TH350C been sitting a few years

[Raider L]

@78C10BigTen,

I don't get it. What did you do with the one in your truck? Or, do you mean you went to the junk yard and bought one and put that one in your truck? I understand about the money part, who has nine bills laying around, but why wouldn't you want a (new) transmission? That way it would last for many years. Probably much longer than the junk yard one, and then it would need to be rebuilt and you'd have to go get another one from the junk yard. Or maybe by that time you'd have saved up the nine bills? Explain your thinking Ted.

 

[78C10BigTen]

@78C10BigTen,

I don't get it. What did you do with the one in your truck? Or, do you mean you went to the junk yard and bought one and put that one in your truck? I understand about the money part, who has nine bills laying around, but why wouldn't you want a (new) transmission? That way it would last for many years. Probably much longer than the junk yard one, and then it would need to be rebuilt and you'd have to go get another one from the junk yard. Or maybe by that time you'd have saved up the nine bills? Explain your thinking Ted.

The one the truck came with had no 3rd, bein a daily and not much money i dumped in a junk yard one... it blew also so a cragslist one went in. That one blew also so i finally found another good craigslist one thats still in there. Needless to say i hate th350's!

 

[Matt69olds]

I’m on a few other old vehicle forums, I hear the same thing from others needing transmission work. I don’t understand why shops don’t want to mess with them, parts are not that hard to find if you take a little time to look. The only thing I can figure is some places just install remanufactured units and don’t want to screw around with rebuilding them. I guess I can kinda understand that, then the shop doesn’t have to deal with potential warranty issues, if there is a problem the rebuilder pays the labor to swap it again.

The 350 (and 350C) is one of the easiest transmissions to work on. The tools needed are cheap and easily made with scrap stuff most people have sitting around in a normal hobby garage.

Unless someone has run the transmission low on fluid, chances are there is nothing that can’t be fixed with a good overhaul kit. And if something is torn up inside, GM built MILLIONS of these transmissions, the parts are available. They aren’t as common as the 4L60 parts, but they are available.

If money is a issue, and the truck is still drivable, I’d suggest trying the rebuild yourself. Find another th350 to build. When the rebuild is done, make the swap. If your comfortable doing a engine rebuild, a th350 rebuild isn’t hard. There are countless YouTube videos, books, manuals to walk you thru it. Probably the hardest part is bushing replacement, that’s something a engine machine shop or transmission shop could do pretty cheaply. Before I had all the fancy bushing drivers I used a cam bearing installation tool to drive the bushings in.

 

[Matt69olds]

The problem with installing used transmissions is without tearing them apart for inspection, it’s hard to guess how much life is actually left.

Of course, whoever you buy it from says it worked when removed. They just never say if it worked right!!!

Properly built, a th350 will handle 550-600hp pretty easily. No question it’s more durable than a 700. Obviously, it’s nowhere near as strong as a 400.

 

[Dmack]

Matt69olds, can you recommend a rebuild kit for the TH350 for just average use, not high hp applications? Thinking about trying it on a spare th350 I may put in my new 1970C20 project.

Not trying to hijack the thread, but thought it was relevant.

Thanks for the help you routinely give here.

 

[Matt69olds]

I order my stuff from this place, ask for Cheryl.

https://www.tealautomotiveinc.com/

They have lots of good used hard parts, they can ship anywhere. I use TransStar overhaul kits, you can get them with standard clutches, race clutches, standard steels, Kolene, with or without bushings, etc.

 

[Dmack]

Thanks for the help.

 

[scenic760]

Matt69olds, can you recommend a rebuild kit for the TH350 for just average use, not high hp applications? Thinking about trying it on a spare th350 I may put in my new 1970C20 project.

Not trying to hijack the thread, but thought it was relevant.

Thanks for the help you routinely give here.

I actually just got pinged there was a new reply to this thread (I didn't get any previously)...no hi jack at all because I was reading the replies and thinking yeah, it probably makes sense at this point to rebuild the trans while the engine is out (I have a couple of issues there I need to resolve before it goes back in too) and I was wondering the same thing!

I have a quick question, someone said they got a quote on a 2wd 350th rebuild...is the 4wd any different?! Should just be the transfer case, no?

 

[Bextreme04]

I actually just got pinged there was a new reply to this thread (I didn't get any previously)...no hi jack at all because I was reading the replies and thinking yeah, it probably makes sense at this point to rebuild the trans while the engine is out (I have a couple of issues there I need to resolve before it goes back in too) and I was wondering the same thing!

I have a quick question, someone said they got a quote on a 2wd 350th rebuild...is the 4wd any different?! Should just be the transfer case, no?

It should just mean it has the tail housing on it. 4wd has a different output shaft and no tail housing as it gets bolted to the adapter with the shaft going into the transfer case.

I would also recommend doing at least a minor rebuild on any used transmission before slamming it in. Basic rebuild kits are dirt cheap. You can get a 350 core and a rebuild kit for probably $300 total. Then just get a 5 gallon plastic bucket and a lid, cut a hole in the lid and go to town.

It really isnt that hard if you have any basic mechanical ability

 

[Matt69olds]

There is no difference internally between a 2WD and 4X4 trans other than the output shaft. You could bolt in a 2wd trans case into a 4x4 once the output shaft is swapped. Obviously, the heavy cast aluminum inspection cover won’t bolt on.

I have done this conversion a few times. There are a couple 4x4 square body trucks running around with Buick 455 swapped in. I converted the BOP 400 trans to 4WD by installing the output shaft in the BOP case.

 

[scenic760]

Thanks again for the info!

I think my transmission is going full on mission creep status...while the engine is out might as well go through tranny, while doing that might as well rebuild, while doing that might as well do a couple of the common performance upgrades, etc..

Been doing a bit of web searches and video watching and this guy seems to know his business and the "dual feeding" of the clutches seems easy enough while it's apart, anyone see any issues with this? It's in the #5 post on the thread.

https://nastyz28.com/threads/th350-rebuild-online-free-diy-post.53671/

I was looking at a video that was almost a follow along and the guy was using a Transtar kit #44008DFHP which I couldn't find with a google search, admittedly I haven't called Cheryl at Teal Automotive yet but I will. This kit seemed to be the closest I found to what a complete kit would look like?

https://cyclonetransmission.com/pro...sprags-red-clutch-high-performance-master-kit

After looking at some videos I think your absolutely correct B, it looks like a series of a lot of things but nothing too difficult. Like anything else be detailed and take your time...I had an old carpenter tell me one time that speed comes when you know where you can **** something up and it will still turn out good...being this will be my first tranny rebuild I have a feeling it's going to take me a bit!

Here is a link to the videos as well
part1

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part2

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[scenic760]

Another question, what is the best way to have the piston cut down for 5 clutches...someone said a brake lathe but if I show up at a brake shop and ask them to cut down the piston are they going to know what I'm even talking about?!

 

[Matt69olds]

I have a buddy that runs a auto repair shop. I use his brake lathe to cut pistons. Since brake lathes only cut .030 at a time, it does take awhile to cut the thickness of a clutch and steel.

Jake knows his stuff, that’s TH350 build description is how I set up my 350 builds. I can tell you from experience the dual feed modification won’t work on a TH350C. For whatever reason, the lockup won’t work. I have never researched the hydraulic diagrams to try and find out why. Just follow all the other steps and you will be fine.

 

[Vbb199]

The number you're looking to take off the piston for a 5 clutch mod is about .120 iirc in the th350 direct

 

[Vbb199]

Tc install is very important to keep is concentric to the internal components.... if you install the tc incorrectly, it'll destroy your pump rotor, cause pump chatter, destroy the tc snout bushing, and maybe wipe out the seal....

I install a tc after checking its depth as matt said by going around to all the bolts, snugging them up, 1 by one, but after snugging them, back them off 1 turn or so, and gradually, 1 by one, working it around, torquing each one slightly a little more each time, to keep the tc centered up... if you just go torquing 1 tc lug bolt down, then doing the next, it'll pull it hard to that side, and wear **** out...


Take note of how loose the tc bolt is in your flex plate.... you can see theres alot of room for error just running bolts down with the impact 1 at a time lol
Its time consuming, but an appropriate tc install is what greatly aides in the longevity of your tranny... especially in high rpm, high hp applications.