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Full Synthetic ATF ??

cuervo

cuervo

Runn'n down a dream!
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So what the story/thoughts on switching?

I burned up my 4l80e towing my boat. Well, it started slipping and overheated. Without the boat it runs fine.

I'm putting in a remain and I'll clean out the cooler and lines, new torque converter too.

So, since I'm changing and cleaning out the old stuff I have an opportunity to switch to a full synthetic ATF if it's worth it.
 
If it didnt call for it, you dont need to run it. It wont hurt anything except your wallet.

That being said, make SURE you clean them cooler lines, that is a huge reason for repeated failures of reman units.
 
I've been told that really the only benefits to running full synthetic trans fluid is its ability to handle the higher heat better, the clutch material still can't handle it though or something like that.

Even still, with the crap I've been dealing with on these things, and the towing I'll be doing with both trucks in the future, I'll be running it.
 
Are you just going to switch to Dexron 6? That is compatible with the older stuff, and it is available at any parts house you go to. I think it would be worth it. It's not much more than the standard stuff.
 
Haven't a clue if it's worth it, but my 700r4 gets Amsoil synthetic and a BIG cooler. Whatever Leprechaun piss makes it last longer. :D
 
I already have a trans temp gauge in it.

As the first post says, I'll be cleaning out the lines and the coolers. I added an external stack cooler a while back. It's a BM and is the same size as the engine oil cooler. I did not by pass the radiator either.

Amsoil makes good products. I'll look into that. Thanks.
 
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Anyone know off hand which is output line on the trans. on the 91 the in and out are close together.

I also pick up a over-sized(3 qt) aluminum finned pan; B&M from summit.

trans.jpg
 
bottom port on a 4l60 is the pressure side and IIRC it's the same for all of them. So literally, the bottom hoes goes to the bottom of the cooler, top goes to the top.
 
K85 Octane said:
bottom port on a 4l60 is the pressure side and IIRC it's the same for all of them. So literally, the bottom hoes goes to the bottom of the cooler, top goes to the top.
Click to expand...

B&M says the lower hose is the return line.

STEP 2. Locate the oil return line to the transmission. On
Chrysler and most Ford transmissions, this is the line to
the rear of the transmission case. On GM TH-350, TH-
400, TH-700R4, and Powerglide transmissions, this is the
upper oil line to the transmission case. On GM TH-200,
TH-200R4, 4L80E and Ford AOD transmissions, this is the
lower oil line to the transmission case.
Click to expand...
 
Clearly there is issue between the manufacturers of aftermarket parts.

4L80E ('91-'96)
Fitting Location Thread Size Flow Direction
Upper 1/4" Pipe Return/In
Lower 1/4" Pipe Cooler Feed/Out

4L80E/4L85E ('97 & Later)
Fitting Location Thread Size Flow Direction
Front 1/4" Pipe Cooler Feed/Out
Rear 1/4" Pipe Return/In
Click to expand...
 
I can't answer the cooler line question but I will address the oil question.

Most "old school" ATF fluids will want to run around 180 to a max of 200 degrees for "normal" operation. A spike to 230+ will shorten the life of the fluid for sure. This is the reason that most older transmissions like to stay in the 180 degree range and we have all seen or experienced guys have issues when their trans. temp went to 240.

The newer synthetic ATF Fluids are typically good to much higher temperatures. How high, I guess that's up to the manufacturer of the oil. We ran amsoil slick shift in the race car transmission and liked to see it run about 200 degrees, we saw sustained 225 degree temps many times, and spiked it to over 260 a few times. Our trans builder always said keep doing what you've been doing your transmissions look good. Please keep in mind we had a very aggressive transmission program that put a fresh transmission in about every 500 miles and for sure before every KOH race. We had issues breaking hard-parts so we had to get them inspected frequently.

Bottom line is that if you use a good quality synthetic fluid chances are the seals will be the weak point when talking temperatures. What temp are the seals good too, well that's a whole other can of worms but I wouldn't want to see temps over 250 for very long with your average everyday rebuild kit type seals. Our builder claimed to have a few transmissions that went over 300 and survived with the seals he used. We didn't want to attempt that feat.
 
Here is a picture of the new cases, the rear line is the return, which means the top one is the outlet, which means the bottom one is the return on the older cases.

IMG_0558.jpg
 
And Dex 6 is synthetic fluid, although I have noticed it shifts softer when installed in older computer controlled trannies.

If you want it to be a little tougher than factory without internal modifications, try a transgo shift kit.
 
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folkenheath said:
Here is a picture of the new cases, the rear line is the return, which means the top one is the outlet, which means the bottom one is the return on the older cases.

IMG_0558.jpg
Click to expand...


Then how does a respected leading in transmission repair/builds have this wrong?

I'm not saying that you are wrong. I'm just confused how TCI would be wrong.
 
I know the rear line is the return in the new cases, it feeds back to the planetaries. However, I did make the assumption that they did not swap the supply line in the new cases. I don't know why they would change the fluid passages in the case while leaving the old lower cooler boss there when it isn't used anymore, but I suppose it is possible. Let me try to do a little more digging in case my assumption was wrong.
 
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