4L60E torque converter question, better cooler

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LVJJJ

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got the dimensions from the internet sites that sell them. One was 8 x 11 the other 11 x 8, they didn't say which dimension was which so could of been just the way they were listed. Anyway, all done now. Thanks for the heads up should I need another one. Not leaking this morning, finally.
 

Schurkey

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still don't know how automatic transmissions work.
PFM

Pure F'n Magic


When going up a slight hill it feels like its shifting down but its not going into 3rd. Stays in 4th but rpms jump about 200. Seems like I've got an extra gear. Once up the hill and back on the level it shifts back up and rpm's drop about 200 rpms. Same thing can happen if I'm in third, usually against a headwind. Trans has not been running hot during these times.

So, what's happening when it "shifts down" slightly? I've heard it has to do with the torque converter "locking up?" or "unlocking?"
Exactly correct. There's a clutch inside the torque converter housing that eliminates converter slip. When engaged, it'll typically drop the rpm by about 200 at cruise.

There's no torque converter torque multiplication when the converter clutch is engaged--so when the load increases they release the converter clutch so the torque converter can multiply torque again, and it also puts the engine farther up in the power band.

Since I do like to tow in 4th...
NOT recommended. The owner's manual will specifically tell you NOT to tow in OD.

From a purely trans-temperature perspective, better to be in 3rd gear with the converter clutch engaged, than in 4th with the converter clutch released. Engaging the converter clutch is what drops trans temperature--the converter slip is what drives temperature up.
 

Pinger

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Someone told me (last week) that the reason not to tow in 4thOD is that line pressure is low and insufficient for the bands and clutches which can cause them to slip.
Only what I was told....
 

LVJJJ

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Just got back from two week RV trip with good news and bad news. Good = The new tranny cooler worked great. Most of the time the temp ran from 150 to 165. One day it was over 100 degrees all day in Eastern Washington, plus had a headwind. The engine never overheated although the clutch fan came on quite often, had the AC on all day too, doesnt' seem to affect the power on the 383 (the cooling system on this Suburban is fantastic). The trans temp stayed at 180 all day, never went over even on hills. Eastern WA Route 28 is up and down a lot, no cut and fill on that highway, almost as bad as Missouri.

Bad news, cracked another exhaust manifold (4th one), probably when climbing long steep hill east of Orondo on Highway 2. Kept it at 3700 rpm and 50-55 mph. I thought the 383 wouldn't do that since it has so much more power and didn't have to work so hard getting up the hill. Probably the fact that weather temp was over 80 that day. Even tho the DW will not like it, I'm getting headers, probably $400 shorties from Summit. I am not going to slow down on hills, although always keep it around 65 mph for tire safety sake.

Thanks for the info on the torque converter operation. I'm only using 4th on long downhills now. Any level or uphill always pull it down to 3rd.
 

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cracked another exhaust manifold (4th one),
SOMETHING is wrong.

Are these manifolds GM or Chinese knockoffs?

Does the timing advance properly? Fuel system set up for the extra cubes? (larger injectors, higher pressure?)

Running retarded or running lean (or both) would be my first two guesses.

I guess next-up would be exhaust system hangers too restrictive, putting pressure on the manifold as the engine torques on the mounts.
 

stutaeng

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Someone told me (last week) that the reason not to tow in 4thOD is that line pressure is low and insufficient for the bands and clutches which can cause them to slip.
Only what I was told....

I see this a lot: people saying not to tow in 4thOD. My K3500 2000 owner's manual states otherwise.

Is this specific to the 4L60e? I don't know much how transmissions work mechanically, that's why I ask.

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Schurkey

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I see this a lot: people saying not to tow in 4thOD. My K3500 2000 owner's manual states otherwise.

Is this specific to the 4L60e? I don't know much how transmissions work mechanically, that's why I ask.
The 4L80E got an upgrade in '97 or '98 that allowed towing in OD. Far as I know, the earlier '80E, and all flavors of 700/4l60/'60E are unsuitable for towing in OD.
 
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