Hj61 hf55 Vs Hj60 hf55

[BushBen]

I have a 12ht with a manual tranmission behind it and I also have a 2h with a manual tranmissinon behind it.
The 2h is in my hj47 and I had a 5 speed from a 60 put into it. I did this because at 100kph the 4 speed did 3000 rpm however in my hj61 at 100 kph it was only doing 2100.
On test driving my hj47 with the new 5 speed I was a little sad to find that at 100 ks the engine was doing 2400 not 2100 as I had expected.
On almost every forum I have read including this one everyone says that all h55f transmissions are geared the same. I dont believe it. I think that the ones put into hj61s were geared higher.
At first I thought it was due to tyre size differences or diff ratios but the speedo and tacho have no idea what diffs or tyres are attached to it so that makes no difference except to actual road speed.
I just want to know if anyone else agrees with me or not.

[skootin]

There is no difference in the 5spd gearing. Yes the tyre size or diff ratio will have an effect on the speedo and therfore the tacho.
2100 does seem very low for 100kph unless you had a very tall tyre or your speedo had issues. Pretty sure my 80ser sits on 2400 @ 100kph.

[RED60]

I just want to know if anyone else agrees with me or not.

Well you know I don't............... but prove me wrong and I'll gladly eat a big slice of humble pie...

[hulsty]

They are all the same ratio, the transfer case may have been played with and have different gears in it, the diffs are different or the tyres are different.

2400rpm sounds about right for a H55F with stock ratios, 4.11 diffs and 32'' ish tyres.

I run at 2100rpm with stock gears and 35'' tyres are 100km/h

[BushBen]

I know you dont buy it red60 but Id love to prove you wrong.
I know everyone says diffs and tyres will affect it but I dont see how. Sure it will affect "actual" road speed but it wont change the relationship betwen the speedo and the tacho.
For example: If i was to put the truck up on blocks with all 4 wheels off the ground and started it up and got it up to 100kph in my garage then my tacho would show 2100 if I then swapped the 4.1 diffs for 3.7s and put 35s on instead of 31s and repeated the experiment at 100kph the tacho would still show 2100. The wheels however would spin at a diffeent rate.
This is because the tacho comes off the bell housing and the speedo comes off the uotput shaft on the gearbox both of which are before the diffs and tyres.
I agree that someone could have altered the gearing ratios in the transfer case. Today I got it up to 100kph in 4th gear and it was doing 2600. My other 5speed does 3000 at the same speed (I think) just like my old 4 speed did. That indicates to me that its all the gears that are slightly higher not just 5th. So the transfer could be responsible for that. I wont know unless I open it up. Ive never heard of different gearing kits for tranfer cases.

I was kind of hoping there would be someone out there with a hj61 who could tell me if their truck does the same as mine. Anyone?

[RED60]

Don't get me wrong BB, I'd actually be happy for you to be right... I always want more gearing and this would be a good way to get it... I just don't think you are... sorry man... I'll try to keep myself out of this thread but will keep watching it... good luck...

[hulsty]

easy to check transfer gearing, pop the PTO plate and count the teeth and compare to other ones, I run a HJ61 transfer in my car, high range is 1:1 ratio low range is ~2.3:1 ratio (transfer is from a auto HJ61)

[skootin]

When you put your truck up on blocks at do this test can you video it for us.
Your spot on with the tacho on the bellhousing and the speedo driven off the output shaft. When the vehicle is up on blocks your not going to prove anything - cause the truck isn't MOVING at 100kph and how do you know that your actually travelling at 100kph when you are driving. Grab a GPS or an iphone with a speedo app do yourself a favour and find out exactly what speed your doing at what rev's. Then search for a tyre speed calculator work out your exact rolling diameter of your tyres and figure it out.

For example: If i was to put the truck up on blocks with all 4 wheels off the ground and started it up and got it up to 100kph in my garage then my tacho would show 2100 if I then swapped the 4.1 diffs for 3.7s and put 35s on instead of 31s and repeated the experiment at 100kph the tacho would still show 2100. The wheels however would spin at a diffeent rate.
The wheels spinning at a different rate is going to determine your actual speed. Or am i having a blond moment.

[macneil]

i diferent diff ratio is going to make the wheels spin at different speeds?? think about it 1:1 to 1:2 it spins twice as fast... really not that hard to comprehend...

[MQfishbucket]

If the 61 came stock with different diff ratios or transfer gears then this will be factored into it's speedo.

I believe the 12HT factory gearing is taller to allow lower highway revs due to the greater torque of the turbo motor.

HTH

[BushBen]

Thanks MQ. Im glad Ive found someone who agrees with me. It is logical isnt it. Why would you turbo a 2h and leave the gear ratios the same. The extra torque created should translate into a fuel saving by haveing lower revs at the same speed. I have not found any proof yet however. Im waiting for another hj61driver to confirm that at 100kph he is/she is doing 2100 rpm too. Anyone?

[hulsty]

Thanks MQ. Im glad Ive found someone who agrees with me. It is logical isnt it. Why would you turbo a 2h and leave the gear ratios the same. The extra torque created should translate into a fuel saving by haveing lower revs at the same speed. I have not found any proof yet however. Im waiting for another hj61driver to confirm that at 100kph he is/she is doing 2100 rpm too. Anyone?

It may be logical but your both wrong, from the factory on Australian spec cars the gearing is all the same.

If you have a import the diff gearing may be 3.73. I suggest you start getting some hard facts and measure things to figure out where your gearing difference comes from. Probably the 12HT is either an import or has the diffs changed, what does the compliance plate say for the diffs? K084 ?

[MQfishbucket]

Thanks MQ. Im glad Ive found someone who agrees with me. It is logical isnt it. Why would you turbo a 2h and leave the gear ratios the same. The extra torque created should translate into a fuel saving by haveing lower revs at the same speed. I have not found any proof yet however. Im waiting for another hj61driver to confirm that at 100kph he is/she is doing 2100 rpm too. Anyone?

It may be logical but your both wrong, from the factory on Australian spec cars the gearing is all the same.

If you have a import the diff gearing may be 3.73. I suggest you start getting some hard facts and measure things to figure out where your gearing difference comes from. Probably the 12HT is either an import or has the diffs changed, what does the compliance plate say for the diffs? K084 ?

I have no experience with 61s, or any idea how many of the ones in australia are imports.

I know my HJ47 with 4spd does 3000 at 100. I know my mate's HJ60 with 5spd does 2400 at 100. If your HJ47 does 2400 at 100 with a 60 5spd she's probably right.

I know all the stuff I've read on the net (armchair expert) says HJ61s do 2100 at 100, so I would assume taller diff gearing. You may be right about australian spec ones having 4.11s, but that would be silly given nearly double the torque.

Someone above said the auto HJ61 has different transfer gears, so to say they're all the same must be an oversimplification.

[harlequin]

Wish i had a hj61 to be able to tell you, but my 5 speed 60 on factory slits does 100km/hr on the speedo @ 2200-2300 but by the gps it is 95km/hr

[RockyF75]

Just came back from a trip and I took notice of my speeds/revs - HJ60, 5spd, 100kph indicated on speedo - looks like 2400-2500. But I have 33"s so this is actually around 110kph actual speed.

Like you said, your tacho/speedo doesn't know what tyres/diffs your running, which means your indicated speed (which wont be correct unless everything is standard) and indicated revs should be the same regardless of what ratios/tyres your running.

So if HJ61's came out with taller gearing, due to a tourqey-er motor, the tacho and speed would have to also be different, to account for this. Other wise the indicated speed/revs would be wrong.

[matts_gemmy]

all these gearbox are all the same gearing nothing changed the gearing in the transfers changed when the went to the vacum 4wd but comes out the same as the changed the LA shaft size from 36mm to the 38mm but ends up come out the same so

[PFJ]

My HJ61 at indicated 100kph reads 2350rpm in 5th. 4.1:1.
Actual is about 102kph using sat nav on level ground with 50% 33s. Not bad given the crude mechanical speedo & tacho which are probably a bit worn too.

Dunc.

[bad_religion_au]

If you have a import the diff gearing may be 3.73. I suggest you start getting some hard facts and measure things to figure out where your gearing difference comes from. Probably the 12HT is either an import or has the diffs changed, what does the compliance plate say for the diffs? K084 ?

This. if factory diffs are 3.7's because it's an import, speedo/ drive gear will be different to compensate.

even if your thought of more torque = lower the gearing (numerically) to take advantage of it, are they going to redesign all the gears in the gearbox, or just throw a different (already existing in their parts catalogue) diff ratio into the thing? smart money = diff ratio.

oh, and another question, do we know the hj60 speedo drive is compatible with the 47's speedo? that could be an alternate source of error.

[80's_delirious]

My money is on a mismatched speedo drive gear in the transfer case.

All 'std' diff ratios may have been the same, but what's to say someone didn't order a car from the factory with different ratios in the diff?

[SCANAS]

My money is on a mismatched speedo drive gear in the transfer case.

X2

Or it's had a speedo correction put in.

On mine 4.11's and stock gearing

With 32's at 100 indicated it's 2400-2500 rpm (maxxis bighorns so small 32s)
With 35's at 100 indicated it's 2100-2200 rpm

And I'm not sure how safe it would be to run a 60 up to 100ks on blocks


EDIT:

2400rpm sounds about right for a H55F with stock ratios, 4.11 diffs and 32'' ish tyres.

I run at 2100rpm with stock gears and 35'' tyres are 100km/h

Hulsty agrees!!

[dexter09]

12ht- 2h all the same box and transfer ratios and all 4.1:1 diff ratios. no difference, tyres affect what they call your "final" drive ratio, the bigger the tyre the taller all the gears become, with actual road speed, it also dramatically impacts your torque my 2h sixty sits on 2600 at 100 with 31's on and 2200 at 100 with 35s on done with a gps. not rocket science really. increase of outside rolling diameter= more distance travelled per revolution of axle. also your revs dont govern how much diesel you use, your foot does, for instance going down a hill and sitting on 2500 but decompressing is going to use alot less fuel then going up a hill with the foot flat to the floor just to stay at the same revs, im pretty sure, dont quote me on this but there should be two vaccum hoses on the top of your injector pump that govern fuel mixture depending on the vaccuum build up from opening the throttle, there should be one before and one after your inlet manifold butterfly.

just to add another varient, lol revs dosnt set fuel amount being used
foot does.
the 12ht is naturally more efficient because it is direct injection, not indirect like the 2H.
because it injects the diesel at just about top dead centre of the compression stroke it dosnt even require glow plugs, you just have a heating element, and it can get away with not using so much because it atomises alot better under compression when it is injected direct into compression unlike a 2h where it is injected as a controlled mist but still a liquid untill the piston rises to compress and atomise it.