Flint differential question

[aussiecowboy]

There is a bad oil leak between the pinion section and the rest of the split housing. I've never worked with this type of axle before and I'm wondering if I can simply undo the 4 bolts and remove the pinion section to make a new gasket or will that mess up all the clearances? It runs smooth and quiet at the moment and I don't want to ruin that. 

[dictator27]

Do you know what the rear axle ratio is? If the pinion and ring gear both have an even number of teeth ie.  10 on the pinion and 36 on the ring gear, this would be a non hunting rear axle. They have 2 as a common factor. It would have to be timed because each pinion tooth meshes with particular ring gear teeth.  A 10 tooth pinion and a 37 tooth ring gear would be a hunting rear axle. They do not have a common factor so they don't need to be timed. Yours is likely a hunting type.

 

 

[Spinneyhill]

4 hours ago, dictator27 said:

Do you know what the rear axle ratio is? If the pinion and ring gear both have an even number of teeth ie.  10 on the pinion and 36 on the ring gear, this would be a non hunting rear axle. They have 2 as a common factor. It would have to be timed because each pinion tooth meshes with particular ring gear teeth.  A 10 tooth pinion and a 37 tooth ring gear would be a hunting rear axle. They do not have a common factor so they don't need to be timed. Yours is likely a hunting type.

 

 

Can you tell us more about this please. I hadn't heard of this concept.

[Rusty_OToole]

If you have a gear drive where the gear ratio is an even number like 40:10 or 30:10 the same teeth  hit the same teeth every time around. This results in uneven wear. Some teeth wear very fast, others hardly wear at all.

 

They found if you use an uneven number like 30:11 then the same teeth don't mesh again until the gear has gone through 30 revolutions. This equalizes the wear and makes the gears run smoother and last longer. The extra gear tooth is called a hunting tooth.

 

This was discovered so long ago, I doubt any car was made without taking it into account. This is why cars always have a rear axle ratio like 4.11:1 or 3.73:1 and never 4:1 or 3:1.

 

The same principle applies to chain drives. An exactly even ratio will result in uneven chain and sprocket wear.

Edited September 21, 2017 by Rusty_OToole (see edit history)

[Bloo]

Hunting vs Non-Hunting? I have heard of it. Rings and pinions break in, and develop wear patterns. In the old days, when the manufacturing was less perfect, they used to start out tight and run fairly hot when brand new as the high spots got rubbed down.

 

If the number of teeth are evenly divisible, the same tooth on the ring hits the same tooth on the pinion every time. This is part of the wear pattern, and if you do not respect it, the gears will have to break in all over again, with the resultant extra wear.

 

If the number of teeth are not evenly divisible, you didn't need to worry about that particular thing.

 

On a used ring and pinion however, if you take things apart it is advisable to check the contact pattern and the backlash before taking it apart, and put it back the way it was, rather than to the settings in the manual. I suspect this last thing is what aussiecowboy was asking about. The thickness of that gasket might set the pinion depth.

Edited September 21, 2017 by Bloo
typo (see edit history)

[Bloo]

8 minutes ago, Rusty_OToole said:

This was discovered so long ago, I doubt any car was made without taking it into account. This is why cars always have a rear axle ratio like 4.11:1 or 3.73:1 and never 4:1 or 3:1.

 

You could be right, but as I recall old Motor and Chilton manuals always cautioned you to look for this and respect it. Im pretty sure I have worked on a 3.00:1 nine inch Ford, but I cant prove it.....

[Spinneyhill]

Interesting. My 1930 Dodge Brothers Eight-in-Line was made 46:10. The DD was 43:10.

 

I must say that when I swapped the CW&P 20 years ago after a CW bolt broke its head off, I just put in another used set from my "collection" (junk pile my Wife says). I knew nothing of this. I set it up as I was told to with blue, but didn't notice any difference in the contacts between teeth. It was silent and is still silent after c. 7000 miles. Maybe I got lucky?

 

So if the pinion teeth were 1 to 10 and the CW 1 to 46, pinion tooth 1 would engage in CW teeth

1, 11, 21, 31, 41
5, 15, 25, 35, 45
9, 19 29 39
3, 13, 23, 33 43
7, 17, 27, 37

 

So it takes 5 revolutions of the crown wheel to come back to the same tooth and it never engages in any even numbered teeth.

Edited September 21, 2017 by Spinneyhill (see edit history)