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-   -   clutch in coasting, OK? (https://ecomodder.com/forum/showthread.php/clutch-coasting-ok-9565.html)

go2guy 08-07-2009 09:14 PM

clutch in coasting, OK?
 
Does anyone here know if any harm will be done by coasting down hills with the clutch held in? Neutral is a long way down from top gear, and I fear safety issues, not being able to immediately re-engage power if needed. I have a 1946 Honda 250 Rebel which currently gets me 70 or so mpg.

SentraSE-R 08-07-2009 09:43 PM

You'll put wear on your throwout bearing, but with a bike's shifting pattern, I'd do that with the clutch lever pulled in, too. The question is, do you save enough gas coasting that way to pay for the expense of replacing the throwout bearing? Can you even find a replacement bearing for a '64?

bluetwo 08-07-2009 10:15 PM

It's said to be a bad idea because the parts weren't meant to do that for long periods. You can go to the top gear and coast for the least amount of engine braking or shift into N for 2nd gear speeds but that's about all that is said to be safe.

MadisonMPG 08-07-2009 10:47 PM

With cars everyone says to not do it, "it'll f*** up bearings", but no one has ever had a problem.

jcp123 08-07-2009 11:08 PM

The Harley manual specifically recommends against coasting with either the clutch pulled in or the trans in neutral, and the clutch let out. It warns of transmission damage? Sounds a little dire to me, but I've been finding myself getting in a tuck and coasting more and more lately.

Christ 08-07-2009 11:18 PM

Quote:

Originally Posted by MadisonMPG (Post 120156)
With cars everyone says to not do it, "it'll f*** up bearings", but no one has ever had a problem.

I bought a '88.5 Escort GT that needed a clutch kit and half the transaxle housing because the driver was going down hills with the clutch pedal actuated.

The throwout bearing exploded, the clutch disk overheated, exploding, and shrapnel damaged the flywheel, pressure plate, and clutch housing bad enough that I didn't want to reuse them.

Some people have had issues with it, but it's more of an issue of you can't re-grease your throwout bearing, as with many sealed units.

MadisonMPG 08-08-2009 04:09 AM

Quote:

Originally Posted by Christ (Post 120165)
I bought a '88.5 Escort GT that needed a clutch kit and half the transaxle housing because the driver was going down hills with the clutch pedal actuated.

The throwout bearing exploded, the clutch disk overheated, exploding, and shrapnel damaged the flywheel, pressure plate, and clutch housing bad enough that I didn't want to reuse them.

Some people have had issues with it, but it's more of an issue of you can't re-grease your throwout bearing, as with many sealed units.

It seems that no matter what I post you contradict me, because of this I am no longer going to read anything you type.

Frank Lee 08-08-2009 04:52 AM

The clutch vs neutral thing has been debated for decades. Many decades.

In cars I have the following opinion: holding the clutch means that throw-out bearing is working against the spring loading of the clutch pressure plate. That is a considerable force. Putting the trans in neutral means some things are spinning and some things aren't, but nothing is under any real loading. Therefore I like going into neutral best.

It's different on a bike. Depending on the bike, it can be somewhat difficult to get neutral, especially from cruise speed. I've done it. The trans sounds "clashy" or "crashy" on the downshifts unless you are going slow. I don't think it's a healthy sound. I no longer try to do that unless I'm going relatively slow anyway.

Then there is the holding the clutch thing. All I've referenced above regarding that holds true for bikes; in addition, you have to hold it with your hand. Depending on how long/frequent the glides are, that can become onerous.

On a bike I'd suggest simply regulating your "glide" as well as you can with just the throttle. Not as good as a car, but oh well, that's what we have to work with unless you are ambitious enough to fit a freewheel system.

dcb 08-08-2009 10:28 AM

It certainly does not sound healthy trying to find neutral on a bike, I use the clutch from the higher gears.

Putting another detent (grind a slot w/your dremel) in the shifter arm between 5th and 6th is an option and what Matsuzawa did.

But since I don't usually use the clutch for shifting, and I have a kill switch, I'm pretty sure I could get it home and fix it if it failed. Run and jump on, dog it into first or second, then time the lights or take the expressway, whatever, been there (sheared a key and lost everything but 5th once, also had snapped clutch cable another time, got home just fine and effected repairs).

Motorcycle clutches and whatnot can be exponentially easier to work on than a car. One bike I had, (old amerachi) the throwout bearing was just a bb at the end of a rod that was pretty easy to get to.

I have not made making another neutral detent a priority because my bike glides just as well using the clutch, since it is connected to the output shaft directly, unlike a typical car,

I am confident the practice won't leave me stranded or cost me a lot of money, have done many miles that way so far (knock on wood).

Though Christ does have a good cautionary tale, if the clutch is constantly slipping, you have a problem (I would take Franks lead and start by hitting the clutch area with a rock :) ), and messing with the lever, maybe try some force on the crank arm in the closing direction, then don't touch the clutch till you get home.

Christ 08-08-2009 11:12 AM

Quote:

Originally Posted by MadisonMPG (Post 120227)
It seems that no matter what I post you contradict me, because of this I am no longer going to read anything you type.

Fair enough. When you make a blanket statement, you should prepare to be contradicted by anyone. I'm just not so shy about it as others are.

If it eases your mind, there were probably other problems with the clutch assembly as well, but the release bearing did, in fact, explode, causing damage to other components. The car had the OEM clutch with 180,000 miles on it, but that's beside the original point.


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