1HDT into a BJ70 (4 Viewers)

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Jan 15, 2011
Hello everyone. Long time since I posted something here.

The story is that i might finally get a complete dissasembled hdj80 for my project.
The idea is to get the 1hd-t into my bj70.
I friend of mine got an 1hz on a 75, so I definitely know that mounting the motor on the bay is very easy (plus a lot of information about 1hz onto bj75 on the web, but not a single bj70 to 1hdt info i could find).

My main concern is what to do with the tranny, since i read different oppinions.

One alternative is to mantain my h55 and get an 1hz bellhouse and source other parts in order to adapt the 1hdt to the h55 (there is quite a lot of information for this)

The other alternative is to put the h151 from the 80 onto my rig

At the moment I like more the idea to use the 80´ h151. The main reasin is that I dont have to source the part to adapt the 1hdt to the h55, and we all know that the h151 can manage the 160 hp of the 1hdt. Cons for this alternative is that, since the gearbox+transfer is longer than the h55, the angles of the ujoint from the rear driveshaft will be high (remember than de BJ70 is the shortest of the 70 series). I might solve this using double ujoints.

The other alternative (mantaing the h55) has the advantage that I dont have to modifiy anything in the driveshaftn (neither front nor rear one). The cons is, firts I have to source everything in order to make the 1hdt to match the h55, which here in Argentina might get tricky. The other thing that worries me most is that I read some time ago in pirates4x4 people saying that the H55 could not handle the 160HP from a 1hdt (which make sence since h55 was used at max with the 130hp 1hz motor).

So this is my dilema right now.

Any imput or information would be very appreciated!
the h151 is a big transmission and fitting under the tub of a 1980's truck may be a bit difficult. Crossmember will not work, and drivelines are least of problems.

A good friend has run a h55 behind a HDT since 1996, so all the lies you have heard about the transmission being sub standard is BS (I ran one for 8 years without issue). The H55 is easier fit, but without knowing production date of truck we cannot tell if the transmission will accept the correct input shaft for the HZ/HDT.

BUY the factory weld on engine mounts to make the placement easy.

Electrically there is little to do.

should be pretty easy. in 2005/6 I put a hdt in JDM 74 series. I have since changed from RHD to LHD so a bit different truck.
I have a 1HD-FT with matching H151 and fulltime transfer case. The way I have it mounted the transmission mount ended up about 1" off of the stock crossmember holes. If I had paid better attention I probably could have fit the transmission mount in the original crossmember holes. Oh well. I did have to clearance the seam under the floor to allow the transmission to come up to about 1" below the floor. I also bought the factory HD engine mounts to weld on.
Coldtaco and original poster.
Note the arrows as center of mounts to transmission crossmember. The 79 series rubber mount for h151 is offset 1" forward compared to an 80 series rubber mount. For reference, the H55 extension housing is 4".

To place a H151 on a H55 crossmember would put the engine fan blade forward of the radiator support.



....and finally, 1HDT is here!!!
After several month of solving some issues with the "donnor´s documentation", yesterday I was able to get this completely disassambled 80. So that´s why I reactivating this post.

Based on Rick_d comments and other oppinons I´ve read though the web, i think I will mantain the h55 gearbox. The h151 is not only larger that the h55, but the reat output is almos on the centerline, while the 70 rear diff is pretty to the right side. So if I decide to use the H151, driveshaft´s Ujoints will be not only suffering from a high angle on the vertical plane, but also on the horizontal plane as well (once again, this is a BJ70, the 2nd shortest Land Cruiser ever build!!!!)

On the other side, I think there is much less work to be done in mating the h55 to the 1hdt. I´m planning to mantain the 1hdt bellouse and build a adapter plate between the bellhouse and the gearbox (I know that there are 1hz bellhouse tha I could use, but its imposibble to source them here in Argentina) , plus modifying the gearbox imput shaft so I can use the hole 1hdt clutch on it (the h55 is the original gearbox of an 1986 deluxe BJ70 which I used to have). I´ll take the 80 motor mounings and just weld them on the 70 chasis. I´m planning also to use almos all of the mechanic of the 80, that´ AC compressor, hydraulic pump, AC radiator, Main radiator, etc. etc.
I will mantain my axels (I have ARB on both) and the coil spring system, dont want to mess with it and I´m really happy how ther work (again, OME suspension kit fitted!).

So, once again, any suggestion will be REALLY appreciated.

Thanks and I´ll keep posting pics when I start the work (I thing 1 or 2 month from today)
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Subscribed! When you are done, you will be able to pass traffic going uphill!! Great idea, good luck
getting it all done. J
80 series has different motor mount.
You'll need an authentic 70 series motor mount in order to stand straight.
Your motor should tilt left for 80 series mount.
That's a great pic ,it should be in the "artistic cruiser thread pics in chat
I don't see any issue with the H55F handling the 1HD-T power even if heavily modified ( H55F in good shape ) .. another reason I like the H55F it's the BF1A behind it, it's much more simple and have more aftermarket of lower gears ..
Yup, not only I´ll be able to do that, but in sand it will be much fun!
I dindt get that abour the motor mount. Planning to take them out from 80 an weld them on the 70 untill the motor gets perfect aligment
Regardin the tcase, this tlc once had the H42 with 2.296 low ratio tcase. I`ve swap only the gbox from an deluxe tlc, wihch has a 4.843 1st gear (but i kept my old tcase). Doing some math I get that my 1stLo will be 10% shorter and the 5thHi will be the same compareing to an 80. Looks like a good start!

I´ve got that place filmed with a drone over here!
The "narrow" one, 4x4 in Argentina

Thanks for comments & info!!!
Ok, as we say here in Argentina.... we are now dancing!!!!
We loaded the 1hdt and took it to where the bj70 stands.
I finally decided to mantain my h55 gearbox. The h151 required not only to rebuild the axles but also a major body trim in order to fit it (i´ts much higher than the h55, and the BJ doesn´t have a center tunnel.
The h151 bellhouse (which is the one i will use together with the 1hdt 300 mm cluch) is 21 mm shorter, so the adaptor wi supply this difference




So, in order to build the adaptor plate, we needed to have the axle center of both gearbox. By removing the front covere of each gearbox, a big bearing was exposed which was perfect since it´s almos on the same plane that the gearbox strud holes (we really used the seger on the bearing). H151 seger was 131 mm, h55 seger 97 mm. So we cutted on a acrylic the biggest hole and I printes on my 3d printer the smaller hole in order to fit on the acrylic big hole. In this way we could center the acrtylic, mark the strud holes on one gearbox, and after that repeat the same with the other gearbox.





Forgot to post here the 1hdt 300 mm clutch disk with the h55 center already modified....

Ok, so the adaptor plate is ready. Fitted like a glove! In this pic the 1hdt bellhouse monted on the h55 gearbox. 3b motor mounts have already been removed.
I wanstn´ going to, but finally a friend convinced me to paint the engine bay, so I started to sand some old rust on the left side (probably caused either by an old battery explosion, or something to do with the original breaking pump.... who knows....).




Well guys, sorry for the delay. Lots of things happened during this months....
But what i wanted to share with you, is the most important thing.
As I told on a prevous post, I bought this motor which has been stored for more than 10 years. And although I took all the possible precautions (I even got it spin with an electric motor for 1 hour in order to "clean" all the oil galleries, cleaned injection pump and injectors, revised oil inlet and many other things), yesterday was de F day:

This video shows the engine star up, aftere 10 years.
I´m as happy as it can be!!!!

Ony a few days left in order to finish this transformation!

Hi Pablo
I want to do a conversion almost exactly the oppersite to you, but it looks as if you adaptor plate would work with very few modifications

Here is my story:
I want to fit a 12HT engine into a FZJ 80, keeping the H151 gearbox from the 80 (I like full time 4x4). No adaptor plates exist for this conversion and I believe that the best option would be to keep the 12HT clutch and bell housing and fit an adaptor between this bell housing and the H151 gearbox. Now tell me if you agree, but you plate should do this job IF :

The H151 shaft is long enough, and the 12HT bellhousing short enough for the adaptor plate thickness. I know that the H55F gearbox used for the 12HT ( and F) engines have shorter input shafts .

Unfortunately I only have the engine at this stage, so its a little difficult working thing out.

If you still have the H151 gearbox, could you please measure the length of input shaft from the tip to the face of the gearbox ( where the bell housing bolts up to?
Would your template be available for me to use if i want to carry on with this conversion?


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