H150 / H151 manual transmission/ gearbox identification?

[cruisingalong]

Hi all

So I’m looking to see if any if you can help me identify my transmission/ gearbox please

Long story short it’s a 5 speed manual, currently mated to a 1hdt, sat in a BJ74..

Bought it as a project and having spent most of the week sorting the wiring out for the engine, I’m now trying to figure out how to wire up the various sensors & switches on the gearbox.. trouble is I’m not sure what box I have..

M guessing it’s a H150 or a H151 Etc, but without removing the box is there a way to know? Ie an identification number or anything stamped on the box?

Further more what transfer box I’m I likely to have? Full time / part time, sadly I have no idea of the previous vehicle details, I’m in the UK so there’s a strong chance it would be a HDJ80, but I’d like to know for sure.

Any help would be greatly appreciated, thanks

 

[AirheadNut]

It should be fairly easy to identify which series of transmission you have (H55, H15x, R15x) just by looking at it. The H55 is a cast iron case transmission, the H15x and R15x transmissions have ribbed aluminum cases with a cast iron intermediate plate. The H15x is significantly larger with more ribbing than the R15x case. As far as which variant (150 vs 151) I'm not sure how to tell them apart in the vehicle without being able to either drive it or rotate the input shaft. The only major differences between the 150 and 151 are the gear ratios in 1st and 2nd.
Here's an H151f:

And an R150f:

I don't know too much about ID'ing the full time transfer case, but if the transmission is from an HDJ80 then it is likely to be full time. This is my part time transfer case:

And this is the transfer case in a full time HDJ81:

 

[cruisingalong]

 

[cruisingalong]

That’s a great help thank you, so looking at your pics and comparing them to what I have here I’d assume I have a h151 with a full time transfer box?

 

[cruisingalong]

Excuse the state of them, the idea is to get the whole truck built up and working correctly, then take it all apart again and refurb it all.

 

[AirheadNut]

Definitely an H151/150 and it looks like a full time transfer case to me. Impossible to say whether it is a 150 or 151, as far as I know the only differences are internal (1st and 2nd gear ratios).

 

[cruisingalong]

Super thank you.. at a guess it looks like the original box that came with the engine, so Chances are it’s a h151 then I think given that it’s bolted to 1hdt.. either way i’m assuming the reverse switch & sensors etc are pretty similar?

 

[AirheadNut]

I would imagine the switches and sensors are the same between the 150 and 151.

 

[cruisingalong]

Great, thanks

so if this is the case.. what’s your thoughts on the full time transfer box mated to the 74 front axle with hub locks.. in theory if I lock them I’ve got a full time 4x4 similar to an 80, but if i unlock them am I right in thinking the front prop, diff and half shafts will still be driving all the time? Perhaps I’m better finding a part time transfer box? I’m guessing from the factory 70’s where part time 4 wheel drive? Sorry to bombard you with questions just trying to work it all out as I go..

 

[AirheadNut]

If you keep the front hubs locked it will be full time just like an 80, if you unlock the hubs you'll have to lock the center differential to have any drive at all. If finding the correct part time transfer case proves difficult you could install an 80-series part time kit. Or, you could remove the locking hubs, install drive flanges and run with full time 4wd.

 

[coldtaco]

Marks gear in Australia I think makes a coversion to part time

 

[cruisingalong]

Ok great that makes more sense.. thanks

And thank you for the heads up about marks in Australia too, I’ll get the wiring all sorted and then see about getting that conversion kit.. cheers

 

[rick_d]

As the front case does not have provision boss' for 70 series t case lever the transmission is 1990-1992 version which could be H150 or H151 with the poorer synchros. It has the electric motor shift on top of t case which is another clue to 80 series origin. We would have to see rear output housing to see if part time, full time, or viscous clutch (thinnest to thickest rear housings).

 

[cruisingalong]

Thanks Rick,

Nice to hear from you again.. do you mean the rear output of the transfer box or the gearbox?

This is a pic of the rear of the transfer box

I’d seen that the box was missing the 3 lugs you mention and assumed it was the weaker synchro model ( I’ll worry about that later ) let me know if you need any more pics and I’ll do what I can. Thanks

 

[rick_d]

medium rear case, thence a full time.
Measure the aluminum rear shell from output flange to the next aluminum section toward the front.
part time are thin, maybe 3". Viscous are maybe 4" longer than yours.

 

[cruisingalong]

Looks deceiving I know but I promise the end of the tape is in line with the back of the output flange.. making the section in question about 5” if I’ve understood you correctly?

 

[rick_d]

correct. This is a part time case rear section

 

[cruisingalong]

Really helpful thanks, so it’s highly likely then that I’ve got the h151f with a full time transfer box, million dollar question is would you hunt around for the later style 151f with the stronger synchros and a part time transfer box, or just modify the transfer box and upgrade the synchros in this box? Never driven it yet either so I can’t even say if the synchros are good or not?

 

[Vitek]

Finding an 80 series part time transfer in UK and EU can be quite difficult, as 99% of the eu market 80s came with the full time transfers.
Probably its easier/cheaper to get a part time kit, but there is nothing wrong with the full time either...

The synchros can be worn or not. Keep in mind that its a huge box, needs some time to warm up and yet it will never be like a more smooth R series box.
You can try to improve it with synthetic oils.
However, it would be very important to find out the production date of your box if you ever want to rebuild it, as they made changes to the synchros, more details about this is here LINK

" Where 2 parts numbers are listed (the synchro ring sets) the first part number is 08 1992 to 08 1996 and the second part number is 08 1996 onward (manufacture dates) they are not interchangeable, they are physically quite different. "

 

[cruisingalong]

Most helpful thank you.. I had thought about the possibility of keeping it as a full time 4x4, but honestly didn’t know how it would affect the manual hubs at the front..

I’m sure I’ve read somewhere that 70’s never where full time 4wd? There must be a reason for this I’m guessing..?