303M HydraMatic rebuild

[rustystud]

I'm still working on installing the back half of the HydraMatic.
After the snap ring is installed, you install the "Rear Planet Carrier". The Planet carrier butts up against the snap ring you just installed.

Here I'm installing the "Reverse Internal Gear Assembly" and the "Reverse Clutch Cone" .

Now it's time to install the snap ring on the Input shaft.

You must install the "Rear Oil Pump" before installing the "Output Shaft Bearing Support" . This is that huge round plate assembly that holds the Reverse Piston Cone and the Reduction Clutch Piston.

After the rear pump is installed, you need to check for "run-out" .

After the Oil tube and "O"ring is installed your finished with the main transmission for awhile.


The Rear Output Shaft support needs to be assembled now.
I already installed new oil passage plugs so I just needed to install the Reverse Piston Cone and Roller Bearing.

 

[rustystud]

I'm not going to install the "Output Shaft Bearing Support" just yet. The "Reverse Internal Gear Assembly" can get "stuck" and not release. In later HydraMatics (1952) GMC fixed this problem by installing a "pressure plate and wave spring" to push against the reverse internal gear releasing the piston. Later in 1954 they made an even stronger release spring. The early model will fit without any modification to the 303M transmission.
Since I have several later HydraMatics laying around I will "appropriate" one of these pressure plates and springs and install it in my rebuild.
I'll post pictures later.

 

[rustystud]

Here is that pressure plate and spring I was referring too yesterday.



I also have the 1954 model.


You can see the difference between a civilian HydroMatic and the Military units "Reverse Internal Gear"
here. The Military uses straight cut gears while the civilian transmission uses beveled gears and also has the outer lugs for the Parking Pawl. You can use the civilian unit in the 303M transmission, but it only has three gears compared to the four the 303M has.
If you wanted to use the later model pressure plate and spring you will have to drill the housing to except the pressure plates four attaching lugs.

You can see how the later style plate locks into the Reverse Internal Gear. This is a much better system.

 

[rustystud]

I'm going to tell you something different from the "Book" about checking runout on the "Governor" .
You do not need to have the "Reverse Planet Carrier" installed when you check the runout. In fact it is far easier to have the "Carrier" removed since you can spin the governor freely. This governor check is for the mounting of the governor assembly on the rear pump shaft. If the runout is more than 0.005" then you need to loosen the governor bolts and "Tweek" it to bring it in line with the specifications.
Later you will be loosening the whole rear pump assembly to fit it to the valve body.


Now that the governor is running true let's install the "rear planet carrier" and "reverse internal gear" and then the thrustwasher and spacer before we drop in the "rear shaft bearing support" .

I installed two guide rods for the "support" and installed the gasket. I coated the gasket with a spray on sealent.


So hear we go with the heavy "rear shaft bearing support" .
Once you get it fully seated (you probably will need to pound on it a bit with a dead blow rubber hammer) and the bolts installed, you can check the reverse piston operation by applying air to this hole.

 

[rustystud]

I'm still having trouble finding anyone who can make up new return springs for the reduction piston.
So, I'm debating with myself about reusing the best spring I have and hoping it doesn't break later on.
I've spent a bit of money modifying this transmission (machining costs alone have come to over $2000.00 not to mention the cost of having new gaskets made up) and would be really pissed off if the transmission broke because of an old return spring. Then again, what good is a half-finished transmission doing anyone !
Better to "roll the dice" then sit on my hands all day.

 

[m1010plowboy]

Thanks again for swapping between greasy gloves and snapping photos of the hydromatic surgery. It's a huge contribution to the preservation of the Early Deuce. I try to follow along with the ORD 9 SNL G-749 Service Parts Manual because it has these great pictures. I don't want to distract from the thread flow but if these help anyone else, I can grab more. Here's that smaller wavy spring.

 

[rustystud]

Thanks again for swapping between greasy gloves and snapping photos of the hydromatic surgery. It's a huge contribution to the preservation of the Early Deuce. I try to follow along with the ORD 9 SNL G-749 Service Parts Manual because it has these great pictures. I don't want to distract from the thread flow but if these help anyone else, I can grab more. Here's that smaller wavy spring.

View attachment 934518View attachment 934519

Thanks Dave !
I was beginning to wonder if anyone was watching out there.

 

[rustystud]

I spent today sandblasting parts from that last 303M I tore down (all the transmissions I picked up in Canada had water damage). Actually, it was originally a 302M but it was converted in 1964 with the "A" and "B" modifications. Basically, they added two more clutch plates in the front drum assembly. That is all the difference between a 302M and 303M transmission.
Why on earth they thought they could get by with only three clutch plates in the front drum I'll never know. Even the civilian cars had a five-clutch drum. I have an original TM 9- 1819AB manual and it is exactly like the later TM 9- 8025-2 manual except the TM 9- 1819AB has some really nice pictures ! My copy has water stains, so I will not be posting any pictures as they don't come out well on my machine.

Here's some of the parts I've been cleaning up. I spent most of today cleaning the main case. Should have taken some pictures to show what kind of mess it was in.

 

[USMC 00-08]

I was beginning to wonder if anyone was watching out there.

You probably have a bigger audience than you think.

 

[m1010plowboy]

I was just being polite and not interrupting. There are over 10,000 views in just 5 months so the audience is large......now that you know......no pressure lol.....unless we're testing oil pressure.

Following in the book helps my right side thinking brain understand how to set up the testing equipment. Before I couldn't wrap my head around how a person shims things and measures the run out, setting up the gauges.......all that detail.

This is a blast watching it go together so back up to the bleachers for this guy.

 

[USMC 00-08]

There are over 10,000 views in just 5 months so the audience is large......now that you know......no pressure lol.....unless we're testing oil pressure.

With that said, we can't give up on that release spring so easy. I'm really hoping we can find a source for new production. Brittle old stuff that might tear everything up defeats the purpose.

 

[rustystud]

With that said, we can't give up on that release spring so easy. I'm really hoping we can find a source for new production. Brittle old stuff that might tear everything up defeats the purpose.

I'm still looking for a manufacturer who will take up the challenge. I totally agree about using an old spring that could ruin the whole transmission if it decides to let go.
I took it to the machine shop last week and asked if he could recommend anyone. He had a few ideas, but they didn't pan out. Still on the hunt though !
Oh and thanks for the support ! Sometimes it seems I'm the only one who cares about this old stuff. My wife sure doesn't understand ! She thinks I should spend all my time working on the house and property.

 

[rustystud]

With that said, we can't give up on that release spring so easy. I'm really hoping we can find a source for new production. Brittle old stuff that might tear everything up defeats the purpose.

I was just being polite and not interrupting. There are over 10,000 views in just 5 months so the audience is large......now that you know......no pressure lol.....unless we're testing oil pressure.

Following in the book helps my right side thinking brain understand how to set up the testing equipment. Before I couldn't wrap my head around how a person shims things and measures the run out, setting up the gauges.......all that detail.

This is a blast watching it go together so back up to the bleachers for this guy.

Funny you mentioned "oil pressure" Dave. I've been looking into increasing the oil volume in the 303M HydraMatic. When new these transmissions leaked like a sieve, now that their old and worn out the oil lose is tremendous !
I posted I was looking for a 301MG transmissions rear oil pump and discharge tube. No answers yet, but hopefully someone out there has one laying around that I can buy. I have another idea brewing !

By the way. If you have those HydraMatics laying outside you should take off the oil pan cooler cover and let all the water out. I just spent over three hours cleaning up and sandblasting another oil pan only to find out it has a five-inch-long crack in the housing ! That makes two housings from "Lyle" that where cracked. He just had the transmissions laying outside. I had "assumed" he had drained them. That's on me then. I just hope one of the three transmissions left has a good oil pan.

 

[rustystud]

Still waiting on bolts. I'm installing all new bolts in the transmission. Stainless Steel with serrated flange where I can. I hate dealing with old rusted bolts.
Took some pictures today but forgot to bring in the camera.
I'm working on increasing oil volume like I mentioned to "Dave" .
The main body rear oil pump does not add any oil to the system. I just dumps out the front cover of the pump. It's main purpose is driving the governor. It does suck out oil from the reduction unit, but that is most likely to keep the gears lubricated, nothing more.
So, if I can find a 301MG pump which "does" add oil to the system, I can incorporate that into the 303M's oil system increasing oil volume !
Either that or somehow drilling into the pump housing and create my own pipe to the "main" oil line. I will also need to tap into the main oil pick-up pipe as the oil from the reduction unit is not enough to keep the pump operating correctly.

Most people do not realize the main cause of clutch failure is lack of oil pressure. Either from leaking or torn oil seals or sealing rings.
Yes shift timing is also important as is how much pressure is exerted on the clutches: like hauling extremely heavy loads or shifting under high speeds as in racing.
But in the end, it all comes back to oil pressure and volume. If you have enough oil pressure and volume to keep that clutch piston compressed against the plates, you will not have clutch failure.
Oh well, tomorrow is another day. Let's see what kind of trouble I can get into then.

 

[USMC 00-08]

Sometimes it seems I'm the only one who cares about this old stuff. My wife sure doesn't understand ! She thinks I should spend all my time working on the house and property.

I didn't see your name on the club roster, so it has been added and here is your t-shirt!



At one time, Tom Wolboldt here on Steel Soldiers had NOS oil pans. I'm not sure if he's still active here, but he used to sell a lot on eBay. I've not see him list anything for a long time. He had a lot of G749 parts and maybe he even has springs. I can try to get his phone number from 1944MB if you can't PM him here.