Diff ratio suggestion for LS swapped 80 series (1 Viewer)
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I'm interested also
I have not swapped over to a LS yet but bought 4.88 gears hopefully it wont be too much when I do swap to the LS.
This depends on many things:
* Intended use of the vehicle.
* Gear ratios of the transmission you have
* HP / Torque curve of the specific engine you have
* Are you going for pulling power, or gas mileage, or comfort, or tire-smoking ability?
All of this is a mathematical equation after you answer some of thee and establish a cruising speed, or intended use and at what RPM.
Start at the tires.
What tire size are you intending to use? (Yes, you must pick one)
Start with the stock gear ratio of the truck, 4.11:1
This will give your revolutions per km.
Then you determine what speed you want the engine to be running at cruising speed (120 kph) looking for 2000 RPM.
Get a HP/Torque curve for that engine and determine where 2000 RPM is on the graph.
If you want to pass someone, what gear does it downshift to?
4th gear is 1:1 ratio on that transmission, I believe. You want peak HP/Torque in 4th gear to line up with your average cruising speed.
Then gearing is used to go lower and more power in lower gears.
If you're crawling, go higher numbers in the differential.
If you're cruising and want better mileage, go with lower numbers in the differential.
NeverFinis
SILVER Star
I am keeping with the stock 4.10s with 35s with my LS swap.
The 6L80 has a lower first gear, more gears, and a better overdrive.
Normally, a 6L80e is most commonly paired with something like a 3.42 or 3.73 diff and not 4.10s.
The first two examples are common differential and tire size combinations on GM Trucks/Vans.
The last one is a LS swapped FJ80.
Overdrive at 60mph:
Seems to me that 35" tires and 4.10" gears are perfect for the 6L80e.
If anything, I would think about changing the t-case gears and not regearing the differentials.
| 6L80E | 4.03 | 2.36 | 1.53 | 1.15 | 0.85 | 0.67 |
| A343F | 2.81 | 1.41 | 1.0 | 0.753 |
The 6L80 has a lower first gear, more gears, and a better overdrive.
Normally, a 6L80e is most commonly paired with something like a 3.42 or 3.73 diff and not 4.10s.
The first two examples are common differential and tire size combinations on GM Trucks/Vans.
The last one is a LS swapped FJ80.
Overdrive at 60mph:
30.5" tires with 3.43 gears will be at 1520 rpm.
31.5" tires with 3.73 gears will be at 1600 rpm.
35" Tires with 4.10 gears will be at 1600 rpm.
Seems to me that 35" tires and 4.10" gears are perfect for the 6L80e.
If anything, I would think about changing the t-case gears and not regearing the differentials.
Anytime I watch a video on YT that is based in Oman/Qatar/Saudi/middle east in general, it is rare they are driving a Land Cruiser on all 4 wheels.
Typically they are on 2 wheels, and when on all 4 they are doing doughnut burnouts.
What do your local mechs recommend?
Whatever it is, I'd say they are correct. lol
Typically they are on 2 wheels, and when on all 4 they are doing doughnut burnouts.
What do your local mechs recommend?
Whatever it is, I'd say they are correct. lol
It's kind of trial and error. Get it running and see how it does on stock gears. If it seems like it needs higher or lower gears after you drive it around a bit than you can calculate where you want the rpm's at while highway cruising.
- Thread starter
- #8
Intended use, daily plus occasional offroad driving (sand dunes etc). No rock climbing/crawling, no towing.
The gear ratios of the transmission:
4.03, 2.36, 1.53, 1.15, .85 and . 67.
Motor specs:
- LSA 6.2L (376 cu in) supercharged
- 556 hp @ 6,100 rpm
- 551 lb.-ft. @ 3,800 rpm
- 9.1:1 compression ratio
Picture attached.
Tire size haven’t decided yet. Either the BF KO2 315/70/17 which is a 34.4” tire or 285/75/17 which is a 33.8” tire.
Yes and the optimal RPM while cruising at 120KM is between 1,900 to 2,100.
- Thread starter
- #9
Thanks @NeverFinis.
I’ve read about t-case regearing and saw this post as well
Transfer case re-gearing
Has anyone heard of or seen a kit to regear the transfer case HIGH RANGE of the 80 series permanent 4wd transfer case? It is available for lots of other types of trucks like Nissan, LandRover, Suzuki etc, but I cannot find such gears for the 80 series. I do find low range gearing kits, but I...
forum.ih8mud.com
Haven’t looked for any kits yet. Any recommendations since the car is triple locked? Keep the same t-case or an Atlas transfer case?
- Thread starter
- #10
I
I have checked with Marks4x4 and they recommend installing the part time 4wd conversion kit for daily driving.
No intentions of doughnuts and burnouts.
Not many local mechanics have done conversions on the LC 80. The majority are on Nissan Patrols with engines taken out from GM cars. Lots of trial and error.
I have checked with Marks4x4 and they recommend installing the part time 4wd conversion kit for daily driving.
No intentions of doughnuts and burnouts.
- Thread starter
- #11
thanks @White Stripe
I'm considering a simple cheaper 5.3 with 6l80 (or an 8/10 speed with the Torfab kit).
I see almost zero reason to regear with the 6/8/10 speed transmissions. I want my interstate RPM low, and the super short 1st means I'll be in a much better place than stock, regardless of ring/pinion.
I see almost zero reason to regear with the 6/8/10 speed transmissions. I want my interstate RPM low, and the super short 1st means I'll be in a much better place than stock, regardless of ring/pinion.
NeverFinis
SILVER Star
Thanks @NeverFinis.
I’ve read about t-case regearing and saw this post as well
Transfer case re-gearing
Has anyone heard of or seen a kit to regear the transfer case HIGH RANGE of the 80 series permanent 4wd transfer case? It is available for lots of other types of trucks like Nissan, LandRover, Suzuki etc, but I cannot find such gears for the 80 series. I do find low range gearing kits, but I...
Haven’t looked for any kits yet. Any recommendations since the car is triple locked? Keep the same t-case or an Atlas transfer case?
I have a LX450 triple locked. I will be keeping the Toyota case as it is plenty strong. I might regear it, but it depends on how it drives when I am done the swap.
Underdrive Gears: Sumo Gear Land Cruiser Transfer Case 10% Underdrive Gear Set - Fits 8x/100 Series
Overdrive Gears: Sumo Gear Land Cruiser Transfer Case 10% Overdrive Gear Set - Fits 8x/100 Series
Lower Low Range Gears: Sumo Gear Land Cruiser Transfer Case 3.1:1 Low Range Gear Set - Fits 8x/100 Series
If you're not aware, check out this site-
Pretty easy to plug in your trans and optimize ratios for a given speed.
Pretty easy to plug in your trans and optimize ratios for a given speed.
- Thread starter
- #15
Thank you for sharing the links
- Thread starter
- #16
Thanks this has been very helpful
I have a stock 5.3, with a 4l60, 37's and 5.29's. Love it! 75 to 80 mph around 2600ish RPMs. i average about 17 to 18 mpg. I also did the part time kit when it was all out.
It's still over geared a little, but I'm thinking about 39's for my next size tire.
I mostly do rock crawling, but I do drive it to the trails.
I live in Colorado so having the extra power when on I70 is great!
It's still over geared a little, but I'm thinking about 39's for my next size tire.
I mostly do rock crawling, but I do drive it to the trails.
I live in Colorado so having the extra power when on I70 is great!
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I'm running a 6.2L LS with 6L80, 4.88 gears and 37's.
I think it would be too much gearing for 35's and definitely 33's.
As suggested, stick with stock gears, 35's and get some seat time. After that, evaluate.
Update: Here's my mph/rpm numbers
70mph / 2165 rpm
75mph / 2350 rpm
I have stock high range gears, 3:1 low range
I think it would be too much gearing for 35's and definitely 33's.
As suggested, stick with stock gears, 35's and get some seat time. After that, evaluate.
Update: Here's my mph/rpm numbers
70mph / 2165 rpm
75mph / 2350 rpm
I have stock high range gears, 3:1 low range
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- Thread starter
- #19
thanks for the insights.
- Thread starter
- #20
thanks for your inputs.
