Just had a curious thought for the transmission guys. Is there any real way to tell or a bench test to you can do to deem a junkyard automatic transmission trash or good enough?

Reading through some articles and watching a few YouTube videos it is apparent that there is no way tell..

just wanted to know if someone out here had something.

 

I would say pull the pan off and see how much trash is in it. If it is fairly clean then it should be a rebuildable unit. If it is full of metal then all bets are off.

 

A TH 400 isn't like a Slim Jim Rotohydramatic. If there is no glitter or clutch material in the pan then change the gasket, put new fluid in it and drive it. I wouldn't hesitate to do this with a TH 400 for my Oldsmobile or a C6 for my f250. The Slim Jim Rotohydramatic and E40D are a different story...

 

My rule of thumb was to get one out of a car with severe front end damage... Tell tale sign it was working at the time of the accident.

 

A good alternate is to post a wanted ad with your location.
There are many of us who have good T-400s in the back of the garage.
I have two, one with switch-pitch.

 

Last week my son-in-law took his th400 to the local transmission shop because it had a leak from the front oil seal. He asked the owner to check it over and change the filter while it was there.
It had given no symptoms that anything was amiss apart from an oil stain on his garage floor where it was parked for the winter.
We had tied a plastic bag to the tailhousing to catch any spills while it was in transit, the oil that leaked into the bag was clean and smelled fine.

However the next day we were sent pictures of delaminating clutch plates and worn out bands.
The shop owner (who I have known for 45 years and is as honest as they come) reckoned giving it an enthusiastic right foot a few times would have brought about its very rapid demise.

So you may get lucky, but a proper look inside it is really the only way to tell if it's good to go or needs some work.
Unless the box can be authenticated as a genuine low mileage rebuild, I would treat it as a core for rebuilding.
There really is no way to tell how good an engine or transmission is merely by looking at it, you will always need to delve deeper than that.

Roger.

 

The only problem with that approach is that by the time you dismantle the tranmission far enough to inspect the clutches it's already torn apart and you MAW rebuild it.

 

I know. But do you want to take the chance?. You may get lucky, you may not. SIL wants to put his transmission back in his Trans Am and forget about it. I agree with him.
I also think he will only have to pay for a straighforward overhaul. Perhaps if he had left it further expensive damage might have occurred.
Mind you, in the UK you can't just go to a junkyard and pick up a transmission for any American car.

Roger.

 

IMO, if you are able to verify the transmission past history/condition as being reasonably trust worthy, install it, but also change all accessible seals and gaskets that don't require completely dismantling the trans itself... Adding new fluid is obviously necessary as well...

 

Thank you all for the inputs guys!

The trans came out of a 1975 cutlass surpreme with the 455 still attached. The car had 20k - 30k miles before it sat for a billion years (dont know why...) then the owners pulled it out just a year ago.

It has a lot of corrosion but not terrible. Its differently restorable even as a core. Haven't had the chance to crack it open but the fluids look good from the dipstick, it shifts, and the torque converter was spinning when we turned over the engine by hand.

 

I would rebuild it while it is out, you'd be surprised how basic these old transmissions are. If you can get a hold of a service manual from a car around that year that used the turbo 400 it would work. Most of the special tools can be made or standard tools will work with some extra difficulty. I made a "Belly Tee" that I used to remove the rear clutch on a few transmissions. I've never done a Turbo 400 but I would attempt it if it were already out. Kits are cheap also unless you want a heavy duty strip type B&M or something. Try it out you might surprise yourself.

 

Sounds fun, I think I'm give that a try! I know the rebuild kits and shift kits arent that expensive. I was calling around for quotes from trans shop to see how much it would cost to just rebuild my th400 and they all have me a ball park price of around $1500... Not really down with that idea.. I think at that point I'd rather just look for a trans that I actually want in the car.

 

Damn, here in Texas a T400 rebuilt with shift kit, deep pan, and some other misc parts ran me under $600.

 

x2

When I had mine rebuilt they put a stock deep pan on it and a new vacuum modulator. It was a bit less than $600 but I didn't have them install a shift kit.

 

I'm in Hawaii. I think they do a one for one swap..

 

Ah that explains it...

 

Pull the dipstick assuming the trans has transmission fluid in it and is full. Wipe the dipstick on a WHITE paper towel and observe the color. Is it red, brownish red, brown or black. The only color you want is red, just like it came out of the bottle. Anything else indicates it got too hot.
Next, smell it. It should smell just like transmission fluid should straight from the bottle. If it smells burnt in anyway it is burnt. It's simple.
If the above pans out I would have no problem using the trans. Otherwise I would assume overheating and that's bad.

 

Good enough for me! Everything checks out good!

 

Yep, just set up a big work area and take everything apart slowly and put it in a line on the bench. That way you know how it came apart and can put it back the same way.