Gearbox change !!

[chompyd]

Problem .... Changed 3F to 1HZ in my 70 series my problem is that i have rock crawlers in my transfer case and the input shaft on the gearbox is 20 mill to short to get to the spricket bearing, so is there another box that will bolt onto my transfer case and to the 1hz ?

[beanz2]

I'm not sure I understand. You are using a gearbox that was mated to the 1HZ and are trying to fit it to your FJ70 transfer case? Did you run into the problem when you tried to fit the input gear from your crawler gears over the input shaft?

If the gearbox was mated to a 1HZ, it will be Jan 1990 or newer. In May 1991, I believe (dumbdunce may know the exact date) the gearbox output shaft on the H55f changed. Toyota made the splines shorter such that an O-ring can be fitted inside the input gear to combat oil leaking problems between the transfer and the gearbox. If you try to fit an older input gear over the newer gearbox output shaft, the gear will not slide into position.

If you are using the gearbox from the FJ70, the 1HZ bellhousing would fit, but the gearbox input shaft would be too short to properly engage the pilot bearing. Swift60 here has successfully mated his to the similar 1HDT by inserting his pilot bearing partially into the flywheel.

Dave

[dumbdunce]

quick60 off this board solved this problem by leaving the spigot bearing half hanging out of the crankshaft, to just engage the tip of the input shaft.

alternatively, if there is more than 3 - 4mm clearance between the end of the shaft at the face of the bearing, it would be about 15 minutes work for a machinist to manufacture a shaft extension for you. there's no need to change the box.

[Ruggers]

when i put my 1hz into my 73 i had to get 15mm taken of the bellhousing 10 from the engine side and 5 from the box end have no problems with this set up

[beanz2]

when i put my 1hz into my 73 i had to get 15mm taken of the bellhousing 10 from the engine side and 5 from the box end have no problems with this set up

Ruggers, are these dimensions for a BJ73 gearbox or for a 3F/2H gearbox?

Dave

[beanz2]

quick60 off this board solved this problem by leaving the spigot bearing half hanging out of the crankshaft, to just engage the tip of the input shaft.

Ooops, I meant quick60

Dave

[chompyd]

Ok so you guys do understand what i'm on about ... cool ..... ok so i am about 20 mill short so, i dont think pulling spigot bearing out will give me enough , so i think getting a shaft extension would probably fix my problem . My ex girlfriend would probably agree !
Cheers for the help ppl Whoo Hoo !! Rock crawler box here we come!

[80UTE]

Machine the bell housing there's 15mm difference between the two boxes, have done this heaps of times converting early boxes to 1HZ's.


Wally

[beanz2]

Machine the bell housing there's 15mm difference between the two boxes, have done this heaps of times converting early boxes to 1HZ's.


Wally

Is there enough metal in the bellhousing lip if I have 15mm taken off?

What is the largest 10 spline clutch disc that suits the 2H/3F gearbox? People are saying the factory 275 mm discs in 1HZ cruisers can't take a turbo very long.

Dave

[80UTE]

Machine the bell housing there's 15mm difference between the two boxes, have done this heaps of times converting early boxes to 1HZ's.


Wally

Is there enough metal in the bellhousing lip if I have 15mm taken off?

What is the largest 10 spline clutch disc that suits the 2H/3F gearbox? People are saying the factory 275 mm discs in 1HZ cruisers can't take a turbo very long.

Dave

10mm from the engine side and 5mm from the gearbox side.

There plenty of 11" clutches available for turbo 1HZ's or a custom 12" 10 spline disc to suit the factory turbo 12 flywheel.

wally

[beanz2]

Thanks for that, 80UTE. For the cost of machine work, would it be cheaper to make an extension instead?

Can anybody make a 15mm input shaft extension? I'd be interested in getting one made.

Dave

[chompyd]

Can anybody make a 15mm input shaft extension? I'd be interested in getting one made.

Dave

Dave I'm looking into it today shouldn't be to hard get a 40 mill piece of stainless rod put on lathe take one side sown to 15 mill and a wee bit more to make it a tight fit and then drill out the other side to almost 15 mill to make that side a tight fit . 20 mill long on imput shaft side and 20 mill long on spicket bearing side . should i order two ?

[80UTE]

What you need to concider is that the clutch disc hub spline will be 15mm further forward that it would normally be on the gear box input shaft and i would estimate it would be only half of the spline engaginging and this is not good. All the conversion kits that utilise input extenstion shafts, extend the shaft a significant amount >75mm and the clutch disc drives on the shaft extension.

Wally

[beanz2]

Dave I'm looking into it today shouldn't be to hard get a 40 mill piece of stainless rod put on lathe take one side sown to 15 mill and a wee bit more to make it a tight fit and then drill out the other side to almost 15 mill to make that side a tight fit . 20 mill long on imput shaft side and 20 mill long on spicket bearing side . should i order two ?

Yes, please. I'll be happy to reimburse you for the costs

80UTE brings up a good point. I wish I have a 3F/2H gearbox and a 1HZ bellhousing to see if clutch spline engagement indeed would be marginal if an adapter is used. How thick is the splined hub on the disc?

Dave