TH350 Pan Bolts on 1978 Big 10

[thefatguy]

Long time listener, first time caller here.

I did (or tried to do) a filter change this weekend on my 1978 Big 10 TH350. I've done two of these before, and each time I swore I would never do another one. But you know how it goes.

Anyway, taking the old drainplug-free pan off was a real pain. The rear-most two pan bolts are almost directly above the cross-member, making it impossible for me to get a wrench on them, even after a trip to the Craftsman Weird Tool aisle. So, I loosened the mounting bolts and jacked the rear of the trans up about an inch, and finally got a nutdriver with a flexible coil shaft on them, and off they came.

I reckoned that would work with putting them back in and snugging them down, but...not really. I simply can't get them snug enough. They are leaking very, very slightly, but it's enough to make me crazy. Especially after taking a bath in Type F. Yes, I did install a new pan with a drain plug. Funny thing -- all I could order from Auto Zone was a chrome one. I spray-painted it with wrinkle black.

So, my question is this : what's the best way to snug those durn things down? Another weird tool? Support the trans and remove the cross-piece? Telepathy? I'm sure this has been answered before, but I couldn't find it in the boards. Or maybe everybody knows the secret already. Anyway, I'm happy to go read a link if you have one.

One other silly question: what size bolts are required for the torque convertor dust cover? Mine was gone when I bought this beast 8 years ago for ranch duty (I'm taking my time on doing this), and I ordered one from AutoZone (same chrome deal on that, too).

And let me add, as a first-time caller, I've found this board to super helpful in keeping Old Ugly running for the last 8 years. It's got a 454 in it, and since it's a Big 10, no smog junk on it. I'm mainly doing this for funsies now, so I can have a nice big-@$$ V8 for my grandson to drive in 14 years. Point being, yall are an awesome bunch of gearheads to virtually hang out with.

[LONGHAIR]

Especially after taking a bath in Type F.

This is the part that stands out the most to me....?

Why would you have type F transmission fluid in your Chevy truck?

[thefatguy]

Bad typing on my part...I had it on my brain. A buddy's got an 89 F150 that needs the same thing.

[ont_guy_38]

I would think that you could undo the tranny mount jack up the tranny a bit to get more access to the bolts

[thefatguy]

Yeah, I did that, and I gained about an inch of clearance. At that point, the U-joint is bumping up against the bed. It's still too tight to get a regular socket on it. I tried it with a flex-joint wrench but the angle keeps it from getting a good hold. I'm thinking that some kind of long-handled offset box wrench might get it.

[Pyrotechnic]

Use allen head bolts on those tricky rear holes, then get a long hex drive set. I bought a deep cast aluminum pan for mine and it came with allen head bolts. The long hex drive is skinny enough to get in there, and of course with a ratchet you can get them plenty tight.

[joe231]

if nothing else works you could always pull the cross-member
maybe you could clearance it so you wouldn't have this issue again?

[thefatguy]

I like that allen-head bolt idea.

[joe231]

yeah sounds like less work than mine
just fyi when you go looking, the proper name for those allen bolts are
socket head cap screws

button head socket screws

flat head socket screw

I assume you will want either the socket head cap or the button head socket

[thefatguy]

The tricky part is finding one or two or 13 that are an 5/16-20 x 5/8". I'm gonna crawl under there in a minute and look at that crosspiece closer.

[Albatrossian]

I've always used a 1/4" drive ratchet with a wobble and a u-joint.. with a short extension, you can get them tight enough so they won't leak.

[80SPORT]

You may have to pull the pan and remove any chrome plating on the sealing surfaces to stop your oil leaks ....we have had problems with chrome plated aftermarket thermostat housings and oilpans leaking ....

[dswancutt]

Originally Posted by 80SPORT

You may have to pull the pan and remove any chrome plating on the sealing surfaces to stop your oil leaks ....we have had problems with chrome plated aftermarket thermostat housings and oilpans leaking ....

Ditto on what 80SPORT said. I had a transmission guy tell me the same thing. He suggested just roughing up the mounting surface with a little scotchbite.

[N2TRUX]

Originally Posted by Albatrossian

I've always used a 1/4" drive ratchet with a wobble and a u-joint.. with a short extension, you can get them tight enough so they won't leak.

That was my method too. Get as much room as posible then use the 1/4" drive with a wiggler.

I think the button head socket screws is a great idea too. You might be able to use those cool ball head drivers.

[spudz]

I tighten all the pan bolts with a quarter inch ratchet... Because that keeps my ass from overtightening.. also with that cork gasket dont use silicone on it... it acts like a lubricant and will squeeze that gasket out the side.. just use gasket adhesive... I have been able to get to them with a quarter inch ratchet with extension and a swivel on the end.. Its either that or drop the crossmember....

[Slonaker]

Hello from another San Antonian...

Like the others, I can do mine with a 1/4 drive ratchet, extension, and a "wobble."

I, too, was only able to find a chrome replacement pan. I'm not crazy about chrome, so it is the only non-factory chrome on my truck.

Slonaker