4.88 + the ect button and the balls to run the rpm's closer to the top of the power curve works. If you really really want to make a difference, drop a V8 in it.
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Here's one thing I learned from my own experience that might help. I had 33's and put 4.88 gears. I would be taching around 3000rpms at 75-80 mph. My truck didn't seem to like it. shifting hard and when I had to down shift rpms would jump way high. When I would tow with that set up especially on steep climbs I would need to slow down and put truck in 2nd gear. It couldn't pull my boat faster than second gear and maintain speed.
Some time later I jumped all the way up to 37's which put me back at stock ratio. Truck shifts way better and what's most intriguing is that on the same hill climb with my boat I still had to shift to second to climb either way. except my trucks mph's and rpm's were more tame to drive. So moral of the story, towing or having a loaded truck with armor and all the goodies is just weight. The truck only has so much hp and torque to get you going. Get the gear ratio that will get you closest to stock with the tire you want and will eventually get. The only exception to this story is In low range for crawling. That's when 4.56's 4.88's and 5.29's will be a real noticeable difference. Hope this helps.
Cheers!
Some time later I jumped all the way up to 37's which put me back at stock ratio. Truck shifts way better and what's most intriguing is that on the same hill climb with my boat I still had to shift to second to climb either way. except my trucks mph's and rpm's were more tame to drive. So moral of the story, towing or having a loaded truck with armor and all the goodies is just weight. The truck only has so much hp and torque to get you going. Get the gear ratio that will get you closest to stock with the tire you want and will eventually get. The only exception to this story is In low range for crawling. That's when 4.56's 4.88's and 5.29's will be a real noticeable difference. Hope this helps.
Cheers!
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5.29s and don't look back!
Grench
SILVER Star
I have been running a supercharger, 4.88 gears and 35s for many years now. 80 mph is right at 3,000 RPM. Better acceleration than my wife's stock truck. YMMV.
Reviving this thread because Ken @gearinstalls.com & I have been talking about the gearing he'll be installing for me along with Harrop e-lockers, front & rear, hopefully. Decided on 5.29s with my 35" tires. Several reasons I've decided to go this way - including towing an off road trailer and heavily (6400 lbs unloaded) armored & outfitted truck that sees a lot of hills & passes on local 2 lane roads. The benefits in off road performance will definitely help towing in the dirt. Reading through this thread, it looks like most agree that 4.88 is the best choice for 35s, but I think that most don't run the weight that I do. I can always install 37s and straddle Subarus, if mpg suffers too much...lol
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Good thread. I’m on 35’s and stock gears. I hate it. I keep looking at trucks on 37’s and feel it’s where I want to be, although I’m cheap. 488’s is where I’d land with 35’s as I load down a little and tow a jumping jack(pretty light). 5.29’s if I go 37’s but I’m waiting to wear out my 35’s or come across a great deal on 37’s before I regear. I have a few other mods I want to finish first. Money doesn’t flow as fast as I’d like so I gotta wait.
I’ve also contemplated a ls swap, as I own everything except tcase adapter. Gearing would be the same for me though. I’ve had 35’s and 456’s, I needed more gear with towing.
I’ve also contemplated a ls swap, as I own everything except tcase adapter. Gearing would be the same for me though. I’ve had 35’s and 456’s, I needed more gear with towing.
I have 35’s on my 95’. And I’m running 4:88’s
It is the perfect set-up for me. I use my truck as a daily driver and of course I do a lot of over landing in it.
The 4:88’s make it so it drives almost like a stock truck. Plenty of power when I need it, and still go 80 mph all day on the highway.
I’ve never not had enough off road, although I always shift to low when things get rough.
With this gear/tire combo, I get about 12-13 mpg on highway.
Good luck and happy trails!
It is the perfect set-up for me. I use my truck as a daily driver and of course I do a lot of over landing in it.
The 4:88’s make it so it drives almost like a stock truck. Plenty of power when I need it, and still go 80 mph all day on the highway.
I’ve never not had enough off road, although I always shift to low when things get rough.
With this gear/tire combo, I get about 12-13 mpg on highway.
Good luck and happy trails!
Here's some food for thought for you guys...
A friend has a '96 with a 4" lift, 35's and 5.29's. I have a 2"ish lift, 33's and stock gears. We both filled up at the same station, hit the road and stopped about 70 miles later to fill up again before we headed off into the dirt. He used a little over two gallons less than me. TWO GALLONS... over 70 miles. I can't recall what the total fill up quantity was, though. You would think that the extra drag from the larger tires and taller lift would have it the other way around. I suspect that even though he's turning a couple hundred more RPM than me, he's doing so at a lower throttle opening as a result of less load on the engine due to the gears.
With winter here, we're not wheeling as much as we usually do in the summer, but plan on exploring this phenomenon more carefully when we get back into it. When we get some hard numbers, I'll post back.
A friend has a '96 with a 4" lift, 35's and 5.29's. I have a 2"ish lift, 33's and stock gears. We both filled up at the same station, hit the road and stopped about 70 miles later to fill up again before we headed off into the dirt. He used a little over two gallons less than me. TWO GALLONS... over 70 miles. I can't recall what the total fill up quantity was, though. You would think that the extra drag from the larger tires and taller lift would have it the other way around. I suspect that even though he's turning a couple hundred more RPM than me, he's doing so at a lower throttle opening as a result of less load on the engine due to the gears.
With winter here, we're not wheeling as much as we usually do in the summer, but plan on exploring this phenomenon more carefully when we get back into it. When we get some hard numbers, I'll post back.
THIS has always been my stance on the whole gear swap deal. Plus it makes the engine/trans/driveshafts work LESS hard, but harder on axle shafts.
Everyone thinks the lower rpms blablabla but I’ve rocked 4.11’s on 235/65/15 (or there about) on a work truck with 1k pounds of crap it it, got 18 average driving like an old lady. This was a 1990 gmc 350/700r4 throttle body spacer, intake, headers, 3” full exhaust(wayyyy more than that pos needed) but it got great mileage.
However, you can spin an engine higher than its efficiency range, and that can deduct mileage.
I still feel 488’s on 35’s is prob ideal unless you’re really loaded down or toe a lot. It would only get crappier mileage on the freeway at higher speeds, around town should greatly improve.
Getting down to pulling my 3rds for my axle maintenance and upgrades. Been thinking about R & P ratios and all that, again
and an engine speed calculator that someone in another thread suggested came to mind. For the 4.5L FZJ engine, USA spec, 65 MPH with 4.10 axle and .77 tranny ratio in our auto overdrive (4th) and other reasonable
combinations:
Axle:1-------------Tire diameter"--------MPH----------RPM
______________________________________________________
4.10 (stock)----------31 (stock)--------65-----------2224 (stock)
4.10 (stock)----------33----------------65-----------2089
4.10 (stock)----------35----------------65-----------1970
4.10 (stock)----------37----------------65-----------1863
4.56------------------33----------------65-----------2324
4.56------------------35----------------65-----------2191
4.56------------------37----------------65-----------2073
4.88------------------33----------------65-----------2487
4.88------------------35----------------65-----------2345
4.88------------------37----------------65-----------2218
5.29------------------33----------------65-----------2696
5.29------------------35----------------65-----------2542
5.29------------------37----------------65-----------2404
One would think that matching stock RPM would be the goal. But, if you think about it, that's only if you're changing the tire size and you want stock performance. But if you're adding mods that add weight you're going to have a performance loss due to the added weight. Just like when you have a full load of passengers and gear - it doesn't seem to have the pep that it has empty.
So does matching the engine's stock RPM at a given traveling speed help regain stock MPG, performance, both or neither when doing mods? I'm thinking that adding weight is always going to make MPG suffer. Regaining stock performance may be possible, but you'll still sacrifice MPG. Engine swap to a more efficient engine is the only way out of this
and an engine speed calculator that someone in another thread suggested came to mind. For the 4.5L FZJ engine, USA spec, 65 MPH with 4.10 axle and .77 tranny ratio in our auto overdrive (4th) and other reasonable combinations:Axle:1-------------Tire diameter"--------MPH----------RPM
______________________________________________________
4.10 (stock)----------31 (stock)--------65-----------2224 (stock)
4.10 (stock)----------33----------------65-----------2089
4.10 (stock)----------35----------------65-----------1970
4.10 (stock)----------37----------------65-----------1863
4.56------------------33----------------65-----------2324
4.56------------------35----------------65-----------2191
4.56------------------37----------------65-----------2073
4.88------------------33----------------65-----------2487
4.88------------------35----------------65-----------2345
4.88------------------37----------------65-----------2218
5.29------------------33----------------65-----------2696
5.29------------------35----------------65-----------2542
5.29------------------37----------------65-----------2404
One would think that matching stock RPM would be the goal. But, if you think about it, that's only if you're changing the tire size and you want stock performance. But if you're adding mods that add weight you're going to have a performance loss due to the added weight. Just like when you have a full load of passengers and gear - it doesn't seem to have the pep that it has empty.
So does matching the engine's stock RPM at a given traveling speed help regain stock MPG, performance, both or neither when doing mods? I'm thinking that adding weight is always going to make MPG suffer. Regaining stock performance may be possible, but you'll still sacrifice MPG. Engine swap to a more efficient engine is the only way out of this
If 0-60 mph and fuel economy are things you lose sleep over, I suggest selling your 80 and saving yourself a lot of pain and suffering.Getting down to pulling my 3rds for my axle maintenance and upgrades. Been thinking about R & P ratios and all that, again
Axle:1-------------Tire diameter"--------MPH----------RPM
______________________________________________________
4.10 (stock)----------31 (stock)--------65-----------2224 (stock)
4.10 (stock)----------33----------------65-----------2089
4.10 (stock)----------35----------------65-----------1970
4.10 (stock)----------37----------------65-----------1863
4.56------------------33----------------65-----------2324 4.56------------------35----------------65-----------2191
4.56------------------37----------------65-----------2073
4.88------------------33----------------65-----------2487
4.88------------------35----------------65-----------2345
4.88------------------37----------------65-----------2218
5.29------------------33----------------65-----------2696
5.29------------------35----------------65-----------2542
5.29------------------37----------------65-----------2404
One would think that matching stock RPM would be the goal. But, if you think about it, that's only if you're changing the tire size and you want stock performance. But if you're adding mods that add weight you're going to have a performance loss due to the added weight. Just like when you have a full load of passengers and gear - it doesn't seem to have the pep that it has empty.
So does matching the engine's stock RPM at a given traveling speed help regain stock MPG, performance, both or neither when doing mods? I'm thinking that adding weight is always going to make MPG suffer. Regaining stock performance may be possible, but you'll still sacrifice MPG. Engine swap to a more efficient engine is the only way out of this
Nah, I like my pain & suffering
You will never regain the MPG lost to increasing tire size and adding an aggressively treaded (compared to stock) off road tire. Larger off road tires increase rolling resistance, have more inertia so require more energy to get rolling, and increase aerodynamic drag. All you can do is get some acceleration back by improving the lost mechanical advantage of the larger tires.
To address the acceleration, you want to undergear 5% or so to gain some extra thrust to compensate for the added rolling resistance, inertia, etc... I run 4.88's with 35's and find it to be perfect. The truck is 5-7% undergeared vs. stock and holds speed nicely on the highway with no hunting or excessive downshifting. The torque converter remains locked nearly all of the time which saves fuel and extends transmission life.
My last set of tires (Nankang Loudstars) were closer to 34's and when they wore down I found the RPMs to be too high for my personal liking cruising at 75+ in SoCal. I have 35" BFG KO2's and it's just right.
Frank
To address the acceleration, you want to undergear 5% or so to gain some extra thrust to compensate for the added rolling resistance, inertia, etc... I run 4.88's with 35's and find it to be perfect. The truck is 5-7% undergeared vs. stock and holds speed nicely on the highway with no hunting or excessive downshifting. The torque converter remains locked nearly all of the time which saves fuel and extends transmission life.
My last set of tires (Nankang Loudstars) were closer to 34's and when they wore down I found the RPMs to be too high for my personal liking cruising at 75+ in SoCal. I have 35" BFG KO2's and it's just right.
Frank
richardlillard1
SILVER Star
I’m fine with 5.29s and tcase gears. But I did run stock gears for about 70,000 miles with no issues as well.
I'm still running stock gears with 35's, Front/rear bumpers. Runs just fine down the road. Tcase gears is likely my only mod, as the truck is a bit too "fast" on a trail in low...
my $.02
my $.02
COYS
SILVER Star
I put on 2200 miles in three days on my 97. It’s got 285s on stock wheels, stock gears. Got about 14 mpg avg driving between 70-75mph cruise.
I cannot imagine running 35s w stock gears. Would not want to. The truck would have to kick down on mole hills even at sea level. No thanks.
Look g forward to my 35s+488s!
I cannot imagine running 35s w stock gears. Would not want to. The truck would have to kick down on mole hills even at sea level. No thanks.
Look g forward to my 35s+488s!
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For the new members here
Also follow the threads about the 5 speed automatic transmission swap coming soon.
It will take care of all your regearing needs.
Or the transfer case gear set.
Just another option or two out there.
Also follow the threads about the 5 speed automatic transmission swap coming soon.
It will take care of all your regearing needs.
Or the transfer case gear set.
Just another option or two out there.
I am not entirely sure I would agree with that. Overgearing will likely make 5th gear useless. There are plenty of FJ cruisers running stock gears and 35's to illustrate this. If anything, you can regear lower than one otherwise would and manage highway RPMs with that 5 speed 5th gear while getting a better crawl ratio as well.
Frank
Frank
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The only diff ratio worth it is 5.29. We figured that out, what, 10 years ago?
35’s vs. 37’s in practice is like 150 RPM difference. It’s less than what the charts say. I did 5.29 when I had 35’s. @gearinstalls.com was right earlier in this thread - with a deep OD all 5.29 costs you is going 90 mph, and even that isn’t bad. I was coming back from Moab at 90 for a bit on I-70 at 3,100 RPM and it was just cruising.
I get 13-14 highway mpg driving between 5,500 and 12,000 feet.
Gauge pics are on 37” BFG ko2.
You have to fix your speedo - it affects shift points. Yellow Box sez I’m about 18% lower than stock.
I have 247K on the motor with mostly new sensors, plugs, wires, etc. and she’s perfectly happy to cruise at 80 at 2,900 RPM all day long.
35’s vs. 37’s in practice is like 150 RPM difference. It’s less than what the charts say. I did 5.29 when I had 35’s. @gearinstalls.com was right earlier in this thread - with a deep OD all 5.29 costs you is going 90 mph, and even that isn’t bad. I was coming back from Moab at 90 for a bit on I-70 at 3,100 RPM and it was just cruising.
I get 13-14 highway mpg driving between 5,500 and 12,000 feet.
Gauge pics are on 37” BFG ko2.
You have to fix your speedo - it affects shift points. Yellow Box sez I’m about 18% lower than stock.
I have 247K on the motor with mostly new sensors, plugs, wires, etc. and she’s perfectly happy to cruise at 80 at 2,900 RPM all day long.
