1995 F350 PSD Dually Crew Cab AUTOMATIC

I have a towing question for you guys. I have a 32' fifth wheel Toy Hauler weighing in at around 11830 GVWR, 7000 unloaded. (For Sale by the way $12,750)

Everyone says to tow with OD (overdrive) off. That means I will turn about 3000 - 3400 rpm's at about 55-60 mph. That's screaming. And then I look up and someone with a larger trailer than mine blows past me like I'm sitting still. How can they run so fast? My engine will blow up if I push it an harder.

Is it OK to run in OD say 65 - 70 on flat ground if it is not changing gears? Some people told me that even if it is not changing gears at higher speeds with a heavy load the tranny is still slipping a little even if I can't feel it and that long term towing like that will burn uo the tranny. I was told with the OD off the tranny hooks up on a 1:1 ratio and will not allow any slipping.

Any comments?
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Everyone that says always tow with OD off is wrong.

In overdrive or even in third gear you can run with the torque converter unlocked which will generate A LOT of heat. It is more likely in overdrive.

Learn what RPM you run at towing speed in overdrive without the trailer. If you are in overdrive and running more RPM with the trailer on your torque converter is unlocked. That will get the trans hot.

Most likely you won't have any problems towing in overdrive.

 

The clowns running 65-70 have a death wish you try to stop that much weight from that speed and it will push you all over the place. This is why they have the speed limits reduced vehicles pulling trailers. Casey is right,if it doesn't hunt for a gear and there is no difference in rpm loaded and unloaded then leave OD enabled and just lock it out on the grades. I drove a 14' service truck loaded to 12,000 to 14,000 lbs like this for 154,000 miles all over Washington State till the trans let go. Just make sure you have a good quality cooler and think about adding an external filter. Thats what we had in the service rig and it does work.

 

I'll jump on the leave the OD on bandwagon. Unless the transmission hunts between 3rd and OD, I'd say to save revs on the engine and save fuel and excess tranny heat.

I'm with Casey regarding TC lockup. You really want to have it in lockup if you can, because otherwise you'll be pumping a boatload of heat to the cooler. The cooler you can keep the tranny running the better. You sure don't want to burn your fluid, because that will eventually kill the transmission.

 

When you guys talk about making sure the torque converter is locked, how do you do that. I thought that the only way to lock the TC was to run with OD turned off. Then I am running very high RPM's. It is a diesel which turns higher RPM's than a gasser.

 

Diesels run LOWER RPMS than a gasser. Did you read my post above where I told you how to tell if the torque converter clutch is on or not? Here is a quote from that post:
The torque converter in your truck can actually lock in any forward gear in the right conditions, but is usually locked in both third and fourth gears.

 

Casey's right, torque converter lock up is a function of engine RPM and time in gear not road speed. Even my Voyager locks up in both 3rd and 4th under the right conditions. You can see when this happens if you have a tack which it sounds like you do. Remember also that if you are running with the overdrive off this will make the engine work harder at the same speed as on and create more heat under the hood and in the radiator hence higher transmission temperature. Good quality cooler and regular servicing (1 year or 15,000 miles for filter and fluid). Stay away from the transmission flushes unless you are going to rebuild it soon anyway.

 

The transmission flush is an excellent way to change all the fluid. There is a good article in the Tech Articles part of FTE that shows how to do it yourself. I've used that method on at least a dozen cars and trucks. It works real well.

 

run my 2003 F250 7.3 in OD all the time as long as we were not in the hills,, normal driving speed was in the 65 to 69 mph,,

down the road truck and fiver were right at 20,000 lbs according to the J Scales,, averaged 12.7 mpg for over 25,00 miles of towing,,

 

Hey Eric C: As one of the clowns who drive 65-75 mph on the interstates and on the 400 series Hwys in Canada, while towing a 30 ft 5th wheel or a 24ft enclosed car hauler. I would like to suggest that rolling road blocks that are traveling in the 50-55 mph range are more of a hazzard that someone hauling at the same speed as traffic. It's not a big deal to leave space in front of your rig if a problem occurs.
If you don't think driving less than the flow of traffic is dangerous, remember the last time you came up on a blue haired old lady or some moron on a mission to force traffic to slow down by holding up a line of traffic on a four lane or worse on a 2 lane hwy. Think about how traffic is backed up and how many dangerous passes and/or wrecks occur in this type of situation. By hauling a trailer below the flow of traffic all you do is make the guy behind you really mad and more likley to attempt a dangerous pass.
By the way I tow in overdrive and keep the revs in the powerband,2000-2200
04 6.0 psd, cc 2wd, 6sp.

 

I say this from spending a lot of time I should have been sleeping or enjoying my weekend instead of out having to pick up the pieces of pepole overdriving thier rigs doing the Volunter Fire Department thing in California. I see a lot of it still with the miles I drive doing field service.

Laws of physics says you start pulling a lot of weight and then try to stop it doesn't happen fast. I pulled a couple of 750 Killowatt generators and got pushed through some intersections and that was with all the brakes locked up on both the truck and trailer so I learned the hard way. I watched a guy lose it in Utah with a 20 foot toy hauler and an Expedition with his wife and thier 4 kids and he rolled it over twice. He went to slow down frow 70 and hadn't even touched the brakes and the trailer came around and there it went.

I've also seen a lot of them on I-80 through Wyoming with pepole thiat had lost control and if lucky just ended in the ditch and saw three of them in one day west of Rawlins while going to the job site and back (50 mile one way). I normally run right about 60-65 when loaded and yes it does irritate me when I get stuck behind the blue hair doing 45 in the fast lane but if you ar getting angry over something you have absolutely no control of it's time to take a break. I have been the receiver of the extreme of this with a guy pointing a 45 at me because he wanted to get around me after I had passed all the traffic that had been jamming us both up and I had been going 75 when he pulled in behind me at 2 feet. There is a balance. My statement is if you pull stay within the limits and keep the greasy side down.

 

F350, t/d. O/d not to O/D that is the question. My personal opinion is that you need a tranny temp guage for towing. Transmissions are all about the temperature so for a few $ have insurance. you spend big $ on these rigs why not monitor your auto trans.

 

I'm having gauges installed at the beginning of next week. What temperatures should I be looking for on the Pyrometer and Tranny temp gauge? In addition, what number should I look for on the boost gauge?

I came on the forums today getting ready to ask the exact same question that slaymdr posted on this thread. My reasoning, too, was because without overdrive, the truck seems to really run high on RPM even at only 50-55 MPH. What about having OD off until you get to 50-55 then turning it on? Is that viable? Since I'll be running a tranny temp gauge, can I run it in overdrive as long as the gauge shows me the tranny is not getting hot?

Thanks.

P.S. I have a 99 F350 PSD, DRW, CC, 7.3L, AT, 4.10 gears

Edit: Let me just ask... is anyone else on this board freaked out about towing? I bought a big truck thinking no prob for a enclosed 22' trailer but I gotta be honest, the posts about tranny failures on here freak me out and make me nervous about towing.

 

Do not worry to much about O/D, it is the trans temp that is important. First make sure that you have the guage installed on the out let line, in the pan the fluid is already "cooled", the cooler the better. When you run in to the 200's you start glazing the clutches and the seals will be degraded. As for temperatures I run 140 -150 on the highway, 180 max in traffic, but I have a large cooler and electric fan mounted in the bumper, when I am in trafic and the temp starts rising I turn the fan on. As far as pyro, pistons melt @ 1240 so keep it down, on the highway I see 900, giving it the boot I get up to 1000 - 1100 then I back off (normally going up a steep grade). My pyro is mounted in the exhaust manifold, to get direct reading. Their is some discussion as to mout pyro pre or post turbo, pre turbo argument is that if the tip breaks off, it could destroy the turbo, but post turbo can give up to 200 difference. Hope this helps.