S3 Transfer case, Help Needed!

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.

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Originally Posted by paulthepilot_5

Here are some more photos of the T-case

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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

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Originally Posted by JDNSW

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

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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

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Originally Posted by paulthepilot_5

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

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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

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Originally Posted by JDNSW

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

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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

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Originally Posted by isuzurover

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.

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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.