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Car Forum / Driving, Maintenance, Tuning / Maintenance and Repair / June 2007Wear in an auto transmission...
Awl-- A mechanic once told me *not* to coast in neutral down long highway hills, to eke out more mpgs, and then throw the car in drive, as I would sooner or later lose my tranny. Even if I bump up the rpm's in the engine to the coasting rpms before shifting back. iow, if I'm coasting downhill at 60 mph and 2500 rpm, in neutral I"d be at 500-800, but before going back into drive, rev back up to 2500 ( like you would in a manual), then shift. Where is the wear? Where is the wear in general in an auto tranny? My understanding is that fluid acts as the clutch plate, so an auto tranny should last forever, except for "bands", etc. Are bands like V belts? If hotrodding in an auto (revving at a light, throwing it in Drive), what goes? would like to see a pictorial of how auto transmissions work. Any leads?  Signature------ Mr. P.V.'d (formerly Droll Troll), Yonkers, NY Stop Corruption in Congress & Send the Ultimate Message: Absolutely Vote, but NOT for a Democrat or a Republican. Ending Corruption in Congress is the *Single Best Way* to Materially Improve Your Family's Life. The Solution is so simple--and inexpensive! entropic3.14decay at optonline2.718 dot net; remove pi and e to reply--ie, all d'numbuhs It is also against the law where you live and in most places in the world to coast down a hill in neutral. The unloaded suspension can 'get away from you' very fast, especially if there is any wear in any parts. In an auto, the engine turns the tranny usually. Some might not like the tranny turning the engine with a high connection speed for wear issues, but I don't know. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 (More Off Road album links at bottom of the view page) > Awl-- > [quoted text clipped - 18 lines] > > would like to see a pictorial of how auto transmissions work. Any leads? >It is also against the law where you live and in most places in the >world to coast down a hill in neutral. >The unloaded suspension can 'get away from you' very fast, especially if >there is any wear in any parts. especially if you're incompetant to the absolute. >> It is also against the law where you live and in most places in the >> world to coast down a hill in neutral. [quoted text clipped - 3 lines] > > especially if you're incompetant to the absolute. No, you don't have to be incompetent to lose it, just damn unlucky to have a cop spot you coasting and too honest when asked about it by said cop. One of the 'first' rules when off roading is to always keep it in gear when descending, having it in neutral and only using the brakes can cause even the most experienced to lose control. The physics are the same whether on or off road. Off road just exaggerates them. There 'is' reason coasting downhill in neutral is against the law in most places in the English world. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 (More Off Road album links at bottom of the view page) >>> It is also against the law where you live and in most places in the >>> world to coast down a hill in neutral. [quoted text clipped - 3 lines] >> >> especially if you're incompetant to the absolute. >No, you don't have to be incompetent to lose it, just damn unlucky to >have a cop spot you coasting and too honest when asked about it by said cop. If you have a cop close enough to read the gear shift indicator on your transmission and you are oblivious to his presence, they you have bigger problems than complete lack of driving skills. Well, coasting downhill at 50-70 mph is not exactly testing the limits of a vehicle or driving skill--not even my limited driving skill. Now, riding a motorcycle at 150.... :) But Q still remains: does shifting from neutral to drive at highway speeds produce wear/tear on the tranny? Signature------ Mr. P.V.'d (formerly Droll Troll), Yonkers, NY Stop Corruption in Congress & Send the Ultimate Message: Absolutely Vote, but NOT for a Democrat or a Republican. Ending Corruption in Congress is the *Single Best Way* to Materially Improve Your Family's Life. The Solution is so simple--and inexpensive! entropic3.14decay at optonline2.718 dot net; remove pi and e to reply--ie, all d'numbuhs >>>> It is also against the law where you live and in most places in the >>>> world to coast down a hill in neutral. [quoted text clipped - 12 lines] > transmission and you are oblivious to his presence, they you have bigger > problems than complete lack of driving skills. I think it puts a big sudden shock load on the automatic transmission parts,that couldn't be a good thing at all.I wonder how many automatic transmissions have blown up from doing that? cuhulin >I think it puts a big sudden shock load on the automatic transmission > parts,that couldn't be a good thing at all.I wonder how many automatic > transmissions have blown up from doing that? > cuhulin I'd agree, except that on all cars/trucks I've done this on, it seems effortless/seamless. No jerking, very smooth. Not saying no damage is being done, just curious as to what/how, given the smoothness. Signature------ Mr. P.V.'d (formerly Droll Troll), Yonkers, NY Stop Corruption in Congress & Send the Ultimate Message: Absolutely Vote, but NOT for a Democrat or a Republican. Ending Corruption in Congress is the *Single Best Way* to Materially Improve Your Family's Life. The Solution is so simple--and inexpensive! entropic3.14decay at optonline2.718 dot net; remove pi and e to reply--ie, all d'numbuhs Proctologically Violated©® <entropic3.14decay@optonline2.718.net> wrote in article <Mrj8i.927$_Y2.42@newsfe12.lga>... > >I think it puts a big sudden shock load on the automatic transmission > > parts,that couldn't be a good thing at all.I wonder how many automatic [quoted text clipped - 5 lines] > Not saying no damage is being done, just curious as to what/how, given the > smoothness. Here are some potential areas I can think of..... 1. Since the valve body circuits have been directing fluid flow and pressure into the Neutral circuit, there has been no flow or pressure in the Drive circuit. The engine, basically, drives the torque converter which is attached to the front transmission pump. Revving the engine merely increases flow in the Neutral circuit until you place the indicator - and valve body control valve - into Drive. Unlike a standard transmission, revving the engine in neutral doesn't get various parts inside the transmission spinning so they will mesh more easily. When you hit drive, fluid momentarily flows through the drive circuit as though you are starting out from a stop until the pressure builds up and resets the various Drive circuit pressure and spring-controlled valves where they should be for the engine and road speeds. I would expect little - if any - wear in the valve body, but I can see the over-running (or one-way) clutch taking some shock loads. 2. You would be engaging the clutch packs at a higher speed than they normally engage - possibly causing premature wear there. They may or may not engage with the correct pressure for the transmission's needs at a particular load. 3. The quick slide up/down through the various clutch/band applications while the valve body adjusts to match the transmission to engine/road speeds may cause some momentary, partial engangements which would contribute to wear. When you place the selector into "D", the valve body actually sets the transmission up to start out in first gear. As pressure, engine and road speed increase, the valves channel fluid and pressure into different circuits to engage second, then high ( in a three-speed auto). When you drop a selector into "D" while the car is rolling, it STILL selects first initially, then rapidly adjusts by applying the circuits until it reaches the correct application for the existing road speed. So, in answer to your initial question, "YES! It DOES place strain on the components." BUT, unless you do it several times per day, it is doubtful that you will ever really notice it. You may take a few thousand miles of life off a transmission.......My transmissions ALWAYS go 200,000 miles, so I would probably never notice a couple thousand (one percent) difference. I used to lower my engine RPM before engaging the A/C clutch until I realized that the A/C clutch cycles on/off automatically while I am blasting down the highway at 70+ mph. Look at your auto tranny in a similar vein. > Well, coasting downhill at 50-70 mph is not exactly testing the limits of a > vehicle or driving skill--not even my limited driving skill. > Now, riding a motorcycle at 150.... :) > > But Q still remains: does shifting from neutral to drive at highway speeds > produce wear/tear on the tranny? Yes, but really not much more than shifting from neutral to drive sitting at a dead stop. Every time the transmission shifts there is *some* tiny amount of wear- wear on the clutch plates, wear on the bands, wear on the actuator bores and rings, wear on pivots, wear on the lip seals that are found on clutch actuator pistons, etc. But you have to remember, automatics are made to do that *millions* upon millions of times over their life, so adding the occasional cycle isn't going to sigificantly shorten the life of the transmission. >If hotrodding in an auto (revving at a light, throwing it in Drive), >what goes? That's a WHOLE different ballgame, because now you're subjecting the transmission (and the whole chassis) to shock loads it was never intended to bear. What usually breaks first isn't the transmission, its a universal joint or some other driveline component. IF the transmission does fail, it will depend a little on the type and layout of the auto trans. In conventional Ford and Chrysler (and I'm pretty sure GM THMs too, although their power flow is a bit differnt) rear-drive transmissions, a "neutral drop" hits the overrunning clutch (aka 'sprag') the hardest. Low gear is engaged by the rear clutch engaging and the sprag catching to prevent a geartrain component from counter-rotating. The clutch can take the abuse, but when the sprag catches it will often crack the whole transmission case wide open because the roller bearings that get "pinched" to engage the sprag generate a huge outward force on the case. It can literally blow the case apart. >> Well, coasting downhill at 50-70 mph is not exactly testing the limits of >> a vehicle or driving skill--not even my limited driving skill. [quoted text clipped - 11 lines] > their life, so adding the occasional cycle isn't going to sigificantly > shorten the life of the transmission. It seems, tho, that the main concern expressed here is not so much shifting back into drive from coasting, but actually the *coasting itself*. Which I find pretty surprising. As far as hot-rodding goes, I guess that's better done on a manual. Signature------ Mr. P.V.'d (formerly Droll Troll), Yonkers, NY Stop Corruption in Congress & Send the Ultimate Message: Absolutely Vote, but NOT for a Democrat or a Republican. Ending Corruption in Congress is the *Single Best Way* to Materially Improve Your Family's Life. The Solution is so simple--and inexpensive! entropic3.14decay at optonline2.718 dot net; remove pi and e to reply--ie, all d'numbuhs > >If hotrodding in an auto (revving at a light, throwing it in Drive), what > >goes? [quoted text clipped - 13 lines] > sprag generate a huge outward force on the case. It can literally blow the > case apart. > It seems, tho, that the main concern expressed here is not so much shifting > back into drive from coasting, but actually the *coasting itself*. > Which I find pretty surprising. Because it is- the coasting itself doesn't hurt the transmission in any way shape or form, so long as the engine is running to ciruclate fluid. Towing the car with the engine off lets too much heat build up in the clutch packs and will roast them, but coasting downhill in neutral? No. Its illegal and dumb, but not damaging to the transmission. > As far as hot-rodding goes, I guess that's better done on a manual. So the clutch gets scragged instead? No, its better done correctly (at the dragstrip, with a trans brake or by properly loading/flashing the torque convertor at the starting line) than by doing something as bone-headed butt-munching stupid as a neutral drop. Automatics are unquestionably superior for one particular form of racing- drag racing- if operated properly. Even with the engine running to circulate fluid, the cluth plates can still drag against each other and create excessive heat. True, fluid is circulating, but no pressure is applied to the clutch. Besides, most automatics can be towed a few miles at slower speeds for short distances without damage. Roy >> It seems, tho, that the main concern expressed here is not so much >> shifting back into drive from coasting, but actually the *coasting [quoted text clipped - 15 lines] > superior for one particular form of racing- drag racing- if operated > properly. > Even with the engine running to circulate fluid, the cluth plates can still > drag against each other and create excessive heat. True, fluid is EXACTLY the same thing goes on when you're driving normally, because any clutch that is not currently engaged is "slipping." Old 3-speed rear-drive automatics didn't have any disengaged clutches once they got into high gear, but any modern 4, 5, or 6-speed most certainly DOES. The fluid flow provided by the pump is more than adequate to carry away the small amount of heat generated in a disengaged clutch pack. >>>> It is also against the law where you live and in most places in the >>>> world to coast down a hill in neutral. [quoted text clipped - 8 lines] > transmission and you are oblivious to his presence, they you have bigger > problems than complete lack of driving skills. Not when you are not aware that it is illegal. The cop said he could tell because the unloaded suspension lets the vehicle 'float' around. This is in a Very hilly city and he watches for it. I was young and lucky and got off with a lecture. Mike >>>>> It is also against the law where you live and in most places in the >>>>> world to coast down a hill in neutral. [quoted text clipped - 8 lines] >> transmission and you are oblivious to his presence, they you have bigger >> problems than complete lack of driving skills. >Not when you are not aware that it is illegal. Something being illegal is often merely the whim of clueless lawmakers. >>>>>> It is also against the law where you live and in most places in the >>>>>> world to coast down a hill in neutral. [quoted text clipped - 14 lines] > > Something being illegal is often merely the whim of clueless lawmakers. Well said, but proly not true. It's calculated fukn revenue raising, just like the seat belt laws. Anyone really think they give a flying f.ck about our safety? Signature------ Mr. P.V.'d (formerly Droll Troll), Yonkers, NY Stop Corruption in Congress & Send the Ultimate Message: Absolutely Vote, but NOT for a Democrat or a Republican. Ending Corruption in Congress is the *Single Best Way* to Materially Improve Your Family's Life. The Solution is so simple--and inexpensive! entropic3.14decay at optonline2.718 dot net; remove pi and e to reply--ie, all d'numbuhs >>>>> It is also against the law where you live and in most places in the >>>>> world to coast down a hill in neutral. [quoted text clipped - 13 lines] >The cop said he could tell because the unloaded suspension lets the >vehicle 'float' around. This is in a Very hilly city and he watches for it. Sounds more like you were just going too fast giving the appearance of "floating" as you went zooming over bumps. Being in neutral isn't going to do much "unloading" of the suspension at any normal speed or during a normal maneuver. >I was young and lucky and got off with a lecture. > >Mike >>>>>> It is also against the law where you live and in most places in the >>>>>> world to coast down a hill in neutral. [quoted text clipped - 16 lines] > going to do much "unloading" of the suspension at any normal speed or > during a normal maneuver. Nope, I rolled out of my driveway and down my steep street 100 yd to a stop sign before putting it in gear like I used to normally do. Cop was parked at the bottom of the hill so I saw him before I even started my car and thought nothing of it. >> I was young and lucky and got off with a lecture. >> >> Mike Mike Romain <romainm@sympatico.ca> wrote in article <4662caf4$0$32367$9a6e19ea@unlimited.newshosting.com>... > Nope, I rolled out of my driveway and down my steep street 100 yd to a > stop sign before putting it in gear like I used to normally do. Cop was > parked at the bottom of the hill so I saw him before I even started my > car and thought nothing of it. If you rolled down the road with your engine off - as the above statement would suggest - then ANY cop with reasonable hearing would and SHOULD write you up! Without the engine running, most cars do not have brake or steering assist - making them harder to control. > Mike Romain <romainm@sympatico.ca> wrote in article > <4662caf4$0$32367$9a6e19ea@unlimited.newshosting.com>... [quoted text clipped - 9 lines] > Without the engine running, most cars do not have brake or steering assist > - making them harder to control. Where in hell would you get that inference from? I 'like' to have brakes and steering working thanks. Are people really stupid enough to do that? Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 (More Off Road album links at bottom of the view page) A few years ago,the power steering belt on my 1978 Dodge van decided to break when I was down town.Untill I could buy a new belt and install the belt,the steering on my van was pretty hard. cuhulin I drove a 67 Caddy without a power steering pump for several weeks. I don't recommend trying it, but the car was drivable. Roy >A few years ago,the power steering belt on my 1978 Dodge van decided to > break when I was down town.Untill I could buy a new belt and install the > belt,the steering on my van was pretty hard. > cuhulin A vehicle with power steering and without the belt, such as my 1978 Dodge van,that will build up your arm muscles if driven like that long enough. People who tow their cars behind their motorhomes, they use a towing dolly with the front wheels of the car on the towing dolly.What do they do about the automatic transmissions in their cars? Do they put the gear shift in neutral? cuhulin > A vehicle with power steering and without the belt, such as my 1978 > Dodge van,that will build up your arm muscles if driven like that long [quoted text clipped - 5 lines] > shift in neutral? > cuhulin no, they buy FWD cars. :) >> A vehicle with power steering and without the belt, such as my 1978 >> Dodge van,that will build up your arm muscles if driven like that long [quoted text clipped - 7 lines] > > no, they buy FWD cars. :) Or they get a drive line disconnect unit. Or if they have a vehicle that can be fitted with them they can even have locking hubs fitted. SignatureSteve W. Near Cooperstown, New York >>> A vehicle with power steering and without the belt, such as my 1978 >>> Dodge van,that will build up your arm muscles if driven like that long [quoted text clipped - 10 lines] > Or they get a drive line disconnect unit. Or if they have a vehicle that > can be fitted with them they can even have locking hubs fitted. I know, but what % of cars in the last 10 years are RWD? :( For most cars, it's a non-issue because they're FWD. Trucks and some/most SUV's with 4wd have a neutral position in the transfer case so you can tow that way. You won't see any Subie's being towed that way tho - my Legacy requires a flatdeck for towing because it's a full time awd setup. Whenever I see cars being towed behind motorhomes, it's either a Hyundai or a Jeep Grand Cherokee. Always one of those, I dunno why. Ray >>>>>>> It is also against the law where you live and in most places in the >>>>>>> world to coast down a hill in neutral. [quoted text clipped - 21 lines] >parked at the bottom of the hill so I saw him before I even started my >car and thought nothing of it. He didn't tell anything from how the "suspension was loaded". Most likely he simply could tell from the way you "took off", which will look a lot different if you simply coast away then if you have it in gear and accelerate away. >>> It is also against the law where you live and in most places in the >>> world to coast down a hill in neutral. [quoted text clipped - 13 lines] >The physics are the same whether on or off road. Off road just >exaggerates them. The laws of physics are the same but the forces acting on the vehicle that you need to worry about are not the same. Off roading you have issues with possibly slipping sideways, having a wheel suddenly lock if you put the brakes on while in neutral, etc. These are not issues in any legal driving on the road where you might want to coast to save a little gas. The thing that gets people in trouble coasting is that they just wind up going too fast then they get all confused when they throw it into gear and discover they need to brake too and oops, that darn guardrail is getting awfully close to them and maybe a little steering input would be a good idea too..... >There 'is' reason coasting downhill in neutral is against the law in >most places in the English world. Yea, there is a reason but that's not it. The reason it's illegal is a hold over from the days of lousy brakes and non-synchronized manual transmissions (and back then almost no one had automatics). There were many accidents from people who's vehicles got away from them when the brakes overheated and they could not get the transmission back in gear. In modern automatic transmissions when you are going downhill you are just about in neutral, it will usually be in Overdrive and the torque converter will be unlocked. If you throw it in neutral there isn't all that much difference. >Mike >86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 >88 Cherokee 235 BFG AT's >Canadian Off Road Trips Photos: Non members can still view! >Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 >(More Off Road album links at bottom of the view page) These are not issues > in any legal driving on the road where you might want to coast to save > a little gas. The thing that gets people in trouble coasting is that > they just wind up going too fast then they get all confused when they > throw it into gear and discover they need to brake too and oops, that > darn guardrail is getting awfully close to them and maybe a little > steering input would be a good idea too..... You seem to infer all the way through this that 'today's' drivers are somehow superior to the older generation and can act better in an emergency situation or that today's vehicles with their throw away non grease (use em till they fall off) suspension and steering parts don't wear out causing steering slop or something. I don't agree. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 (More Off Road album links at bottom of the view page) > These are not issues >> in any legal driving on the road where you might want to coast to save [quoted text clipped - 11 lines] > >I don't agree. That's not what I said. To the contrary, I am suggesting that today's CARS are much better. No one has their brakes overheat anymore because we all have disk brakes. So you could safely coast downhill in neutral now if you wanted to but it's rather pointless because everyone has overdrive (manual or automatic) which is just about neutral any ways. And if they do want to downshift, everyone has synchronized gears/automatic shift so no one misses a gear anymore and winds up out of control because they can't brake and can't get it back in gear. And the "non-grease" is a similar silly issue. I've had a lot less worn out parts on my non-grease parts then my grease parts. My 92 Explorer is still running all the original non-grease front end wear parts at 127,000 miles. >> These are not issues >>> in any legal driving on the road where you might want to coast to save [quoted text clipped - 15 lines] > CARS are much better. No one has their brakes overheat anymore > because we all have disk brakes. Guess you don't live anywhere near any real hills or mountains then. Overheating brakes are still VERY common. With companies making the brake parts lighter it is getting worse. So you could safely coast downhill > in neutral now if you wanted to but it's rather pointless because > everyone has overdrive (manual or automatic) which is just about > neutral any ways. WRONG. Neutral means NO connection from power input to output. It also means less control available to the driver. I can just picture the scene of someone coasting down a hill while talking on the cell phone and eating a burger.... And if they do want to downshift, everyone has > synchronized gears/automatic shift so no one misses a gear anymore and > winds up out of control because they can't brake and can't get it back > in gear. Everyone? Never been around a real heavy duty truck have you. Most are still using straight cut gears and no syncros. There are also a LOT of older vehicles out there that don't have OD. And the "non-grease" is a similar silly issue. I've had a > lot less worn out parts on my non-grease parts then my grease parts. > My 92 Explorer is still running all the original non-grease front end > wear parts at 127,000 miles. Very lucky, and not the norm at all. SignatureSteve W. Near Cooperstown, New York >>> These are not issues >>>> in any legal driving on the road where you might want to coast to save [quoted text clipped - 19 lines] >Overheating brakes are still VERY common. With companies making the >brake parts lighter it is getting worse. We have lots of steep mountains here in Arizona. Phx to Flag is a climb of about 6000 feet over 125 miles. Phx to Payson is about 5000 in 90 miles. On some roads there are both significant up/down grades combined with substantial curves. Several sections have runnway truck ramps there were so many big trucks loosing it. > So you could safely coast downhill >> in neutral now if you wanted to but it's rather pointless because [quoted text clipped - 5 lines] >of someone coasting down a hill while talking on the cell phone and >eating a burger.... I'm only talking about small vehicles, cars and small trucks. Not Semi's. > And if they do want to downshift, everyone has >> synchronized gears/automatic shift so no one misses a gear anymore and [quoted text clipped - 4 lines] >still using straight cut gears and no syncros. There are also a LOT of >older vehicles out there that don't have OD. I was only referring to small vehicles. Very few large trucks run disk brakes so they have plenty of overheated brakes. If you want to go there then sure, it's crazy if they try and run downhill in neutral. That's why we have the runaway truck ramps. > And the "non-grease" is a similar silly issue. I've had a >> lot less worn out parts on my non-grease parts then my grease parts. >> My 92 Explorer is still running all the original non-grease front end >> wear parts at 127,000 miles. > >Very lucky, and not the norm at all. I don't think we will ever have more then opinion but I suspect that the car makers did the cost benefit ratio on this one and found that the sealed units have a lot less warranty issues. We have hundreds of vehicles at work and it's exceptionally rare that they need front end work before 100K. >> These are not issues >>> in any legal driving on the road where you might want to coast to save [quoted text clipped - 24 lines] > My 92 Explorer is still running all the original non-grease front end > wear parts at 127,000 miles. Brakes sure do overheat still. 'IN GEAR' isn't anywhere 'close' to 'IN NEUTRAL', eh..... I know 'lots' of folks with standard trannys that have lost or have very poor syncros and lots of big trucks still have old style trannys. This is a world wide group read by more than car drivers eh. I take issue with the non grease parts though. Just because 'you' forget to grease them so they wear out, doesn't mean the rest of us do. I replaced 'all' the fittings on my CJ7 with non grease fittings when I did a frame up in 2000 mistakenly believing their 'lifetime' BS. 'All' of them have failed since and been replaced with greasable parts. The old parts that get greased with oil changes get inspected at that time as the grease goes in and an upcoming failure is usually easily spotted by the amount of play the grease causes. The new parts do not get inspected until they are literally ready for a catastrophic failure. That is the only time enough play happens for folks to check it or they just fail. This is a world wide forum and preaching unsafe potentially deadly advise needs a counter, sorry. Mike 86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 Canadian Off Road Trips Photos: Non members can still view! Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 (More Off Road album links at bottom of the view page) >>> These are not issues >>>> in any legal driving on the road where you might want to coast to save [quoted text clipped - 32 lines] >poor syncros and lots of big trucks still have old style trannys. This >is a world wide group read by more than car drivers eh. I was only addressing the car/small truck driver issue. Don't disagree at all that with large trucks putting it in neutral would be insane. They just don't have the brakes. >I take issue with the non grease parts though. Just because 'you' >forget to grease them so they wear out, doesn't mean the rest of us do. Hardly. They got greased plenty. Just because "you" had some wear out too soon, doesn't mean the rest of us did. In the absence of some valid statistical repair data it's just opinion. You are welcome to yours. >I replaced 'all' the fittings on my CJ7 with non grease fittings when I >did a frame up in 2000 mistakenly believing their 'lifetime' BS. 'All' [quoted text clipped - 7 lines] >catastrophic failure. That is the only time enough play happens for >folks to check it or they just fail. An interesting scenario. What you are saying amounts to a statement that they only fail because you noticed them failing before they failed and that if you hadn't noticed them failing they would not have failed till some later point in time, if ever. You almost made mention of the parts failing due to lack of people greasing them. If we remove ourselves, you and me, from the discussion and simply look at what happens in the world of the average vehicle owner, we might agree that the average vehicle owner probably doesn't pay any attention to whether their ball joints and tie rod ends get greased and that the high school kid at the jiffy lube may not even grease them even if the owner thinks that's whats happening. So sticking with what happens to the vast ocean of indifferent vehicle owners, the non-greasbale, sealed for life are very likely to give that large group of owners better service than the greaseable ones even if, which I don['t particularly agree is the case, even if the greasable ones actually would last longer then the non greasable ones. >This is a world wide forum and preaching unsafe potentially deadly >advise needs a counter, sorry. I agree with the safety issue on the large vehicles. I see no reason to believe there is any safety issue with using neutral on the small vehicles that's specifically related to using neutral. As with most things on these forums, it's all just unsupported opinions. >Mike >86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 >Canadian Off Road Trips Photos: Non members can still view! >Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590 >(More Off Road album links at bottom of the view page) In article <2Ie8i.11$cZ.3@newsfe12.lga>, "Proctologically Violated©®" <entropic3.14decay@optonline2.718.net> wrote: > Awl-- > [quoted text clipped - 10 lines] > > Where is the wear in general in an auto tranny? Clutches, bands, bearings, bushings, seals, O-rings, gears, pivots, valves, bores... > My understanding is that fluid acts as the clutch plate, so an auto tranny > should last forever, except for "bands", etc. The clutch plates act as clutch plates. > Are bands like V belts? No, they are more like the belt that holds up your pants. > If hotrodding in an auto (revving at a light, throwing it in Drive), what > goes? Money. > would like to see a pictorial of how auto transmissions work. Any leads? There are a multitude of automatic transmission designs - one answer can't fit all. Coasting in neutral, or towing with the engine off and drive wheels on the ground, can cause lubrication and overheating problems in some designs since the transmission may rely on the circulation of transmission fluid from pumps driven by the input shaft. Revving the engine and throwing it in drive is the best possible way to proctologically violate your transmission - Most hotrodders love cars and would never do that. > Awl-- > [quoted text clipped - 18 lines] > > would like to see a pictorial of how auto transmissions work. Any leads? >Awl-- > [quoted text clipped - 8 lines] > >Where is the wear? The wear is that you have all the clutches freewheeling and rubbing gently against each other at a time when some of them are supposed to be locked together. That combined with the low amount of fluid circulating due to the engine being at idle speed means you can easily cook the fluid that's between the clutch plates and burn up the transmission. >Where is the wear in general in an auto tranny? In general the wear is the clutch plates and the rubber seals that keep the fluid from leaking past the pistons. If the seals leak too much the clutch pack can't build up enough pressure to lock the clutches and they slip. If the clutches wear down too much they just can't lock together anymore or you get to the point of metal on metal. >My understanding is that fluid acts as the clutch plate, so an auto tranny >should last forever, except for "bands", etc. >Are bands like V belts? The fluid is not the clutch, it just lets the clutches slip while engaging and it carries away the heat, but it's the clutches that lock together and when they are lock the fluid is just putting pressure on the piston that pushes the clutch plates together. >If hotrodding in an auto (revving at a light, throwing it in Drive), what >goes? You can crush a roller thrust bearing due to the high load, you can tear the ears on the clutch plates, you can over stress the cams in the over running one way clutches and cause them to fail, the high shock load might blow out an internal seal or make a snap ring jump out of the groove, in a band transmission you might snap a band. >would like to see a pictorial of how auto transmissions work. Any leads? > Awl-- > [quoted text clipped - 18 lines] > > would like to see a pictorial of how auto transmissions work. Any leads? Some trannys don't send fluid trough the cooler in park or neutral. |
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