 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
Car Forum / Driving, Maintenance, Tuning / RVs / April 2007towing in overdrive
HI All, I have a gmc safari mini van that is a 6 cylander engine and I tow a Jayco 1206 that is about 1700 lbs I figure with a full load in the van and very little in the camper. So far it tows ok (run from HOuston to South Florida and back)but I have towed in overdrive only and have several people tell me to tow in D instead. The GM dealer says to use the 'OD and 1 tranny mechanics have told me to use D until I get on the hwy going 60 and then go to OD. Another mechanic told me to always use D and only D unless I am going up a steep hill. What have you learned. I only seem to be able to average 60 mph and that is on flat land My business partner tows a pop up with a 4 cyl and goes 70........... Cindy > HI All, > [quoted text clipped - 8 lines] > Another mechanic told me to always use D and only D unless I am > going up a steep hill. Read your users manual. It should state whats recommended. It varies with makes and models. Generally I opt to tow with OD off. If your transmission shifts up and down too often then defiantly turn off OD. Some have stated driving with OD off isn't an engine power issue. The transmission may run hotter in OD which isn't desirable. Install a transmission temperature gauge. If the temp is low and the transmission isn't shifting back and forth then I'd say OD was fine. If you dont know the temp I'd play it safe and keep OD off unless your owners manual states otherwise. > hunyf...@aol.com wrote: > > HI All, [quoted text clipped - 20 lines] > the temp I'd play it safe and keep OD off unless your owners manual > states otherwise. my owners manual says nothing about towing in od or otherwise. It just says to pay attention to your wieght for the load in the van plus the wieght of what you are towing... I have an transmission cooler installed for the tranny >> hunyf...@aol.com wrote: >> > HI All, [quoted text clipped - 29 lines] > load in the van plus the wieght of what you are towing... > I have an transmission cooler installed for the tranny My personal experience in our 98 Toyota Sienna V6: We have been towing for the 188K life of this minivan and have never turned off the OD (no transmission cooler). The transmission also does not hunt between the top two gears either. Then, this is not your vehicle either. I would go by whether it is hunting between the gears. If it stays in one gear then the transmission is not slipping around generating extra heat and might be just fine. If it does do a lot of the hunting, then I would pay the extra price in MPG and keep it in the lower gear until going fast enough to where it will not hunt anymore. my US$0.02, Tomes > If it stays in one > gear then the transmission is not slipping around generating extra heat > and might be just fine. When towing in OD the RPM's drop and thus less fluid is being pumped to cool the transmission. This is why on many vehicles towing in OD will increase heat even if the engine has plenty of power and the transmission is not hunting gears. Knowing what temperature the transmission is running at is key. >> If it stays in one gear then the transmission is not slipping around >> generating extra heat and might be just fine. [quoted text clipped - 4 lines] > transmission is not hunting gears. Knowing what temperature the > transmission is running at is key. Makes sense. > HI All, > [quoted text clipped - 14 lines] > > Cindy I used to tow with an S10 with the same drivetrain as your Safari. Definitely tow in overdrive unless the transmission begins to hunt for a gear. Your top speed may be limited due to the gearing in your rear end. In my case I had highway gears in the S10 which was terrible for towing and fuel economy. In any case I and most others would suggest that you install an aftermarket transmission cooler, preferably one that is thermostatically controlled. It should cost less than $100 installed and is very cheap insurance for your very expensive transmission. If you are very concerned about your tranny you could also install a tranny temperature guage for about the same price. As it is heat that kills transmissions it can help your determine optimal towing conditions. Good luck, Andrew > As it is heat that kills transmissions > it can help your determine optimal towing conditions. Towing in OD can easily elevate the transmission temperatures even if it is not hunting gears. Keep OD off unless you have a gauge and know for sure or the owners manual clearly states OD is fine while towing. >> As it is heat that kills transmissions it can help your determine >> optimal towing conditions. > > Towing in OD can easily elevate the transmission temperatures even if it > is not hunting gears. Keep OD off unless you have a gauge and know for > sure or the owners manual clearly states OD is fine while towing. My owner's manual for the S10 with the same drivetrain recommended towing in overdrive. And yep, overdrive reduces the flow of trans fluid and can cause more heat buildup. It also reduces the flow of lubricant to the nether regions of the transmission such as the bearings at the rear. Fortunately the Safari has a pretty robust drivetrain and it is not at all like you would find on a normal minivan. At the very least that Safari should be rated to tow 5000# and possibly up to 7000# IIRC. I'm sure the cargo and a 1700# popup shouldn't be too taxing. In any case. An upgraded cooler and a fresh fluid change will go a long ways towards protecting that transmission. Andrew > > As it is heat that kills transmissions > > it can help your determine optimal towing conditions. > > Towing in OD can easily elevate the transmission temperatures even if it > is not hunting gears. Keep OD off unless you have a gauge and know for > sure or the owners manual clearly states OD is fine while towing. The Safari is essentially the same vehicle as the Astro (with exactly the same drivetrain). My owners manual explicity states to tow in Overdrive unless the transmission is frequently downshifting, or if towing in the mountains. We have towed that way (with a trailer twice as heavy as the OP's) for 25,000 miles. The van has a total of about 180,000 miles. We service the tranny regularly, and there has never beeen any indication of scorched fluid or excess metal in the fluid or filter. While many transmissions circulate less fluid on overdrive, many also mechanically bypass the hydraulic clutch in overdrive, thereby not generating as much heat in the first place. Austin >>> As it is heat that kills transmissions >>> it can help your determine optimal towing conditions. [quoted text clipped - 15 lines] > mechanically bypass the hydraulic clutch in overdrive, thereby not > generating as much heat in the first place. We also tow with a 2002 Astro (same as Safari), and I confirm what the owners manual says: tow in OD unless it is hunting. OD is nothing but another name for 4th gear, there are no other special conditions that go with it. Any reduced fluid flow in the transmission between OD and 3, is no different in principle than between 3 and 2. Also be sure to engage Tow/Haul mode with the button on the end of the shift lever. In this mode the transmission shift points are altered, and, most importantly, the torque converter clutch will lock up more of the time. The latter is very important because when the torque converter (fluid clutch) is slipping, the transmission oil is being heated. When the torque converter is locked, this heat source is eliminated. In normal mode, the TC unlocks a lot of the time, while in Tow/Haul mode it only unlocks when shifting gears, or when traveling less than 27mph. We have our Astro equipped with inlet and outlet temperature gauges on the transmission oil, and also with a light that comes on with the TC clutch to indicate when it is locked. With these two devices, and no additional cooler, it is easy to keep the transmission cool. I should mention that we tow a Starcraft Starflyer, which weighs less than 2000lbs loaded. We traveled though the Rockies with 4 people, the trailer and gear, and only had elevated temperature on two passes. Both times road conditions kept us below 27mph for an extended distance, and so the TC unlocked the temperature went too high. We just pulled over and waited a bit to cool, or for traffic to clear so that we could exceed 30mph. While a cooler is never a bad thing, I would not be comfortable without a temperature gauge. Having the temperature gauge, I know that the Astro has enough transmission cooling capacity for almost any condition (that I will encounter with our load), and thus I have no need to add a cooler.  SignatureNOTE: to reply, remove all punctuation from email name field Ned Forrester n_f_orrester@whoi.edu 508-289-2226 Applied Ocean Physics and Engineering Dept. Oceanographic Systems Lab http://adcp.whoi.edu/ Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA > >>> As it is heat that kills transmissions > >>> it can help your determine optimal towing conditions. [quoted text clipped - 31 lines] > Tow/Haul mode it only unlocks when shifting gears, or when traveling > less than 27mph. I do nto have a "tow/haul mode. I just have the gears and my cruise control has not worked in over60,000 miles I have a tranny cooler but no gauge for a transmission. It sounds like I will get one when I can afford one... > We have our Astro equipped with inlet and outlet temperature gauges on > the transmission oil, and also with a light that comes on with the TC [quoted text clipped - 22 lines] > Oceanographic Systems Lab http://adcp.whoi.edu/ > Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA > I have a tranny cooler but no gauge for a transmission. It sounds > like I will get one when I can afford one... A temperature gauge is rather inexpensive. I added a small gauge pod to the drivers side A-Piller to mount it. Looks great. If you tow much change the fluid frequently and possibly use synthetic. I change mine every 15K-20K miles. > hunyf...@aol.com wrote: > > I have a tranny cooler but no gauge for a transmission. It sounds [quoted text clipped - 4 lines] > change the fluid frequently and possibly use synthetic. I change mine > every 15K-20K miles. Thannk you, I need to see my mechanic on monday anyway so I will ask him... my battery is getting drained by something....I have spent a week trying to find the problem.....allternator tested,new battery installed yesterday,electic system checked...but the tester light still glows and if I dont start the van everyday,it wont start joy joy oh happy joy cindy Hi. Maybe have an answer for the battrery drain.... Do you have a tail lite / turn sig / brake lite converter on the vehicle ??? I have had TWO of them (converters) that developed a "slow leak" and graduly took the battery down. Whsn they were removed - wa-la - battery stayed up/// Thanks - john b - Wisconsin Cheesehead '83 GL1100a - - - - '06 Aspen Classic - and other toys >> hunyf...@aol.com wrote: >> > I have a tranny cooler but no gauge for a transmission. It sounds [quoted text clipped - 16 lines] > > cindy > Hi. > [quoted text clipped - 9 lines] > Thanks - john b - Wisconsin Cheesehead > '83 GL1100a - - - - '06 Aspen Classic - and other toys do not know I have the towing light kit installed though the problem may be fixed but until I jusst leavt it for 3 days and do not start it I will not know. My mechanic says the short is now fixed and it only ran me 25.00. cindy > <hunyf...@aol.com> wrote in message > [quoted text clipped - 20 lines] > > > cindy > While many transmissions circulate less fluid on overdrive, many also > mechanically bypass the hydraulic clutch in overdrive, thereby not > generating as much heat in the first place. Most modern transmissions have lock up converters when in OD. My Dodges both do yet the manual specifically states not to tow in OD. The newer Dodges have a tow/haul button that locks out 4th or 5th gear depending on transmission. However, in the case of my Durango 4th gear is still OD. > Towing in OD can easily elevate the transmission temperatures even if it > is not hunting gears. Keep OD off unless you have a gauge and know for > sure or the owners manual clearly states OD is fine while towing. Remember that "overdrive" or "OD" is [drum roll] Just Another Gear. It is "slippage" that causes heat build-up in ANY gear. If not hunting (between actual gears) it is a regularly UNLOCKED torque converter that generates the most destructive heat. When towing with my S10 (back when...), a good eye on the tachometer revealed when the torque converter was - and was not - locked. Forcing the converter to lock is the primary function of the Tow/Haul function on my current vehicle and it's a GREAT towing feature. Signature:) JR 2000 Skamper Ultra 249 TT 2002 Chevrolet Silverado 2500HD Vortec 8100 - Allison 1000 > Remember that "overdrive" or "OD" is [drum roll] Just Another Gear. > > It is "slippage" that causes heat build-up in ANY gear. If not hunting > (between actual gears) it is a regularly UNLOCKED torque converter that > generates the most destructive heat. That is true. However, OD will often cause more heat because of lower fluid pump rate even if lock up occurs. Tow/Haul mode on my Dodge does not force lock up. It does hold gears longer and keeps the TC locked longer but it's still in drive and will unlock or downshift if needed. > HI All, > [quoted text clipped - 14 lines] > > Cindy Some great followups on this. And timely, as my Grand Caravan is in the shop for the second time getting it's tranny pulled apart -- in less than 88k miles. I generally have towed with OD on and cruise about 65-70MPH. When I encounter hills or long grades I switch OD off. OD on equals lower RPMS and slightly better mileage. OD off turns higher RPMS, and I thought the engine temp was higher -- but the guages are not digital and coudl be wrong. I do not have a transmission temp guage but really think I will get one. My biggest problem is driving about 65-70 with OD off on long grades, the engine/tranny will throttle back for a brief moment, as if to shift (..into OD), then come back to the previous power level. It is annoying and I believe a major factor in why the internal 3-4 gears and clutch assembly in my tranny keep requiring repair. >> HI All, >> [quoted text clipped - 31 lines] > and I believe a major factor in why the internal 3-4 gears and clutch > assembly in my tranny keep requiring repair. Grand Caravans ate tranny's without towing.
|
Reply to this Message |
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2008 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.