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.

 

[rustystud]

Here's some information for people needing to check their pressures in the 303M.



Hope this helps "Blake" .

 

[USMC 00-08]

Could some of the cracks in the cast iron be welded and repaired? I'm not a welder and know nothing about it, but I have seen some weld it with success. They weren't welding engine or transmission castings though.

 

[jeffhuey1n]

Could some of the cracks in the cast iron be welded and repaired? I'm not a welder and know nothing about it, but I have seen some weld it with success. They weren't welding engine or transmission castings though.

I’m no welder but I’ve been trying to learn the trade. One of the things with cast iron is it’s a pain to weld. Yes, it can be welded. One must have patience however. The piece to be welded must be heated up. The don’t know the exact temperature but it depends on factors such as thickness. There’s some pretty detailed videos on the web that show the entire process.
I’d take some scrap cast iron and try out the procedures before attempting to repair a must not be destroyed part.

 

[jeffhuey1n]

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.
View attachment 944939 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.

The world will be sadder if we lose you Rusty. As far as wasting time, in my case, what else would I be doing? Better yet, what would I rather be doing? I can’t think of anything better than tinkering around my shop and the multiple projects that will bring me a sense of satisfaction. Yes, many of my projects end up in the scrap pile. For every failure, I probably have two to three successes.
A wise man once said, probably my Dad ‘cause he was a lot smarter than me, it’s not the destination that is the goal. It’s the journey and experiences getting there that makes one feel satisfied.
Just a thought.

 

[rustystud]

Could some of the cracks in the cast iron be welded and repaired? I'm not a welder and know nothing about it, but I have seen some weld it with success. They weren't welding engine or transmission castings though.

I was a commercial welder for 10 years. During that time I welded "steel", "aluminum" , "stainless steel" , and cast-iron" . The cast-iron was the worst. One of the major problems is that cast-iron is very porous. That is especially important when welding cast-iron that has absorbed oils like transmission fluid.
When the metal gets hot, the oil comes out of the metal ruining the weld. I once spent 2 hours trying to weld a 2-inch section of cast-iron. I heated it with a torch and welded with a TIG unit. It blew back at me and spit and boiled and did all sorts of nastiness. I finally got it welded. It was not pretty, but it worked.
That item had only been subjected to oil laying on it, not submerged in it.
The next item to consider is the place the crack is located at. Right at the "water" cooler and "oil" sump. You could not pick a worst place to have a crack in an Automatic transmission. Remember water will destroy fiber clutch plates. Since this has happened to three oil pans, that tells me there is a defect in the casting from the factory. Really no way to fix that.
If the 303M had an "aluminum" housing that could be welded safely. I've done that.
Bottom line, I will not rebuild and send out a transmission that I cannot trust to work properly.
Cracks in the housings ? Trash can it.

 

[rustystud]

The world will be sadder if we lose you Rusty. As far as wasting time, in my case, what else would I be doing? Better yet, what would I rather be doing? I can’t think of anything better than tinkering around my shop and the multiple projects that will bring me a sense of satisfaction. Yes, many of my projects end up in the scrap pile. For every failure, I probably have two to three successes.
A wise man once said, probably my Dad ‘cause he was a lot smarter than me, it’s not the destination that is the goal. It’s the journey and experiences getting there that makes one feel satisfied.
Just a thought.

I have good days and bad days. That post was a bad day. Though it has been getting harder trying to keep a positive attitude about these old 303M HydraMatics.
Now with the "border" issues with Canada I don't even know if I will be able to see "plowboy" in Edmonton this June. Really pissing me off !!!
I'm still going, but maybe not with the trailer. I have a "special" gift for "Dave" I've been working on. I will get up there, I just don't know if I'll be able to get back !
That kind of thing bums me out.

 

[rustystud]

Well I did it again !!!!
I had the machine shop make-up some throttle valve shafts so I could replace all those bent ones, but I didn't ask for a quote. Again !
I didn't think having 20 small shafts made would cost so much. WRONG !!!
Here's what $1002.00 will get you.
The wife wasn't too happy with me .

Also I found out what the cost of making new front pump vanes would be.
$35.00 each vane. That's right, $240.00 to make one front pump work.
Oh, there was a minimum order of 70 vanes. That's $2450.00 being laid out.
At this point I'm not going to have the machine shop make any more parts up for this transmission.
I've already spent more than $6,000.00 on machining alone, not to mention all the other parts I have bought, like gaskets and clutch plates and seal rings and "O" rings, and the actual transmissions themselves which I've paid up to $400.00 each for, just to mention a few things. All that money spent, and I can only build-up 5 transmissions due to the lack of good cases and oil pans.

Oh well. Time to get back on my Allison transmission project for the M35 Deuce.