S3 Transfer case, Help Needed!

[paulthepilot_5]

Found out the other day whilst changing the oil in the transfer case that i need to replace the input gear in the T case, as it had a missing tooth :censored: . The problem is my landy has a 3.6L ISUZU 4bb1 engine and matching IZUSU gearbox joined via an adaptor plate onto the landy T case. The particular gear which has been damaged is neither Landy or IZUSU and has been made as part of the conversion. So i have been trying to track down the company or person that may have produced the adaptor plate and gear for the Gearbox and T case conversion, so that i have a chance of replacing it.

Any Ideas fellow landy owners?

[crossy]

Are you 100% sure it's not a landie gear? sounds strange as it would be heaps easier to mod the shaft to suit the original gear rather than tool up to make a custom gear. PICS of the gear and shaft would be good.

[JDNSW]

Are you 100% sure it's not a landie gear? sounds strange as it would be heaps easier to mod the shaft to suit the original gear rather than tool up to make a custom gear. PICS of the gear and shaft would be good.

yes, or it may be a modified Landrover gear - I imagine the Isuzu engine has a larger diameter shaft, and it could have the centre of the gear remachined to fit. The people who do the high ratio conversion for Series boxes is a likely candidate for someone who could make the gear or modify a standard one.
Someone here should be able to give you their name.
John

[crossy]

it would be a cheapish option to get a series gear broached to fit the isuzu shaft if the shaft is bigger than the major diam of the landie splines. should be around $200 - $300 for anealing, turning, broaching and re-case hardening.

[paulthepilot_5]

the gear in definatly not a modified landy gear, i have already looked into that.

here are some photos of the very unusual layout of the Isuzu output shaft and input gear

photos are taken from the top inspection pannel of the T-Case.

The Isuzu output shaft without gear.
http://img206.imageshack.us/img206/6115/outputshaftlp1.th.jpg (http://img206.imageshack.us/my.php?image=outputshaftlp1.jpg)

The output shaft with gear, spacer, shaft extension, bearing and T case rear cover plate
http://img96.imageshack.us/img96/5719/outputshaftassembledef7.th.jpg (http://img96.imageshack.us/my.php?image=outputshaftassembledef7.jpg)

This is a layout of the gear and output shaft components.

The gear slides onto the spline of the isuzu output shaft, followed by a spacer. A shaft extension is screwed onto the end of the output shaft which locks onto the thread with two grub screws. the rear cover plate of the T-Case has a bearing pressed into it which locates onto the end of the shaft extension when it is mounted on the T-case
http://img208.imageshack.us/img208/2923/outputshaftexpandedlayohh3.th.jpg (http://img208.imageshack.us/my.php?image=outputshaftexpandedlayohh3.jpg)

[JDNSW]

the gear in definatly not a modified landy gear, i have already looked into that.

Looking at your pictures, the damaged gear looks like a modified standard gear - as far as I can see it has had the centre turned out (removing the PTO dog) and a new spline machined to fit the larger shaft on the Isuzu box. It has then had the rear cover modified to take a larger bearing, and the special nut and spacer made to match.

John

[paulthepilot_5]

The diameter of the gear is about 10mm greater than a landy gear, so the gear ratios in the T-Case must have also been changed

[JDNSW]

The diameter of the gear is about 10mm greater than a landy gear, so the gear ratios in the T-Case must have also been changed

Hmmm - interesting! If this is the case, then either the gearbox mainshaft is not in the same position as the original (and the end plate looks as if the shaft is in the original position) or the intermediate gear has been changed or its position moved. This does suggest that a talk to the firm that does the high ratio boxes would be worthwhile, as this is the sort of thing they do, and it is possible they modified that box. Could it be a modification of the standard output (high) gear with the intermediate shaft position moved? (and a standard output gear).

John

[D110V8D]

This link may be of some help if nothing else comes up.:)

http://www.hardmanbros.com.au/

[paulthepilot_5]

Here are some more photos of the T-case

http://img58.imageshack.us/img58/9339/tcasebottomcr4.th.jpg (http://img58.imageshack.us/my.php?image=tcasebottomcr4.jpg)

http://img65.imageshack.us/img65/9835/tcaserearxe3.th.jpg (http://img65.imageshack.us/my.php?image=tcaserearxe3.jpg)

[Killer]

Give Zenith Engineering at Milton a call Ph 3369 4599. They repair Fairey overdrive drive dogs and also distribute Isuzu diesel engines so they may be worth talking to.

Cheers, Mick.

[JDNSW]

Here are some more photos of the T-case


I have had a look at these photos and compared them to a Series T/C, and as far as I can see it looks as if the intermediate shaft is in the original position. This means, that, provided the gearbox centreline is in the same position as the original, and it certainly seems to be from the photos, then if the input gear is not the same size as the original, all three gears must be different - this sounds rather unlikely. Have you actually compared your input gear with a standard one? Can you give me the measured diameter and number of teeth?

John

[paulthepilot_5]

I have had a look at these photos and compared them to a Series T/C, and as far as I can see it looks as if the intermediate shaft is in the original position. This means, that, provided the gearbox centreline is in the same position as the original, and it certainly seems to be from the photos, then if the input gear is not the same size as the original, all three gears must be different - this sounds rather unlikely. Have you actually compared your input gear with a standard one? Can you give me the measured diameter and number of teeth?

John

I have measured the gear, it is 88mm diameter and has 27 teeth, the shaft for the intermediate gear seems to be of a greater diameter than what is shown in the service manual

[JDNSW]

I have measured the gear, it is 88mm diameter and has 27 teeth, the shaft for the intermediate gear seems to be of a greater diameter than what is shown in the service manual

The standard gear is 27 teeth, and I make it 86mm, but that is with a ruler, not calipers. Sounds like a modified standard gear to me - if the gear has the same number of teeth and is meshing with the same intermediate gear (and why would that be changed?) it must be the same gear as far as the teeth and diameter go.
The intermediate shaft changed with gearbox suffix B and your picture looks the same diameter as the one I was comparing it to. It is quite likely that the pictures in the service manual were unchanged.

John

[isuzurover]

The standard gear is 27 teeth, and I make it 86mm, but that is with a ruler, not calipers. Sounds like a modified standard gear to me - if the gear has the same number of teeth and is meshing with the same intermediate gear (and why would that be changed?) it must be the same gear as far as the teeth and diameter go.
The intermediate shaft changed with gearbox suffix B and your picture looks the same diameter as the one I was comparing it to. It is quite likely that the pictures in the service manual were unchanged.

John

I agree with John - T-case has not had the intermediate shaft moved (so isn't a High Ratio t-case), and output gear looks standard. The intermediate gear shaft almost doubled in size when the suffix B was introduced, and the low gears changed in size.

Just track down a 2nd hand output gear the same (not a new one they are very poor quality), then shop around until you can find a shop with a broaching tool that can cut the ISUZU spline in the gear.

Can you measure the major and minor (root) diameter of the spline? It is probably 45o Pressure angle, but could also be 30o

[JDNSW]

I agree with John - T-case has not had the intermediate shaft moved (so isn't a High Ratio t-case), and output gear looks standard. The intermediate gear shaft almost doubled in size when the suffix B was introduced, and the low gears changed in size.

...........

Actually, the change in gear ratio was with suffix C, making suffix B gears useful as you can have both the lower ratio transfer gears and lower ration main gearbox gears by putting the transfer gears in your suffix C or later (including all S3) box.