Internal Reaction (Ring) Gear shattered in 700R4..

[robert213]

The Internal Reaction (Ring) Gear shattered in 700R4 of my 1982 GMC 2500 4x4 with 98K miles.


http://www.geocities.com/pm67/m01horse01.jpg

I have inherited a 1982 GMC 2500 4x4 from my mother. I had automatic trans fluid replaced at 70K miles three years ago. Everything appeared to be normal.

Last week, I put transmission in "Drive", proceeded to step on gas pedal, and heard the most gawd-awful noise I had ever heard.

Local Buick/GMC dealership originally said that I shattered the Sun Gear and Shell in the transmission. I visited the dealership to take a look at the transmission for myself.

Now, I know why they call it the Sun gear. There are three planetary gears that revolve around the Sun gear. From what people have told me, it is very common to experience problems with Sun Gear and Shell. Actually, my Sun Gear and Shell were not damaged.

It was the collar ring with teeth that mate with the three planetary gears. It is offically called the "internal reaction gear". It is now in three pieces. The teeth on the corresponding "internal reaction gear support" were completely ground down.

Upon a closer examination, there was another problem brewing. At one end of the transmission case -- on the inside -- there is a channel for a seal. Something called "low reverse piston". It appears that this is another common problem. This channel becomes jagged and causes wear and tear on the seal. This causes reverse and manual low to fail. My transmission was no exception. My channel was very rough. I was told that the seal is supposed to be square. Mine was very rounded.

So, my parts lists, if I decide the have my transmission rebuilt by local transmission rebuilder...

New Transmission Case
New Low Reverse Piston Seal
New Internal Reaction (Ring) Gear
New Internal Reaction Gear Support
New and Improved, Stronger Sun Gear Shell

Question #1. Should I have my transmission rebuilt or should I purchase a rebuilt transmission or should I purchase a new crate transmssion?

Question #2. Where can I find a rebuilt transmission? a new crate transmission?

Question #3. I have never abused the transmission. Other than the problems that I mentioned, the transmission was very clean -- looked like new to me (as a person with no experience in transmissions). The truck only has 98K miles. Any thoughts as to what caused my transmission to let go?