Seals in a 9 drop out...can I ???

[MYTANG]

The front yoke seal leaks, and the pinion case to the main case. I plan on taking the impact, and remove the yoke to replace the seal. When Im done, I will use a breaker bar to run the nut back up snug, so I dont change the crush sleeve. I should be OK doing this much right? Second, is to split the case and reseal it between the two halves. The whole pinion would come out of the case at this point. Now would this mess the unit up? Dose the teeth on the pinion have to mesh back to the ring gear in the exact same teeth as before? Cant be off two or three or so Let me know please. Thanks.

[PrecisionTrans]

For my time and money, I would pop the pinion cage out and replace both the pinion seal and the spacer. If your unit has the "Daytona" cage, it should have a solid spacer. Be sure to check the pinion yoke for rust, roughness, and/or grooving.

Some OE ratios, like 3.00 : 1.00 are timed, and the pinion and ring gear are marked with paint. Paint marks will line up with one pinion tooth and two ring gear teeth. These must be reinstalled properly. Most other ratios are what is called a "hunting tooth" ratio, meaning that eventually each pinion tooth meshes with each ring gear tooth. These can be installed in any convenient mesh.

No, you will not change the pinion depth specification doing this job unless you change bearings, and even then it's unlikely.

I would also suggest you change the "O" ring on the cage. It's cheap.

Hope this helps. If you have any other concerns or questions, don't hesitate to ask.

Don

[MYTANG]

My centersection is a N case, 31 spline, 3:50 gear ratio, limited slip. Hunting tooth OK for this gearing then? Thanks...

[Greg'66 5.0]

Many times, gear ratios are specifically chosen so that the pinion tooth count and the ring gear tooth count aren't multiples of each other - meaning that the pinion meshes with different teeth on every revolution of the ring gear. This evens out the wear on the gears. The pinion does not have to mesh with the same teeth that it was on when you took it out - once the ring gear turns around once, the pinion will be on different teeth.

There is no worry with pinion depth changing during the whole process as long as you put the same shims back in between the carrier housing and the pinion housing. The shims don't compress, so tightening everything up won't change a thing - that's why there's a o-ring seal there instead of a gasket. No worries on the housing gasket either. Any slight change in the 3rd member position due to gasket thickness does not make a difference in the alignment of the axle shafts. The change would be so small that it probably wouldn't be measurable.

[Al Newman]

Your 3.50 gear ratio is what they call a partial hunting ratio, and even though some ring gear teeth are shared with more than one pinion tooth, not all teeth will eventually come into contact with each other. You will have to be careful to re-install the gears exactly the same way they came out.
When tightening the pinion nut, first tighten just until there is no in-and-out movement of the yoke on the pinion shaft, then tighten another 1/5th turn. That should set the preload close enough for government work. Loktite on the threads is your friend.
If you are having noticeable leaking between the pinion housing and the carrier housing, there is a good chance the o-ring has failed, probably after having been pinched from an earlier removal and re-set, and a new o-ring will have to be used.
Best,
Al