Downhill in neutral causes damage?

Why would this be any different as far as the transmission is concerned from any other shift into the same gear at the same speed?

Reply to
Mark Willstatter
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Another issue, applicable to auto or manual transmission, I seem to recall from a long time ago it is illegal (in British Columbia anyways) to coast in neutral more than 50'. But I admit I coast all the time (clutch depressed) when approaching a stop sign or red light, I'm sure more than 50' in neutral. Does this ring a bell with anyone? Or one of those urban myths that persists? If true, then coasting downhill in neutral is against the regulations if they are enforced.

-------------------- snipped-for-privacy@vcn.bc.ca Vancouver, BC Canada

Reply to
Tony

50' as in 50 feet, that is 15 meters, meaning that you're breaking a law if you have the clutch depressed for half a second at highway speeds. Sounds like and urban legend to me.
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Baudolino

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Tom Resi

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Tom Resi

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Tom Resi

Reply to
skydivertu

Coasting downhill in neutral has been done as long as cars have been around. In the fifties we called it "Mexican Overdrive", with all due respect to the challenges of making ends meet in the depressed economy south of the border.

The main risk involved is that the vehicle will develop so much momentum that the driver will loose control. This was a real issue in the days of drum brakes, which would not work well ("fade"), or at all when they became hot due to the expansion of the drums. Although disk brakes work better than drums when they get quite hot, they too can suffer a loss of braking ability when used heavily and repeatedly. But most modern passenger cars with disc brakes can manage some fairly heavy braking with out experiencing fade. Trucks are a different story, and their greeter weight demands the use of the engine to assist the brakes in stopping.

Therefore, IMHO, the judicious use of coasting in neutral is ok under normal driving conditions. I would not advise using this technique when descending mountain passes, or even hills of more than a couple of hundred feet in height, which we have a lot of here in CA. Also, at the first sign of brake pedal softness when descending, get the thing in the lowest gear possible ASAP!

I have done this for decades, but once the transmission is in neutral the clutch should be released. The clutch plate and the throwout bearing suffer no wear when the clutch is released, and I try to keep the clutch released whenever possible. I have gotten over 200K miles out of most of my clutches... Volvos, VW's, Fiats, and a Toyota.

Larry El Cerrito, CA

Reply to
Lawrence Radcliffe

You, being a Californian that exhibits a functioning synapse or two, ought to be ashamed of yourself to even suggest that the majority of the motoring public has the mental capacity to safely operate an automatic, ABS, traction control, collision avoidance equipped vehicle while grooming and/or operating their cellphone or even watching a movie and practice coasting concurrently.

--TW Don't say "There oughtta be a law..." in CA because they will make it if they haven't already.

Reply to
Tundra Wookie

How fast are you planning to coast? If you are planning to get up around

150, to 200 miles an hour, I'd say....there might be an issue about, safety, or getting it back in gear. As long as the engine is still running, in neutral, and your foot is off the clutch, the transmission's mainshaft is turning the countershaft, which is whipping the oil up and lubricating the trans. As far as getting it back into gear, whatever the vehicle, 18 wheeler, or 4 wheeler, you have to match the engine rpm's, to the road speed of the veh., to the gear you want to get back into, to get it back in gear without damaging something. If you are coasting downhill in your VW, TDI, at ...70-75..in neutral, and you are going to put it back in 5th gear, first, with your foot off the clutch, you have to rev. the engine to what the expected rpm's for 5th gear would be, running along at 70-75 mph, probably around, what, 26 to 2800 rpm's? Then push the clutch in, and put it in 5th. It should drop right in, with no noticeable jerk. No harm done. Problems start when, going downhill at 70-75, you would leave the engine idling, push the clutch in and put it in 5th, then let out the clutch, and the engine would be dragged up to road speed rpms... that would be hard on the entire drivetrain. All this might be a no-brainer to some, but it was a good question to ask, 'cause alot of people probably hear stories about the downhill in neutral thing, and would most likely tear up their stuff trying to do it without knowing how. You can simulate the same situation running along on flat ground. Drive along at any speed, but in top, (5th gear) and look at your rpms. Take it out of gear and coast, now go to put it back in gear, first revving up to just a little less than what you were doing when in gear (cause you probably slowed down a little) and put it back in 5th. If you do this on the flat roads, you should know what to do if you choose to do it down hills.
Reply to
Nod

Good point!

I forgot to mention the obvious, that is, to minimize clutch wear one should always match engine speed to vehicle speed before de-clutching. True for shifting up as well as down.

Larry

Reply to
Lawrence Radcliffe

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