Question regarding HZJ75 Gearbox (1 Viewer)

[azz419]

Hi there, just joined this forum, very informative. I have recently purchased a cheap HZJ75. One of the reasons I got it so cheap was that the gearbox (H55F) falls out of 5th gear on over-run. (such as taking your foot off the throttle)

When I got the ute, the guy that sold it to me gave me another gearbox he had lying around, It is identical to the currently installed one to all outwards appearances, but I am led to believe that the splines on the input shaft changed between petrol and diesel models, or over the years anyway.

Since this ute is my daily driver, and the gearbox is fine in all other respects, it it easier for me to re-build this other box on the bench at work (Mechanic by trade) and then swap it over, thus reducung the time this vehicle spends immobile.

The vehicle is a 1994 cab-chassis model, and is in Australia if it makes any difference. Any help on this matter would be much appreciated. Thanks!

Azz

 

[roscoFJ73]

Hi there, just joined this forum, very informative. I have recently purchased a cheap HZJ75. One of the reasons I got it so cheap was that the gearbox (H55F) falls out of 5th gear on over-run. (such as taking your foot off the throttle)

When I got the ute, the guy that sold it to me gave me another gearbox he had lying around, It is identical to the currently installed one to all outwards appearances, but I am led to believe that the splines on the input shaft changed between petrol and diesel models, or over the years anyway.

Since this ute is my daily driver, and the gearbox is fine in all other respects, it it easier for me to re-build this other box on the bench at work (Mechanic by trade) and then swap it over, thus reducung the time this vehicle spends immobile.

The vehicle is a 1994 cab-chassis model, and is in Australia if it makes any difference. Any help on this matter would be much appreciated. Thanks!

Azz

Welcome to MUD
The petrol and diesel gearboxes in your model are not interchangeable unless you change the input shaft.
This could be done during the rebuild if you have another 21 spline shaft although the time saved would be minimal.
Not only is the spline count different,the shaft is a different length.

You will also have to do the t/case and probably the clutch and have the flywheel machined

The ones that were interchangeable were the 2H,12HT and 3F gearboxes from 84-90.

Some owners drive round with a bungy cord holding it in 5th.
Jumping out of 5th is often blamed on a history of too much pedal and not enough speed .

 

[Clint79]

Are all 4.2 diesel boxes the same till 99 in the 75's rosco?
What box did the aus 90 to oct 92 3fs use in the 75's

 

[azz419]

Thanks rosco, nice to see a fellow West Australian on here! (I live in Bridgetown down in the south-west) So basically, the input shaft I am after is a 21 spline one, everything else will carry over (including ratios?) If that's all I have to worry about then I should be fine. As a mechanic gearboxes are not exactly my strong point, having only ever done a few basic ones, but I have the factory manual so I don't think I can go wrong. I will strip the transfer case and replace as neccesary while I'm at it, so I have a reliable vehicle.

Azz

 

[roscoFJ73]

Are all 4.2 diesel boxes the same till 99 in the 75's rosco?
What box did the aus 90 to oct 92 3fs use in the 75's

The 75 series all had H55f until 98 when the 78/79 series was released.

The pre 1990 3F and 2H H55f gearbox were the same although they had their own bell housing.
I would say the 92 model 3F would also have the earlier 11 spline (or is it 10 spline) gearbox
These are swappable with 60 series of the same type and year

 

[roscoFJ73]

Thanks rosco, nice to see a fellow West Australian on here! (I live in Bridgetown down in the south-west) So basically, the input shaft I am after is a 21 spline one, everything else will carry over (including ratios?) If that's all I have to worry about then I should be fine. As a mechanic gearboxes are not exactly my strong point, having only ever done a few basic ones, but I have the factory manual so I don't think I can go wrong. I will strip the transfer case and replace as neccesary while I'm at it, so I have a reliable vehicle.

Azz

Nice town Bridgetown
I havent done the input shaft swap but we have had some extensive threads on here and the conclusion was it could be done.
The gearbox ratios are the same ,they vary the t/case ratios on some models but I think the aussie models are all the same after 84.

You can get the input shaft from roodogs4wdspares on ebay TOYOTA LANDCRUISER GEAR BOX MAIN SHAFT - eBay, Other Car Parts, Accessories, Car Parts, Accessories, Cars, Bikes, Boats. (end time 28-Apr-09 12:07:50 AEST)

or 4WDParts in Welshpool

Did you buy that 97 model for $6500 with the yellow sticker in Carine by any chance?

 

[azz419]

You're right, I just had a look at this box, and the input shaft has 11 splines, so that would make sense. Everything else being the same, then theory has it I can buy a new main shaft and rebuild this box to suit.

I got this vehicle from a farm for $5,500, the motor runs well and the frame is straight, body is reasonable with fibreglass windscreen panels and roof, A very slow fixer upper as I have the cash.

I will start stripping this box to see what is wrong with it, Like you said, the swap will involve a new clutch and flywheel skim, rear main seal, and clutch hydraulic cylinders.

 

[Hulsty]

Regarding the input shaft, if its the same length but wrong spline couldnt you use the 11 spline clutch plate or the 11 spline clutch centre in a 1HZ clutch?

 

[roscoFJ73]

I will start stripping this box to see what is wrong with it, Like you said, the swap will involve a new clutch and flywheel skim, rear main seal, and clutch hydraulic cylinders.

Dont forget the spiggot bearing

 

[azz419]

Dont forget the spiggot bearing

Don't worry I won't. Gonne take me a long time to get this machine up to scratch, but it's a good base to build up from.

Attached (should be anyway...) is a pic of the old girl down at "the gap" at Peaceful Bay on the south coast over the easter long weekend.

 

[roscoFJ73]

Don't worry I won't. Gonne take me a long time to get this machine up to scratch, but it's a good base to build up from.

Attached (should be anyway...) is a pic of the old girl down at "the gap" at Peaceful Bay on the south coast over the easter long weekend.

Peaceful Bay sand looks as soft as ever

If thats a steel tray ,ditch it and get an alloy. You'll notice the power and economy improve