Transmission Case Defect - How to overcome?
 

There is an "edge" in the transmission input shaft seal hole that grabs and ruins the seal on install.

This transmission appears to be all original and never removed; indeed, the yellow paint was untouched on the drive shaft connection.

This edge appears to be some sort of defect in casting? How did the seal get installed? FYI it wasn't leaking noticeably, just a little hint (I'm in the middle of a clutch job & changing a few extra things while I'm there)

The "edge" is like the starting thread on a threaded hole in nature... except behind it is flat (ie. this edge is the face end of the smooth flat surface the seal sits on).

It starts at one point (where there are two tiny holes in the case material) & wraps about half way. The seal catches at the last part where the edge is recessed about as far as the original seal face sat

How do I approach this?

https://cimg1.ibsrv.net/gimg/rennlis...9d0f75cf79.jpg
https://cimg3.ibsrv.net/gimg/rennlis...dca99b5ff8.jpg
https://cimg6.ibsrv.net/gimg/rennlis...40c80b6506.jpg

I would clean up the edgy with emery paper.

What worries me is this "edge" is more like a lip--it's pretty high! It's not a ridge that can be flattened; it is literally the end of the smooth flat surface behind it (the surface the seal sits on)

To smooth it out, I'd have to add material to extend the smooth flat surface behind it to the end of the case hole.

It's almost like the last part of the hole was suddenly damaged; like the cutting tool got pulled down as it left the hole or something.. or.. since the new seal starts off tight, like the hole suddenly jumps up there (out-of-round?)

So...is the cross section: _____/\ or ____/\__ ?

It's like this: ---------------,__

Here's an updated image with better explanation

https://cimg2.ibsrv.net/gimg/rennlis...bdf4cd7b19.jpg

Are you planning to remove the shaft from the case to work on the whole separately or will you be doing the work with the shaft still installed if the shaft is still installed I think some Emery cloth as suggested before and possible a little RTV sealant behind the seal to make up for the irregular surface might be your best option. If you're planning to remove the shaft possibly some machine work to add a spacer similar to a bearing race behind it to bring the surface back up to a uniform method or machine it over sized for a slightly different seal

I'm not planning to remove the shaft; just changing the seal. Took another look with better lighting.. I have a better explanation of the issue:

I don't know much about the construction of these things, but to me, it appears that there is a long smooth sleeve pressed into the transmission case hole. This sleeve stops short of the opening--about 1.5 or 2mm. Material is added to fill in the difference and create a bevel or smooth drop to the opening.

This bevel material is missing in the problem area. Thus, I have a smooth rise all around except for the problem area which is now a step.

The surface that the seal rests on is perfectly smooth. Problem is, I can't get the seal "up" past the first 1.5mm in the problem area where the bevel is missing.

(The workshop manual says to push the seal in 1.5mm and the original was set in about that much)

What kind of material can I use to fill in the missing bevel?

Circled in Red is the good, smooth bevel. The problem area with missing bevel is in yellow below
https://cimg3.ibsrv.net/gimg/rennlis...f5fce82670.jpg

Here, the red shows the area where the bevel is missing
https://cimg5.ibsrv.net/gimg/rennlis...789e384f6e.jpg

I'd just fill that edge with jb weld and file/sand a new bevel.

I wouldn't be concerned about this. As others have suggested, sand / file down any edge or lip that is "higher" than the smooth bore's radius. The oil seal you will install has a wide surface that faces the bore, so loss of a bit of that surface to this lip won't be an issue.

Be sure to set the radial oil seal deep enough that its lip rides properly on the input shaft surface. Pack the seal with grease before installing so that its gaiter (metal spring) is kept in place. Be careful guiding the seal over the splines - I use the factory "condom" tool when installing but I do a lot of transmissions and can justify its expense! Good luck,

You can also use electrical tape to wrap the input shaft splines to protect the seal while sliding it over.

Tonight, I applied JB Weld "Steel" to try and restore the missing bevel area.

Have to say, this JB Weld stuff isn't what I thought it would be; it's quite brittle and dry, difficult to finely drag along a 2mm line. Kept crumbling then suddenly got too hard.

I used a toothpick to work it.. finger doesn't fit in there lol. Will see tomorrow if there's enough of it there to harden up and become one with the case
https://cimg8.ibsrv.net/gimg/rennlis...b6266b53b9.jpg
https://cimg9.ibsrv.net/gimg/rennlis...4ae0cfc039.jpg

I haven't looked very far into this, but it looks like a 222540 seal is compatible and made with a steel outer. That might go past the irregularity without deformation...