Different gearbox behind a 1hz

[Feass]

Hey,

I have a 105 series cruiser with a 1hz in it and im just curious if anyone has put a different gearbox in them? It just seems like its missing 6th on the freeways, i would be curious to know what the options are...

Cheers

[popeyehj60]

the only gearbox ive seen put behind the 1hz would be the h150 out of the turbo diesel 100 series. this is done for the strength factor.

IMO with a NA 1hz you wouldnt be using 6th that much. itd struggle to maintain 100 unless downhill

[old ed]

I also think the hzj75 needs an extra gear. pulling away uphill the 2 to 3 change is a killer. I don't really think it needs a higher overdrive.

[Feass]

Na, ive got a GT2876rs bolted on running 35's... i have no power issues, even when towing. On the freeways doing 110-130 it pulls almost 3000rpm, just be nice to drop into 6th down to 2100rpm or something..

[popeyehj60]

ah k. i didnt know u had a turbo.

maybe have a look around the commercial toyotas. i know some of the coaster buses ran the 1hz. might find a truck that has a 6 speed or something. might have to import from japan

[80's_delirious]

fit 37"s

or change to a higher diff ratio, then fit reduction gears in the transfer to keep low range crawl speed low.

80series had 4.1:1, 105s have 4.3:1 diffs, I notice the difference between my old 80 and my 105, I keep reaching for 6th, which I used to do in the 80 but got used to it.

[1MadEngineer]

NV4500 is a common fit in the US, they have ~0.7:1 OD and either 5.6 or 6.3:1 granny low first

[oldmate]

If you did any amount of towing i'd say leave it. the 1hz, even turboed is a high rever. peak torque is 2200-2400 from memory, it's actually higher on the factory turbo motors.

With 35's and an r15x box you shouldn't have a high reving problem. Are you accounting the speedo error when running 35's? Also going 130kph is going to mean high revs full stop. these trucks weren't really designed to go that fast.

You could drop to 4.1 diffs for a bit more, but you will really be lugging it around town sort of traffic. You'd have to be prepared to run 3rd gear on even slight inclines at 50-60kph

The current model coasters and dynas have a 6 speed box, behind a 15bt motor. Bolting that to a transfer, and the engine, and accounting for the side mounted linkages is probably more hassle than it's worth. Additionally the gear ratios might not work with your diffs and tyre size.

I don't know much about the nv4500, other than it's in US made pickups, and I doubt you'd find an adapter to mate it to a toyota diesel, of which none were ever sold in the US.

[oldmate]

THe other option, which is expensive, but not really any more than a decent gearbox conversion is to get a custom 5th gear made up for the gearbox.

I'd say that is a total waste of time on an R box, but if you were to convert to a H box at the same time it would be more worthwhile.

[Feass]

Interesting responses guys, thanks.

Yeah they are a high rev'er, i dont usually do 130-140 but sometimes you need to when over taking etc.. Yeah, 94kph is 100kph with the allowance of tyre size. I think i might just stay with the box i got i think or eventually upgrade to a better stronger tojo box when this ones gives out. They shoulda wacked a 6th gear in, sometimes its nice when you just cruising with the power of the turbo etc, but im sure they are designed to have a bit of power on the highway when you have a N/A version.

Cheers

[SimonInAustralia]

THe other option, which is expensive, but not really any more than a decent gearbox conversion is to get a custom 5th gear made up for the gearbox.

Don't need custom, there is another box with a compatible 5th gear set that drops straight in to the R151F to give a higher overdrive.

That would give a larger gap between 4th and 5th though, which may or may not be OK.

[1MadEngineer]

I don't know much about the nv4500, other than it's in US made pickups, and I doubt you'd find an adapter to mate it to a toyota diesel, of which none were ever sold in the US.

what like this adapter plate? http://advanceadapters.com/product/2229/712579.html" onclick="window.open(this.href);return false;

[SimonInAustralia]

I don't know much about the nv4500, other than it's in US made pickups, and I doubt you'd find an adapter to mate it to a toyota diesel, of which none were ever sold in the US.

what like this adapter plate? http://advanceadapters.com/product/2229/712579.html" onclick="window.open(this.href);return false;

Does that work on a 1HZ, seeing that it is made for the F-series Toyota engine?

[RV80]

What about an auto?

[old ed]

the nv4500 seems to be mainly to convert 4 speed petrol to 5 speed. what would get my juices moving would be a 6 speed conversion. for my money the standard ratios are a poor selection. the gaps are just too wide.

[Kitika]

the nv4500 seems to be mainly to convert 4 speed petrol to 5 speed. what would get my juices moving would be a 6 speed conversion. for my money the standard ratios are a poor selection. the gaps are just too wide.

If you find all the gears to far spaced you are lacking in power/torque. I coast around town in 3rd everywhere unless i have to come to a stop and first gear on the 1hz h150 box is way to low and I pretty much never use it now i have power. 5th isn't much different from 4th but a 0.70 overdrive should do the trick.

[SimonInAustralia]

I coast around town in 3rd everywhere unless i have to come to a stop and first gear on the 1hz h150 box is way to low and I pretty much never use it now i have power. 5th isn't much different from 4th but a 0.70 overdrive should do the trick.

Is there a way to get a 0.70 overdrive/5th gear in an H150/151?

[Kitika]

I think marks adapters were trialling a bigger overdrive but I think the 5th gear cog is in the centre of the gearbox making it hard to change it's size. You can get an overdriven transfer case that is .92:1 instead of 1:1 which would do the same thing but to all the gears.

[ledgend80]

found this on ih8mud a guy fitted a 6 speed to his 1fz

http://forum.ih8mud.com/80-series-tech/ ... bling.html" onclick="window.open(this.href);return false;

http://forum.ih8mud.com/hardcore-corner ... orion.html" onclick="window.open(this.href);return false;

he has gone to alot of work and did a good job on it

[ferrit]

With a turbo and 35's, its only a matter of time before your hunting down an H150 from a TD100 series to replace an exploded R151, they are a pissweak box.

For what its worth, my TD100 series manual is pulling 2400rpm @ 100kph and 2600rpm @ 110kph on 285/75R16's (GPS speed)

[bj on roids]

Go with a GQ box.

[GO79]

With a turbo and 35's, its only a matter of time before your hunting down an H150 from a TD100 series to replace an exploded R151, they are a pissweak box.

For what its worth, my TD100 series manual is pulling 2400rpm @ 100kph and 2600rpm @ 110kph on 285/75R16's (GPS speed)

and the petrol 80s ,100s, 105s ,75s,78s,79s run the h150 box for a few more search options also to search for if upgrading , but the h150 has a worse over drive than the r151