Turbo 350 Build

[HotRodPC]

And that's all there is to that folks. Slow and Tedious !!! I now have new threads. Towel and gasket is now removed. All shavings were vacuumed off the towel and gasket. And I also carefully removed the towel and gasket as if it did have shavings on them, just in case I may have missed some with the vac. So back to where I left off and ready to install the pump AGAIN !!!

As previously discussed and pictured. The pump is now installed, torqed to spec, input shaft end clearance checked again, input spin test in both directions and all is well to this point.

The transmission is now taken out of the hole on the table, and laid on its back with vavle body area facing up. Its now time to install the vavle body and all the externals and get this thing finished finally. Fingers crossed, hoping to not have any more unforeseen incidents.

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[HotRodPC]

Next part to be cleaned and inspected is the vavle body.

I will not be using this valve body. I have noticed the 2-3 accumulator spring is missing. I know this because the accumulator piston is not putting any pressure against the C clip holding the piston in place. So I'll use the donor valve body and keep this one together for a spare vavle body. In the event I come across a bad valve body, I'll rob the accumulator piston spring from the damaged body and install it into this valve body. The 2-3 accumulator is designated by the red arrow.

The Blue arrow designates the detent pressure vavle. It is easily removed by using a 7/16 wrench or socket and removing the bolt over the retainer. The detent pressure valve is what gets connected to you detent cable that goes to the throttle linkage. Most often reffered to as the kick down or passing gear cable. The detent valve does more than provide passing gear. The transmission also depends on the detent valve to help determine shift point of the transmission. Although, your transmission will shift early, no harm will done to your transmisison by not having this cable hooked up or correctly adjusted like the 700r4. In the 700r4 transmission, the Throttle Valve (TV) Cable also regulates pump pressure. The Th350 has its own seperate pressure regulator vavle seperarte from the detent pressure valve and why you can get by without hooking up the detent cable on the Th350.

The White arrows are pointing to retaining pins of the other valves in the valve body. The will all need to be removed one at a time to remove the valves and springs form their respective bores.

 

[HotRodPC]

To remove the detent pressure valve, use a 7/16 wrench or socket and remove the bolt and retainer. The valve and springs slides out. As will all vavles in the valve body, use caution when pulling or allowing valves to come out, as some are spring loaded. Nothing extreme that a finger can't hold in place, but you know how spring loaded things like to take off and never to be found again until long after you have given up looking for them.

This is the detent pressure vavle, spring and retainer removed from the valve body.

Using some kind of clamp, whether it be a C clamp or Vice Grip clamp, compress the 2-3 accumulator piston so that you can remove the C clip holding the piston in its bore. Use caution and compress this piston very slowly. Reason being, there is more than likely plenty of fluid still behind this piston and it will squirt out at you into your face, eyes and all over your clothing. Once compressed use a small screwdriver, remove the C clip, then pull the piston from its bore.

This is the 2-3 accumulator spring that is under the piston. This is the spring that was left out of the original valve body. I will assume the previous builder was hoping for a harder 2-3 shift by leaving the spring out.

Notice the sealing ring that goes to this piston. You should have a new sealing ring in your rebuild kit, that after you clean the piston, you will install the new ring in the piston groove.

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[HotRodPC]

Removing the other valves can be a bit challenging. I've seen videos where someone used a magnet to remove the valve retainer pins and thought, cool I learned a new trick. It didn't seem to work for me. Normally, I flip the valve body over and lightly tap it on some softer type wood or block. You do this while using a finger to push in on the valve to take the tension off the pin retainer. Once you get the pin above the valve body surface, you can then use pliers to pull the pin completely out, while applying a little pressure to the vavle. You want to do this anyway because some vavles are spring loaded and you don't want them just flying out of the valve body.

Occasionally you're going to come across stuck valves. Using a pick or small screwdriver, you can gently help the valves out of the bore. Many times taping on the valve body with a hammer handle will jar them loose also. You must be careful not to score the valves or the valve bores. This is very critical to not damage valves, springs and their bores.

As you pull the valves out of the valve body, you want to keep them laid out in the order they were removed. Usually on cloth or something that will keep them from rolling away.

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[HotRodPC]

Once all the valves and 2-3 accumulator is removed from the valve body, now its time to give it a bath. Clean it in a solvent bath as much as possible.

Its just about impossible to get it completely clean in the solvent bath, but that will get the majority of the grime off the body. Next spray the valve body clean with Carb Cleaner. Spray it down the bores and across the top of the body. Carb cleaner is good at removing and disolving grime for the bores. After a good cleaning. Allow the valve body to air dry for 30 minutes to an hour. It can air dry why you are cleaning the valves and springs. You can also use a blow gun or air nozzle to speed up the process a bit if needed.

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[HotRodPC]

I also use spray carb cleaner to clean the valves and springs. Keeping them in order, just turn and twist them as you spray the cleaner.

Once you have the valve body clean and all the valves and other parts clean. Use a flashlight and look down the bores of the vavle body and look for any deep scores in bores, or possible burrs and blockages. Its very important as you install valves in their bores, before you put the retainers and pins in, rock the vavle body and make sure each valve is going to slide back and forth in the bore. DO NOT use lube on the valves and in the bores. This can hang the valves up temporarily. The valves will get lubed with transmission fluid as soon as your tranmission is installed and the motor has been started up. The valves do not turn rpms, so lubing them for initial start up is not necessary and can actually be more of a negative issue. However, some builders may suggest to lube the valves. The worst that can happen in most cases, if using TransJel, is that the fluid might have to get good and hot to melt down the lube before the transmission works properly.

 

[oneluckypops]

This valve body stuff is very intimidating to me. I don't know how you keep track of all the little pieces and stuff, it's like working on a brain, lol.

beleive it or not it is not that bad, Yeah the first one you tear apart will get overwhelming but do as he said keep the valves in order and you wont have any problem.

After your first or second build you will have ALOT more confidence, lucky for you all you have had a write up to follow and videos to watch, For Hotrod and i we werent so lucky.

I still say you would be better off finding a cheap tranny (TH350) to disect, Dont even worry about having a rebuild kit for it at first, Just tear it down to the piston packs, and reinstall everything. Do this 2-3 times and when you think you got the hang of it THEN go ahead and remove the pistons and put the new lip seals on and completely rebuild then.


Doing a great job Hotrod, you need to go ahead and get busy with an 4L60E Transmission

 

[89Suburban]

Yah, good job on this HR, really appreciate all the work. Some day I may have a practice tranny to fool around with.

 

[HotRodPC]

This valve body stuff is very intimidating to me. I don't know how you keep track of all the little pieces and stuff, it's like working on a brain, lol.

When YOU LET things intimidate you, is when YOU CAN'T do them. So, don't let things intimidate you. Attitude is Everything !!! With a bit of confidence and pride, you can build an automatic transmission.

So you need to do as Pops suggested and watch these videos he has posted, look over the threads of information I have provided, study this write up in its entirety. Then get you a Th350 to disect. I wouldn't pay over $25 for a Th350 core. And I'd prefer to get one with the intermediate 9in tailshaft. Reason being, when you decide you don't need it anymore, you are more likley to find a buyer for it, or use it yourself in a Squarebody.

As you are disecting it, and them putting it back together, you always have this write up and videos to reffer to. The Th350 is the perfect transmission to learn the basics and the fundamentals on. It has a bit of everything, but is very basic and not complicated. The valve body is cast iron and hard to hurt, the pump body is cast iron and hard to hurt where later model transmission have aluminum pumps and valve bodies. They are more complicated in how you MUST inspect them because the aluminum bores do wear out. So do a Th350 a couple times and get the basics and fundamentals down. Then move into a Th400 if you want another confidence builder or have use for one. If you don't have use for a Th400 and don't have one, then skip that step because you usually won't find a Th400 core for $25. You might score one for $50, but most want $100 for Th400 core. So move onto a 700r4. They are very plentiufl as cores these days. I have picked them up for $20-$30. the most complicated thing on a 700r4 is knowing what changes were made every year and what is backwards compatible and what is not. Yes, changes were made EVERY SINGLE year of the 700r4. Then about the time they got it right, it turned in a 4L60-E, which is the same transmission as a 700r4 except its shifted by Electronic Solenoids with directon from the ECM rather than Governor, Modulators, TV Cables etc. The 700r4 and 4L60-E also have aluminum pump bodies and valve bodies. Not any more complicated other than more valves, but more delicate and more prone to wear and failure requiring more attention to inspection and tolerances.

When you build your own first transmission (and its done properly) and you take it for that first test drive around the block the feeling is awesome. Just putting it in R or D and feeling it go into gear is enough to give you wood !!! Then when you take off and feel that first shift into 2nd you're wood gets a little bigger and then into your final gear and you know you have all gears is about all you can stand with pride. Then when you nail the gas pedal and feel it kickdown is all you can handle and you blow your goo and have to get home and change your britches !!! If you think I'm lying, build your own transmission someday.

 

[HotRodPC]

Thanks guys. Yes, I sure hope someone gets some use out of it. Its taking much longer than I ever expected. I did the Th400 before but didn't go into near as much detail. I'm now up to 397 pics taken for this thread. Of course I am not using them all and only using the best of the best. But even then I still have to crop and resize them for the forum. Then upload and embed them in the post. After that type up the caption to go with the pic. Very very time consuming !!!

When you measure that tailshaft length it's the housing right?

Yes, you can measure the tailshaft. They only come in 6, 9 and 12 inch, so if its anywhere close to 9in on the tailshaft housing, then that's the one. What I am building here is a 6in for an El Camino. If it doesn't have a taishaft housing and the output shaft looks a bit stubby and is not tapered on the end of it, then that is a 4x4 model. Those are usually fairly easy to get rid of too and also harder to find.

 

[HotRodPC]

After you have the valve body clean,

Lube the accumulator bore. Replace the metal sealing ring on the accumulator piston and install in reverse of shown using the C-clamp or Vice Grip clamp. Don't forget the spring.

After cleaning and reinstalling all the valves, the valve body should look similar to this. Now set the valve aside, and get the case prepped for valve body installation.

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[HotRodPC]

Now is a great time to remove some of the small parts from the solvent batch and wipe them clean.

Assemble the band servo including the new sealing ring from your kit, in the order laid out here. Notice I have 2 Servo pistons show here. One is from the donor trans and I will be suing it. The picture does not show it well, but the original pistons is beat on. Likley wouldn't hurt to use it, but when you have access to better parts, use them. The reason the original servo piston was beat on, is due to no spring installed in the 2-3 accumulator which is what pushes on the servo to activate the band in the case.

After the servo is assembled as laid out, it should like this. The servo is now ready for install into the case.

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[HotRodPC]

Lube the servo bore in the case with TransJel. Install the servo into the bore of the case while holding and helping the the sealing ring to collapse to fit the bore. Using a pick or small screw driver can help. See the Blue arrow. The Servo is now installed.

Also time to install the pump filter screen. I've seen many transmissons run without this in the past. If you have it, use it. You'll notice I have it in place unidentified, in the upper right hand side of the pic.

Insall the 4 check balls. Many kits will include new check balls. If so use them. If not, wipe the original check balls clean and install them in their proper places in the case designated by the White arrows.

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[HotRodPC]

Next up, install the manual valve linkage. Start by finding the case seal for the linkage in your kit. Lightly tap it into place. It is somewhat recessed in the case, so you'll need to use a socket of similar size and lightly tap it in the case until you feel it stop.

Install the linkage as shown. Remember to put the tightening nut in place before you push the linkage all the way into the case. You need to allow enough space to start the nut before before pushing the linkage all the way into place.

After all the manual vavle linkage is installed, it should look like this.

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[HotRodPC]

Clean the seperator plate and the support plate in preparation for valve body install.

Once the plates are clean to satisfactory condition, this means no old gasket material left behind and plates are free from any grit, dirt or old grease, then find the valve body gaskets that match your appication. Most Th350 kits now come with 2 sets. One set for Lock Up Th350C and a set for Th350. This happens to be a non lock up model. If you don't know the difference, just match up your old gaskets. The difference is obvious so its not hard to match them up.

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