So i have been reading a lot about towing and from what I can tell the key to not overheating your tranny is to make sure the T Q is locked as much as possible.. So how can i tell?

 

Easily, assuming you have a tach. When the TC is locked, and you give a little gas, the RPMs only rise with speed. When unlocked, the RPMs rise and lower with the gas pedal. Give it gas, RPMs rise, let off they fall.

 

Gotcha.. so say I was in 3rd pulling a hill at 50mph and notice that it is unlocked, what can i do to get it to lock?

 

Not much other than to drop off the gas pedal enough to put everything into a state that the computer will lock it. Unfortunately, for this purpose, the computer is programmed to unlock the torque converter in situations where you have to apply a certain amount of throttle compared to speed so thta the vehicle will accelerate and not just load up.

However, there are tunes that you can get for towing. One good place to call is Troyer Performance.

Darrin

 

heres a video i took for you yestday on my way home.
70mph in OD 4th gear converter locked.. then a lil bit in the video you see the rpm's go up a couple hundred thats 4th gear converter unlocked. then as i floor it it goes converter unlock drop to 3rd. then when i let off the truck shifts to 4th and locks the converter.

 

Just to add to what Darrin commented about 'what to do if you find it's unlocked'....

In my experience with that same scenario (up a hill in third, TC unlocks) I find that the hill is just enough to not maintain speed in third, so I will press the gas pedal gradually to see if I can get the rpms up to a point where the comp will signal a lockup again... But, what usually happens is that if this is occurring in the first place, the engine isn't producing enough torque at it's current rpm range to hold it locked anyway... So, the trans will downshift to 2nd.. Now, you have plenty of rpms to hold speed AND stay locked, albeit in 2nd gear now...

I'd rather be in locked second, pulling higher rpms then in unlocked third pulling lower rpms.. If you have a trans temp gauge, you'll know why!

Gas engines ain't like diesels, so they need rpms to get into their torque range to get you up that hill..

Hope that helps!

Mitch

 

Great info! thanks for the tips- i'm pullin our 8500 lb travel trailer to the lake tomorrow so i'll make sure i'm keepin it locked up the hills..

 

So that answers something i've always wondered-- when my truck feels like its shifting down but I know it doesn't becuse the RPM's are lower then i know they would be in 3rd it's just the TQ unlocking.. SWEET!!

 

no prob glad i could help. i wonderd that for the longest time too then my trans guy told me what it was and it all made sence to me. and when i saw this thread i knew right what you were talkin about. glad to see my video helped ya out

good luck with the trailer...why 8500 lbs in a trailer? i think my bed would hold it

 

Ha Ha i'd love to see that!! yeah it's like 34 feet long, kind of a pig!!

 

in my haulin/towing thread i had a pallet of bricks that weghed somewere between 5,000-6,000lbs easily and i hauled it in my bed. my bump stops were flated on the axle and i had 0 shock travel it was a bumpy ride.

 

I wasn't aware that the TC would lock in 2nd - I thought it was just in 3rd and 4th......

8500# and 34 feet with a 1/2 ton truck is really pushing it..........

 

This got me to thinking.......

There is some signal that is sent to he trans to lock the T/C, correct? Why not hook up an LED to indicate locked/unlocked status?

I plan to dig into the circuit diagrams this weekend, but maybe someone already has the data?

Andy

 

... and started a separate thread HERE.

Andy