4.10 to 4.88 conversion and compatibility questions

[frawstme]

Hey everyone,
I'm looking to add rear locker and gear up to 4.88 on my 2000 uzj100, but there's a lot of conflicting information out there. I'm trying to get the parts together but I'm having some issues making decisions. I have little experience with differentials and gearing, but I have a good general idea of how everything works.

I've read that pre-2003 models use 27 spline pinions on front diff. Initially I was thinking that meant that I needed to find kits compatible with 27 splines, but I now see that you can get flange/yolk kits to convert to 29 splines.

My first question is, does the 29 spline conversion makes for a stronger differential? Are there any pros or cons of going one way or the other (aside from price)?

My second question is something that I'm guessing will be difficult to answer. On my JDM land cruiser, when I did the differential seals I noticed that the smaller seal is on the opposite side of the vehicle when compared to the NA model. I'm thinking that this essentially means that my differential housing is flipped. Will this cause any issues for me? It doesn't seem like it would, but I wanted to make sure.

The last question is that these master kits seemingly replace all components within the diff, is there anything else that I should replace while I'm in there? or upgrades that are available to increase the life of my diff? I have no intention of touching the diffs for years after this

Thanks much

 

[frawstme]

I'd like to bump this. I have searched this forum and google, there isn't much information out there. @cruiserpatch you seem to be very knowledgable on the topic, do you have any insights?

My first question can be ignored, I realized that it's nearly impossible to get the 27 spline kit so I will be going 29 spline with the yolk and flange conversion.

For parts I was thinking these:

Rear:

Ring and Pinion Gear Set - UZJ100/URJ200/LX570 Rear Axle Gears - 4.88 Ratio (TOYLC488R200)

Toyota Land Cruiser Ring & Pinion Gear

cruiserteq.com

Front:

Ring and Pinion Gear Set - 80 & 100 Series FRONT Reverse Cut Gears - 4.88 Ratio (TOYLC488R)

Toyota Land Cruiser Ring & Pinion Gear

cruiserteq.com

For the front there are two options: PN35110TG and PN35110, but it doesn't say what the difference is between them

ECGS master kit:

TOYOTA 8" IFS Land Cruiser Master Install Kit

This is a full set up kit to do the job right. It includes: Carrier bearings Pinion Bearings Pinion Nut Pinion Seal Crush Sleeve or Preload Shims Pinion Shims Loctite Marking Compound Adju

eastcoastgearsupply.com

ARB rear air locker (seems compatible):

https://exitoffroad.com/product/arb-rd152-rear-air-locker-toyota-9-5-32-spline/?srsltid=AfmBOop4qgeRzKnsx-mx1m8uN0FtT1-5cr-3qHWtJUM3FMBfsS7L6zoT

I'm unsure about which compressor to use, that can be decided later. I haven't done any research on what the wiring and plumbing process is like but I'm not too worried about that.

New diff seals while I'm in there:

OEM 100 Series Front & Rear Differential Pinion Seal (sold individuall

Sold individually (1x) OEM front & rear differential pinion seals for the 100 Series Series Toyota Land Cruiser and Lexus LX470. 01.1998-02.2002 (fits front & rear early 100 Series) includes: OEM front & rear pinion seal (1x): 90311-38066 Fitment details (90311-38066): 02.2002-05.2005 (fits...

www.cruiserpatch.com

I'm still feeling very unsure about the differential being flipped, but after watching some install videos I feel like it will be okay. I don't think it will affect anything, but some reassurance would be nice before I spend this money lol

 

[cruiserpatch]

Call @cruiseroutfit and they can answer all of your questions. They've been in business much longer than I have and are more knowledgeable on this topic.

Personally I would be looking into a transfer case regear before going with reverse cut flips for the front

 

[frawstme]

Call @cruiseroutfit and they can answer all of your questions. They've been in business much longer than I have and are more knowledgeable on this topic.

Personally I would be looking into a transfer case regear before going with reverse cut flips for the front

Understood, thanks for the reply.

The reason I am referring to 4.88 is for more of a better daily driving feel, and because I want to install rear locker. I figured I'm intending on regearing eventually and installing them while doing the locker cuts out some of the labor. It's my understanding that transfer case regear is also costly but affects mostly just low gear and off roading and doesn't do much for daily driving

 

[GTV]

It's my understanding that transfer case regear is also costly but affects mostly just low gear and off roading and doesn't do much for daily driving

Your transfer case has high (for the road) and low (for off road) gearing. You can change either one or both. It is much less money than digging into the differentials.

 

[Scotty UZJ100]

Your transfer case has high (for the road) and low (for off road) gearing. You can change either one or both. It is much less money than digging into the differentials.

Also a lot more diy friendly

 

[discoverydave]

Ran into the same confusion when I was putting together a build list for an 80 a while back. A couple things that might help: the 4.88 gear set in a 100-series is a common swap but the carrier break is different above and below 4.56 — make sure you know which carrier you have before ordering. For the 27-spline question, most of the Japanese domestic 100-series came with the stronger 30-spline rear axle, not the 27-spline — so you likely have more options than you think. Check the axle tube diameter at the backing plate, or just pull the cover and look for the cast number on the carrier. R&P sets from Yukon or Nitro are the way to go if you want something that holds up — the cheap stuff from the parts houses tends to have sloppy gear meshes out of the box.

 

[cruiseroutfit]

My second question is something that I'm guessing will be difficult to answer. On my JDM land cruiser, when I did the differential seals I noticed that the smaller seal is on the opposite side of the vehicle when compared to the NA model. I'm thinking that this essentially means that my differential housing is flipped. Will this cause any issues for me? It doesn't seem like it would, but I wanted to make sure.

That is not correct. They don't flip the differential on RHD vs LHD models. Differential tube seals are the same as a US spec UZJ100/LX470

RH: 90311-47012->90311-47027 (69mm OD / 46mm ID)

Differential CV Seal Front RH - Fits 1998 - 2021 100/470 & 200/570 Applications (FA47012)

Toyota Land Cruiser CV Seal

cruiserteq.com

LH: 90311-47013 (80mm OD / 46mm ID)

Differential CV Seal Front LH - Fits 1998 - 2021 100/470/200/570 Applications (FA47013)

Toyota Land Cruiser CV Seal

cruiserteq.com

 

[cruiseroutfit]

For the front there are two options: PN35110TG and PN35110, but it doesn't say what the difference is between them

The brand/specs. The PN35110TG is Trail Gear and includes their dual lip seal and 4-pattern flange. The PN35110 is a kit we build in-house and it features the OE 29spline seal and 2-pattern. Both have the pattern for the 100 front.

 

[cruiseroutfit]

Understood, thanks for the reply.

The reason I am referring to 4.88 is for more of a better daily driving feel, and because I want to install rear locker. I figured I'm intending on regearing eventually and installing them while doing the locker cuts out some of the labor. It's my understanding that transfer case regear is also costly but affects mostly just low gear and off roading and doesn't do much for daily driving

The t-case high range under-drive gearing absolutely improves daily driving the exact same way axle gears do, just different ratios.

Your JDM spec 2000 UZJ100 has 4.30:1 gears in the diffs.

Changing to 4.88:1 in axles would give you a ~13.5% reduction in both high and low.
Changing to 10% underdrive would give you the equivalent of 4.72:1

So for the money, the t-case gears are great bang for the buck and for most, a far easier install process. BUT if your axles need overhaul, the axle gearing will be a more cost effective solution.

We stock 100% of these parts and we ship and install them daily here at Cruiser Outfitters. Give us a call if we can be of help.

 

[frawstme]

The t-case high range under-drive gearing absolutely improves daily driving the exact same way axle gears do, just different ratios.

Your JDM spec 2000 UZJ100 has 4.30:1 gears in the diffs.

Changing to 4.88:1 in axles would give you a ~13.5% reduction in both high and low.
Changing to 10% underdrive would give you the equivalent of 4.72:1

View attachment 4119454

So for the money, the t-case gears are great bang for the buck and for most, a far easier install process. BUT if your axles need overhaul, the axle gearing will be a more cost effective solution.

We stock 100% of these parts and we ship and install them daily here at Cruiser Outfitters. Give us a call if we can be of help.

Woah- thanks for the info and the info in your other posts, I will take all of this into consideration. I need to take some time to absorb all this info and do some research. I honestly know little to nothing about transfer cases other than it's general purpose.

If my ratio is 4.3 then I would be reconsidering, but I was under the impression that A04B was 4.3 ratio. Mine is A02B..when I googled this before it said 4.10 and I didn't think much else of it. Now that I'm googling it again, there's not a lot of great sources on it. A few sources are saying that code is 3.73 but I don't see any saying that's 4.3

Do most people typically regear both high and low at the same time?

 

[cruiseroutfit]

Woah- thanks for the info and the info in your other posts, I will take all of this into consideration. I need to take some time to absorb all this info and do some research. I honestly know little to nothing about transfer cases other than it's general purpose.

If my ratio is 4.3 then I would be reconsidering, but I was under the impression that A04B was 4.3 ratio. Mine is A02B..when I googled this before it said 4.10 and I didn't think much else of it. Now that I'm googling it again, there's not a lot of great sources on it. A few sources are saying that code is 3.73 but I don't see any saying that's 4.3

Do most people typically regear both high and low at the same time?

Send our team an email with your VIN / Model Code and they can quickly determine which ratio you have.

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No, many do just the high range as they want to improve road driveability.

We stock all the ring/pinion and tcase options so we can help either way.

 

[frawstme]

Send our team an email with your VIN / Model Code and they can quickly determine which ratio you have.

Cruiser Teq | Powered by Cruiser Outfitters

Cruiser Teq is powered by Cruiser Outfitters. Get high quality OEM and aftermarket Land Cruiser parts direct to your door, fast!

cruiserteq.com

No, many do just the high range as they want to improve road driveability.

We stock all the ring/pinion and tcase options so we can help either way.

Perfect, done, thanks. Lockers are on my agenda at some point regardless so I'll be regearing diffs in future. After some research though, I'll probably do tcase first for drivability then diffs/lockers/tires later