Towing in O/D

[farmall]

Ok guys, here's my question. I have been told 10 different things by 10 different people.



Can you tow in O/D when you are on the Interstate holding a steady speed, in relativley flat ground?



I have been told yes with no problem, yes but be careful, no it will burn itself up, no it just won't work. So what's the answer. I have always towed with it off in my other vehicles, but this dang thing I can only get about 56 mph out of it loaded in drive.



Thanks, Bill

 

[paccool]

Bill, Before giving you my thoughts on this I have a question. What kind of weight are we talking here? How often do you tow it?

 

[farmall]

Anywhere from 8,000 to 20,000 lbs. Tuesday had a load of hay that put me gross 26,500. Bill

 

[Bob Wagner]

keep your RPM's over 1600 in OD

 

[BushWakr - RIP]

I agree with Bob W.....

Nothing under 1600-1800 RPM and watch your EGT's either one will tell you when it's time to "pick up a gear"... . transmission temps in the 230*F range are too high as well... (we can see highs of 270*F in our 1st Gen trannies. )

Our stock convertors are just too inefficient below that RPM range.



I've carried/towed combined weight myself and did not run less than 1800 RPM in OD, transmission temps ran about 185-195*F, and EGT's around 900*F.

That was before major mods, to be fair.



bob.

 

[cerberusiam]

Like the rest of the guys said, 1600-1800 rpm to use OD, watch the trans temp, service the trans frequently. I would add a deep pan like the mag-hytech and turn up the line pressure a bit.



Not to be the naysayer in the bunch, but, 26k is flat too much gross weight without major upgrades. You are into medium duty truck weights and even though the engine and rearend will handle it the transmission was never designed to handle that weight. The "safe" range is somewhere between 17K to 19K and even that is beyond design limits.



You did not say whether the trans has been rebuilt so assuming it is stock with 200k it could be an issue. The material in the clutches and the number of clutches, especially in the OD unit, was a major failure point in the A518. Upgrading to the newer trans with better parts would make mid 20k GCVW easily doable.



The main reason the A518 got such a bad rap when it came out was everybody that bought it thought they could consistently pull the heavy loads. I watched multiple acquaintenances tear up the autos, and the manuals, then get into yelling contests with the dealer when the dealer not want to warranty the problems anymore.



I realize you probably need to haul as much as possible, especially if this is your business, but dropping multiple transmissions in a year tends to lower the profit margins. In my experience, making multiple trips was much more cost efficient. Good luck and if your experience proves me wrong, so much the better.

 

[paccool]

Well, if you were pulling 4000 or 5000 lbs, I would say use the OD on flat ground. Thats what I do. As soon as I hit the hills, I turn the OD off and get the RPMS up in the range the guys were talking about above.



My truck is on the third transmission, this one is the only one that I have put in and it is doing well so far. The last failure was in the OD section and that pumped crap through the transmission and really messed things up. This one has a shift kit, extra discs in the packs, and the pressure turned up some. Can't tell you how much, the rebuilder didn't give me all of that info.



I would not use OD for any thing over about 8,000 lbs. I'm sure there are some who do, but this is my opinion.

 

[dpuckett]

I towed 4-12K all summer long the year I worked for a moving company based in Loveland CO. THis was a stock transmission, stock engine, and I went 65-75 all the time. No problems. Truck had 150-170K at the time, original trans, I believe. My mom bought it that following winter (00-01), and it seems to be nearing its end now, though she wont redo it until it wont go anymore, so it has 50k left in her mind. I think line pressure could be bumped up a bit, but she wont get it done, costs money.

If you have a lighter load, say under 15K GCVW, I'd go for the O/D; if over that, stay in 3rd and go a little slower. Sounds like you have 4. 10 gears. Mom's will do 70 in 3rd with 3. 54s. My 5speed will do 78 in 4th w/3. 54s.



Daniel

 

[DPKetchum]

I pull around 9600 lbs with mine if i did'nt use overdrive i wouldn'nt get anywere. Been all over Ga. Tenn out west etc. Run around 62 to 68mph uphill and down. Punch od off it would be in the REDLINE. I do agree with the weights your pulling it sounds like you need a medium duty truck. You know at dealer level all the broke trannys were 94 up. Saw lots of 1st generations but auto trans issues were hardly never brought up. It was always 2nd generations. As a added note. This was why the TRANSGO tech line mentioned using motor oil in the automatic. They said 90 % of driving and towing was in O. D. and that motor oil added a cush to the bearings and gears that were in the O. D. section.

 

[JStoll]

is the a518 the trans that looks like a 727 with the new process OD on the back if so we had a bunch of them in a fleet of paratransit vans I used to take care of with 360s these traneys seemed to drop dead at 100K mi like clockwork it was weard & allways it was a thrust bearing in the OD section as I recall that fed itself to the rest of the trans

one thing I tell people about driving with allot of weight & automatics is what people are saying here keep the rpms up because the torque converter produces most of the heat in the trans & the time when most heat is produced is durring sliping or torque multiplication when you are pulling a big load you dont want to use the TC as the gear reduction drop it down a gear you want to keep the TC above the stall speed to keep temps down

take care

JAK