As mentioned above, if you just rotate the engine so you see a part of the ring gear that is NOT damaged, you'll see the proper bevel; you want to create that same bevel on the teeth that are damaged.

 

Here is another way to perceive this.
I have brightened up and increased contrast of your original photo (below) for more clarity.
Enlarge this photo as much as necessary to get a very clear view of each gear. probably 4x would be good. (save the image to your computer if that works better).

Lets imagine that the gear teeth in the image are threads on a large bolt. This bolt must be threaded into a mating hole with female threads. However, somehow the threads on the bolt were damaged, as if they had been struck by a large dull chisel. Now the bolt cannot thread into the hole because the threads are damaged and out of proper shape to fit into the female threads. Some of the metal on each of the damaged threads has mushroomed out and that mushroomed out metal is stopping the thread from turning into the female thread. We can call the mushroomed out metal on each thread, a "burr"

Each burr needs to be filed off flush (level or even) with the undamaged part of that thread so that thread can then turn freely into the female threads without interference.

The metal that has been chipped away from the thread and is no longer there doesn't matter. There will be just an air gap where that part of the thread is gone - so after the burrs are removed the remaining thread will be of the proper shape and dimension to turn easily into a female thread.

Now for the 'Bevel'. Technically, what we want is not a bevel, it is a Chamfer.
The difference is shown in the second image below. Scroll down and I will type more below that image.





In this image pretend that you are looking directly up at the gear teeth from under the van, head pointed toward the back of the van. Each of the images represents an adjacent tooth on the ring gear. The top of the teeth in the image are pointed toward the starter.

The chamfer in the image is far to large. We only need a very tiny chamfer, a bit less than 1/16 inch measuring that chamfer line. In my opinion 1/32 inch minimum is enough but can be slightly more and 1/16th would be the upper limit or too much. I would try to stay under that. This chamfer dimension is not very critical in terms of exact measure.

Any other opinions on chamfer dimension?

The chamfer needs to be at BOTH corner edges of the gear tooth going down each edge almost to the bottom of the gear tooth. A bit more than 3/4ths of the way down should be well good enough.

LOOK AT YOUR FIRST IMAGE- The lesser damaged teeth. You can SEE the shiny part of the teeth where the starter gear engaged with it. THAT is how far down the chamfer should go on the edge of the tooth, or just slightly beyond.

That chamfer dimension of 1/32+ is just based on my perceptions of what I've been looking at. I do not have one to compare or a closeup view of the FLEXPLATE ring gear teeth for this vehicle. Manual transmission flywheel ring gear teeth are different. I don't see a chamfer on those. Flywheels are rigid and they don't flex which is probably why.

So what does the chamfer do in this case? Lets again pretend that this gear is a bolt thread. The chamfer helps guide the starting edge of the bolth thread into the a the female threads of a threaded hole. It makes it easier to start the bolt into the threaded hole. In this case the chamfers on the ring gear teeth help to guide the teeth on the starter gear into the teeth of the ring gear. The starter gear teeth are already well machined in a couple of ways to make that gear slide into the ring gear but this slight chamfer on the ring gear teeth will help a little bit- PLUS with the slight chamfer you can be quite sure that the burr is completely gone.

As mentioned before, look for a good ring gear tooth and see how large the chamfer is- it will be very small and if you match that it should be good enough otherwise I think what I wrote is a good dimension.

As for the far less damaged teeth, just a slight touch up with a file is all that's needed, just touching up rough edges of the teeth and a very slight chamfer .

 

Out if all the possibilities, this answer should be the most considered.

 

I tend to agree and that is probably going to be a very very small chamfer. The only thing that concerns me is any rough, sharp or jagged edge on the end of a gear tooth where adamkat22 placed the blue trapezoid to cover it.

It's a very minor detail that I didn't introduce before in order not to further confuse adam's understanding.

In the edited image of the gear teeth that I posted, such damage is visible along the damaged bottom edge of all of the gear teeth that are fully shown. My concern being, the starter gear is likely to glide over such defects and possibly scratch the starter gear while it squashes down and smooths out such defects.
"Gliding over" is why I thought the chamfer could be a little bit bigger than very, very tiny.

Very technically speaking, a scratch in metal is a strength defect, affecting 'notch toughness' (physical metallurgy which I've studied) which is mostly a concern for fatigue strength which doesn't much apply here but on a microscopic scale could cause faster wearing of the starter gear (long term...). I would smooth those edges out just enough to prevent that and those defects are obvious in the image so adam probably saw that(?)

That said, I am a perfectionist,most often beyond what is necessary or practical but achieving 'perfection' is always compromised by feasibility and practicality so the result is, "Do the best I can with the resources and time that is available and be practical." Practical is just touching those up with a file, NOT a lot of filing.

I don't think we can go any further with this without 'hard surfacing' precision grinding, polishing and make it look like it is chrome plated, so,

Where adamkat22 is? What he gonna do, done already or whatever? He probably hasn't seen these posts so I'll try to send a message to him.

 

hmm. for some reason i guess my last post didn't actually 'post'. this weekend i got under there with a file and took away anything jagged. i wasn't really able to add the chamfer very well though...just because i can't really get an angle on the tooth.

its a work van and so far i haven't had to use it very much but i started it up a couple ten times this weekend and it did spin out one of those times. maybe an improvement but obviously didn't 'cure it'. this weekend i'll see if i can keep going with it.

in the mean time i'm also starting to read up on how to drop the trans and everything else i will need to do in order to replace the ring gear...just in case.

thanks for everyones help

 

ok. sorry this thread is getting epically long. its still having issues. i am going to have a buddy help me drop the trans and replace the ring gear altogether. not many threads dealing with that procedure. anything besides the new ring gear i should be ordering (gaskets, seals, etc)?

thanks

 

After the filing, you didn't mention "Starter" "gear" / Bendix as it was called back then. That gear must be chewed up some. They are very easy to replace, you can order that assembly and put it in your starter.

I think the right way to do it is to replace the ring gear and DO FIX the starter. I am going to assume that since that bulletin in 1985 the starters for IDI automatics have improved accordingly so you can just repair the one you have.

NEW FRONT(Input) AND REAR(Output) TRANSMISSION SEALS!! VERY CHEAP AND EASY! You wont have to pull the transmission again later if/when the seals start leaking. Be sure to coat the rubber part of the seals with transmission fluid or some light weight grease.

Here are some videos that cover the seal replacement plus drive shaft removal/replacement NOT on Ford diesels but is all pretty much the same so a picked a few that look about the same. Mark the drive shaft before you remove it so it will bolt on the same as before for balance- one guy does it with paint, another by scratching it. One video is about installing a torque converter and that is important to watch. - different transmission and engine but it's all pretty much the same.

With these and your repair manual and your helper you should do well. The drive shafts in the videos won't look like yours but that doesn't matter, the principles are the same.

First, here is a real quick one on C6 seals. I recommend using the Seal Puller tool shown in one or two of the videos. OEM/2 tips seal puller 25014 at AutoZone.com - 1 reviews
You'll probably use it again on other seals for axle shaft seals or whatever on any vehicle. I might have used one once or twice out of about 30 seals replaced. Next time I'll buy one of these.

Since the transm. will be out you can use a big screwdriver, needle nose vise-grips, or tin snips to cut the top edge of the seal from the rubber to the edge- bend it up and grab it with channel locks, and pull it out or whatever - don't worry about damaging the seal, it's going in the- recycle bin? The main thing is not to damage the inside surfaces of the hole that the seal is tapped into. If you are careful you can drill a small hole and use a sheet metal screw with aggressive threads (off your van - not a little one) that will hold better and pull it out as shown somewhere in these vids.

Ford C6 Seal removal and replacement this video is high speed in parts and a little bit sloppy on technique to put the seals in so you can see approximately what you are going to be doing BUT the other videos show much better methods of installing the seals. Removing the rear seal with a screwdriver and hammer tapping along the exposed edge of the seal as he does here is an OK way to remove the rear seal but not the front one.

By the way, I've used just a block of wood and hammer to seat the front seal before, just tapping around it to get it in straight and seated.
C6 Transmission


Try to get them started in straight and driven in straight, they may start a little bit off with a high side but you can gently tap that down and if you continue as shown in the other vids it will go in straight. Tap it in until it is well seated but not so hard that you dent or bend the metal part of the seal, once it's going in straight it should go in and seat with some moderate taps. You'll know when you do the job.

Replace rear transmission oil seal 2000 S10

I like this guys technique for installing the rear seal and you'll see how he paints the drive shaft before removal as well as the Seal Puller tool.(although much easier with transm, out of the vehicle)

Transmission Transfer case Tailshaft Seal

Basically the same. Here he scratches the drive shaft to mark it.

Finally here is the the torque Converter install, technical explanations but it's quite easy to do.
The torque converter should have been drained by now for the new tranny fluid (it will pour out- you'll see). ADD 1 to 1-1/2 quarts into the torque converter before aligning it and pushing it into the transmission. You'll see the front seal up close here too and don't forget to lubricate the rubber part of the seal and the torque converter shaft before installing it.

EDIT: by the way there are alignment studs or pins (not threaded) on the torque converter that will fit into holes on the flex plate. I've never done a C-6 and the last time I pulled transmission and transfer case was a 904 series (999) on my Jeep Cherokee in about 1995 and I dont recall how that fit up to the flex plate. I was replacing a torque converter, seals etc. and checking the chain in the transfer case.

Sorry this was so long.. or was it? 5:40 AM with no sleep last night.. so I'm not concentrating well.

Good luck, adamkat22, you'll do well. It's not so confusing (if at all) when you are actually doing it.