Turbo 350 Build

[HotRodPC]

After being sick for 2 weeks and having my son for Spring Break, I am fianlly getting to start this build. So here we go. I'll start with some pics of the kit. The steels in this donor trans looked great, so I just ordered a Banner Kit. Which is usally the bare necessities to build a trans. I also have a set of new left over steels that was not needed in a previous build. The bushings even looked good. This trans had been previously rebuilt with low miles on it, but the guy broke the input shaft. So it makes a good core for my bro's El Co where he needed a new case.

If you have not seen it yet, I also have a Turbo 350 Dissasembly Thread, which you should view first before this buld thread. http://www.gmsquarebody.com/forum/showthread.php?t=911

You may also want to visit my Th350 Information and Fact Thread. http://www.gmsquarebody.com/forum/showthread.php?t=891

Kit w/ Steels, Filter and New Kevlar Band. This started out as to be a hipo build. But bro decided against the hipo and wants stock dependable for this car now while running a stock OEM 350 motor.

This kit obviously has some parts I won't use since its for both th350 and th350C. I am building a th350, non lock up converter th350.

Here is the kit partially opened up.

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[HotRodPC]

Always the first thing to install in a Th350 is the rear case bushing. This one is good, so moving on to the Low/Reverse clutch piston assembly. This will require a special tool, or a homeade tool. Before I bought this special tool shown, I made my own out of a piece of all thread, an angle bracket that I bent in a vice, and ran the allthread out the back of the case through the output shaft hole. Had a straight edge with a hole in the center over the alltheatd, then a flat washer and a wing nut. As I tightened the wing nut, it compressed the return spring retainer. Use your imagination, you can make your own if you don't build alot of transmissions and can't justify the expense of the tool. The tool does also work in 700r4, 4L60-E and Turbo 200 if for some stupid reason you build a Turbo 200.

Here is the end table I drilled a hole in the center of to make a trans build table for in the house. Perks to not being married !!! And the low/reverse clutch piston assembly in parts. Seals, return springs, retainler ring, and snap ring along with the clutch piston and the tool used to install the assembly.

Notice I matched up the old seals with the new seals. All 3 new seals are now installed and lubed for piston insallation. I like TransJel for assembly lube. Its probably nothing more than Vaseline with trans fluid mixed in it. If you don't have have TransJel, use Vaseline. Do NOT use other grease as assembly lube in a transmission. Vaseline works well becuase it's a petroleum based product and with low heat, it will melt down and become part of the transmission fluid and cause no harm whatsoever.

I used a hard rubber dead blow hammer handle to tap the piston into postion. Notice the black marks on the piston. They will come off.
You can use a wood handle too.

Springs installed in the piston. This is the old style where the springs are seperate. Newer style, had the springs and retainer as one piece. I bit easier for install but no other advantage and works the same as this old style.

Return Spring is laid over the springs. Now ready for the special tool.

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[HotRodPC]

Next, intsall the tool to compress the clutch retrun spring assembly and install the snap ring that retains the complete low/reverse clutch piston assembly in place.

Tool is installed in the snap ring lugs, then tightened down to compress the retainer ring low enough to be able to install the snap ring that holds the assembly in place.

Now the snap ring is isntalled and the tool is removed and that assembly is installed.

Once you have that assempbly installed. You want to air test it to make sure the piston compresses properly and that you did not tear or rip a seal. Use a rubber tipped blow nozzle and hold tightly against hole shown in the underneath section where the vavle body goes. Do this test NOW. Its to late to do it once you have installed other parts and no access after you have installed the vavle body. You want to test it NOW, so if there is a problem, you fix it before you go any further.

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[HotRodPC]

Whats the difference between a th350 and th350c? How do you tell them apart?

Th350C is lock up Converter Clutch, Th350 is NON lock up. There is a solenoid on the driver side of the case if its a lock up C model.

 

[oneluckypops]

I am sure Hotrod already knows this but for those that dont, Becarefull air testing when the clutch pack is NOT installed. TOO much pressure and the springs cant hold the piston in its bore and will come apart.
I prefer to install the clutches, steels, pressure plate, and the retaining ring, BEFORE I air test.

 

[HotRodPC]

I am sure Hotrod already knows this but for those that dont, Becarefull air testing when the clutch pack is NOT installed. TOO much pressure and the springs cant hold the piston in its bore and will come apart.
I prefer to install the clutches, steels, pressure plate, and the retaining ring, BEFORE I air test.

You're right. I only did a 20 PSi test. Very low air pressure to be sure its working and I can see the whole piston assembly and all working. I'll probably hit it again with about 40PSI after I get that far. I have been cleaning parts and soaking clutches and haven't put anymore together since I'm taking pics.

Would you beleive I finally found a bad planetary on a Th350??? I got pics of it. Glad I had another one here. You can see the needle bearings and all to this things on one gear. And I found it, blowing dry after being cleaned and hit it with air and it didn't sound right. So I investigated and sure as ****. Its junk. First ever bad planetary in a Th350 ever, and I bet I have built probably 500 of those things. Planets sound cool when you spin them real fast using air.

 

[HotRodPC]

Moving on. Now its time to install the output shaft assembly. I call it an assembly because its together with the outer ring gear of the rear planetary. Notice I didn't disassemble the assembly. There is no reason to unless you need to change the output shaft or the ring gear itself. FYI, the assemply is help together by snap rings and it comes apart easily without need for special tools. First, set the rear Torrington bearing in place. Either in the case, or slide it over the output shaft into position. I choose to add lube and set it in the case and then set the output assembly thru the bearing. Also, sometimes you may have some selective shims for setting the proper end play. In this case, none were there when disassembled, so I am going without any now too.

Output shaft assembly shown here with rear Torrington Bearing and Thrust washer, shortly after being taken out of the solvent bath and allowed to dry.

Output assembly with rear Torrington Bearing in place to make sure it fits snug, moves freely and is not damaged. You also notice the hole in the install table. Now is when the hole is required for the assembly of the transmission. I prefer to use this method instead of using a high dollar GM installation tool, which would make it easier, but I've done without it this many years, I think I'll continue to do fine without it.

The front thrust washer is in place with TransJel to hold it in place during assembly.

I've now put lube on the Torrington bearing to hold it in place while I slide the output shaft assembly thru the bearing, and out the back of the transmission case, thru the hole in the table.

Output shaft assembly now installed in the case.

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[HotRodPC]

Next up is to install the rear planetary gear set. Very important to check the pinion planets for smooth operation, and no chipped gears. Its very uncommon to find them in poor condition stock to mild perfomance vehicles. But, its the one that you don't play close attention to, that will get you and ruin a complete build in short order. And we're about to find this out on the paticular build. In the rear planetary unit, its also part of the outter ring gear that the low/reverser clutches will ride on.

Rear planet installed, with the first low/reverse steel installed over the outer ring gear onto the low/reverse clutch piston.

Next is the first low/reverse clutch. Then a steel, then a clutch, then a steel and so forth til you have installed 5 clutches and 5 steel seperators. 5 clutches is standard for a V8 or higher performance V6 motor. 4cyl and 6cyl models use only 4 clutches and steels. If you are building a core out of a 4cyl or 6cyl model, you can easily interchange with V8 clutch pistons that are shorter, allowing more space for the extra clutch and steel. You can do this to use the transmisison in a V8 auto, or even just as an upgrade for a 4 or 6 cyl transmission.
Also notice the clutches are saturated in clean transmission fluid. This is because you want to soak them in trans fluid for at least 20 minutes before installation. This prevents a dry start up when you first install the transmission, and the pump has not yet ciruclated trans fluid throughout the valve body and the transmission. Very important to do this step. You can actually knock thousands of miles off the life of your new transmission if you don't do this step.

This is called the Anti Clunk, or Anti Chatter Spring. This spring holds the center support/low/reverse clutch pack pressure plate steady and keeps it from shifting and moving around in the case when pressure is not applied to the low/reverse clutch pack. Without this spring, the center support/pressure plate will actually shift around and back and forth in the trans case and beat on the case lugs destroying the trans case to the point its trash. So this little spring is a very important part. Do not forget it or overlook it. If you realize you forgot it before you have installed the transmission, whereever you are in your build, stop, backup, take it apart to the point you can install the spring. Its that important.

Here I have altered this pic with an arrow and a close up view of where the anti clunk spring goes in the case. Right after you have installed the low/reverse clutches and steels, is the perfect time to install this spring. For now, it will actually just sit in the case, so its important to put plenty of lube on the spring to hold it in place while you install the center support/pressure plate which is the next piece to be installed.

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[HotRodPC]

Now that the low/reverse clutch pack and anti clunk spring is installed, its time to install the low/reverse clutch pack pressure plate. Some builders will refer to this part as a center support and why I reffered to it as a center support. Technically, it is NOT a center support at all. Turbo 400 uses a center support and actually acts as a bridge for the shafts to go thru and be supported. This pressure plate does NOT support the shafts although it does help join the front and rear planetary gear sets. You will find many builders have differant names for parts and they are not always correct. Many times its also a matter of opinion, so there will be times, I will be told I am not right either I'm sure. Just saying, I don't call this part a center support. I refer to it as the low/reverse pressure plate.

Pressue pushed into place over the anti clunk spring. Then the snap ring the holds the pressure plate in place and keeps if from moving forward or out of the case is installed. The one way roller clutch is pushed back into position, and the thrust washer is lubed to hold it in place as pictured.

Then the sunshell and sungear are installed.

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[HotRodPC]

At this point is where the front planetary gear is set over the sun gear. As I mentioned previously. Always inspect your planetary gears for wear, noisy or bad bearings, chpped teeth etc. Its rare in a Th350 you will find bad planets, but as I was cleaning this one, and blowing it dry with air, It made an earie noise that I have not heard before. So I was prompted to inspect it further and find out why. I found a bad planet pinion. Very excessive gear travel up and down to the point it even exposed the needle bearings, The pic isn't very clear since I was trying to get a very tight close up. I see where the play comes from. The pinions have thrust washers above and below the gear. The lower thrust washers or spacers simply are gone allowing the pinion to travel up and down, and off its bearings to a certain degree. Luckily I happen to have another planetary gearset here that can be used to replace this gearset.

Front planetary gearset. Notice these are manufactured as 1 piece. These are not serviceable by the trans builder.

See the needle bearings and all the space between the cage and the pinion? Not Good !!!

Also notice the wear on the teeth form obviously being previously run at an angle or not totally straight. Clearly a bad pinion.

Better shot of the exposed needle bearings.

And the replacement planetary gearset that is good. It has a little rust on it from sitting on the shelf for some years, but nevertheless, a little trans fluid and wire brush, it will be cleaned up as well as possible and workout just fine. This happens to be a later planet and is totally interchangeable with the older style hard parts.

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[HotRodPC]

Back to business. Install the new/used planetary gear set simply by placing it over the sun gear.

This is a little snap ring about the size of a quarter. Its very easy to forget about this part. But DON'T forget it. Its very imoportant as with all pieces to a transmission. This is the last piece that goes on the end of the output shaft, holding all the previously installed assemblies in place

The snap rings installs in a slightly recessed area of the front planetary, so it can be a bit challenging to get off and on. Its very important to veify that you have it firmly seated in its groove on the output shaft.

Now the snap ring is installed properly and the thrust washer is installed in place over the planetary with TransJel to hold it in place, awaiting the outer planetary ring gear to be installed over the top of it. Have you noticed yet that no hard parts are actually touching each other??? Every hard part is seperated by either a Torrington bearing or thrust washer. Knowing this is very helpful in remembering all your parts. Small things like thrust washers and snap rings are the easiest things to forget, but yet they are so very important. I've done enough Th350's in my life I don't even look at diagrams. Someone could bring me one in a box disassembled and I could tell you what parts were missing if any and reassemble it in my sleep. I don't like to do those jobs, but I have for people who THOUGHT they could handle a trans build, but soon realized they were in over their head, so they brought it to me. Disassembling a transmisison is part of the diagnosis process to see how things come apart and their current condtion or position. If its brought to you in a basket disassembled you don't get to do a full diagnosis on where any failure may be or what might need special attention. But, you can usually tell by looking at parts too, its just better when you can disassemble it yourself.

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[HotRodPC]

Install outer ring ring gear over the planetary gearset.

And then the thrust washer. At this point now. The direct and forward clutch drums and input shaft assembly will install over the outter ring gear all as one unit. So up next, I'll be disassembling the direct and forward clutch drums for new seals, and clutches. At this point, we have a bit of work to do without installing anything into the case. This is as far as we can go without rebuilding other assemblies.

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[HotRodPC]

OK guys and now girls... Its another evening. I'd have had this transmission done long ago, but taking pics, resizing, doing write ups on each part and trying to be as thorough as I possibly can, it is multiplying the time by at least 3.
You all are actually in for a treat this build. This is a good one to be doing a write up on since I am running into problems with it now with the direct drum, and you also got to see a bad planet gearset already which of all the Th350's I've done, I have never come across a bad planetary.
I don't want to blow my own horn here, but I am going to anyway, without being arrogant. Up there in the last couple posts, I mentioned someone could bring me a Th350 in a basket disassembled and I could rebuild it and know whats missing and put it together in my sleep. Its actually been over 15 years, closer to 20 years that I have built a Th350. I have built a few Th400's, 700r4, and a couple Dodge transmissions in the last many years, but nowhere near as many as I used to. But I can say, I still got it, and where I thought I might be rusty, its obviously like getting back on a bike. You'll see why as I proceed with the build. Why do I bring up such an instance??? You might think its to brag, but I'll assure you, its not. Its to point out, that experience in transmission building goes along way and its not for the shade tree mechanic as I had already suggested in this thread. I suggest when your doing your first trans rebuild. You dissassemble it slowly paying close attention to everything you can, and suggest you do your first one or 2 builds with someone like myself or Oneluckypops who has done many.
If you consider yourself better than a shade tree mechanic or a weekend wannabe builder, or you're just in a bad financial bind and need to build your own transmission to get by, I hope with this write up, and the Th350 video thread that Pops has posted, that you can do this on your own. I don't want to sound contradictive by saying you should do your first one with someone experienced, then saying anyone with average intelligence can build a transmission at the same time, but its true. With write-ups like this, videos that are posted on this site, a book or 2, and some of the diagrams and exploded views I have posted on this forum too, most of us here can probably build a Th350 transmission. Enough ******** now. How about we got on with the build, and you will then see why I paused to make this post about experience paying off.

 

[HotRodPC]

Its now time to disassemble, clean, and reassemble the clutch drum assemblies with new seals and clutches, and inspect things like bushings, return springs, steels presure plates and snap rings. The first drum I am going to work on is the direct drum which also consists of the intermediate overrun clutch aka Intermediate Sprag assembly.

I've already inspected the overrun clutch on the other side of this drum and its fine. We'll get to see another one shortly and you'll see why. So next step is to remove the snap ring holding in the clutces and steels. A screwdriver works fine for this.

Remove the pressure plate, tip the drum over and spill the clutches and steels out of the drum.

Notice the color of these clutches. These are not stock clutches. They appear to be High Energy clutches. But also notice how the upper clutches in the drum are worn almost completely smooth, and the first clutch isn't. That right there is enough to tell me, something isn't right about this clutch pack other than just wear.

Now is where you need some type of clutch spring compressor tool. There are several types and styles avaiable. I happen to have used this Haggerty Snapress since I bought it new in about 1989. Compress the return springs and retainer to remove the snap ring that hold them in place.

With the snap ring now removed, you can release the clutch spring compressor.

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[HotRodPC]

By the way, this paticular drum uses the old style springs and retainer.

DOH !!! Now wait a minute. We are missing some return springs here !!! There are supposed to be 17 springs. One on each piston lug. This could explain why the uneven clutch wear. This clutch probably does not release fast enough and drags the clutches. Someone may be thinking the clutch can apply faster with less springs. True that, but again, as mentioned above, I think it would cause slow release too. I think I'd prefer to enlarge the feed holes to increase the pressure to this pack for faster apply rather than short the return springs that pull off the apply piston.

I had already noticed this bushing here does not look very favorable and was thinking I am going to use another drum anyway since I don't have this bushing here, and I am not going to wait 3 days to order it, or spend $15 in gas and an hour in time to go get it locally. This is a busy drum of the transmission. You should probably just order this order bushing in the first place as I didin't, and replace it regardless every time you build a Th350. I'd imagine its part of the common bushing replacement set. This is exactly why it pays off to have an assorment of transmission hard parts laying around. Even if I had a bad drum and it had a good bushing, I could rob it from another bad drum, or if I have a good drum and the bushing is good I can use it. Just so happens that I do have another drum and it has an almost new bushing. Its from a transmission that was basically a low mileage rebuild behind a performance truck engine and the guy broke the input shaft with to much power. I stepped him up to a Th400 and part of the deal, I kept his Th350 core. Also note, I didn't build his Th350 or I'd have suggested a hardened input shaft or Th400 for his amount of hp/torque. Snapping the input shaft is the 2nd most common failure of a Th350 but usually only happens at above 400hp.

Now with the retainer and return springs removed, we can remove the direct clutch drum piston.

DOH !!! Houston we have a problem here !!! Here is where experience pays off. I know for a fact there is supposed to be a seal here in this drum. For someone on their first trans build who tore this transmission apart, would not even know a seal goes here, and wouldn't put a new seal back in its place. This drum is missing a seal. Seals don't just dissapear. This tells me, whoever built this transmission before, did NOT install the seal. So someone was trying a dual feeding process to the direct drum. That is a whole other subject for hi po builds. But, I am not seeing the others things to be done to permit dual feeding in the front of the this case. Just saying, if someone say to leave that seal out, don't do it, unless you know what other procedures to do also. You can get dual feeding also by installing a B&M Shift Improver Kit, or Trans Go Kit. Some prefer the backyard method over the kit method. I've have good luck with the kit method in the past and will simply stick to what I know works and have had good luck with.

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