A440F transmission vs. large tires question (1 Viewer)

[krüger]

hope to hit the right forum her...

planning some drivetrain setups for a' 100% yota offroad build (not a' street rig)
short story: would run a' bi-turbo'ed 12h-t in front of a' A440F tranny, onto 4:11 diffs and 39" iroks...

have searched alot around online for any A440F tech, but no luck on my specific question, my thought are about the A440F's toughness, the gearbox was running ok out of the street fj62 it came out of, but do any of you guys think it would be to much for the 440 with such tire size/diff ratio?

also a' bit wondering the fact if it only Locks up in 4th, it could be running hot when climbing long hills...


many suggest its sucks engine power (but hope to compensate for that with plenty of food for the 12h-t and rotating lifesupport on the intake )

have no "hands on" exsperience with automatics, have only wheeled my 3b(t) and 12H-t j4's with the H55 for many years in offroad.

please enlighten me with your thoughs


would like to use a' all yota and run a' standard parts bolt on solution, if not I will adapt a' 727tf or th400 I have lying around for the job.


from DK

 

[RockDoc]

39" tires with 4.11 (stock) diff ratio will be way beyond comfortable for the A440F. With that gearing, the torque convertor won't lock up below ~110 km. Stock tires with the A440F and 4.11s are ~28" (at least in North America on a FJ62). With 5.29 gears 36" tires would give a "stock" gearing feel, so 39s may work regeared to 5.29.

 

[krüger]

39" tires with 4.11 (stock) diff ratio will be way beyond comfortable for the A440F

was also my fear exactly.

just to be clear, the A440F from Fj vs the Hj are the same basic, only flexplate/converter/bellhousing differs?

I actually thought the hj6 (diesel) a440f's had same diff ratio as hj6 h55f's, the 3.70's diffs, does the fj6 then run 4.11 with the a440f in front, like the old BJ's...
(all Danish hj's are 3.70, and the BJ's are 4.11, but fj's are reare in these parts, so don't know the ratio in them) that's why I hoped a' bit that if the 440 was comfortable with the "high" 3.70 gears in the hj axles (seems no problem with HJ-a440f-33" here) then shifting to Bj 4.11's and larger wheels could balance it a' bit out, at least in the low range...

the build will never see public road, and probably never leave the low range anyway, but perhaps I should start of on smaller tires, and then consider a' set of 5.29's and if its any problem still, either drop the 39" or build a' full-time low range chain driven transfercase for the 440....



was just so keen on building me a' j4 pickup "thing" on 39" and stacks full of black smoke behind the cab with a' Yota automatic

 

[RockDoc]

If it is going to stay in low range, you may get away with 4.11 and 39" fine. Low range will drastically reduce the stress on the transmission.

 

[krüger]

If it is going to stay in low range, you may get away with 4.11 and 39" fine

see that was just the answer I wanted

I am probably doing the setup anyway but like said before, I really liked to hear those input/thoughts on the 440 - 4.11 vs 39" like your 1.st post, because I believe you guys in the States have more automatic yota's running than we do, all though I think so

thanks a lot so far, when my old trusty Hj45 with 12H-t conversion is up and running over the summer, I exspect this is next on the project plan

 

[boots4]

As with any automatic heat will be a killer. A huge dedicated tranny cooler with a fan (since this rig is offroad only and will see slower speeds), a tranny temp gauge and some tranny work (I thought I heard of a better valve body that helps with line pressure), along with a better torque converter could give this a fighting chance. But at the same time if you already have a stronger tranny with better aftermarket support why not step up to that instead especially if you plan to throw more power at it?

 

[krüger]

Well, I would like to be able to call it a clean Toyota build, but the 3 speed 727tf would perhaps be the better choice, but again, the 440 is a' bolt-on unit, an oil cooler with a fan assist offcourse, some line valve tweeks and then we will see if it pops. doubt if I get more than 200 and a bit hp, out of the old 12h-t.

I sure get your point on a better aftermarket for the us gearboxes, well worth considering too. The old 3 speed 727tf I can source here are mid 80's range rover's and with right side drop transfer case...

 

[jb BJ73]

Bit of a late reply, but wholesale automatics here in oz do heavy duty upgrades to Toyota autos. Things like billet torque converters, valve body's and extra clutch discs. The valve body's have a 3rd and 4th lockup option as well, maybe something worth looking at. I've been doing a bit of research my self for the same sort of setup.
And if you do a twin turbo 12ht be sure to put a write up in the diesel section, would be awesome to see that.

 

[Tapage]

since this old thread it's back .. Krüger could you share your 12H-T build . here or somewhere else .? very interested in the twin turbo setup.

 

[krüger]

since this old thread it's back .. Krüger could you share your 12H-T build . here or somewhere else .? very interested in the twin turbo setup.

so sorry to disappoint you on the turbo setup, havent been her for a' while

have had enough to do with running my business + keeping our old 40's MOT'ed and road legal along side of that

I am still thinking about the offroad build (planning is over 50% of a' project you know well plans we have enough of)

I did get around to finding some turbo's, bougth 2, used but ok, KKK k14's for the project, these are used in 5 cyl. 2,5 102hp vw vans here, and they pull great from low rpm's in the vw, so we will see...

the 12h-T engine turned out to be a' mess, cracked liner in 1 cylinder, bad injection pump and shot crank bearing... put it back on the shelf to do some thinking, have talked to a' engine shop about a' rebuild (they have done a' few 12h-T's) not too bad aprox 2000 USD for the rotating bottum (rebuild liner, new bearings, and new pistons) but then I might as well do the injectors, pump, and check the head/valves at the same time.. in all it would be in the area of 4500 USD for a' re-build 12h-T (without the turbo) if I do all the dis-/assembly my self

for now it is on hold

 

[larry butler]

We've got 40's with 529's and it seems bullet proof. 40's on 411 didn't roll.