Wear in an auto transmission...

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

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

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

Very lucky, and not the norm at all.

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 (More Off Road album links at bottom of the view page)

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.

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.

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.

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.

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.

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

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.

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

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.

I'm only talking about small vehicles, cars and small trucks. Not Semi's.

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.

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.

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.

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.

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.

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.

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.