My R151F needs replacing... H55 or H152? (HZJ78) (1 Viewer)

[Aidan Klimenko]

Hey all,

My modified Troopy's gearbox (r151F) is in need of a rebuild and I need some help determining if I should spend the extra money on a H152 or go with a H55 as a more robust, lasting transmission.

A little background: the truck's original, NA 1HZ has 365,000 km on it , I'm the second owner. First owners ran into transmission issues in Australia at 100,000 km and rebuilt it, and then had the gear box out again and rebuilt with "complete reinforced Australian parts set from desert-tec.de in Germany', as a preemptive measure, in Namibia at 180,000 km. The truck currently weights in at 7400 lbs, which I believe to be only 250 lbs more than it's original weight, pre camper.

Just last week, five years into owning the truck and just off a trip down the South American bit of the Pan-Am, the trans stopped shifting and there's steel bits in our very 'brassy-metalic' looking transmission fluid after only 1000 miles since a fluid change. Syncros are likely shot. Was lucky to have this happen pretty close to a Land Cruiser specific shop (Overland Cruisers) in Bozeman, MT, and for them to be willing to take on a swap to hopefully prevent this from happening yet again.

I'm wondering if the H55--older technology, but as far as I understand, still more robust than the R151f-- is a solid option for a replacement, or if I'd be better off going with the H152. The difference in the quoted prices for the two swaps is significant, and enough for me to hesitate.

Advantages of the H152 are:

• Factory new unit
• Much lower highway cruising rpm (by I think 20-25%?)
• More similar ratios of gears 1 and 2 to the R151, easier to accelerate
• Newer design
• More robust than H55 (?)

Advantages of H55:

• Cheaper
• Can use my current transfer case
• Maybe easier to shift? I've seen this mentioned here and there but don't know the validity.

I have been reading as much about the two as I can but I don't have any hands on experience with either of these so I'm curious if anyone feels strongly one way or the other.

Thanks in advance.

Aidan

 

[coldtaco]

If the H152 fits I would go that way. The H55 shifts like a 80’s school bus, even new ones.

 

[AussieHJCruza]

If the H152 fits I would go that way. The H55 shifts like a 80’s school bus, even new ones.

So does a H15#

The H15# is a much heavier-duty transmission, would go down this path if you can.

 

[Greek Cruiserhead]

Early H55F 5spd boxes are known here in Europe for a weak 5th gear (pops up). Seen in person the problem in France, when I rode a Cruiser lighter than yours, a Soft Top BJ46 of a fiend.
A Swiss friend of mine (Toyota mechanic and 7X40-Series collector) told me at Buschtaxi annual meeting that the H41 4spd boxes are more robust and reliable than the H55F.
Don't get me wrong, my BJ42 has the factory H55F and I love it, but it has been rebuilt from the previous German owner (found a pricey four digit Toyota dealership receipt in the car's papers).

My 2cent is that if Toyota did not fix the problem since, I would seriously consider the H151 box.

PS. It is interesting what some Mudders say about the 5th gear of the H55, when in stress (e.g. #10 and #17 in this thread):

Towing with a 2H

Morning, Anyone done much caravan towing with their 2H? I have a caravan with tare weight of 2300kgs, my HJ75 (1989) has a towing limit of 2500kg. The car struggles up hills as it is, I wandering whether towing a caravan that heavy over a considerable distance will just be too much for the old...

forum.ih8mud.com

 

[Aidan Klimenko]

Early H55F 5spd boxes are known here in Europe for a weak 5th gear (pops up). Seen in person the problem in France, when I rode a Cruiser lighter than yours, a Soft Top BJ46 of a fiend.
A Swiss friend of mine (Toyota mechanic and 7X40-Series collector) told me at Buschtaxi annual meeting that the H41 4spd boxes are more robust and reliable than the H55F.
Don't get me wrong, my BJ42 has the factory H55F and I love it, but it has been rebuilt from the previous German owner (found a pricey four digit Toyota dealership receipt in the car's papers).

My 2cent is that if Toyota did not fix the problem since, I would seriously consider the H151 box.

PS. It is interesting what the Mudders say about the 5th gear of the H55, when in stress (e.g. #10 and #17 in this thread):

Towing with a 2H

Morning, Anyone done much caravan towing with their 2H? I have a caravan with tare weight of 2300kgs, my HJ75 (1989) has a towing limit of 2500kg. The car struggles up hills as it is, I wandering whether towing a caravan that heavy over a considerable distance will just be too much for the old...

forum.ih8mud.com

Interesting. The previous owners of my truck told me the same thing about 5th. They advised me to not even climb hills in 5th (as if the 1HZ had that ability in the first place!).

Ok good insight so far! Thanks.

 

[Kroll]

You’ll have to budget an H1FA tcase if you choose the H152 route. I would also opt for the 300mm flywheel and clutch kit.

I have done over 9000km since swapping my R151 with an H152 behind an 1HDT and I love everything about it. It gets easier to shift after a few thousand km’s on it. Doing 100km/hr my revs are about 2050-2100 with 285/55R16 tires and 4.3 diffs.

 

[Aidan Klimenko]

You’ll have to budget an H1FA tcase if you choose the H152 route. I would also opt for the 300mm flywheel and clutch kit.

I have done over 9000km since swapping my R151 with an H152 behind an 1HDT and I love everything about it. It gets easier to shift after a few thousand km’s on it. Doing 100km/hr my revs are about 2050-2100 with 285/55R16 tires and 4.3 diffs.

This is great to hear. I was curious if the H1FA would bolt onto the H152 or if the H152 required the HF2AV (which would then need to be converted to part time 4wd).

Did you have to swap the input shaft? And where did you source yours? Looks like you’re stateside, like me.

Thanks.

 

[AirheadNut]

One thing to consider when looking at an H152f is that the taller 5th gear might actually be a performance downgrade in a heavy rig with a naturally aspirated 1HZ. It would be worth looking at some gearing calculators and comparing ratios and their resulting cruising rpm, you might be better off with an H150f or H151f.

 

[Greek Cruiserhead]

Interesting. The previous owners of my truck told me the same thing about 5th. They advised me to not even climb hills in 5th (as if the 1HZ had that ability in the first place!).

Ok good insight so far! Thanks.

You're welcome.

 

[rick_d]

33030-6A414
US number for later (2020) R151. You may need a HS7 to order. Cheaper solution and a new version of your old transmission.
You might also ask about 33030-6A413 if easier to find.

 

[Aidan Klimenko]

One thing to consider when looking at an H152f is that the taller 5th gear might actually be a performance downgrade in a heavy rig with a naturally aspirated 1HZ. It would be worth looking at some gearing calculators and comparing ratios and their resulting cruising rpm, you might be better off with an H150f or H151f.

This is a good point. Anyone out there with a 1HZ and a H152 (or H151 with aftermarket taller 5th) who can share some experience?

 

[Aidan Klimenko]

33030-6A414
US number for later (2020) R151. You may need a HS7 to order. Cheaper solution and a new version of your old transmission.
You might also ask about 33030-6A413 if easier to find.

Thanks for this. Good to have if I choose to stick with the R. Guessing the modern R isn’t much stronger than a 2001?

 

[rick_d]

So you won't trust a new $1,900 R151 drop in for 150,000 miles? The truck has 225,000 miles so the tcase and ps etc are all getting wear.

To pursue a H15x transplant you are well over $3,500 because you need the tcase as well (no mating your t case to that transmission)

And the later transmissions (R series) are improved over the 20 and 30 year old variety.

 

[Aidan Klimenko]

So you won't trust a new $1,900 R151 drop in for 150,000 miles? The truck has 225,000 miles so the tcase and ps etc are all getting wear.

To pursue a H15x transplant you are well over $3,500 because you need the tcase as well (no mating your t case to that transmission)

An the later transmissions (R series) are improved over the 20 and 30 year old variety.

This is what I’m here to find out. All I know is the previous owners needed to rebuild the original R151 at 60,000 miles (as noted above). I’m simply here asking about options for extending that lifespan and mitigating the risk of finding myself down some remote road somewhere with a broken transmission and no $1900 R151s lying around, kicking myself for not having spent a bit more to upgrade to a stronger box.

Kind of a “don’t make the same mistake three times” situation.

If there’s a way to avoid that without spending an arm and a leg, I’d love to explore that option!

 

[OGBeno]

The R series transmission behind a 1HZ is fine. It is not going to leave you stranded. Trust me. There are literally hundreds of thousands of 70 series trucks with this pairing. You are going to be fine with this transmission going to the Starbucks.

Do what @rick_d recommended. He's been around the block a few times with the 70 series platform. He won't give you bad advice.

There is one R151F in Toyota's depot chain currently.

 

[Aidan Klimenko]

The R series transmission behind a 1HZ is fine. It is not going to leave you stranded. Trust me. There are literally hundreds of thousands of 70 series trucks with this pairing. You are going to be fine with this transmission going to the Starbucks.

Do what @rick_d recommended. He's been around the block a few times with the 70 series platform. He won't give you bad advice.

There is one R151F in Toyota's depot chain currently.

Wow. Going to the starbucks? Trying not to take that as a dig. Thought this was supposed to be a supportive community! and from a moderator…

The R has failed twice under the previous owners, and once with me. I thought that’d validate looking for a stronger option.

 

[Rigster]

This is what I’m here to find out. All I know is the previous owners needed to rebuild the original R151 at 60,000 miles (as noted above). I’m simply here asking about options for extending that lifespan and mitigating the risk of finding myself down some remote road somewhere with a broken transmission and no $1900 R151s lying around, kicking myself for not having spent a bit more to upgrade to a stronger box.

Kind of a “don’t make the same mistake three times” situation.

If there’s a way to avoid that without spending an arm and a leg, I’d love to explore that option!

Do you have the history/receipts of the rebuild? There are "fixes/rebuild kits" that address the weaker points in these transmissions.

What was the previous owners' driving habits? What were the circumstances when the transmission failed? I have an R151 behind a 1HZ with a turbo and I pull a trailer from time to time. I had to upgrade the clutch to a HD one. When off-road and when towing, I drive it reasonably, understanding that I am putting additional strain on the drive train. To date, my R151 has been smooth and flawless. To be clear, I do not "baby it", but avoid sudden jarring movements, and make sure I am shifting/clutching smoothly.

If money is not a huge factor in the equation, then upgrading to an H152 would be something I would consider for your own peace of mind, but it really depends on use case, your driving habits, and what you plan to use the cruiser for. All the best in your decision!

 

[Aidan Klimenko]

Do you have the history/receipts of the rebuild? There are "fixes/rebuild kits" that address the weaker points in these transmissions.

What was the previous owners' driving habits? What were the circumstances when the transmission failed? I have an R151 behind a 1HZ with a turbo and I pull a trailer from time to time. I had to upgrade the clutch to a HD one. When off-road and when towing, I drive it reasonably, understanding that I am putting additional strain on the drive train. To date, my R151 has been smooth and flawless. To be clear, I do not "baby it", but avoid sudden jarring movements, and make sure I am shifting/clutching smoothly.

If money is not a huge factor in the equation, then upgrading to an H152 would be something I would consider for your own peace of mind, but it really depends on use case, your driving habits, and what you plan to use the cruiser for. All the best in your decision!

Thanks man! Glad the R is working for you.

I have documentation from the previous owners. The first time they had it out (100,000 Km) they replaced it with a new R151f, and the second time (180,000 Km) they had it rebuilt with one of the reinforcing kits you mentioned.

They were very meticulous owners who drove conservatively, but not without some adventure. They took the truck around the world (fun photos of their adventures posted here), but were very careful about not pushing the engine/transmission. I think that blowing up the gear box in Australia that first time made them nervous. When they sold it to me they we're adamant about not pushing it, which I tried not to.

But I'd love something that I can beat up!

 

[renago]

I had a 78 with HZ1 turbo with standard R151 gearbox , with problem after 110 k km .
Changed it for a H150 , slow shifting , but much more robust.
You will need to regear THE diff , as THE final ratio is different .
I would go with the R150 , especially with an Overland vehicle .just my 2 cents

 

[Aidan Klimenko]

I had a 78 with HZ1 turbo with standard R151 gearbox , with problem after 110 k km .
Changed it for a H150 , slow shifting , but much more robust.
You will need to regear THE diff , as THE final ratio is different .
I would go with the R150 , especially with an Overland vehicle .just my 2 cents

Thanks for the input @renago. Just to clarify, you would go with the R150 despite having had those issues? Or did you mean H150?