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When can you tow in OD?

3K views 27 replies 15 participants last post by  busyfixin 
#1 ·
So in what year or transmission types can you safely tow in overdrive? Reading a post here about the new transmissions being able to handle it....

My '94 Suburban 7.4L 4.10 gears, towed up buddies Samurai to West Branch this past weekend. Left it in Drive to check mileage. Towed without issue, I left it around 63mph on cruise control. I averaged the trip up at 7mpg. On the way back I set it in overdrive and cruise on at 63mph and I netted 8.5mpg....

The only time it downshifted while in OD was when I took it into Drive to get over the Zoo. I don't have a trans temp gage, so can't say anything there....

Is that old of a trans "safe" to do OD in if it doesn't hunt for lower gears often? Manual and door says DO NOT TOW IN OD in bold print :d:

Lucas
 
#3 ·
Lucas I would recommend the owners manual first.

Second I don't believe they had the tow haul mode in 94, so I would be hesitant.

However I would think if you can hold OD with the Torque converter locked up you would be ok.

Do not take that for anything other then what I would "think" would be ok. Maybe someone with more experience/knowledge could confirm.
 
#7 ·
correct me if I'm wrong, but I was always told that towing in OD isn't what hurt the transmissions, it is when the vehicle is always downshifting/shifting in order to maintain speed.

towing flat, and not an extremely heavy of a load is ok in OD as long as the truck isn't kicking down alot. once it starts downshifting, is the time to take it out of OD. :confused:
 
#9 ·
you are correct...that whats hurting the tranny, shifting in and out of OD a lot. I never use OD when towing my camper as its too heavy of a load for my 350ci to maintain 4th gear. The other day towing a empty 18' car hauler I left in OD, towing it on flat level roads.
 
#8 ·
my 99 tahoe does not have tow/haul either. it's manual says to use OD unless it's hunting for gears. I tow in OD some of the time and take it out of OD when it's hilly or hunting. I know with the 'hoe it really depends on the speed and also, it does better when I do NOT use cruise. i'm able to modulate the gas pedal to keep it from shifting easier that way.
 
#11 ·
simple answer. light loads OD heavy loads no OD. get a temp gauge there cheap insurance. if it's hunting for gears at freeway speed then shift into 3rd and leave it. there is a diffrence between shifting and the TCC cycling. you will notice if the TCC cycles it's only 300rpm change versus 700 or so when it downshifts. if the TCC cycles thats nothing to worry about.
 
#12 ·
Wow, about everything in this thread is what I stated in the other one that you most of disagreed with me on.

lgottler, as Kodiak stated above is very accurate in my opinion. My question would be, what is the excitement about towing in OD? In the long run, you will not save money in gas mileage (based on weight and torque required). If you get in a situation where he trans "hunts", you will actually be costing you money.

Like Kodiak stated, I will tow my bike trailer in OD but that is about all (95 Tahoe). Its weight is about 300lbs.
 
#27 ·
It made a difference for me by using OD for my mileage, thats really why I ask. If I netted a 20% increase in mileage (which I did) by using OD, I'd like to use it!!

Do they make any fancy chips for the older trans' to allow a tow/haul mode or is all that older stuff controlled with new valve do-dads?

Lucas
 
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