Gearing: HJ60 2H with 33s will become built 12H-T with 35s down the track (1 Viewer)

[fabianspeth]

Hey guys!
First up I'm a little unsure if my topic is better qualified for the Diesel Tech category or here in the 60 series area.
If it's better in the Diesel Tech section I'm happy to be transfered over!

I'm a little torn in regards to regearing and am collecting different opinions to make my own!

I currently have a HJ60 with a 2H and 33s on the truck, 3.7 ratio axles. It has become a bit of a slug uphill, especially uphill on the Autobahn. However it cruises so much nicer at 100kph (60mph) than before, dropping the rpms by about 200.

I bought a donor HJ61 with stock difflock axles (also 3.7 ratio) and a 12H-T, both of which will be transfered into my 60 in time.
The axles will be first at the beginning of November, and in the process I'll be rebuilding the diffs and axles.
Would be the perfect time to regear IF I have to.

The future plan is to freshen up the 12H-T and put it in as is with the 33s still on.
A little later I plan on upgrading the turbo, putting a front mounted intercooler on the girl as well as a 3" exhaust system.
About the same time 35s will go on the truck.

Now I'm wondering if I should regear now, or even at all, considering the future plan! Or better save the money of regearing and put it into turbo upgrades later on.
One opinion from a 60 series guru was the following:
Leaving the gearing as is (3.7), and having a bit of a slug until I have the stock 12H-T in, which should componsate for it in power (and keep the nice cruising rpms). Using the saved money for the 12H-T upgrades which again should have enough power to then turn the 35s.

Or I can spend the coin and change over to 4.11, 4.56 or even 4.88!?
I'd really like your opinios on the matter, keeping in mind that the gearing end goal should be for a built 12H-T (aprox: 180hp) and 35s setup.
Theoretically there's also the option of regearing in the transfer case!

Thank you so much to everyone who gives an opinio on the matter!
Here's a bit of 60 series eye candy after the long text and as a thank you!
Cheers from Germany
Fabian

PS: Does anyone know if the stock diff lock 3rd members from a 60 fit into 80 series axles as well? I heard that normal 60 and 80 series 3rd members are interchangeable!?

 

[cruiserpilot]

My truck:
12HT H55 with 500 kgs of bumpers, sliders, 285/75R17 Toyo MT’s. Average trip 6000 - 10000 kilometres
in northern Canada. Low range 3.0:1 transfer 1:1 high range. 4.11:1 axles with Toyota 4 pinion Limited slips
front and rear. Last trip average speed 90 kph. Average fuel economy 10 litres/ 100 kilometres
30x60 intercooler with 76mm piping, GTurbo Grunter upgrade. 76 mm straight out the rear exhaust.
Contemplating going back to 3.73 gears, but towing 550-800 kg utility trailer with 6-10 % mountain passes makes that a poor choice.
Get the engine conversion done first. You don’t mention if auto or not. Make sure you baseline the engine, valve adjustment, injectors services, timing injection pump and compression check.
Once you’ve run the engine for a while then decide on gearing, as needs and driving might have changed by then.

PS - More info on that tire step wrap. Very cool.

 

[kevin in okinawa]

the 12h-t is a workhorse engine that doesn't really need a bigger turbo or FMIC; save that money for a front winch and sliders and SOA if you want a lift. if you must get more power, install a boost gauge and EGT gauge and bump the boost and fuel settings, maybe advance the timing...you'll be happy with the grunty tractor motor. Find some stock 4.10s or wait and go to 4.56 when you get 35s. I've had 5.29s and 4.88s but they won't get you great fuel economy just decent.

 

[fabianspeth]

My truck:
12HT H55 with 500 kgs of bumpers, sliders, 285/75R17 Toyo MT’s. Average trip 6000 - 10000 kilometres
in northern Canada. Low range 3.0:1 transfer 1:1 high range. 4.11:1 axles with Toyota 4 pinion Limited slips
front and rear. Last trip average speed 90 kph. Average fuel economy 10 litres/ 100 kilometres
30x60 intercooler with 76mm piping, GTurbo Grunter upgrade. 76 mm straight out the rear exhaust.
Contemplating going back to 3.73 gears, but towing 550-800 kg utility trailer with 6-10 % mountain passes makes that a poor choice.
Get the engine conversion done first. You don’t mention if auto or not. Make sure you baseline the engine, valve adjustment, injectors services, timing injection pump and compression check.
Once you’ve run the engine for a while then decide on gearing, as needs and driving might have changed by then.

PS - More info on that tire step wrap. Very cool.

Ah sorry, it's a H55F as well! Also sorry for the late reply, had a tough week.
Did you change gearing in your transfercase? I don't know the stock ratios. or are 3:1 and 1:1 stock ratios?
I currently average around 11 to 12l/100km, going up to 14l in heavy city driving

Okay, so your suggestion is to stick with the 3.7 and don't regear while I have the diffs apart. I mean it would definetly be the cheaper one, putting the money into the engine first, until then I have to live with the poor power on the highway/autobahn and a bit worse milage.

The step wrap is from GMB Mount, a German company near Stuttgart! However Frontrunner has a somewhat similar model which should be available in the States as well! I prefer the GMB one for better looks, and value for money.

the 12h-t is a workhorse engine that doesn't really need a bigger turbo or FMIC; save that money for a front winch and sliders and SOA if you want a lift. if you must get more power, install a boost gauge and EGT gauge and bump the boost and fuel settings, maybe advance the timing...you'll be happy with the grunty tractor motor. Find some stock 4.10s or wait and go to 4.56 when you get 35s. I've had 5.29s and 4.88s but they won't get you great fuel economy just decent.

Well neither winch, sliders nor SOA was mentioned as alternative upgrades for the money. That particular money is either for regearing or the engine. Not saying that a winch or sliders won't come in the future, but don't really have anything to do with the topic. FYI a coil conversion is planned in the far future, one wouldn't assume, but it's easier to get through german TÜV. SOA is pretty much impossible to get legally done here we have incredibly strict rules and the coil conversion with 80 series parts is already a long leap.
Those could be plans for the "stock" engine to make it even more capable before going all out.
4.56 always seemed like the middle ground between 4.11 wich are supposed to be perfect for 33s, and 4.88 for 35s.


As of now my tendencies are to either stay with 3.7, bite the bullet until the stock 12H-T is in which will compensate for the lack of power. Or find original 4.11 which should be cheaper to get than import Ring&Pinion from the States or Australia.

Still undecicive yet and happy for more input from others!

All the best and have a great Sunday you all!
Cheers
Fabian

 

[Earwigg]

For 35s I'd be regearing. The 35s and 3.7 diffs felt to tall in low range for me and ment dropping to fourth for more hills on the highway.
But its not going to make to 2h quick. Maybe save the effort for swapping the 12ht in it will pull the 33s happily.

 

[cruiserpilot]

Stock transfer case gearing is around 2.63:1, the lower 3:1 kit I installed did not effect high gear
but makes it a bit nicer for those low range times. I definitely suggest doing the motor work first.
I got carried away and did a GTurbo upgrade and added a FMIC. There is a company right there
in Germany that does a really good stock turbo upgrade that really improves the street ability of
the engine.
When I drive around town and short trips around home, the truck is far better in traffic and the
stop and go of daily driving. I drive consistently around 90 kph, but occasionally if I want to hurry
it will run 110 all day - at the price of fuel economy. I have about 5% error with the speedometer
and 34” tires, it would be 12-13% if I was to run the 3.73:1 gears. But for me, no autobahn with the
4.11:1 gears.
Is it Wink the name of the company doing turbos there? Another item to consider, proper 3” exhaust.
Look through my turbo build I think I posted pics of a really good 3” dump from the turbo that has a
proper 3” opening and flow. Getting good exhaust on 12HT really makes it run better as well.