Hello,
This is my first Allison and I have been reading these threads and I still have a couple questions:
1) when driving in town, would it be better for the tranny and the milage to lock out th O/D?
2)When towing my '85 23 foot travel trailer (about 3300 lbs) should i use tow haul? should i lock out Over drive? is it ok to tow with over drive activated?

This is a great web page, thanks in advance for all the great info!

Others can chime in RE towing, but on question #1 I'd ask what kind of in-town driving you do... Stop & go? 25-35 mph? 35-up mph? I ask because mine won't shift into 5th until about 35 mph with T/H disengaged. With T/H engaged, it won't shift into 5th until a little over 40 mph. RE mileage, I find my truck gets its best mileage in 5th at about 50 mph -- the DIC isn't the most accurate way to measure, but it reads around 30+ mpg at this speed. RE 'best for trans', if you're in traffic, but going fast enough to get to 2nd gear (anything other than stop & go) being in T/H will lock the torque converter and build less heat in the trans fluid, which is good, although in colder weather it won't matter a lot. Again, unless you're going faster than 35 mph OD lockout doesn't buy you anything.

I am sorry, i should have said that yes i drive about 4 miles in town where there is a stop light about every 2 blocks. So i dont get much speed untill i hit the state route where i can go 45-55. I drive 40 mins to work and 15-20 minutes of it is stop and go and low speeds.

I am sorry, i should have said that yes i drive about 4 miles in town where there is a stop light about every 2 blocks. So i dont get much speed untill i hit the state route where i can go 45-55. I drive 40 mins to work and 15-20 minutes of it is stop and go and low speeds.

No prob, man -- the most difficult part of getting a good answer is knowing what question to ask. In your case, I'd pop her into T/H for the 20 mins you're in stop & go and not worry about OD lockout, then click out of T/H for the 20 mins you're at 45-55 and let her cruise in 5th. Should give you good mileage traveling at those speeds.

Great!
I appreciate the info and I will post the towing questions in the right area.:o:

I would think you would get bad milieage in t/h on the street. You will hold 1st gear way too long and there is no reason to. Put the lever in o/d and just drive it.
mike

too much thinking to do....

GM built the truck to drive. Put it in OD and forget it. When towing, I like the TH feature for grade braking, but thats just me

When romping on it, I use TH all the time.. I think its " Lock it and Rock it"

Mike L and dmaxallitech have seen the inside of a lot more trannies than me, so their advice is worth a lot in my book. I'm in stock tuning trim right now, so I like it to be in T/H in town for the very reason that it keeps me in a gear longer -- there's less shift business getting on and off the throttle, if you spot an opening in the traffic & need to get through it it's helpful to be in the lower gear already, and I hardly ever have to use the brakes because the tranny does the work for me. I'm sure they're right that having it in OD isn't going to hurt anything, but I do like the lower fluid temps I see in T/H on warm days. I don't see a whole lot of mpg difference in-town (driving under 35) with or without T/H. Watching the DIC instant econ thing, it seems like it really sucks fuel accellerating from a stop no matter whether you're at 1/4 or 3/4 throttle. I can appreciate, having just invested in a real expensive truck and not exactly walking around with a silver spoon in my mouth, wanting to make sure you do everything you can to ensure it's longevity... Then again, I'd be the first to call myself a little on the obsessive compulsive side when it comes to this rig.

I will test out both theory's tonight on the way home and see which one feels better for me.
I guess everyone has their own way of driving. I am still getting use to the power of this thing...too use to the old 94 GMC 5.7 gasser i had....
thanks for all the info guys!

Siphon
I agree with you. Drive the truck the way that satisfys you. You are hurting nothing. I was just pointing out the things that I don't like about t/h for stop and go driving. " Lock it and Rock it"
mike