Towing in overdrive?

Crankworm · **Posted:** Thu Mar 11, 2010 5:00 pm

I've got a question about towing with my crd. I bought it in Nov. and already had the toys put up for the winter so I haven't had a chance to tow anything yet. I'm planning a trip this weekend and will be pulling a 16' open car hauler with 4 quads on it. Will I be able to use overdrive and run 70 down the highway? I'm not real keen on driving that fast not in overdrive because the rpms seem a little high but I like to get where I want to go. I also have a 17' Lund I will be towing a lot this summer, I am going to guess the boat, motor, and trailer can't weigh maybe 2,800 lbs. at the most, will I be able to run overdrive with this? I just want to keep my drivetrain happy. Apprciate any input. This is an awesome forum, everyone has been super helpful even if they don't know it. I'll try to include a pic of my boat.

grywlfbg · **Posted:** Thu Mar 11, 2010 5:07 pm

No problem. I pull 3,500lbs at 65mph in OD on flat roads all the time. If it's hilly I'll keep it in OD with just enough pedal to keep it from kicking down. As the speed bleeds off, once I hit 55mph I'll hit the OD button. With the OD button off the torque converter will lock in the lower gear and it'll pull up anything. Once I crest the hill I jab the OD button and repeat.

CRD Joe · **Posted:** Thu Mar 11, 2010 5:19 pm

Normally you hear that towing in OD isnt a good thing for the tranny. Im not sure about these babies. Especially since 4th and 5th are OD's..

Joe Romas · **Posted:** Thu Mar 11, 2010 9:01 pm

You'll know when you need to turn OD off. I've towed our 17' 3500# travel trailer in OD. Just like grywlfbg says, when you hit a big hill your speed will drop and then the tranny will down shift to third and the engine will scream. Then push the od off button and let it lock the tc in 3rd. till you crest the hill :jester:

We sure could use a better shift programming. It seems they are saving 4th gear for some special occasion as there seems to be no way to keep it in 4th for those occasions

Joe

RTStabler51 · **Posted:** Thu Mar 11, 2010 9:22 pm

grywlfbg wrote:

No problem. I pull 3,500lbs at 65mph in OD on flat roads all the time. If it's hilly I'll keep it in OD with just enough pedal to keep it from kicking down. As the speed bleeds off, once I hit 55mph I'll hit the OD button. With the OD button off the torque converter will lock in the lower gear and it'll pull up anything. Once I crest the hill I jab the OD button and repeat.

Same here, except I'm probably around 4-4500lbs.

geordi · **Posted:** Thu Mar 11, 2010 9:46 pm

And I'm the crazy fool that pulled a 6840 lb generator at 65mph in OD... And got 19mpg doing it. Pulled like it was half that weight.

Just follow GryWlfbg's directions, he's got the plan for anything resembling a hill.

As far as the transmission goes, I have never seen the "trans temp" light while pulling, but the hardest tugging in OD still only got my manifold-mounted (pre-turbo) EGT probe up to 1400 degrees for a short bit, never sustained over 1100-1200. From what I've learned here, that means an outlet temp (post turbo) like 200 degrees cooler... All in the safe range AFAIK. So if the turbo, which heats up MUCH faster than the trans isn't running hot... The trans should be just ducky.

Besides... a 2800 lb guess on that little dinky boat? Pfft. Your car hauler is probably tipping close to 1800 by itself, 1 ton on the outside, add 500 each for the quads... So 2 full tons hauling. Since there won't be any real wind resistance to add loading, you should be great in OD. Just watch the stoppng, and make sure the quads are tied down securely. You can't over-tie things like that.

coldkj · **Posted:** Thu Mar 11, 2010 10:00 pm

I've towed a 22 ft skiboat (ca 2700lbs on the trailer) at 60-70 in 100ºF ambient temp no problem. You should be fine.

BTW is that a rubber fish?

yakers · **Posted:** Thu Mar 11, 2010 11:40 pm

I tow a 3,000 lb travel trailer up/down the Grapevine and up/down the grades into Tahoe. On the flat across the desert I keep it in 4th @ 60MPH, not letting it go into 5th. When I hit a hill its OD off and occasionally, like up the Grapevine I will go in 2nd mostly as a matter of fitting into the truck traffic. Never saw the trans heater warning light so even if the temp gauge climbs I have learned to be less nervous. But these are only minutes out of a long trip, across the flats its easy to forget I'm towing although I would have more wind resistance than your boat. I prefer 60 in 4th as it just fells like less strain, better MPG and pushing less wind then there is always the issue of brakes, don't want to go faster than you can stop and while the Liberty has enough power to tow there can still be issues with its short wheel base for handling.

RTStabler51 · **Posted:** Fri Mar 12, 2010 9:26 am

geordi wrote:

As far as the transmission goes, I have never seen the "trans temp" light while pulling, but the hardest tugging in OD still only got my manifold-mounted (pre-turbo) EGT probe up to 1400 degrees for a short bit, never sustained over 1100-1200. From what I've learned here, that means an outlet temp (post turbo) like 200 degrees cooler... All in the safe range AFAIK. So if the turbo, which heats up MUCH faster than the trans isn't running hot... The trans should be just ducky.

I have a trans temp gauge and mine rarely gets over 120 when moving. If I sit, maybe 130 or so. The only time it got 'hot' was in Chicago traffic that was stop and go.

LibertyCRD · **Posted:** Fri Mar 12, 2010 3:56 pm

6,700 lbs. hooked to my previous bone-stock CRD at 65-70 MPH on the Interstate in OD. Even got 14 MPG doing it which is what my pickup truck would have gotten running empty. :SOMBRERO:

yakers · **Posted:** Fri Mar 12, 2010 11:11 pm

Sort of hijacking the thread a little, but do any of the folks here who tow a lot still have the original trans/TC? Seems like towing a lot of weight, towing fast and towing in OD would strain the system but if the trans never heats up too much maybe it will last longer than commonly feared (or at least what I worry about).

geordi · **Posted:** Sat Mar 13, 2010 1:50 am

yakers wrote:

Sort of hijacking the thread a little, but do any of the folks here who tow a lot still have the original trans/TC? Seems like towing a lot of weight, towing fast and towing in OD would strain the system but if the trans never heats up too much maybe it will last longer than commonly feared (or at least what I worry about).

Starting, stopping, being in any condition OTHER than full lock-up is what will wear out the transmission the fastest, on any vehicle. Better that it shifts hard, which minimizes clutch slip... Than buttery smooth b/c it is grinding away the clutch surfaces each time. Unlocked TC operation means that you are spending engine ponies to heat up the transmission fluid, which must then be cooled off... Etc.

The transmission itself is the one from the heavy Hemi trucks, IIRC it is designed to handle the abuses of 500+ lbs of torque being dished at it. We aren't that high... (yet) but the TC is where the weak component in our transmissions is. I would tend to believe that if the near-idle line pressure was higher by design (with more aggressive fluid vanes in the TC) then the much higher torque at low RPM of a diesel wouldn't faze it at all.

I have a replacement TC, original transmission. I didn't know whether the TC had been replaced when my CRD had the F37 done to it (before I got it) but for the $100 that the replacement cost me while my engine was in pieces... Well worth it. I was having the engine done by a shop that specializes in transmissions, and I told them about the plastic stator in the TC, and asked them to ensure that there wasn't ANYTHING weak that couldn't be built up in this new one.

So far... Flogging it constantly, I have only felt it shudder ONCE, and I couldn't get it to reproduce it. It was when the engine was behaving strangely b/c of this weird sensor-power-loss thing I've been experiencing for months now. But the TC while towing has been rock-solid.

I had to pull my 7.5x20 box trailer 20 miles over hills... FULLY LOADED with 7,000 lbs of gack in it, and the CRD hauled it perfectly.

As always, YMMV.

RTStabler51 · **Posted:** Sat Mar 13, 2010 3:19 am

geordi wrote:

yakers wrote:

I have a replacement TC, original transmission.

Same here.

Crankworm · **Posted:** Tue Mar 16, 2010 11:09 am

Thanks for the help everyone, my liberty hauled the quads all the gear and 4 people 260 miles round trip and averaged 19.5 mpg. I am very pleased with the Jeep.

geordi · **Posted:** Tue Mar 16, 2010 2:43 pm

And there you go. :pepper:

Every time I have been towing anything of weight (and not wind resistance) I've gotten 19mpg from the tractor. The only exception has been my big box trailer, not b/c it was 7000 lbs, but b/c it is 7.5 feet wide and 7 feet tall... And basically flat across the nose. So I'm towing a big black parachute.

UNLOADED when I bought it, I couldn't get the CRD over 65mph... Actually saw the temp gauge rise for the only time ever while towing anything... And got a staggering 12mpg. Yech.

But considering I bought it for pulling behind my RV... That doesn't bug me. The RV only lost 1mpg pulling that beast at 7k lbs. What does that tell you?

jdm25 · **Joined:** Fri Jan 29, 2010 12:17 am **Posts:** 22

Just towed my pop-up camper (3000lbs) 260 miles each way from Florida to Georgia.

On the way out: AC on, 64 MPH (Overdrive), some stop and go (Overdrive off) got 22.5 MPG.

On the way back: No AC, 64-70 MPH, no stop and go, Overdrive... got 23.8 MPG!!!

No issues.

Crankworm · **Posted:** Tue Mar 16, 2010 9:01 pm

Off topic but JDM where did you get that pushbar grill guard thing? It looks sweet way better then anything I've been able to find.

jdm25 · **Joined:** Fri Jan 29, 2010 12:17 am **Posts:** 22

Sorry Crankworm, can't help. I was told by the person I bought the Jepp from that it was installed at the dealer. No clue where they got it from. You are right, it looks pretty sweet!

danoid · **Posted:** Thu Mar 18, 2010 8:30 am

5600# camper trailer = 15 mpg. Leave yours in OD and keep it around 65 (that's the speed rating of all ST - Special Trailer - rated tires BTW).

http://i177.photobucket.com/albums/w224/danoid/DSCN2466.jpg

That's the prime benefit of these trucks. They're the only thing on the road that can get upper 20's mpg and pull things around that make people look twice...

geordi · **Posted:** Thu Mar 18, 2010 11:22 am

That camping trailer is probably about the same size as my cargo trailer. It isn't the weight that gets you on that, its the giant face into the wind creating wind drag.

As for the tires... Why run ST tires? Are they radial and beyond-strong for the weight? My cargo trailer has dual 3500 lb axles (AFAIK, they might be 5k, it DID have a 2-5/16" ball on it) and I'm running it with 235/75/15 SUV tires... 2100 lbs rated each.

I always want to have more tire capacity than I need for the weight, especially on the trailer - You aren't riding in it to know when something goes wrong instantly.

Towing in overdrive?

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