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Some of those cars run the transmission pump off the output shaft instead of the input shaft as is normal, and the manufacturer states they can be towed four down. Stick or automatic doesn't matter, the specific transmission has to be capable of self-lubricating without the input shaft turning. And some 4WDs can put the transfer case in neutral like EightBit stated. RVers will buy cars specifically because they can be towed four down.
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Feb 15, 2013 04:50
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Not saying you're wrong, but how does an auto trans work at all with the fluid pump on the output shaft? How does it bootstrap from zero pressure at startup to getting enough pressure to engage the clutches without having any pressure to do so? Hondamatics I can understand doing that since IIRC they are basically a torque converter and solenoids added to a manual transmission, but something just doesn't make sense about how that would work otherwise. And how would it work when you're sitting at a stop light? e: oh yeah. On a similar subject, chrysler autos. Horrible mechanical failures (from the factory anyways) because for some reason they decided it'd be good to not bother supplying lubrication oil to a lot of the transmission when the gearshift is in park or neutral, so they burn bearings and cook the fluid in a hurry if you work them hard and then let them sit, or just let them idle/rev too much in park or neutral without oil flowing. Bravo, a sound engineering decision! (this applies to at least the 46r, 47r, 48r, and possibly 42/44r series as well - not sure if hydraulic vs electronic control systems are relevant, but it's certainly true for most of the common ones in trucks/SUVs) kastein fucked around with this message at 05:16 on Feb 15, 2013 |
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Feb 15, 2013 05:13
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I don't understand how automatic transmissions work but isn't the torque converter itself basically a vaned pump? It would still be circulating fluid if the engine is idling even if the pump is on the output shaft and not spinning, although maybe there isn't enough pressure to shift gears?
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Feb 15, 2013 05:31
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You...answered your own question?
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Feb 15, 2013 05:33
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Geirskogul posted:You...answered your own question? There....are several questions in my post which I still don't know the answer to?
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Feb 15, 2013 05:36
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The Saturn S-Series can be flat towed without damaging anything. Tell me you haven't seen at least one behind an RV in your life.
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Feb 15, 2013 05:37
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Throatwarbler posted:I don't understand how automatic transmissions work but isn't the torque converter itself basically a vaned pump? It would still be circulating fluid if the engine is idling even if the pump is on the output shaft and not spinning, although maybe there isn't enough pressure to shift gears? Effectively yes. Problem is, in some designs, if left for a while (and at first startup) it's difficult to keep the converter completely full. At least, they've always been half full when I pulled them out of a transmission that had been sitting for a while. A vaned pump doesn't really work well when it's not full because air is a lovely compressible fluid that doesn't really transmit force well at low pressure. However, the torque converter isn't the fluid pump that drives the hydraulic clutches and stuff in most autos. It just... converts torque (when properly filled with fluid) and its neck happens to drive the pump (when it's on the input shaft of the transmission, anyways) by virtue of the fact that the outer shell of the torque converter spins at engine RPM at all times, and slots into the front of the transmission. That makes it an ideal way to connect the trans fluid pump to the engine to get line pressure when not in gear, but still keep the transmission/torque converter as a fairly self contained unit rather than having a separate pump mounted to the engine somewhere.
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Feb 15, 2013 05:41
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kastein posted:Not saying you're wrong, but how does an auto trans work at all with the fluid pump on the output shaft? How does it bootstrap from zero pressure at startup to getting enough pressure to engage the clutches without having any pressure to do so? Hondamatics I can understand doing that since IIRC they are basically a torque converter and solenoids added to a manual transmission, but something just doesn't make sense about how that would work otherwise. And how would it work when you're sitting at a stop light? I don't know honestly. Maybe they have two pumps. Maybe the clutches use hydraulic pressure to release. Don't most autos just use a sprag clutch and band for low? The transmission probably has to be designed specifically for towing (Saturns, which were actually marketed for four down towing) or designed specifically weirdly and works in a niche application by pure accident (Honda).
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Feb 15, 2013 06:07
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Throatwarbler posted:There....are several questions in my post which I still don't know the answer to? Was replying to kastein, your post popped while I was typing it
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Feb 15, 2013 06:12
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Left Ventricle posted:The Saturn S-Series can be flat towed without damaging anything. Tell me you haven't seen at least one behind an RV in your life. I was going to say that it's easy enough to buy another piece of poo poo saturn if the transmission stops working.
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Feb 15, 2013 06:48
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Splizwarf posted:Whoa whoa whoa, let's not cross a broken axle off the list of possibilities. A broken axle which broke in such a way that it locked one wheel while allowing the other or the input gear to freewheel? If it was locked up and the other side was still being driven it'd be turning double speed to make everything work out in the differential, which while the 4.0 V6 is a solid motor it's never really been known for being powerful.
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Feb 15, 2013 07:09
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They add an auxiliary ATF pump to vehicles so they can be flat towed. Either belt driven off an axle or an electric pump to keep up the pressure to lubricate bearings in the transmission. About the picture of the truck with a worn in half rim. The post on reddit stated it was a flat tire which caused that.
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Feb 15, 2013 14:54
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Oh, the answer is that simple? Well, poo poo. Friend: "well, that rod is bent." I think he may be understating the issue somewhat... But at least it didn't break and ventilate the block.
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Feb 15, 2013 17:03
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That rod looks perfectly straight to me. It just isn't attached to the hub at the right angle, that's all.
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Feb 15, 2013 17:33
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kastein posted:Oh, the answer is that simple? Well, poo poo. What motor is that? Looks like a Yamaha 62T based 2-stroke?
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Feb 15, 2013 19:02
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Honestly not sure. He works in a shop that specializes in small motorsports engines so you are probably right - iirc they do a lot of jetskis, dirtbikes, etc. e: KozmoNaut, it may still be straight in both planes, but it appears to be somewhat twisted.
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Feb 15, 2013 19:14
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I'm guessing oil starvation caused the big end bearing to lock up. The end of that rod is heat-discolored and it's got bearing dust all over it. It's indeed very lucky that the cases didn't get holed. Should only need a crank. Either the owner forgot to premix, or more likely, the oil injection for that side failed.
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Feb 15, 2013 19:17
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Left Ventricle posted:The Saturn S-Series can be flat towed without damaging anything. Tell me you haven't seen at least one behind an RV in your life. When my sister had her first car ('95 SL1) I stumbled across quick-disconnect CV shafts for it at least once while looking for parts. I think they were popular primarily because they were cheap and lightweight, not that the automatic was well suited to being flat towed. I mean, you can actually buy cable disconnects for a rear driveshaft.
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Feb 16, 2013 01:02
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kastein posted:e: oh yeah. On a similar subject, chrysler autos. Horrible mechanical failures (from the factory anyways) because for some reason they decided it'd be good to not bother supplying lubrication oil to a lot of the transmission when the gearshift is in park or neutral, so they burn bearings and cook the fluid in a hurry if you work them hard and then let them sit, or just let them idle/rev too much in park or neutral without oil flowing. Bravo, a sound engineering decision! I don't understand how Chrysler can fail time after time at making good autos when the old ones where so good? Easy to work on, reliable and well thought out. Fun fact (since there was talk about towing earlier), first generation Torqueflites (up to 1965) had two pumps, one front and one rear. The rear pump made it possible to both bump start the car and tow it without having the driven wheels off ground.
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Feb 16, 2013 03:36
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Nidhg00670000 posted:I don't understand how Chrysler can fail time after time at making good autos when the old ones where so good? Easy to work on, reliable and well thought out. Fun fact (since there was talk about towing earlier), first generation Torqueflites (up to 1965) had two pumps, one front and one rear. The rear pump made it possible to both bump start the car and tow it without having the driven wheels off ground. More pumps = more poo poo to go wrong though. Automatic transmissions already have enough extra moving parts compared to manuals, and few enough people flat tow that I can understand the manufacturers not really putting the extra cost into making sure it works. Is it that much harder to pull a small trailer with an RV?
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Feb 16, 2013 06:31
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EightBit posted:Is it that much harder to pull a small trailer with an RV? RV owners probably view it as another "vehicle" to store, plate, register and insure and I'm sure there's a fractional improvement on fuel economy by just towing the vehicle rather than towing the vehicle on a trailer. I used to drive more than anyone other than OTR truckers and vehicles being flat-towed behind RVs was far, far more common than being tow-dollied or on a flatbed trailer.
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Feb 16, 2013 06:38
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IOwnCalculus posted:When my sister had her first car ('95 SL1) I stumbled across quick-disconnect CV shafts for it at least once while looking for parts. I think they were popular primarily because they were cheap and lightweight, not that the automatic was well suited to being flat towed. I remember a big selling point for Saturn, at least in their first 10 years, was that they could be towed on all 4 wheels - they used to market heavily to the RV crowd as well. I don't have any print ads from back then anymore, but I remember reading a lot about that in the early-mid 90s. *Source: grandfather owned several GM dealers when he was alive, including a Saturn dealership (briefly). A lot of that went out the window when they started sourcing their transmissions from other GM models instead of designing everything internally, though apparently the Aisin 5AT they borrowed from Toyota could be flat towed if you followed a specific procedure.. every 7 hours. We won't discuss the bastard child CVT they used briefly, though I think that was limited to the 03-04 Ion coupe and not shared with the other USDM Delta cars.
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Feb 16, 2013 07:41
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Geoj posted:RV owners probably view it as another "vehicle" to store, plate, register and insure and I'm sure there's a fractional improvement on fuel economy by just towing the vehicle rather than towing the vehicle on a trailer. I used to drive more than anyone other than OTR truckers and vehicles being flat-towed behind RVs was far, far more common than being tow-dollied or on a flatbed trailer. The main thing you are all leaving off is space size and cost. Most places won't let you completely take up as much space as you want. You have a 40 foot RV, a trailer that adds x amount of feet, then your tote. Most places brag about 50amp 50 foot pull through.
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Feb 16, 2013 09:01
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Not to mention its a lot nicer if you manage to get yourself in a tight space when you can drive the "trailer" on its own. Unfortunately its also sort of required if you end up needing to make a multipoint turn, you can't really back up very far with how steering works in a four-down configuration.
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Feb 16, 2013 10:21
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So manual transmissions win again. Got it.
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Feb 16, 2013 12:08
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Plinkey posted:So manual transmissions win again. Got it. Nope, tons of manuals are lubed by the input shaft.
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Feb 16, 2013 17:40
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FatCow posted:Nope, tons of manuals are lubed by the input shaft. I had to pull the driveshaft on my 2wd manual tacoma to flat tow it across the country. Pain in the rear end. If you look through the RV magazines, they'll usually have a yearly "dinghy" edition that runs through many of the manufacturers' car and light suv lines and rates them on flat-towability. Some autos are rated as "flat-tow anywhere, anytime, no care required". Some autos have the stipulation that you need to fire up the engine every few hundred miles and idle for 5 minutes to circulate fluid in the tranny. And some autos require an auxiliary pump to be installed that deals with lubing the tranny while on the move. Manual transmissions and 4wd transfer cases are just as much of a hodgepodge. Some can be towed without worry, some need the driveshaft pulled if you're going more than a few miles. The owner's manual will sometimes say what's allowed, and otherwise you have to search out the info for your specific model of transmission.
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Feb 16, 2013 18:56
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Most low power FWD manuals have their oil grabbed by the differential's ring gear that splash lubes the rest of the transmission, having an actual pump is only common on higher power boxes like the turbo MR2's and such.
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Feb 16, 2013 19:01
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Most truck manuals are also splash lubed as far as I have seen, too. I've only really messed with old top loader 4 speeds, new venture 3550/3500/4500s, and a small assortment of aisin warner boxes though.
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Feb 16, 2013 19:24
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kastein posted:Most truck manuals are also splash lubed as far as I have seen, too. I've only really messed with old top loader 4 speeds, new venture 3550/3500/4500s, and a small assortment of aisin warner boxes though. I was dealing with an aisin in my tacoma obviously. The issue with a rwd manual tranny isn't that the bulk of the transmission is splash-lubed, as that doesn't necessarily cure all your problems. It's commonly a specific concern about the bearings in the tail housing not getting any lube when flat-towing, since the tranny is in neutral, and thus most of the gear train isn't turning to create the splashing effect, but the driveshaft is still spinning the tailshaft of the tranny at highway speeds sans lube. Some manuals handle this fine, some don't, including some aisins.
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Feb 16, 2013 19:37
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Good point. What case, R150 series? Those are quite similar to the AX15s I'm used to, and yeah, I hadn't considered the fact that none of the gears would be connected to the tailshaft and thus nothing would lube the rear output seal or bushing/bearings. On my 4x4 AX15 I don't have any real worries about that because it's got a late model NP231 behind it, which runs the lube pump off the rear output shaft and keeps the input and output shafts disconnected when the transfer case is in neutral. So I get full lubrication to the transfer case, leave the transfer in neutral and the transmission in 1st (only matters if going long distances) and it Just Works. Assuming there's fluid in the transfer case, that is 
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Feb 16, 2013 19:43
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kastein posted:Good point. What case, R150 series? Those are quite similar to the AX15s I'm used to, and yeah, I hadn't considered the fact that none of the gears would be connected to the tailshaft and thus nothing would lube the rear output seal or bushing/bearings. W52 in a 2wd, cousin of the W56 found in 4cyl Toyota 4x4's, but I don't recall if that series ever got used in the Jeeps (maybe in the 4cyls?). The W series isn't so different from the R/AX15 series, so I think this concern would extend to 2wd jeeps. At least with the NP t-cases you can shove the t-case in neutral and go, but most of the Toyota aisin t-cases don't allow flat-towing at all.
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Feb 16, 2013 19:54
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murphle posted:W52 in a 2wd, cousin of the W56 found in 4cyl Toyota 4x4's, but I don't recall if that series ever got used in the Jeeps (maybe in the 4cyls?). The W series isn't so different from the R/AX15 series, so I think this concern would extend to 2wd jeeps. At least with the NP t-cases you can shove the t-case in neutral and go, but most of the Toyota aisin t-cases don't allow flat-towing at all. Oh, for some reason I assumed you had the V6 not the 4-cyl. Yeah, the W/G series Toyota RWD transmissions are very closely related to the AX4/AX5 - same bolt pattern holds the bellhousing on, etc. I found this out when ACEofsnett and I were bullshitting about his knocking 22re in his old daily driver (86 hilux) and after a bit of google research it turns out that we actually could put a jeep/amc 2.5 into his toyota without replacing the transmission  R series are close cousins to the AX15, W/G series are related to the AX4/5, and a few GM vehicles use similar boxes as well. Either way, yeah, 2wd ones definitely shouldn't be flat towed without pulling the driveshaft as you said. Some earlier NP cases are stupid and lock the front/rear driveshafts together in neutral (so it's more like non-driven 4x4) as far as I know, I've heard of people blowing up their drivelines trying to flat tow a jeep built like that. Sucks that the Aisin cases don't allow flat towing, it's not exactly difficult to design for it, just make sure the case is splash lubed or has a rear driveshaft driven fluid pump and design the mode/range shift gate so neither driveshaft is linked to the input shaft when in neutral.
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Feb 16, 2013 20:06
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IOwnCalculus posted:I realize it was probably towed but I have some small hope that some numbnuts was actually trying to drive that thing, sparking and howling down the road. Like this? https://www.youtube.com/watch?v=vX23cZ1dShU
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Feb 16, 2013 21:08
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http://youtu.be/_JQdxC63vCQ Holy poo poo.
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Feb 16, 2013 21:38
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InterceptorV8 posted:http://youtu.be/_JQdxC63vCQ They tried to reject the takeoff well past V1, and overran the end of the runway. Everyone walked away, luckily.
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Feb 16, 2013 23:13
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THAT FITMENT!  Seriously though, I kinda wonder how the hell he's keeping it straight on the road. It's got to be pulling badly to the left.
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Feb 17, 2013 01:05
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kastein posted:THAT FITMENT! Well any hellaflush car is usually just a trailer queen. Wasn't it a Golf or something that had the treatment that some guy tried to drive and got arrested? I think this one is however more mechanically sound than the Golf
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Feb 17, 2013 03:26
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Feb 17, 2013 03:35
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Free-range
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Feb 17, 2013 03:38
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