Videos & Photos of rebuilding transmission

brittle gaskets

had same problem ordering from memphis,ask them to soak the gaskets in a pan of warm water,and tape them between 2 pcs of cardboard before shipping,works wonders,soak them in warm water before trying to install them,and you wont end up breaking them trying to install them,works on the cork gaskets also,THANKS STEVE,even though i wont have to do my tranny this time around,i am doing the front axle,(leaking 90 wt out the of thebrake drums),had thought about same idea as you about posting pics of this job,have gradually accumulated all parts to do brakes,seals,knuckles ,hopefully the brngs are still good,good luck to all on their projects

Re: GMC Hydromatic

M215 said:

Hello Steve,
I have just had a chance to read your thread about the tranny rebuild project, all I can say is THANK YOU!!!!

I have a spare Hydromatic for our GMC that I would like to rebuild, your info will be very helpful.

Was Memphis able to supply all the needed parts for the rebuild? I thought some of the rebuild parts were no long available. I had to reorder the large gasket for the belly pan 4-5 times because they were so brittle from age they would disintegrate during shipping.

I installed a carriage bolt in the shift towers slot to prevent accidental shifting into hi-range reverse.

Karl

Click to expand...

You're right Karl,
The front oil pump as a whole unit is no longer available. I don't know if they still have parts for that.

Back in 1999 I also ordered two transmission kits that also had the oil pan gasket and other gaskets dry rotted from age. Since the gaskets were too brittle to use I just ended up using them as templates, also a couple of seals were not available. Back then John from the parts department told me since there was such a demand for the rebuild kits, they (Memphis Equipment) were looking into finding a manufacturer to start making all the seals and gaskets again.

The kit I received today was amazing, it looks like a complete kit and the quality is superb. All looks like new, even smells like new. I think I even have the seal that fits around the Reduction Piston. Have to wait and see when I take the piston out. It should be, it’s as big around as the reduction section-housing gasket. If it is, then someone’s making the kits again. 6 years ago, this gasket was nowhere to be found.
The day I ordered this last kit, John was too busy to chit chat, so I don't know how or where all this stuff came from.

Re: brittle gaskets

butch atkins said:

had same problem ordering from memphis,ask them to soak the gaskets in a pan of warm water,and tape them between 2 pcs of cardboard before shipping,works wonders,soak them in warm water before trying to install them,and you wont end up breaking them trying to install them,works on the cork gaskets also,THANKS STEVE,even though i wont have to do my tranny this time around,i am doing the front axle,(leaking 90 wt out the of thebrake drums),had thought about same idea as you about posting pics of this job,have gradually accumulated all parts to do brakes,seals,knuckles ,hopefully the brngs are still good,good luck to all on their projects

Click to expand...

Please do, document everything, and take notes, take pictures, and take a video if you can, the more information you can give the better the project.
Also it sounds like you know what you are doing and you have a good grasp on it, good job!

butch atkins, this is not aimed at you but to anybody who is thinking of doing the same thing. If posting a thread on proceedures on how to do a certain project, make sure you follow every step in the manual. If you don't have a manual not only are you risking ruining you vehicle, but someone else's if they follow your advice. Make sure you give torque values, measurements, and most of all go into detail of how each part works.

Does your truck have 90 wt oil in the universal joint? if it does Drain it and put grease in it, even though the housing has plugs on it that look like you service it with gear oil, you need to put grease in it.
Take both plugs out, and start pumping a high quality teflon grease that is not subject to temperture change in from the bottom plug, keep filling until grease comes out the front side plug hole.

The three M211s I had as part trucks had a type of teflon grease packed in the constant velocity joints. There was no sign of wear and that grease was stuck to everything, also that stuff was so slick, I could not hold on to anything with out it slipping out of my hand. I don't know how long that grease was in there, but the constant velocity joint and the inside of the housing looked new and clean.

RE: Re: brittle gaskets

Well I was fibbing, after a closer look at the seals, Im missing a seal, it looks like its inner clutch reduction piston seal. in this case it's the least used seal, used when you are in low, usually not in low for a long time.
These seals with a little cleaning usually get revived enough for a second go around. We just have to be extra careful not to damage any seals when we disassemble the transmission, just in case we have to reuse them again. As long as they are still pliable and pass an air check, things are good to go.

videos & Photos of rebuilding transmission

Sorry it took me awhile to get this all worked out, I made a video of just the drive line section showing just the drive-line. This video is a working format of the cutaways that I have shown you earlier on this thread.
So the easiest way for me to do this was to get my own web site so I don't run a 100 page thread on S.S.

just click on the link and enjoy the short presentation. Please note that this website is still under constant construction. when I put anything new in there such as this video, I'll post a notice on S.S.

http://web.mac.com/stephenfeldmeier

Thank-you
Steve

RE: videos & Photos of rebuilding transmission

Great website Steve. Looks like the deuce is coming along nicely. I don't think a lot of people realize what is involved in restoring a military vehicle or why we even do it. Realy can't explain it but everyone who owns one knows why! Keep posting, we all thank you for your dedication to the hobby.

I am an old GMC (civilian) truck fanatic, having grown up around and with these trucks. I am also a user, being an ex-trucker who owned CCKW's as loader trucks. Last winter we resurected an M-135, put a 5 yd. gravel box on it to haul sewer sand up a river on the ice to a house building site. We hauled 200 cu. yd. on this job. This was a tough pull, climbing the bank off the ice, snaking through the woods, turning around and dumping that taxed the trucks power to the limits. This was the first experience I had with the M series. I have been following the discussion on the Hydro-matic with interest and have some questions to ask of those who have more experience. It is not recomended to use high reverse because it supposedly overloads the reverse gear. As a mechanic, I find this logic puzzling. If high range put too much strain on the reverse gear, full power application in low range (which I have had to do, even to the point of running out of power) should have broken the reverse gear as well. I have never heard of a civilian truck equipt with Hydro-Matic having this trouble. The biggest complaint of Hydro-Matic users back then (when I worked as a truck mechanic in a GMC dealership) was that it shifted down on hills when you didn't want it to, causing you to spin out which usually meant bobsledding backwards down the hill. I worked with a guy who was in the motor pool in the Army who told me that they had trouble with the sprag clutches locking up if the truck rolled backwards. Reos were notorious for that, you couldn't get them out of gear unless someone pushed you ahead to get slack in the gear train. The truck I drove last winter bound up a couple times in low-reverse. I wasn't going very fast so it didn't hurt anything, I just pulled ahead a little till it let loose. My point in all this is: could it be that the cause of reverse gear breakage is the sprag locking up at a higher speed and the inertia of the truck weight coming to a sudden stop broke at the weakest point? If the reverse gear didn't break, maybe a drive shaft would have twisted off.
I'm trying not to come across as a complete idiot here, but as a restorer of old GMCs, I am being called on to work on the M series more and more. I need to learn what I need to know. I don't want to cause someone to have to divert his beer money to buying unnecessary truck parts. One could get lynched for that up here.
I'd appreciate any educational input.
Frank

I'm sorry, after rereading my very breif explaintion of HI reverse, I feel I should have presented it in a more professional way so here we go.

This cutaway is LOW Reverse

Go back and read the reverse section and reduction section on page 2. You have to have a full understanding of how reverse and reduction works in this transmission.

If you look at this cutaway, Starting with the output shaft (orange) you can see the Reverse Gear (Green) being held to form the ring gear in this planetary gear section by the Forcing cone and stationary cone (Pink). If you follow the output shaft to the end, you will see that the end of it is the sun gear for the main reduction section. As you know any time we go to a reduction, torque is increased at the point of exit. Since we have a 3 to 1 ratio, The reverse gear (GREEN) has 1/3 the torque force while the Ring Gear(RED) for the Reduction Unit Output Shaft (Blue) is receiving 2/3 rd of the the torque force.

This cutaway is HIGH Reverse


With the understanding at every speed (RPM) Reduction section in this transmission, we have a Torque value increase respectfully. So in other words as we reduce speed (RPMS) at each step of this transmission, we gain torque force respectfully. So basically in reverse we have high engine rpm with low torque force at the input of the transmission, with a low (RPM) and a high torque force coming out of the rear of the transmission.
So when we start to rebuild this transmission, you will see how the components in this transmission start getting bigger and heavier the further back we go from the engine.

So looking at the cutaway, there is no reduction after the reversing gear is locked into a ring gear. so ALL the force from that point out to the drive shafts themselves and transfer case, is being placed on that SMALL reverse gear.
Now if our transfer case was a reduction unit (which it's not) the torque force would be placed on the Reduction Box.

So the Hydra-Matic 303MG that does not have a reduction unit on the end of the transmission most likely had a true reduction gear box that the drive line went in to. in this case the reverse gear was suitable, but putting it in the 303M and the way the reduction section was designed, the reverse gear should have been a little more beefier.

So I hope this is starting to become a little more clear. If you want I can make a power point presentation on what was covered thus far. I don't want to add any more threads on this or you will have to be flipping through so many pages to get the whole story. It will have clearer pictures and be a little more detailed. But I want everybody who wants it have a very clear understanding on what's going on inside these things.

Safety and the manual

We are going to start this project very soon and this is a good time to mention a few things about safety and the manuals.

1st safety,
The reduction section in this transmission has a pre loaded accumulator. It consists of two springs, the outer spring free length is 13.6 inches, and is pre-loaded at a force of approximately 500 lbs. the inner spring has a free length of 13.7 inches and is preloaded at 300 lbs of force. With the two springs together has a force around 700 lbs. When you remove the accumulator assembly, the springs will still have 4 inches of travel left.
The only thing holding this force are two snap rings on each end of the piston rod. This accumulator can KILL you if it your not careful with it. So when you do remove it, DO NOT POINT THE ENDS AT YOU FACE. DO NOT THROW THE ASSEMBLY AROUND OR ROUGH HANDLE IT. THE BEST WAY TO HANDLE THIS ACCUMULATOR IS TO DO YOUR INSPECTION ON IT, DO WHAT EVER YOU HAVE TO DO WITH IT, THEN PUT IT BACK IN THE HOUSING. You don't need this loaded gun laying around the work area unnecessarily.

To remove the accumulator assembly, the proper procedure is to loosen the four bolts a couple threads at a time while alternating bolts. When the cover reaches 3/8 of an inch, and there is still spring pressure against the cover. STOP and tighten down the bolts, because one of the snap rings are broken.

Well me being me, since Mr. Murphy love's me so much, he gave this present one day.

Up until now there was not a written out safety procedure on how to remove this acculamtor assembly safely if this has happened. So here is how I did and we will treat this as a written procedure.

To remove this safely, get 4 bolts of the same diameter that have at least 6 inches of the same thread pattern. Screw on nuts with the same thread pattern all they way up to the head of the bolt. Remove one cover bolt at a time replacing it with the longer bolt with the nut on it. Once the bolt is screwed in place, screw down the nut until its tight against the cover. Once all 4 bolts are replaced, then loosen the nuts ONLY a couple threads at a time while alternating nuts until both springs are fully extended.

The other thing I want to talk about is the manual its self.
Its broken down into sections and each section will occasionally give different procedures on a item.
For instances - if we remove the reduction section control valve under the instructions in Chapt. 5 Disassembly of the Transmission. It just simply states to remove the control valve. Now if we look in Chapt.4 Removal of the Reduction Control Valve. It will state to loosen the pressure regulator plug and the reduction blocker line connector at the valve body before removal of control valve.

Know the manual front and back before rebuilding, In the video I will point all these out and the reasons why.

Power point

Well I started the rebuild of the transmission, for those of you who want to follow along you can, I will be posting a power point presentation now and then on the different sections of the transmission. If you have any problems along the way, don't hesitate to call or email me, I'll be more than glad to help.
Please note: if you don't have the manual and you are rebuilding this transmission by my videos or power point presentations only and run into problems, DON"T call me, the first thing I'm going to ask you is what page are you on and what is the component you're having problem with. This book is confusing enough if you are not familiar with the location of the parts or what the parts look like.

This power point presentation is still on the cutaways but I added pictures some pictures and gear drawings to show a different way of looking at the gear changes.

You have to have a full understanding of this for you to tear into these things and fix a shifting problem. So for those of you who want to learn, I'm getting you up to speed on the operation and basically what each component looks like and what it does. You can train a monkey to remove and replace a part, but knowing what that part does or how it effects the operation of the transmission is where we separate the monkeys form the men. Well this is the speech I gave to the men and women I've trained to work on the C-130.

The more you see of my presentations the more pieces of the puzzle fit, then you will start seeing the big picture.

Ok guys one more bit of information then everyone should be getting the idea of how this thing works.

When I explained going from 2nd to 3rd I explained it in the way the transmission distributes its power but in reality it's a little different then the way I explained it. I needed you to get an idea between the rear and front planetary units and how they differ.

Hopefully by now some of you have asked yourself this question and if you did, you're learning. Why would any one design a transmission and have the torus halves be operational only half the time?

So here it is

Now when we go from 2nd to 3rd, we assist the torus halves and the transmission goes into direct drive by assisting the torus halves.

When we select 3rd we release the band on the rear drum and activate the rear clutch pistons, this squeezes the main shaft clutch plates which turn the drum and it's ring gear. Since the ring gear is turning 1.55 to 1 the planetary gears (connected to the output shaft) driven by driven torus shaft sun gear turns the output shaft to the same ratio. Due to the pressure on the driven torus shaft sun gear from the drive torus, it acts like a rotating locked sun gear.

When this happens, the planetary gears can't turn because the drum is locked to the main shaft. At the same time and the drive torus is supplying constant pressure to the driven torus and the driven torus shaft sun gear locking it from turning in the opposite direction, which in this case would be required for the planetary gears to rotate. This shows the main shaft and the drum’s ring gear are supplying the majority of the force to turn the output shaft.



Now do you see how easy that is to understand now, If I told you this two weeks ago, this would of not made any sense.
Now if you guys can answer this question and answer it by going through all the shafts and components such as servos and clutch pistons, then you understand what is going on in this transmission.

Why does the rear planetary unit have to be in neutral for reverse? How does it do it?

I added a BRIEF power point presentation on the disassembly of the transmission. This only covers the removal of the components and an BRIEF explanation. This is only to show you where all the components are in relation to one another. The rear reduction case, oil pan and valve cover are removed. It was too big to add to S.S. so you have to go to my link to download it. If you have any problem, I'll email the pictures to you.

Also, as far as explaining to you the detailed operation between the oil pump governor to the control valve, I can't. I don't have the information as to the position of each valve in each phase of operation or what specific operation the governor has at each phase. I only have an idea and my idea is not good enough to post.

So if anyone has that specific piece of information in writing, please help us out.

Steve , thanks for doing this, what is a good used tranny worth out of a M135? Or the whole truck? Is 800 worth buying it? He says the engine is bad. The truck is in rough shape.The truck is in Newyork .

Well pa.rich I read in one of these threads that a truck scrapped would bring around $700 - $800 if worst come to worst. I don't know your mechanical back ground or what capabilities you have as far a access to spare parts, or shop to rebuild one. But the transmission alone if it has low milage under 10,000 miles should sell for around $300 to $500.

A rough truck and bad engine me personally I would not pay more then $500, again it all depends what you have available for spare parts to rebuild it. Because if you add up all your time and the price for all the replacement parts, don't be surprised if it ran up to $3,000 to $4,000 when its all said and done with. For that much money, you can buy a nice multi-fuel.

Tell you the truth, even though I bult one from 4 spare trucks that were given to me, I still had to spend around $3000 to get it to the shape it is in now. That's not even counting my 2 years of labor on it.
But the fun factor and how I felt when I saw the truck for the first time when I finished it. PRICELESS!!

pleasantpeasant_01 said:

I am an old GMC (civilian) truck fanatic, having grown up around and with these trucks. I am also a user, being an ex-trucker who owned CCKW's as loader trucks. Last winter we resurected an M-135, put a 5 yd. gravel box on it to haul sewer sand up a river on the ice to a house building site. We hauled 200 cu. yd. on this job. This was a tough pull, climbing the bank off the ice, snaking through the woods, turning around and dumping that taxed the trucks power to the limits. This was the first experience I had with the M series. I have been following the discussion on the Hydro-matic with interest and have some questions to ask of those who have more experience. It is not recomended to use high reverse because it supposedly overloads the reverse gear. As a mechanic, I find this logic puzzling. If high range put too much strain on the reverse gear, full power application in low range (which I have had to do, even to the point of running out of power) should have broken the reverse gear as well. I have never heard of a civilian truck equipt with Hydro-Matic having this trouble. The biggest complaint of Hydro-Matic users back then (when I worked as a truck mechanic in a GMC dealership) was that it shifted down on hills when you didn't want it to, causing you to spin out which usually meant bobsledding backwards down the hill. I worked with a guy who was in the motor pool in the Army who told me that they had trouble with the sprag clutches locking up if the truck rolled backwards. Reos were notorious for that, you couldn't get them out of gear unless someone pushed you ahead to get slack in the gear train. The truck I drove last winter bound up a couple times in low-reverse. I wasn't going very fast so it didn't hurt anything, I just pulled ahead a little till it let loose.

My point in all this is: could it be that the cause of reverse gear breakage is the sprag locking up at a higher speed and the inertia of the truck weight coming to a sudden stop broke at the weakest point? If the reverse gear didn't break, maybe a drive shaft would have twisted off.

Click to expand...

I'm trying not to come across as a complete idiot here, but as a restorer of old GMCs, I am being called on to work on the M series more and more. I need to learn what I need to know. I don't want to cause someone to have to divert his beer money to buying unnecessary truck parts. One could get lynched for that up here.
I'd appreciate any educational input.
Frank

Click to expand...

You have point Frank, it's possissable to have the reverse gear to break beacuse of the sprag clutch locking up if you are in reverse, as I never gave it that much thought until now. I wish I would of took a picture of the broken reverse gear that I took out of my transmission. If everyone could see how the gear breaks, then one can see how the torque forces are applied and why a jerking action would very easily snap the "forcing ring" off the gear.


I finally got my voice back to where I can start videotaping again. I'll be back in the garage this week to continue on the project.

My 1952 M211 tranny isn't what it used to be. I purchased the truck in 1983 and fixed quite a few things but haven't done much with the tranny short of changing the fluid. For the last 3 or 4 years after a cold startup, when I put the truck in gear it would take some coaxing with the engine RPM to get her to start moving. After a minute or two everything seemed pretty normal until I would get 7 to 10 miles from home. I then couldn't get the tranny to shift into 4th gear anymore. I tried lots of things that were recommended to remedy the issue but always got the same result. I gave into the fact that I couldn't get far from home and if I did travel far I was destined to drive home in 3rd gear. I aquired a transmission out of a very rusty parts M211 that was thought to be good even though it hadn't moved under it's own power in about 20 years. After putting the tranny in my truck this winter I now have a tranny that engages like it means business as soon as I put it into gear and I can't remember my old tranny doing that in years. Only problem now is I only have 1st and 2nd gear as I can't get her to shift into 3rd. Is it likely that the valving that allows fluid flow to the 3rd and 4th gear functionality is hung up from sitting so long? And if that is the case should I be able to remedy that while the tranny is still in the truck? What's your best guess for a solution?
> Thanks, WC63
>

wc63

sorry for taking so long to get back you but here's the easiest way to narrow this down. the first thing is to make sure your linkage is dead on. if its off more than an 1/8" of an inch, then you can run into all sorts of problems. The old saying goes close enough for goverment work does not apply to the linkage adjustments os make sure it's dead on. Also make sure your governor valve on the distributor isn't rusted open and the diagram on the carburetor is in good shape and the linkage is hooked up to the butterfly valve. If you know for sure that is not the problem , then take your control valve off your old transmission and put it on the one you just installed. this does two things, troubleshoots your old transmission and troubleshoots your newer transmission.
your control valve might have a sticky control valve shuttle in it. since you have to remove it to clean it you might as well swap out the control valves to see if clears the problem or does it transfer the problem you had with you old transmission one the new one.
After swapping out the control valves and there is no change to the shifting problems, then drop your transmission pan and remove the rear servo. the bigger one with the spring on it. When you take it out see if there is a band adjusting claw on it. if not then your rear band is out of adjustment. . but any way once its out swap it with the one from your old transmission. again we are trying to troubleshoot two transmissions at once here. if swapping out these two components do not effect the problem you are having with your shifting problems, then you are going to have to do a tear down and check all the clutch places, bans and ring seals for wear or damage. Again first swap out the control valve first and try it if no change swap out the rear servo then try it. if no change a tear down is required.

I know dropping these transmission is a big pain but once you find the problem inside you have an golden opportunity to check everything else and fix anything else that might be worn. Then when you put it all together again, you know you have a NEW transmission.


Stephen Feldmeier

Sorry for the delays, but ran into several SNAFU's along the way,
1st, was furloughed from the railroad and had to find a second job which I had to work 6 days out of the week
2nd got half way through the video, then if you look on page 156 in TM 9-8025-2, I ran into the problem of end play between the "output shaft" and input shaft" Problem with bearing "B" One size bearing to thick no end play, the next smaller bearing too thin much end play.
3rd Since I was at a stand still, A welding project arose and had to box up the tranny, and convert the section of garage into a welding shop.
4th Since I was furloughed which pissed me off, I got involved with the "T.E.A. Party Movement so that took up a lot of my time.
Now that the welding project is over, the elections are over and the American people are waking up to what's happening to America, I can put down my Patriotic Drums for now and restart this project I promised.
I have to do a through cleaning of the garage this winter, repaint the floors and convert it back to rebuilding the tarnny and hopefully find out the end play probelm.

Steve, I just read through this for the first time and you are doing an outstanding job. I have no experience with these transmissions but even I can understand their operation through your very well worded explanation. Thank you for all the effort you are putting into this. It will help a lot SS members.

On your bearing problem can you shim the smaller bearing to get the proper end play??