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

go2guy 08-07-2009 08:14 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 08:43 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 09:15 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 09:47 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 10:08 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 10:18 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 03:09 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 03:52 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 09:28 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 10:12 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.

theycallmeebryan 08-09-2009 02:46 PM

I've heard people talk about this before as well. After doing this for 10,000 miles, i have yet to see any side effects. I do a LOT of Engine off Coasting with the clutch pulled in, and the only thing i have noticed is the clutch cable slowly stretching... but thats normal, i simply make the adjustments for it.

I will say that there is definately still friction on the drive gears even when the clutch is pulled in. You notice it more with a motorcycle because its much lighter than a car.

DCB, do you have any more information about what matsuzawa did? I'd been looking into ways in moving my nuetral gear between 5th and 6th on my ninja, but this sounds easier?

By the way: Congrats on your recent 100mpg tank :)

janvos39 08-09-2009 03:48 PM

A neutral gear can be made between each gearchange by grinding a slot for the spring loaded neutral blocking lever like DCB explained.
Probably that is what Matsuzawa also did. Most Japanese bikes are build so that you can get access and do that by taking the side cover off.

Frank Lee 08-09-2009 05:59 PM

Cool! I did not know that. Might have to try it.

go2guy 08-09-2009 06:35 PM

Thanx to all who replied, seems safe within limits. Probably won't do alot, but occasionally, as there be hills between home and work!:)

theycallmeebryan 08-09-2009 09:15 PM

Quote:

Originally Posted by janvos39 (Post 120449)
A neutral gear can be made between each gearchange by grinding a slot for the spring loaded neutral blocking lever like DCB explained.
Probably that is what Matsuzawa also did. Most Japanese bikes are build so that you can get access and do that by taking the side cover off.

It really does sound interesting. Does this mean the only mechanism that differs a sequential gearbox from a non sequential is a neutral block lever? That seems too easy.

I cant imagine it would deter shifting very much if done properly, as long as your foot makes a full shifter motion to complete the shift all the way through. It would be like going from 1st,through neutral, into 2nd (as it is now), but on every gear change.

Would you guys be able to provide me some more information on this? And i mean besides just simply talking about it. I'd like to know what to do.

dcb 08-09-2009 10:38 PM

Basically the shifts are controlled by a drum that rotates. Each gear HAS to have a point where it is in "neutral" between gears, otherwise something would break, so you figure out which shaft has the neutral detent on it, and figure out how many degrees that shaft turns per shift and put your additional detent slot(s) at those intervals from the existing slot.

For starters, you should be able to put the bike on centerstand and put it in top-gear, then by hand do a "half downshift" and get the rear wheel to freewheel (by hand). Might take a few tries.

On my bike I can unscrew the detent ball and look at the shaft, so I could possibly mark it there (or at least get in the ballpark), but you do have to be pretty precise with locating the detent groove. With a removable ball, I could manually find the "best" high neutral by hand, then put some prussian blue on the detent ball and screw the ball holder in then out and I should have a blue mark precisely where my second detent should go.

It "may" be possible to do it externally, by having a "stop" for the gear shift lever that you engage with some hand control or switch or something. For example, imagine a substantial bolt (so you can adjust it easily) that you can swing (accurately and repeatably) into the way of the downshift lever with a small hand lever or switch. If you want to go to neutral then move the bolt in the way of the shifter and hold the "half shift" down on the stop with your foot. No promises, just thinking out loud.

naturalextraction 08-15-2009 10:51 PM

Having built and rebuilt transmissions in cars and bikes for 20 years now, I've done plenty of study on worn components and to their cause. I ride an 02 SV 650 and live in a mountainous area. The benefits to coasting have been great. I've been coasting daily, yes I drive this even on winter days providing the snow is not an issue, and literally just about every day (I've put as much as 32K in one year) now for 2 years straight on this particular bike and have never had a problem. The coasting alone gets me anywhere from 15 to 26 extra miles per tank. I also shut the bike off at lights knowing I'll have about 3 minuets as I roll up on a yellow. (not all lights, just when it seems appropriate, no need for a starter yet either.) Depending on the amount of city to rural driving makes a big difference on mileage. Bike clutches have less rotational parts to worry about, like throughout bearing. The cable and connection pieces also don't seem to ever be a problem even with my high mileage driving. I don't use the clutch much for up shifting or down shifting anyway.
I have some heavy duty Barnett clutches and springs on my Turbo 82 Yamaha (no they didn't make one that year it's a custom job) and the only difference of course is holding in the clutch for any length of time. But I'm used to it and it's truly not a concern. I figure I coast more than most and I will say though that getting a car in neutral is easier than a motorcycle. Yes a clutch pull is worth it and doesn't seem to provoke any pre-mature wear or hurt anything. It would take many years to really put any fatigue on the metal springs and spacers. By then you need a new clutch pack anyway if you really ride it that much!
PS. A 1946 250 Honda Rebel? That can't be right. 1986 or 96 I can see. Correct me if I'm wrong.

FastPlastic 08-16-2009 02:49 AM

I tend to do a lot of clutch in coasting on my Ninja. So far I've put on about 2000-3000 miles with no sign of any problems. I also like to shift to N when approching a red, It tends to coast even farther, and gives me the option of 1st or 2nd depending on how fast I'm going when I hit the light.

Christ 08-16-2009 11:34 AM

So.. you have one strong hand, right? LOL.

dcb 08-16-2009 01:29 PM

It's not so bad, some bikes have stiffer clutch handles than others though. do you own a motor bike?

Christ 08-16-2009 04:11 PM

I had a large ducati something or other (Duke frame, Something else for engine, etc.) for awhile when I was like 14, but after that, not so much. Turns out, you shouldn't go through chicanes at high speed. ;) I sold the bike, never bought another one. I'm in the market (sort of) for a Ninja 250 or other small sport bike, though.

dcb 08-16-2009 04:38 PM

You could recycle some of that old house into a bike :)
http://img47.imageshack.us/img47/6647/woodbike9gr.jpg

Christ 08-16-2009 08:15 PM

L. O. L. That is all.

Froggypwns 08-17-2009 03:12 PM

This thread has me wondering, how is coasting clutch in any different than sitting idle in gear clutch in? The MSF teaches you to stay in gear and ready to go, should the person behind you decides they don't want to stop in time.

Christ 08-17-2009 03:14 PM

Quote:

Originally Posted by Froggypwns (Post 121848)
This thread has me wondering, how is coasting clutch in any different than sitting idle in gear clutch in? The MSF teaches you to stay in gear and ready to go, should the person behind you decides they don't want to stop in time.

Not that most riders are actually watching behind them at an intersection...

bluetwo 08-17-2009 05:15 PM

The MSF definitely has the best intentions but honestly they have a few ideas that I'm not at all inclined to agree with.

I say the main thing is just to decide what works for you and always be careful.

go2guy 08-21-2009 08:08 PM

wrong year
 
Sorry folks, I must've fatfingered the year on my Rebel:eek:. It's a 1986.:D

Formula413 08-23-2009 09:54 AM

I'm glad I noticed this thread. I just recently started pulling the clutch in going down hills or approaching stops at times when I would have just let the engine brake previously, and it has produced a small but noticeable improvement in FE. From a strictly financial standpoint it's probably not worth it if it results in increased wear to the throwout bearing (which I would have to learn how to repair as I'm not yet familiar with my bike's internals). But I also like the idea of less pollution, and I know that engine braking means lots of unburned hydrocarbons coming out the tailpipes. The problem with my bike is that it has very short gearing. I can descend a 7% grade in 5th gear and not exceed 40 mph. I'm already half way to the redline at about 55 mph. Time to get a manual and see how hard a throwout bearing is to change. Incidentally, would a throwout bearing failure be sudden and crippling, or something that could gradually get worse and not leave you stranded?

dcb 08-23-2009 11:10 AM

Quote:

Originally Posted by Formula413 (Post 123095)
Incidentally, would a throwout bearing failure be sudden and crippling, or something that could gradually get worse and not leave you stranded?

Here 's my take on it
http://ecomodder.com/forum/showthrea...tml#post120238

Stranded is an inverse function of resourcefulness :)

Formula413 08-23-2009 11:44 AM

If I read your post right what you are saying is that you would suddenely have no clutch, right?

naturalextraction 08-23-2009 12:39 PM

For what it may be worth to you, please consider this: I've been riding for over 30 years. I ride motor bikes now and can easily put 25k to 30k miles a year. I've NEVER had a problem in that area. In fact if you shift without the clutch which is completely normal your chances of wearing any rotational parts out for the duration of your ownership is slim to non. I'm also a machinist and have worked on transmissions and automotive components most all my life. So I hope you'll take my submissions with some decent amount of merit. Don't worry and have fun.

seymorerage 09-04-2009 06:58 PM

Quote:

Originally Posted by jcp123 (Post 120164)
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.

It is just giving you a Warning because it is a Harley and damage is what they do.lol Just kidding I think you would be fine. I was always told all the way out or in it is the in between that kill you.

yanlapanic 09-05-2009 10:41 PM

Quote:

Originally Posted by naturalextraction (Post 123126)
For what it may be worth to you, please consider this: I've been riding for over 30 years. I ride motor bikes now and can easily put 25k to 30k miles a year. I've NEVER had a problem in that area. In fact if you shift without the clutch which is completely normal your chances of wearing any rotational parts out for the duration of your ownership is slim to non. I'm also a machinist and have worked on transmissions and automotive components most all my life. So I hope you'll take my submissions with some decent amount of merit. Don't worry and have fun.

and if im riding aggresively with my motrcycle ? shifting at 8-9-10k most of time .... should i use clutch?

dcb 09-06-2009 06:41 AM

Quote:

Originally Posted by yanlapanic (Post 126090)
and if im riding aggresively with my motrcycle ? shifting at 8-9-10k most of time .... should i use clutch?

RPM doesn't matter. Proper clutchless upshifts are faster and smoother and work well with a non-synchro sequential gearbox (motorcycle, F1 cars). I think all the f1 cars do when you hit the paddle is cut the fuel for an instant to make some slack, and pop it in the next gear. It really is a lot faster and smoother than pretending you are driving an old dodge with a three on the tree.

But it is really hard for people to get over their fears of NOT using the clutch on a bike. It's a little kookie in fact, but something cyclists *should* understand better than they do, generally.

yanlapanic 09-06-2009 09:39 AM

Quote:

Originally Posted by dcb (Post 126174)
RPM doesn't matter. Proper clutchless upshifts are faster and smoother and work well with a non-synchro sequential gearbox (motorcycle, F1 cars). I think all the f1 cars do when you hit the paddle is cut the fuel for an instant to make some slack, and pop it in the next gear. It really is a lot faster and smoother than pretending you are driving an old dodge with a three on the tree.

But it is really hard for people to get over their fears of NOT using the clutch on a bike. It's a little kookie in fact, but something cyclists *should* understand better than they do, generally.

how do you know there is no syncro in my bike ?

a tractor do not have syncro and we can hear it if we shift too fast

But i agree that we can shift easyli without clutching on a motorcycle , just relase the gas a little and push the lever on the next gear ....

But im not sure about the fact that it wont domage anything . IT will be violent to shift at 9k ...poor chain .

Formula413 09-06-2009 10:13 AM

Quote:

Originally Posted by dcb (Post 126174)
But it is really hard for people to get over their fears of NOT using the clutch on a bike. It's a little kookie in fact, but something cyclists *should* understand better than they do, generally.

Can you elaborate on this? I'm not sure what the benefit of not using the clutch would be.

dcb 09-06-2009 10:39 AM

Benefits:
faster and smoother shifting, less wear on clutch and related components. Once you get moving in 1st you can keep a better grip on the bars (or do something stupid/not shift related with your left hand). I haven't see any evidence of increased transmission wear in countless thousands of miles, though people who have never done it will swear that it is a bad thing to do.

Yan, your tractor isn't sequential, and most bike don't have synchros. You have to get back on the gas of course, as quick as you can flick your wrist and lift your toe if you are accelerating hard.

Christ 09-06-2009 11:52 AM

Yanal, in a sequential gearbox, the gears aren't engaged the same way as your tractor's gearbox. In your tractor, you need to physically disengage from one gear before going into the next. In a sequential gearbox, you're actually engaging the next gear WHILE disengaging from the first, hence the reason that synchros aren't needed, and would, in fact, be extra weight and complexity for an otherwise (fairly) simple piece of equipment.

I shift without a clutch in almost everything I drive, as it saves wear on my left knee. Screw the car, it doesn't cost $10,000 to replace a clutch... knees, on the other hand, are a different story.

The only clutches I've had to change in my cars are ones that are worn when I get them, and ones that I burn out racing/pulling stuff. My 1988 Honda Civic LX had the OEM clutch in it when I bought it, with over 200k on it. By the time I sold it with a blown engine (amateur bracket racing), it still had the OEM clutch, and almost 300k on it.

The clutch is only necessary for taking off from a dead stop if you can't get a roll going, such as when pointing down a hill. I don't even use it when I stop, frankly.

naturalextraction 09-06-2009 05:54 PM

Just to say that Christ and dcb are correct and explain well this technique, from some one who has rebuilt these things for over 20 years. Once you learn how to do it, which is easy, it can become habit fairly quickly. It can save as much as 20k to 30k miles of wear on your clutch components (plate, throw out bearing etc, according to ATRA) with that technique. Motorbikes (cycles) are considerably easy even the older ones. Do some other research, talk with others who have made it a habit. Coasting as you know can save an enormous amount of gas over time, especially if you live in hilly areas. Don't fear it, do it.

jcp123 09-07-2009 03:26 PM

Yeah, I used to shift w/o clutch in my Focus, it freaked people out! I do it on my bike too when I'm lazy :p


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