DIY 4.3 Re-Gear (2 Viewers)

[TeCKis300]

Awesome. Glad to hear it. I finished my install early yesterday morning. Then started the break in procedure for the new rear gears which is a 10 mile drive then 20 to 30 minute cool down, and do that 5 times. Then change the fluid at 500 miles or so. The break in fluid is non-synth 75w140. I'm going to put synthetic 75w90 once the break in is done.

It made a huge difference in drivability with the 35s. I don't have a bunch of added weight like full bumper and armor builds. I've just got the sliders and roof rack. I'll eventually be getting a dissent rear bumper. I'm babying the gears for the break in (rear). So I can't do any hard acceleration tests but these gears coupled with the superchargers low end tq is just so different vs the 3.90s. No longer downshift all the time. Doesn't hang on to a gear forever before shifting (under normal driving). It's essentially behaving just as it did when it was 100% stock. I can be doing 50 and goose the throttle a bit to accelerate up to 60 without it downshifting to 4th like it used to (it would downshift to 5th and then when it wasn't enough cause it was barely gaining speed, I'd have to give it a touch more throttle and bam, it'd shift to 4th). Now it just stays in gear and accelerates swiftly.

All in all, very happy with the preliminary results. I'm sure I'll see a slight bump up in fuel economy simply because of the elimination of all the bad shift behavior it had before.

I like how you described the change. Part of it is gearing, but the better part might be how it corrects the shift logic back to stock.

Wish our cars had transmission tuning support to correct for ratios, but until that's available, this is it.

 

[cubaniche]

Do you have the ability to check your rear diff temps? Sounds like the idea is to keep temps below the 200-250F range. I picked up a $15 temp gun on Amazon that is remarkably accurate for the price.

Yep. I've got one of those laser temp guns. But it didn't occur to me to check since I'm sticking to the 10 mile and cool down process. I'll check it though to see what it's doing. Im about to go out and do my 4th round.

 

[ElJayBird]

This is something I’d love to do to mine. Is it possible to get a parts list and high-level write up? The swap is WAY over my skill level but would love to find a shop in WA to tackle it for me.

 

[TLC2013]

@TeCKis300 , @bloc, @linuxgod ..etc
Is anyone able to confirm the torque spec for the 4 axle bolts that secure the axle assembly/hub to the rear axle?
From what I've found is that the Tundra spec is 123 ft lbs. Is the 200 different?

 

[bloc]

@TeCKis300 , @bloc, @linuxgod ..etc
Is anyone able to confirm the torque spec for the 4 axle bolts that secure the axle assembly/hub to the rear axle?
From what I've found is that the Tundra spec is 123 ft lbs. Is the 200 different?

View attachment 3651690

That sounds way too high. Generally that thread size and pitch is closer to 70. Let me look in the FSM and get a real number.


Edit: looks like 44 is the number.

 

[cubaniche]

This is something I’d love to do to mine. Is it possible to get a parts list and high-level write up? The swap is WAY over my skill level but would love to find a shop in WA to tackle it for me.

That's a tall order. A full high level write up would take time. Although most members here are really helpful, I doubt you'll get a full write up. Theres just too much to it if you were to write down every step. Your best option if this is not something you can figure out yourself, is to find an off road shop that's familiar with Toyotas or specifically specializes in them, to do this work for you. Or find a shop that only works on axles/ring and pinion work, call them.and ask if this is something they can do.

The issue I believe you are going to run into is that 95% of most shops will not install used parts like what is outlined in this thread. Some will do the actual regear for you but you'll have to remove and reinstall the diffs yourself. Maybe if you tweak the your approach like buying new Toyota or aftermarket gear sets like others have done here, they might be more amenable to doing the work.

It's just going to take some research on your part in speaking with the local shops and presenting them with what you want to do and see where it goes from there.

 

[TLC2013]

That sounds way too high. Generally that thread size and pitch is closer to 70. Let me look in the FSM and get a real number.


Edit: looks like 44 is the number.

View attachment 3651715

Great thank you! Proves to show never trust a random youtube channel for torque specs.

 

[cubaniche]

That sounds way too high. Generally that thread size and pitch is closer to 70. Let me look in the FSM and get a real number.


Edit: looks like 44 is the number.

View attachment 3651715

Great thank you! Proves to show never trust a random youtube channel for torque specs.

Is it OK that I used about 4 and a half ugga duggas from my milwaukee high torque impact?






Lol JK
Can't remember where I found the specs posted during my fra tic searching in my 120* temp garage but I did 47ft/lbs. Idk where that number came.from but it seemed accurate enough. Glad to see I wasn't too far off

 

[grinchy]

This is something I’d love to do to mine. Is it possible to get a parts list and high-level write up? The swap is WAY over my skill level but would love to find a shop in WA to tackle it for me.

I used the nitro associated shop in Cashmere. it appears to now be closed, which leaves torfab as the turnkey option

 

[ElJayBird]

I used the nitro associated shop in Cashmere. it appears to now be closed, which leaves torfab as the turnkey option

Thanks - I'll drop Torfab a line to see if they can help.

 

[FJRanger]

So, after re-reading several posts through this thread I’m still left with the following thought/question. Is it the general consensus the 3.91 gears from the 6 speeds 200s is a great option for those of us with the 8 speed transmission if we’d like to go with 34ish to 35” tires?

 

[ElJayBird]

So, after re-reading several posts through this thread I’m still left with the following thought/question. Is it the general consensus the 3.91 gears from the 6 speeds 200s is a great option for those of us with the 8 speed transmission if we’d like to go with 34ish to 35” tires?

I have 34's and the 6spd in my 2014 and it could use 4.33 - it's tolerable but definitely hunts too much on the highway and doesn't feel nearly as punchy as it was on 33's

 

[TeCKis300]

So, after re-reading several posts through this thread I’m still left with the following thought/question. Is it the general consensus the 3.91 gears from the 6 speeds 200s is a great option for those of us with the 8 speed transmission if we’d like to go with 34ish to 35” tires?

Yes, for the 2016+ 8-speed rigs, 3.9 is where you want to be at. This will have you at better than stock gearing for anything up to a 37. And way better gearing than any 6-speed with even 4.88s. If you're looking to go 37s and beyond, could warrant 4.1s. I know some say this is subjective, but too much gearing can be just as bad as too little gearing. The stock tranny ECU is setup with fixed parameters for stock overall gearing, and we currently have no ability to recalibrate the shift maps. Being close to stock overall ratios will have a better chance to see OEM polished gear changes and minimize hunting. The torque converter will lock up more consistently as designed to keep MPG up and tranny heat down.

More analysis here.

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

The heavyweights weighing in

In this case, they are used in a different vehicle (Toyota Dyna) that also has the 9.5" rear differential. The 2016 split, while coinciding with the Land Cruisers move to the 8 speed transmission and 3.31 ratio, has nothing to do with that aspect of it. The 2016 will likely do well with 3.90 or 4.10, as mentioned above.

There is no gearsets for the 2016+ that fits the rear third member or front carrier in the front diff for the 2016+ truck. So if you want to regear you need a rear diff from an ealier truck as well as a carrier.

Same is for the lockers. However not sure 4.88's are a good match for the truck. I think that is way to much gear. You would be to use the old truck diffs (3.90's) that would be a better ratio than the stock 3.30's in the 16+

 

[FJRanger]

Thanks @TeCKis300, that’s the exact information I was looking for. Bookmarked!

 

[skrypj]

I like how you described the change. Part of it is gearing, but the better part might be how it corrects the shift logic back to stock.

Wish our cars had transmission tuning support to correct for ratios, but until that's available, this is it.

They do

 

[cubaniche]

They do

Care to elaborate?

 

[TeCKis300]

They do

Copy and I'm glad to hear of progress. But until someone shares successful results, and how it can be done, it's still elusive.

Maybe you can share more. Perhaps a writeup?

 

[CanadianRockyCruiser]

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).

 

[CanadianRockyCruiser]

...

 

[CanadianRockyCruiser]

This is something I’d love to do to mine. Is it possible to get a parts list and high-level write up? The swap is WAY over my skill level but would love to find a shop in WA to tackle it for me.

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...mine looked beautiful and I chose not to replace them) 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, for my 2013...more for the 2016+ models, if I'm not mistaken)
-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 (83 ft lbs, I believe is the correct torque spec...please let me know if that is wrong.)
-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...this took me a while to find a set of long needle nose pliers that would work
-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)