Ok, I’m an idiot… or better, I was an idiot. Now I’m just a slightly better educated moron. So, I did my first transmission swap a few months ago. I went into it knowing absolutely nothing. The truck started and ran ok, but I never could get out of 1<sup>st</sup> gear, so I just assumed I had all the basic problems, low fluid, bad vacuum, bad modulator, etc… The problems gradually got worse. I can’t even put the truck into gear without it immediately stalling out. I am about to swap out the transmission for a fairly low mileage TH350 that is good and running, so I decided to do some research about how to do the swap right, and I found out how much I botched up the original. Here’s the short list of how I messed up the first install: -I had the torque converter bolted to the flexplate before the transmission. -I never checked for any gap between the flexplate and torque converter. -I never heard the necessary clicks from the converter when putting it up to the tranny. -And best yet, I used the bolts on the engine to feed the transmission up to the block. I find it amazing that the truck ever actually moved. Anyway, so how bad have I messed this thing up? Think it’s worth a rebuild if I torched it? I welcome any hazing and advice for my next swap! -Hawk
You probably ruined the pump, just for starters. Did you break any of the bolt ears on the transmission?
Not that I'm aware of. Are you referring to the dowel pins used to align the bellhousing to the block? I think you're right on the pump. Any chance I locked up the torque converter?
^^x2, pump will be toast almost for sure. Was it whining? Most likely, it will need new clutches and steels as well. Converter is probably fucked too. Look at this as a chance to learn how to rebuild automatics. Its not really that difficult. Get a shop manual, and tear it down.
Definitely needs a new pump. Could possibly need a converter and input shaft if the splines didnt line up and were just forced together. Get an asg manual for the rebuild process.
You might want to check the trans mount positions, trans lengths, also the trans splines are usually different (larger) on 400s than on 350s. So unless the 350 trans is good, and FREE, you may be money ahead to have the 400 checked out. 'Cause the 400 to 350 is not necessarily a direct swap. On the plus side, you now know what NOT to do when hooking up your trans. Good luck Buddy BILL RINALDI
That's sort of how I'm looking at it now. I'll definitely be giving it a shot later on. I never heard any whining, but with open exhaust, it's hard to hear much else, and I've never heard anything in the videos I've taken. Here are a couple if you want to see/hear how it was acting: <iframe src="http://www.youtube.com/embed/YhjnMWK2-Uo" allowfullscreen="" frameborder="0" height="315" width="560"></iframe> <iframe src="http://www.youtube.com/embed/cwmpAtv4bVk" allowfullscreen="" frameborder="0" height="315" width="560"></iframe>
No, it's not a direct swap. I'm going to have to change my tranny mount and driveshaft length. The TH350 is only $100, and I don't have to pull it. I thought about getting a TH400 from a junk yard, but I'll end up spending a day in the yard and about $200. How much does a rebuild normally run? To have someone else do it, I mean. I don't have the money to waste to mess it up myself right now.
Assuming your motor is basically a stock or mild street rod engine, why are you running a TH 400 ? They require a lot of power (parasitic loss). Unless you are pulling some big load or have a big hp motor, change to the TH 350. Just sayin....
I used the th400 because I had it, no other reason really. The motor is nothing fancy, 350. Maybe sitting around 220 hp.
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