Th350 general questions

Howdy,

Just grabbed a th350. Have a few questions.

1) the dipstic tube is loose fitting into the assembly and I assume missing a grommet of some kind. A quick search shows o/ring type and boot type. How do I know which I need? And if the old fell out into the housing, will I see it when I do a filter change and be able to remove it?

Let's start with that. I have a few note questions, too.

Thanks all!

Drew

 

The dipstick will have a groove around it where it goes into the case if it needs an o-ring. It will be smooth if it uses the boot type seal.

 

thanks! It has a groove so right on.

Next question:

2) I have never installed an auto transmission. How, with the thing not running, do I put the propped fluid level in? I see some still in the torque converter - a beautiful color of red so Lord willing it's a good transmission - but I want to dump that (any trick?) and then what? Fill it as much as I can? How much into the pan?

 

If the transmission has been drained by removing the pan, then you want to add 4 quarts to it using the dipstick tube. Then start the engine, run the shifter through the gears, and check the level when it's running (idling in Park), you have to wipe off the dipstick then poke it all the way in, then pull it and read it. Read it carefully, look at both sides, make sure you're seeing the actual level. It will probably be too low to register with only 4 quarts added. If it's not up to the ADD mark, then add more, but don't fill it above the ADD mark while it's still cool. Each time, add one quart, run the shifter through the gears, and then check it again. You want to sneak up on it, so you don't overfill it. Once you get it up to the ADD mark, go for a drive, get it warmed up, and then make sure it's between ADD and FULL.

If the transmission is fresh rebuilt (dry, no fluid) and the converter is dry, it will take about 11 quarts. I would expect one like yours to take about 6-8 quarts

 

Thanks! What about draining/filling the torque converter before putting it all together? Engine and Trans are on tires on the garage floor. And the above is how I have done transxels since I was a young kid so glad it's all the same! My story is backward to most. I learned on computerized front wheel drive stuff and just got into the good ol Detroit iron a few years ago

 

I would drain all the fluid from the convertor that you can. Some people will put a quart or so of fluid in the convertor before installing it I never did that in any of the hundreds of transmissions that I have built over the years, but some do that

 

It's an odd shape - a Taurus I believe is the name of the 3 dimensional object - like a glazed donut. Any trick to getting it all out? This thing sat for a while

 

Put it upside down in a drain pan, and let it sit for an hour or two. It won't drain all the way.

Torus.

 

Good call on the spelling. Not my strong point. So I don't need the kick down right? We're taking about a 3500 pound car with 300hp when I am done

 

I always connect the kickdown. But I like messing with that stuff, and having things work properly.

 

Before anyone gets any funny ideas, the TH350 is the ONLY transmission I know of that will live with the "kickdown" installed (OK, TH400, too, but that one's easy to do). This is because on nearly every other transmission, the cable (or rod) is NOT a "kickdown". It is a throttle position rod, which adjusts pressures in the transmission to the throttle position.
Then there is the whole "doing the job correctly" thing, which I'm not going to go further with tonight.

Cosmo

 

Remember when installing the torque converter to push it into the transmission and to keep turning it to engage it completely. Failure to do so will result in failure!
KK

 

Ok - then let's install it. Anyone have any general idea how to? From scratch? I'll need a new one mine is freyed

 

This ^
Very important especially if it's your first time.

 

Yes cause there is two sets of splines. If i don't seat the second it will be tight against the flywheel right? I just learned that before coming here and starting this form. I like to really talk things over before diving in. Saves me many headaches

 

And thank you guys cause that could be devastating

 

Now would be a good time to check the starter teeth on the flex plate and replace it if they are worn. Also, put some trans fluid on the stub of the converter where it goes into the pump splines. It will keep the seal from getting torn. Just like you would on a balancer going into the timing cover seal. Good luck, the TH350 is a pretty bullet proof trans.

 

To drain the converter, you will need to suck out the fluid with some type of hose or pump. You can never get it all without drilling a drain hole. You can get most of it though. When installing it, you should hear it drop into place over the pump. To double check its location, your fingers shouldn't be able to fit around the back side, the case will be pretty close to touching. When its wrong, there is enough room to grab it from the back. I hold the center of the converter where it goes into the crankshaft end with my right hand, then with the left hand spin the converter while pushing with the right hand. You can lift or drop the with the right hand to help align the pump, it usually drops right in with a clunk.

Change the converter seal while you have it out, they are cheap and easy to do, same with the tail shaft seal. Rock auto will have them for $3 or $4 dollars.

The kick down is not needed to run and live. Just plug the hole with a rubber stopper and use the cable clamp to hold it in place. Mine has over 10,000 miles on it and still going strong.

One note on checking with a dipstick, you need to wait for all the fluid to run down the tube and it takes a while if the tube is long. You can pickup fluid on the way out and get false readings.

 

If the trans has been sitting for a while jack the rear wheels off the ground while you're filling/running it. You want to start it off with no pressure on the internals.

 

there are kickdown cables available readily, the fun part usually is finding the correct bracket to mount it in the correct place relative to the carb. What do you have now? some engines already have the mount for it, it's a bracket with a square hole, that is in line with the bottom of the throttle lever on the carb.

also to double check that the converter is in all the way, the finger test is ok, but you can also measure from the edge of the trans case to the converter lugs, and compare this with the measurement from the back of the block to the pads on the flex plate. You want a little extra room there, you should have to slide the converter out a little bit to meet the flex plate.

 

The block and the trans were from the same car and the bracket is there. I think I'll just order a cable for the donor car (74 nova)

How is this dipstic tube supposed to seal? The recess for the apparent o-ring is quite deep... Can't imagine a standard o ring would make a seal if I found one that for. How sealed should it be?

Also, how does the transmission and the torque converter exchange fluid?

Thanks all. This is helping a lot. I like to learn stuff before I jump at it with wrenches and a welder

 

If the dipstick tube has a groove for an O ring, you just put the O ring in it, smear some transmission fluid on it as assembly lube, and stick it in. It works. Unless the tube is bent, or cracked, or something.

the later design used a sleeve instead of an O ring, there is no groove on this type of dipstick tube.


The fluid is pumped into the converter, and goes back out again, as part of normal transmission operation. Also, much of the heat developed in the transmission is from the converter. you might find a hydraulic diagram of the TH350 somewhere online, they put them in the old factory shop manuals.

learning is good.

 

I know it was mentioned but.....rotate and gently push the converter into the input shaft......clunk, 3 times as the inner parts of the converter spline onto the input shaft and pump drive. Also you should be able to freely rotate the TC after the bell housing is mated with the engine block DO NOT FORCE IT. With the trans bolted up you should able slide the TC rearward the space between the TC boss and the flex plate should be 1/8" or less. Not all torque converters are made the same and you want to have as much positive engagement to the pump drive with out binding. BTW plenty of you tube vids.

 

Thanks guys! I appreciate it. I have to get an o ring that fits. Someone gave me one but its to big for the groove.

I have been told that the angle of the output shaft of the transmission and the input shaft of the rear end must be the same. even if both aren't parallel with the ground, they must be parallel with each other. I am curious to here from experienced car builders how this is done. Thanks!

 

We'll need the can opener for the can of worms.....I think I have a gas powered one. Study the chart. you should not exceed 3 degrees between driveshaft and yoke or you will get a nice grumble. Sorry pic is kinda small if you Google (images) driveline angles you'll find plenty of good info.

 

are you replacing the whole drivetrain all at once? if so, you need to put the spring perches on the new open drive rearend at the right angle, etc.

btw, if you get just any O ring that someone gives you, it's probably the wrong one for the application. You need to get the correct O ring. There are many different sizes and materials....only one is right. An old transmission shop might be the best place to find one these days.

 

Yea measuring that seems over my head... Open to suggestions

 

measuring what? The rearend, or the O ring?

 

Measuring the trans angle and then lining up the rear accordingly. Or do I just try to keep the engine "level" (the top of the carb via a bubble level) and then aim the rear end at it? Pardon me if I seem thick headed

 

Use an angle finder



to find out what angle the cranshaft centerline is at. It should be about four degrees nose-up relative to the car's frame, if you have the frame level, and the carb flange on the intake level, and the transmission pan level. Then set the rearend so the pinion is pointing up almost at that same angle of about four degrees. I like to leave the pinion about one degree down relative to the crank centerline...since the axle winds up a bit (the leaf springs will allow some twist), and driveshafts seem to like it better if the rear end points down a tad relative to the engine.

there are lots of threads on the hamb about setting up driveline angles, and there are also lots of ways guys do it, and describe how they do it. Many of these methods work.