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towing/hauling with 4L80E & fluid type/Cooling system ?'s

M123KT-450

M123KT-450

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(1)
I have heard lots of conflicting stories about how to tow a trailer or haul loads with the 4L80E.

Some say just leave it in OD.

Some say run it in DD.

Some say Run OD till you hit a hill then down shift to DD then shift back up to OD.

Now i'm sure i'll hear a bunch more of these 3 claims again but i would like to know whats the Correct GM operating procedure for the opertation of the 4L80E ?
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(2)
Now for Fluid type is this better off on Dino oil or run with a high end synthetic Fluid ?

How often should the fluid and filter be changed in these units ?

What type of fluid exchange would be best for these units ?

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(3)
Now how about the cooling of these units ?
Do these Trans pan coolers work ?

The extra 1qt in volume with flow threw cooling tubes ?
or
The extra 3qts in volume with cooling fins ?
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(4)
Now is the GM factory Cooler mounted by the Radiator the best way to go ?
or
Should and after market unit unit be used ?

some say get the GM cooler and bypass the Rad.

Some say get the GM cooler and run it inline with the Rad.

Some say after market next size bigger than your gross GVWR inline with Rad.

Some say next size bigger than you GVWR bypass the Rad.

Whats the best setup For the 4L80E ?
....................................................................................................................

Sorry for the long post guys just trying to find out every thing i need to know about this transmission and what works best. i have numbered the Questions so you can either answer all 4 or any combo of the 4 . just note the number or quote the number so i know what question or questions are being answered.

Mike
 
Run the biggest cooler you can fit and afford within reason. I change mine ever 25-30k and run dino in it... I use OD unless a lot of hills and it wont stay locked..
 
GM's stance according to the label they put in the door jam is to NEVER tow in OD, always put it into D. Now if you have 4.10's and stock tires like I have, your topped out at about 75 in D. I always towed in OD once I got up to highway speeds, and if I had an incline coming up I would slow down slightly to 65 and put it into D. If I didn't slow down to 68 it would hit the limiter when the torque converter unlocked and shifted to 3rd.
 
I think i only got like 3.42's with 7.50-16's.
Truck is ok empty under a load it gets doggy very fast.
OD=70mph@2250Rpm/DD=60mph@2,250Rpm.

Mike
 
Mike, what is your tire height, or ratio to width? Are your tires only 7.5 inches wide or your wheels? Those would be some skinny tires! You have 245/75 16 tires?

Do you have a trans temp guage? I think a bypass setup rail cooler would be good for each engine and trans oil for a towing truck. Want to keep things away from engine area and not put anything else in front of radiator.
 
no wonder you are slow off the line :) really tall tires, good for overdrive, bad for low end gears.

You might have 3.73 gears but with those tires your effective ratio could be almost 3.42 now if the stock was 225/75 16.

Do you have 4wd or 2wd?

I wish I could have found some cheap/used 16"x7" wheels with the 5x5" bolt pattern so I could have used 235/85 16
 
Off Line ? LOL thats where my truck beat him was off the line and almost threw first gear my truck shifts at 3,500rpm he started gaining on me arouns 3200rpm in first gear once i hit second gear it was done the peppyness was gone. . . .

My truck is a 4wd yes GMC K2500. . .
Them tires work great in the snow i was thinking of getting some of the Mudder type 7.50-16's for the Muddy season.

Summer tires:
https://www.tiresavings.com/tires/powertraction.jpg
or
http://www.euroshina.com.ua/catalogs/tyres/160/cooper_courser_traction_lt.jpg

Snow/Winter tires:
https://www.tiresavings.com/tires/pktraction.jpg

Any one of the 3 is way better then BFG AT KO's man i hate them tires they look like they should do well but they pack up and get stuck. . .

The Cooper Courser traction LT's are sold at farm n fleet those i think are the tires i may go with for my Summer tires i'll be putting them on my mickey thompson rims.

19.5 Conversion:
http://www.ricksontruck.com/

Idealy at some piont i would love to do a set of 19.5's and never have to change tires again.
But in order to do that i will need 4.10 or 4.56 gears i am sure.

Mike
 
Check in your glove box. There is a sticker with a bunch of codes on it.
For Gear Ratio....
GU6=3.42 GT4=3.73 GT5=4.10 G80=gov lock posi

Being 4WD I dont know if they offered 3.42 stock. I bought mine just because it had 3.42 gears and 2wd since I mostly just commute, maybe have the bed loaded.

Also, you can get the USB cable to hook to a laptop to verify all your sensors, tranny temp, engine temp, boost, and actual RPM from crank sensor. Sometimes the tach guages are off, because it runs off of the alternator and a slight change in pulley size will throw it off a bit.
 
95 K2500 came stock with 245/75/16 tires(only option) and either 3.73 gears or 4.10(many came with 4.10 with the 6.5). 1500's came with either 245/75/16 or 265/75/16 stock depending upon wether it was a Z71 or not, and could have 3.42's or 3.73's out back. In 1500 SUB's they all came with 245/75/16's and 3.42's.
 
My local GM dealer debunked that statement saying yes 7.50-16s could be had on that truck if the owner so wished.
anywho i'm not going to really argue about it they are on it now speedo is right on the money so weather or not GM put them on in 1995 or not the truck was at some than redesigned to run those tires.

I soon would like to recalibrate n regear the truck for 19.5's.

Mike
 
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1. many tow, including me, in OD- depends on load, speed, tcc lock, etc.
2. GM now specs dex6, synthetic for all autos, at least to the 50's.
3 & 4. trans pans can help, but longer fluid is heated, longer takes to cool. replaced stock aux cooler with one rated for 28k lbs, relocated stock to secondary location under truck, Turbinedoc also runs similar setup, he probably b4 me. works very well on cooling. too cold and high viscosity could damage seals. thermostat and fans work very well, ask TD.
 
according to GM, any auto that used dex 3 is now to use dex6. DO NOT use in Ally's, will void warrenty and very likely to do seal damage. if you use dex6 DO NOT use dex3, you can ony upgrade. (dex6 backwards compatible all the way)
 
no doubt, there are many superior products- as long as we know what gm specs for warrenty and seal life, get the better product. side note, gm is no longer licensing dex3, so dex6 comes into existance
 
not sure, have not even seen one of those before. I do know that a larger replacement for factory cooler and secondary cooler with fan does a good job. what do you run through tubes and do you provide hardware to put tubes in series????:confused:
 
it a whole new pan man the tubes are welded in and air fron under the truck passes threw them. . .
i figured with this pan the factory cooler and Synthetic fluid it would run great ?

Mike
 
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