. Another side effect is that shift points are slightly off as a result of being overgeared.

A couple years ago I switched to a 37" tire. A gearing calculation shows 4.88's and 37's being within roughly .02% of stock gearing with stock size tires. So if you are wanting a stock-like feel, then 4.88's and are a near perfect match for 37's. There are plenty of people that will say to absolutely go to 5.29's with 37's. Back to my earlier comment, this is based on a preferred "feel" in how the truck drives, but will exhibit the same side effects as 4.88's and 35's with an incorrect speedometer and incorrect shift points. FWIW, I love how my truck drives with 4.88's and 37's. An unexpected but logical benefit of the combination was a total correction to my speedometer. It now reads a dead accurate match to my GPS and Ultragauge.

Transfer case gears are a viable solution and definitely less cost than regearing the diffs. They won't be a perfect match for tire size (35's or otherwise) but will improve driveability with larger tires if the high range gears are changed. Lower tcase low range gears will be a nice improvement in control offroad if you like being on more technical trails. Personally I have not changed my transfercase gears. With the automatic I feel like I can crawl the truck well enough on technical trails. But I will probably change the low range gears at some point when I have a bit of extra mod money.

Back to one of the original questions.....If you're already into the diffs to add lockers, I would definitely regear the diffs while you're in there. There's no point in adding the cost of tearing into the diffs again to regear later.

 

[inkpot]

Didn't know you could re-gear the transfer case. Is re-gearing the transfer case easier and cheaper that doing both axles? Would that put more strain on the driveshaft u-joints?

Yes, and no.

 

[LandCruiserPhil]

Stock gears on 35's club

below is a 7% hill, over 100°, at 4500'

 

[thatcabledude]

Stock gears and 35s many years.

 

[junior80]

my thoughts and experience is that it is completely worth it to re gear. I drive my 80 daily, the 35s zapped the power and that annoyed me around town and even on the highway for the few long uphill grades with the whole family in the car was just a bit too much of a slug.

I went with the transfer case re-gear 10% under drive hi range and had the low range gears fitted too. super happy with it now, it's way nicer to drive, torque converter is not slipping as much and the floor of the car doesn't heat up as soon. and by that I mean it took around 5 or 6 hours of driving for the heat to soak into the car and that's now extended to about 8hours of constant driving. but your results may vary.

 

[girupb]

I am in the process of going 4.88s because after going to 35” tires I began having overheating issues at higher speeds on the interstate and when pulling our Turtleback. Do you guys expect the regear will solve the problem?
I should also note that we are dealing with bumpers, roof rack, winch and soon to be sliders as well as a loaded down rear storage area.

 

[OffRoadScott]

I am in the process of going 4.88s because after going to 35” tires I began having overheating issues at higher speeds on the interstate and when pulling our Turtleback. Do you guys expect the regear will solve the problem?
I should also note that we are dealing with bumpers, roof rack, winch and soon to be sliders as well as a loaded down rear storage area.

your overheating issues might be something else. I’ve been told when I car/vehicle is running at higher revs it actually cools better, maybe someone can confirm this.

 

[Box Rocket]

I am in the process of going 4.88s because after going to 35” tires I began having overheating issues at higher speeds on the interstate and when pulling our Turtleback. Do you guys expect the regear will solve the problem?
I should also note that we are dealing with bumpers, roof rack, winch and soon to be sliders as well as a loaded down rear storage area.

I wouldn’t count on the regear helping your cooling issues. It’s possible it might help a little if the engine isn’t having to work as hard but I would have your eye open for other reasons for the high temps.

 

[girupb]

I wouldn’t count on the regear helping your cooling issues. It’s possible it might help a little if the engine isn’t having to work as hard but I would have your eye open for other reasons for the high temps.

I should probably run a head gasket check but it runs great and shows no other signs. Radiator is a tyc that is 4 years old and it has a aisin blue fan clutch on it.

 

[96bruizer]

I am in the process of going 4.88s because after going to 35” tires I began having overheating issues at higher speeds on the interstate and when pulling our Turtleback. Do you guys expect the regear will solve the problem?
I should also note that we are dealing with bumpers, roof rack, winch and soon to be sliders as well as a loaded down rear storage area.

I was in the same boat as you. I installed an Ron Davis radiator, blue clutch fan, engine running perfectly with no head gasket issues 4.88’s, 35’s etc, ran to Moab last year in June and my engine was running very hot. I am fully armored with trekboxx storage in the rear. My rig weighs 8,200lbs. I believe my hot temp issues had every to do with how hard I was pushing the engine. It was always floored. Even climbing steep trails in 4 low I’d have to floor it to get over obstacles. So I don’t think the gears will fix it.
new for this year I installed a hood scoop and a turbo. I’ve noticed a big difference in temps already with the turbo. My engine runs cooler because it’s not working nearly as hard. I’ve got a Turtleback as well. I’ll be doing a trip down south with the Turtleback in the next 2 weeks so that will be the true test. I’ll have to let you know how things work out.

 

[OffRoadScott]

With the rig running hot I would first take a good look at the whole cooling system. Assure you have a working water pump, thermostat, flush it several times (distilled water) then run Toyota red and consider running Redline water wetter. While you have everything apart I would recommend changing out your heater control valve if it hasn't been replaced. The factory temp gauge is very vague, I would consider running an analog or digital gauge and drill/tap the aluminum elbow near the distributor for a good source of coolant temperature readings.

 

[6806goats]

Yes, lower gearing gives you more torque or more load on the drivetrain. @96bruizer is saying the opposite, so I’m asking what his reasoning is.

I can see where regearing the TC with the 10% under would add more strain to the drivetrain but regearing the axles would decrease strain to like the driveshafts and ujoints. That's the way I see it anyway. Was thinking LS swap with 6L90, 35's and 4.56 would be about on par with stock type RPMS and such. Going to 4.88's with the 6L90 wouldn't be too big of a deal and program the speedo. Off target for this thread though.