DIY 4.3 Re-Gear (1 Viewer)

[TeCKis300]

With many thanks to @TeCKis300 and the other trailblazers who contributed to this thread, I was able to knock out the front and rear installs this week. It took me a total of about 10 hours working alone, taking my time, with hand tools. I would say the rear was very straight-forward, while the front took a bit of work to get the Tundra diff into place...If I had a better transmission lift, or more hands, it would have probably been easier.

The sluggishness on my 33's is definitely gone, although I've been driving like a granny during the rear diff break-in interval...I look forward to upsizing to 35's next. Body-mount-chop is next, and again, I'll be following the pioneering efforts of others, in preparation for the inevitable 37's (I just need the LX to fit in a 6'7" parkade, so I need to temper elevation gain, and may actually decide to reduce my sensor lift a bit).

Way to knock it out! Sounds like another beast in the making now that the supporting mods are there.

 

[CanadianRockyCruiser]

Way to knock it out! Sounds like another beast in the making now that the supporting mods are there.

Yeah, I think I have to moderate tire size to an inch of lift at a time, so my wife won't notice...

 

[highfructose]

Put Landcruiser/LX570 on jack-stands (under rear axle and front frame)

Rear

-remove all tires

-drain differential

-remove calipers (I just balanced them on the axle, to keep them out of the way)
-loosen parking brake star nut to enable easy rotor removal

-remove rotors (I had to remove my wheel spacers too)
-remove parking brake hardware (springs) and then cable (10mm bolt on the backing plate)

-remove brake lines from the backing plate, and re-attach them outside the backing-plate mount to avoid brake fluid loss and mitigate future bleeding needs

-remove 4 17mm axle bolts, put a drain pan under the axle housing to collect any remaining fluid in the axle housing, and then pull the axle out
-mark your differential to ensure you keep it in phase, then remove the 4 x 14mm bolts on the propeller shaft that connect to the rear differential
-get your transmission jack ready

-remove the 10 x 14mm bolts on your rear differential and let her down gently

-regear your diff (if that’s your approach) or replace with a new gasket (as I did)
-tighten the 10x 14 mm diff bolts (65 ft lbs, I think?)
-re-attach the prop-shaft to the diff and tighten the bolts to 65 ft lbs
-replace the axle (and new axle shaft seals & o-rings, if yours don’t look great) and tighten the 4 x 17 mm nuts to 44 ft lbs
-re-attach the brake lines to the backing plate and torque the brake line 10 mm / 17 mm connection to 10 ft lbs

-re-attach all of the rear parking brake hardware (yeah, that’s fun!)

-install rotor

-install brake calipers (65 ft lbs, I believe?)

-install wheels

-torque the rear diff drain plug (36 ft lbs)
-fill the rear diff with gear oil

-torque the filler plug (36 ft lbs)

Front

-remove skid plates

-remove two 22 mm bolts from the bottom of each knuckle, near the lower ball joint

-drain the front differential (10mm hex)

-disconnect the differential breather using some long pliers and mechanics-yoga (it’s on top of the diff, facing the drivers’ side CV, and just a few inches above the CV)

-using jack stands or other, extend the caliper and hanging brake rotor and knuckle assembly and hold “up and away” from vehicle

-pull on cv’s (I use a block of softwood on the hard cylinder face and a hammer to knock them out), then pull them out of the way
-remove the 4 x 14mm propeller shaft bolts on the ( I used a 17mm wrench and a jack stand to provide resistance from the transfer case side)
-place transmission jack under the transfer case

-remove the 3 x 19 mm front diff mounting bolts…I also removed the arm that is closest to the propeller shaft

-remove the front differential using the jack

-rebuild or swap (in my case Tundra 4.3 swap)

-reinstall front diff (fun!)

-torque the 19mm mounting bolts (I don’t know the correct spec, but will update when I figure it out… I used 100 ft lbs)

-reinstall the CV’s gently, but firmly, with a bit of rotation as necessary

-reconnect the lower knuckle bolts and torque (211 ft lbs)

-reconnect the differential breather, using long pliers and mechanics-yoga

-reconnect the propeller shaft and torque the 4 x 14mm bolts (65 ft lbs)

-torque the front diff drain plug (29 ft lbs)

-fill the front diff

-torque the filler plug down (29 ft lbs)

-mount tires, and torque all wheel bolts to 97 ft lbs

Next steps

-chug 6 beers, shower, sleep in any order

-run any new diff gears (only after effects of 6 beers have worn off) with new oil for 500 miles (800 km) gently, with frequent stops to cool completely

-replace gear oil in any diffs with new gears after the fist 500 miles (800 km)

wow. Thank you for this write up.

 

[MNNorthWoods]

I am re-gearing my 2021LC to 4.30 and installing Eaton e-lockers front and rear.
For the rear, I am installing a complete new 3rd member with Revolution(?) gears entire package assembled by Cruiser Outfitters.
For the front, I want to give clear directions to the driveline shop I am using here in Minnesota.
I have a front differential from a 2007 Tundra.
I read in this thread that the carrier offsets are different between the Tundra front diff and the LC front diff.
- Is this true or is it possible to install the Tundra gear set into the LC front differential housing?
- Is the best or only option to swap on the axle tube from my 2021LC?
Other mods needed:
- remove the Tundra ADD gear/shaft?
- if I use the Tundra front differential housing and gears, is it recommended to replace both driver and pass side needle bearings with journal bearings from ECG?

Any other advice on what else I need to ensure is done?

 

[TeCKis300]

I am re-gearing my 2021LC to 4.30 and installing Eaton e-lockers front and rear.
For the rear, I am installing a complete new 3rd member with Revolution(?) gears entire package assembled by Cruiser Outfitters.
For the front, I want to give clear directions to the driveline shop I am using here in Minnesota.
I have a front differential from a 2007 Tundra.
I read in this thread that the carrier offsets are different between the Tundra front diff and the LC front diff.
- Is this true or is it possible to install the Tundra gear set into the LC front differential housing?
- Is the best or only option to swap on the axle tube from my 2021LC?
Other mods needed:
- remove the Tundra ADD gear/shaft?
- if I use the Tundra front differential housing and gears, is it recommended to replace both driver and pass side needle bearings with journal bearings from ECG?

Any other advice on what else I need to ensure is done?

So you go on eyes wide open, 4.3s in the 8 speed cruiser is going to result is really really short gearing. If that's what you're looking for, and you're running really huge tires, Great.

To your other questions
- Yes, Tundra front axle housing and gear is done
- Yes replace Tundra ADD with LC axle extension
- Bearings and wear probably depends in degree of lift, with larger lifts creating more load. I'm still in the Tundra needle bearings 45k miles later.

 

[MNNorthWoods]

So you go on eyes wide open, 4.3s in the 8 speed cruiser is going to result is really really short gearing. If that's what you're looking for, and you're running really huge tires, Great.

To your other questions
- Yes, Tundra front axle housing and gear is done
- Yes replace Tundra ADD with LC axle extension
- Bearings and wear probably depends in degree of lift, with larger lifts creating more load. I'm still in the Tundra needle bearings 45k miles later.

I’m running 34s and debated between 4.30 and 3.90 and went down the 4.30 path. If I regret it, I’ll have to reverse it to 3.90’s… that would cause a bit of marital friction but another regear could be done.
Main reason for the regear is for better towing - I tow a 5800# 29’ Imagine travel trailer and towing in the mountains isn’t much fun.
Good to know about the needle bearings.

 

[CanadianRockyCruiser]

I’m running 34s and debated between 4.30 and 3.90 and went down the 4.30 path. If I regret it, I’ll have to reverse it to 3.90’s… that would cause a bit of marital friction but another regear could be done.
Main reason for the regear is for better towing - I tow a 5800# 29’ Imagine travel trailer and towing in the mountains isn’t much fun.
Good to know about the needle bearings.

I tow a 6,200 lb 29' Imagine 2400BH all over the Canadian Rockies (fully loaded more like 7,500lb). It's a 2013 with the 6 speed, and the 4.3 gears definitely seemed to improve towing over high mountain passes. I've been running 33" tires, but will be moving up to 35" in the spring. No hesitation to pull.

For a 2019, I'm inclined to think you will be running short in the gears, which may not be ideal at highway speeds.

take a look at Teckis300's post here, if you haven't already:

Definitive 200-series Gearing Reference

EDIT: Expanding tables for 8-speed and 40s So I had a little time this morning to put together a chart combining transmission gearing of 6-speed vs 8-speed, diff ratios, and tire sizing into an overall gearing reference. Hoping this will be useful for those trying to understand how their...

forum.ih8mud.com

 

[grinchy]

I have the 6 speed and 4.88. Final drive on the 8 speed with 4.3 is similar, but with that already low 1st gear I could imagine some jerking going from 1st to 2nd on the 8 speed.
I like the 4.88 ratios fine for what I’m doing. I don’t tow. I do run 35s. I have plenty of gear to coast down hills in manual without having to brake. I have low ratios for crawling type stuff. Freeway rpm and shift points are completely fine. I get torque converter lockup as I should, and for a little longer going uphill I think due to the little bit higher rpm.

I never worry about weight or aero, but I get pretty atrocious mileage. It does lock me into 35 or bigger tire sizes.

If I had it to do again I’d consider 4.3 (3.9 in the 8 speed) more seriously, but probably go with 4.88s (4.3 in the 8 speed) all the same. My thinking was that I’d always have enough gear to keep the truck peppy no matter what mods I decided to do.

 

[TeCKis300]

I’m running 34s and debated between 4.30 and 3.90 and went down the 4.30 path. If I regret it, I’ll have to reverse it to 3.90’s… that would cause a bit of marital friction but another regear could be done.
Main reason for the regear is for better towing - I tow a 5800# 29’ Imagine travel trailer and towing in the mountains isn’t much fun.
Good to know about the needle bearings.

Looking out and I don't mean to bash, but 4.3s on the 8-speed isn't going to be what you expect even towing. It's a full 30% change and more akin to 5.29s (if that existed) on the 6-speed. 4.1s on the 8-speed is closer to 4.88s on the 6-speed. And the 8-speed will always have an advantage with bigger spread and deeper low gears.

It's going to be like lots of engine RPM with constant gear changes.

More theory but gearing doesn't make HP, only wheel torque. Once off the line, it's actually all about HP. Even hill climbs are all about HP. What I'm getting at is that gearing often isn't what people make of it and has to be considered as an overall system. I also tow heavy with 8k lbs and I wouldn't recommend that much gear.

4.1s if you want to be aggressive, but 3.9s will do much better.

 

[linuxgod]

I’m running 34s and debated between 4.30 and 3.90 and went down the 4.30 path. If I regret it, I’ll have to reverse it to 3.90’s… that would cause a bit of marital friction but another regear could be done.
Main reason for the regear is for better towing - I tow a 5800# 29’ Imagine travel trailer and towing in the mountains isn’t much fun.
Good to know about the needle bearings.

I really really really think you want 3.90s if you have the 8 speed. I have 4.88s in the 6 speed which results in similar gearing, and they are a lot of gear to have even with a 6000# trailer on 35s with poor aerodynamics. I’m not complaining when towing, but I can’t imagine running 5.29s and for you a 4.30 ratio will be similar to that. To me on the 6 speed 4.30 gears on 34s would be ideal and 4.56 gears (if you could find them) on 35s or 37s would be spot on when towing.

 

[TeCKis300]

4.56 gears (if you could find them) on 35s or 37s would be spot on when towing.

That unicorn Toyota ratio would be magic to have for the 6-speed.

 

[linuxgod]

That unicorn Toyota ratio would be magic to have for the 6-speed.

4.88s are good for towing with 37s, but I can’t bring myself to go past 35s given what’s required on the LC.

 

[TeCKis300]

4.88s are good for towing with 37s, but I can’t bring myself to go past 35s given what’s required on the LC.

Yup, can't say I'm not thinking about that.

 

[cubaniche]

Yeah I wish 4.56 was an option for the 9in/9.5in diffs. It would be the perfect happy medium between 4.30 and 4.88.

 

[linuxgod]

Upside of 4.88s when towing is I can sometimes run in 5th gear with the torque converter locked, giving me a few tenths better MPG. Downside is when I can’t hold 5th gear locked up, 4th ends up at 3500+ RPMs on the highway all day long, which is like 6 MPG

 

[bloc]

@bjowett do you know whether factory 4.56s are available for the early 200-series diffs?

 

[bjowett]

There may be a 4.56 for the rear diff, but nothing exists for the front.

 

[skrypj]

4.10’s with the 8 speed and 35’s would put you around 2000 rpm at 70 and 2200 rpm at 80. That’s almost exactly what my F150 did with the factory 3.73’s and 32” tires.

3.91’s drop it about 100 rpm at each speed.

One thing that’s interesting to me about the 4.10’ is that it almost perfectly drops the gear ratios by 1 gear vs the 3.31. So 7th would be equal to the original 6th, 6th = old 5th, 5th = old 4th. It would let you run one gear higher and have an extra climbing gear.

 

[TLC2013]

Its now been 5,000 miles on the oem 4.30 gear upgrade that I installed on my 2013 LC. Very happy with this setup.
Carrying around 1000 lbs of metal bumpers, armor..etc with 34" tires was definitely eating into the powerband and was especially noticeable at altitude and when merging onto the highway. Low speed crawling is significantly improved. All in all I should have done this years ago.
Mpgs are about the same and still aweful . Hard to tell but its maybe 0.5-1.5 mpgs lower on the highway and the same around town.

I am now parting ways with the oem 3.90s.

For Sale - SF Bay Area-CA: 200 Series OEM Front & Rear Differentials

I have for sale the OEM 3.90 front and Rear Diffs out of a 2013 Land Cruiser. Mileage was 130k when removed, they received regular fluid changes, and are in perfect working condition. Drop in ready gear upgrade for the 2016+ 200 series. Pick up in the SF Bay area Price: $1200 for front and...

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