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CRD Transmission and Towing
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=27887		 Page 1 of 1
Author:  yakers [ Mon Dec 24, 2007 10:40 am ]
Post subject:  CRD Transmission and Towing
I am going to repeat a question I posted under the general CRD Transmission thread because I really need to understand the optimal use of the AT when towing:

what is the difference driving wise between choosing third gear and just switching OD off? Is 3rd gear with OD off a lower gear? Is it more important to keep the trans from shifting between gears or keeping it out of OD? I plan to tow a 3,500 LB trailer. If I had a 5 speed manual I would choose 4th for most flat driving, shifting down to 3rd for hills. With the CRD it looks like I would choose OD off for most driving and 3rd for hills? And for really big hills(like thee California Grapevine) 2nd? And does external temperatures count? I expect my towing to include places like Death Valley with steep uphill grades and 100+ temps. When would I need to turn off the AC?
Author:  chrispitude [ Mon Dec 24, 2007 10:50 am ]
Post subject: 
The most important thing is to keep the torque converter locked up. Manually shifting the center console selector to 3 might keep you in third gear, but I think it will be unlocked. When overdrive is on, only 4th and 5th gear can lock up. This means that you can only tow locked up at about 52mph and up. When you turn overdrive off, the TCM will allow third gear to lock up at about 37mph.

I've towed a 26' 5000lb travel trailer up some long grades. The peak torque of the CRD is between 1800rpm and 3000rpm. Try to keep it in this range, and if two gears will pull equally well up a grade (ie - 3rd at 50 or 4th at 55), favor the lower gear as the higher RPM will be friendlier to the drivetrain by way of smoother power impulses from the engine. At low RPM under heavy load with full boost, each combustion event from the little VM engine is a sledgehammer blow to the drivetrain. The temperature gauge did rise to one tick below 3/4 at one point. I haven't tried it yet, but I've read elsewhere that the ORM (unplugging the MAF) will keep the heat from the EGR out of the cooling system, effectively improving cooling capacity. If the engine temperature becomes alarming, turn off the A/C, crank the heat up to full blast, and open the windows! I haven't had to do this with the CRD, although I've needed it for other vehicles in a pinch.

3500lbs is no problem for the CRD. You should find it an enjoyable experience, and I suspect you won't need to worry about too much of the above.

- Chris
Author:  Joe Romas [ Mon Dec 24, 2007 12:52 pm ]
Post subject: 
I also have a 3500 pound travel trailer and since I put on my lift pump it has no problems at all towing that load. Before the pump it was constantly shifting up and and down on the slightest incline. Since our CRD's are drive by wire we don't know where the ECM has the "digital skinney pedal" as far as loads go. So with a drop in power from air in the fuel filter the engine the ECM has the digital peddle down and the transmission yells "torque reduction", the ECM cuts torque, transmission down shifts, engine requires less fuel and gets over it's lack of fuel so the digital peddle raises and the transmission shifts back up. then it starts all over again. If you don't have a lift pump and this happpens you'll know why :shock:
Author:  BioCRD [ Mon Dec 24, 2007 6:36 pm ]
Post subject: 
chrispitude wrote: The most important thing is to keep the torque converter locked up. Manually shifting the center console selector to 3 might keep you in third gear, but I think it will be unlocked. When overdrive is on, only 4th and 5th gear can lock up. This means that you can only tow locked up at about 52mph and up.

Help me out here - My 06 LTD has no "3" - only "1, 2, D".

I tow a 2200 lb trailer a lot, in the mountains, and struggle to outwit the tranny shifting inappropriately.

I understand from the Owner's Manual that the OD off button keeps you in fourth (which we know is an overdrive ratio too), but there seems no way to select third. I'd love to know how. Anyone?
Author:  chrispitude [ Mon Dec 24, 2007 6:56 pm ]
Post subject: 
BioCRD wrote:
- My 06 LTD has no "3" - only "1, 2, D".

I tow a 2200 lb trailer a lot, in the mountains, and struggle to outwit the tranny shifting inappropriately.

I understand from the Owner's Manual that the OD off button keeps you in fourth (which we know is an overdrive ratio too), but there seems no way to select third. I'd love to know how. Anyone?


Yep, I got that wrong. Sorry about that. The CRD is my wife's daily driver, so I couldn't go down and check it, and assumed that's what the original poster meant about forcing it into third gear.

I do know that turning off overdrive keeps the transmission in 3rd gear. The RPM/mph is shorter than the locked up behavior in 4th or 5th.

- Chris
Author:  RTStabler51 [ Fri Dec 28, 2007 6:33 pm ]
Post subject: 
I've towed my cars on 18' dual axle trailer and leave the transmission alone unless going up step grades I'll kick it 'out' of O/D. I haven't seen any odd trans temps either.
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