12ht to 80 gearbox

[stockhorse]

Has any body done or have any information on mating a 12ht to an 80 series auto?

[tobie]

There was a fella about who put a 12ht in his 75x, did a smart job, he mated a h150 to the 12 ht.
Do a search and see of u can find it

[Ice]

why not use the a440 ?

[stockhorse]

I am currently running the stock a440f. the 440 can only have tc lock up in 4th (standard) and 3rd and 4th (wholesale auto mod). the 440 runs a lock up torque convertor. The 442 can have torque convertor lockup in all gears and it is controlled through the valve body. A modification kit (wholesale autos) allows this to be done automatically or manually. Having manual control over lockup and being able to use it in all gears would greatly assist engine braking on step decents and take the load off the braking system and give better control.

[RED60]

I am currently running the stock a440f. the 440 can only have tc lock up in 4th (standard) and 3rd and 4th (wholesale auto mod). the 440 runs a lock up torque convertor. The 442 can have torque convertor lockup in all gears and it is controlled through the valve body. A modification kit (wholesale autos) allows this to be done automatically or manually. Having manual control over lockup and being able to use it in all gears would greatly assist engine braking on step decents and take the load off the braking system and give better control.

Is the 442 that can have lockup in all gears the solenoid type or the hydro type..... certainly would be a handy addition.....

[Gaza520]

The a440f will marry straight up to the 2h,12ht,1hz,2f petrol and also the 3f petrol I have done this conversion several times and the a440f is a wickedly strong box I am using one in my winch truck behind a 5ltr injected v8 with no dramas at all,

[RED60]

The a440f will marry straight up to the 2h,12ht,1hz,2f petrol and also the 3f petrol I have done this conversion several times and the a440f is a wickedly strong box I am using one in my winch truck behind a 5ltr injected v8 with no dramas at all,

My understanding on the a440f is, while the box itself may be strong the torque converter isn't a particularly good design and suffers badly from overheating if asked to work hard under load (ie soft sand/heavy tow) not locked up..... this heat is passed on via the atf to the clutch packs and this heat causes their premature failure or at least cooks the atf which does the gearbox no good either......

520, do you run a huge cooler and what mods, if any, have you had done to the box/converter behind the 5ltr....

[Gaza520]

Torque coverter has been done to suit the work car does and I run a big oil cooler in front of radiator other than that box is standard

[stockhorse]

Yes Gaza the a440f is a straight match, the 12ht came from the factory with it. The a442 is solonoid type , thus the switchable lock up.
According to wholesale auto I would need another transfercase (not sure why) that they have available new for $2k then a differnt input shaft etc etc etc and a rough cost would be $7k for a complete unit.
They actually suggested a set of reduction gears would do the job for the downhill work and that would run to $3k fitted
The torque convertor does seem to be the weak point as it is the clutch (not sure that is the right name for it) in the torque convertor wears and doesn;t lock up properly and this causes the overheating problems.

[Gaza520]

For down hill braking I used 5.29 diff Gearsets and that also gives me a very fast take off and take a lot of load off trans cost $500 for both sets now I can play in rocks and race it doesn't get hot at the end of the day and money is no problem you have a lot of options available but you can get the results you want for a fraction of the cost . Just look at the final drive eg diffrratio

[stockhorse]

Gaza , who do you use for your convertor mods please.?

[RED60]

Stockhorse... do you actually HAVE a lockup in all gears 442 or have you just enquired/read about them....

Some 442s were hydraulic as well, same as the 440s....

[stockhorse]

Hi red, yes the early 442 where hydraulic, the later ones conrolled by solonoids. You would need the later 442 box. I have driven an 80 with this system http://www.automatictransmission.com.au ... wsId=41076" onclick="window.open(this.href);return false; and it was terrific to drive giving lots more control in steep downhill situations.