303M HydraMatic rebuild

[rustystud]

Since tearing down all these 303M HydraMatics I've come across several things of interest. The number one being what is the difference between a 302M and a 303M unit. We know that the military had durability problems with the 302M . The question has always been "why" ?
Over time I have found out several things wrong with the 302M unit. The biggest being the front clutch only having three fiber plates instead of the five it has now.
I've now found and confirmed another big one. The front "servo" .
In the 302M transmission the "apply piston" is noticeably smaller, compared to the later 303M unit.
The left on is from a 302M and the right one is from a 303M .

The problem I've found though is this smaller servo was not always changed out when converting the 302M to a 303M unit. I have seen several 303M's have this smaller servo. The TM 9-8025-2 lists the size of the servo bore in the 303M to be 1.438" which is the larger bore shown above.
The size difference makes a big difference in the "holding" power of the front band so if your 303M has the smaller servo you should try and change it out to the larger size servo.

 

[rustystud]

On a sadder note, I know most of you know that "Tom Woldt" passed away a few months ago. He and I were working on finding parts for the 303M HydraMatic transmission. In fact he was going through his inventory for me when he died. I didn't realize he had passed for awhile since he told me to give him some time to look. When I tried to call him back I got no answer. Not unusual with him so I let it pass for several more weeks. Then I saw the memorial information here on Steel Soldiers.
I also lost another source of parts when "Brad" in Yelm, WA. lost his lease on that large chunk of land where he kept all those parts this last year. Seems his deceased partners wife wanted to liquidate all their combined assets. Brad lost the court battle and was forced to move out. Last I heard all those parts were scrapped out !
Lately I just want to say "no more" and stop working on all these old military trucks. Seems no one really cares anymore. I'm still planning to go see "Dave" up in Edmonton this summer as I did promise him. Beyond that maybe my wife is right and I should just play in the garden until I die.
I know that sounds like I'm just depressed, but battling trying to find solutions to keep this silly HydraMatic transmission alive just wears a person down. This last week alone, out of three 303M transmissions I tore down I was only able to save one main case, one oil pan, and two main bearing support housings. So out of three transmissions I can only build one. The oil pans have a major weakness. They tend to develop a crack between the water area and the oil area. Right along the seem. No way to fix it. The cracks are usually over 4 inches long.
You cannot see this crack until after you have spent hours cleaning the housing. All that work down the toilet. This is the third one having this same crack in two months.

Oh well, I'm just tired. I had surgery last Monday . I had to have an implant in my spine. Little electrodes giving me little jolts to confuse my brain. The power source was implanted in my upper butt cheek. So this is literally a pain in my ASS !!!
Hopefully I'll feel better in a few days and will have a brighter outlook. Then again maybe I'll just pack it in and go work in the garden.

 

[rustystud]

This is just a "general" wake-up call to everyone in the military vehicle community. Our parts are old and getting older. Cast Iron in particular becomes more brittle with age. Today after spending hours cleaning a bellhousing, I found a major crack in the flange. I couldn't see it until all the grime was cleaned off.
So not only did I lose three hours of my time, but I also paid for and lost an irreplaceable part. The crack extends down on the outside and will only get larger over time.
So here are my "words of wisdom" for today. Be careful with your cast-iron housings and parts !
Do NOT throw them around. Gently place them, not drop them. Don't pile other heavy objects on them.
Once you break them, that's it. You're done.
Now don't get me wrong. Cast-iron is strong and when for example the Bellhousing is bolted to the engine and the transmission is bolted to the other end, it becomes an extremely strong piece of equipment. It all works together. Individual parts though are easily broken.
So, take care of your old parts.