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Diff rebuild /ratios for 1997 80 series 1hdft

Olafs

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Hello Landcruiser friends!
I am at the point where i want to rebuild front and rear diffs. Before taking everything apart, i want to order all the necessary parts because the car has to work and it can not stand on axle stands for days or even weeks, so i want to be as ready as i can.
Therefore, i have few questions for guys with experience :)
Info about the cruiser-
Year-1997, Engine-1hdft, Manual transmission, NO factory diff locks, VIN-JT111TJ8207406479, Model- HDJ80L-GNMEWW, C/TR/A/TM- 3H4/FP10/K302/H151F
1. Diff ratios? I have done quite a lot of research in forums and more i look, more confused i get. On the vin plate under axle number it says K302. All I could find was for K304 (3.727:1) and for K294 (4.1:1), both of them does not apply to my case. So,does anybody know what diff ratios i could have?
2. Since, i am planning to rebuild front and rear, maybe it is worth to just buy regearing kits? Car will soon be on 35s and it will do quite a lot of towing 3500kg trailer. If so, do you have any experience regarding this? Where to buy, what ratio...
3.Diff Lockers. I don't really need them right now, but after some time i will install a rear locker(probably electronic). If my axles didnt come with factory lockers, do i need to swap whole axle or they fit in these diff housings as well? And, since i will take it all apart, maybe it is worth doing it in the same time. If so, then would love to hear your experience on which manufacturer lockers are reliable and which you have used.
4. I am located in Denmark and therefore european shops (If you have any suggestion) would be highly appreciated.

I understand that i am asking quite a lot, but would really appreciate some information to guide me through all this. The main goal is to rebuild those diffs and to do it correctly first time. I am still new to 80 series and i am just learning about it. Right now i am giving it a birthday by replacing and rebuilding parts so she can run in a happy and reliable manner.
Huge thanks in advance and have a wonderful day!
Cheers,
Olaf
 

Chris

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Well the first thing that you need to know is that a rebuild will require parts that will be differnt to the originals, most namely, shims. I have a shim library that I have built up so when I do a diff, I can swap in what's needed. If you don't have those then you'll have to measure what's needed and order them which will take a while. Now, they're not that expensive so you could just order a large range of them but you will only need one for example in the front and who knows it might be the one you already have! You'll need a stand, a dial indicator, marker paint, torque wrench etc and some other home made tools as well as bearings, seals and crush tubes. The FSM does cover all of this in detail. Manual transmission regrears perfectly up to 35" toyres by simply swapping diffs to those from an auto. Rear diffs rarely need work and front diffs are faily easy to do and you can get gear kits for them easily. So I'd find a set of decent auto diffs and drop those in. Probably easier especially if you can get the ones with lockers.
 

Olafs

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Thanks Chris!
Thats a wonderful input. Well i don't know why i didnt thought about this myself... changing diffs sounds way easier than rebuilding them, the only problem is that we don't have many 80 series cruiser in the wreckers over here. But i will probably look in the neighbor countries and maybe will get lucky. If not, then probably will rebuild them to 4.88 ratio.
Regarding TLC FAQ - 9.1 Axle Codes - [Leaving Land Cruiser Club] automatic cruisers will have 4.10 ratio and my cruiser has 3.727 ratio?
 

Olafs

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Is there any difference between 80 and 100 series diffs?
 

AndycruiserguyLomas

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automatic cruisers will have 4.10 ratio and my cruiser has 3.727 ratio?
That's right.
The 2 indicates a 2 spider open diff. 3 is 2 spider LSD 4 is 4 spider locking diff 5 is 4 spider LSD.
The 30 part of the code is for 3.7 ratio 41:11 if that makes sense.
 
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Chris

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Having a couple of diffs on the bench does mean that you're not off the road whilst you do them.
 
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Olafs

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@Chris Yes, that is true. The thing is that it is not easy to get them over here where i live. Otherwise i would just get another set and slowly would rebuild them. Right now the only reasonable option seems to be to just rebuild the existing ones. Although, after doing more research it seems that the perfect scenario would be to get a set from automatic 80 series with lockers. It would give me a better gear ratio for towing trailer and would have lockers as well.
Therefore, Is there somebody who has a set of diffs from auto lc80?:D
 

AndycruiserguyLomas

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Therefore, Is there somebody who has a set of diffs from auto lc80?:D

Auto diffs tend to fare better than manuals due to the softer nature of the power delivery plus ( at least in the UK) all the petrol versions are auto's. This might help locating some however all UK 80's have diff locks so I'd research if they will retro fit to the open diff axle cases.
 

Chris

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With a manual of course, towing and ratios are far less important. Just don't change up so early!
 

Olafs

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@Chris I see, makes sense, but wouldn't it be much easier for transmission and drivetrain with higher ratio? I mean less stress for these components? Or the difference would be so small that it wouldn't matter in this case?
 

Olafs

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@AndycruiserguyLomas Thanks for the input, that will help me ;) Regarding Diff locks, how is it with open diff axle housings, does the original or even an aftermarket locker fit in there? I mean, i understand that everything is possible, but how difficult the job would be? And, what would be the most reasonable route for me to go since i have open diff axle housings. I mean, would it be better to rebuild these current diffs and then later i could somehow fit e lockers or should i just source diffs with factory lockers right away to avoid unnecessary costs later on (if i can install them in these axle housings)?
 

Chris

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Well the cheap test is just to try it, isn't it, Whack on some 35's and go for a drive. The difference isn't that great. Plenty of people here put 35's on stock autos and they've not struggled. My manual is on 35's and auto diffs, yes and it's great to drive, but I had the diffs on the shelf and the tools etc to rebuild the front one from scratch. It does sort of set everything back to standard if you like and with an adjuster box from Mark's 4WD the speedo reads bang on too. Like I say, try it. See how it drives on the taller wheels.

On lockers, the axle housing is actually different. You can't easliy put factory electric lockers in unless the housing on the diff case is there. You can go for air lockers or Detroits or swap the entire axle of course.
 

Grimbo

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I would concur that going to 35's on a manual will need a diff ratio change ....
Even on my 285/75/16s the manual is over geared for towing 3.5 tons .... a steep hill start requires a bit of clutch/throttle juggling .
Not towing it's perfectly OK....the speedo is 100% accurate and even under reads slightly at 50mph against accurate GPS speed...
I'm looking for a set of UK spec auto diffs at some point .....
 

Olafs

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@Grimbo Thanks for the input mate! I have exactly the same setup right now and i would agree that it is OK to tow. Here in Denmark we dont have steep hills so i don't feel a lot of need for shorter gears, but i have been in situations when on a highway it gets really windy and the car is struggling a bit (Trailer has terrible aerodynamics and is 3.5m high). So i have come to conclusion that auto diffs or slight regearing will be just helpful in my situation. So i will just go one of those routes.
Thanks guys for replying and have a good one! ;)
 

Chris

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It's a turbo called a G Turbo. Garret do a Big Boy, there's the Winke lads in Holland and others too. Not really up on turbos. You can also gt a supercharger. Mmmmm. Nice. Not a clue what one of those is though but sounds good. I want one.
 

Iwan

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I would concur that going to 35's on a manual will need a diff ratio change ....
Even on my 285/75/16s the manual is over geared for towing 3.5 tons .... a steep hill start requires a bit of clutch/throttle juggling .
Not towing it's perfectly OK....the speedo is 100% accurate and even under reads slightly at 50mph against accurate GPS speed...
I'm looking for a set of UK spec auto diffs at some point .....

You've nailed it there, it's all to do with what terrain and if you're towing, with 35's hilly terrain no traffic ques an auto will return 15mpg (12v) or less and take a lot longer to get your (over) loaded trailer to its destination.

Same truck converted to manual 35's same loaded trailer auto gearing will return you on the same journey in less time and provide 22 - 23 mpg (24v).

So an auto isn't good for the conditions above. absolutely no way going to run an auto again! Lol :laughing-rolling: (auto is the best! give me a break!) :thumbup:
 
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