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Old 10-28-2008, 08:45 PM   #46
bonox
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Quote:
Originally Posted by Conestogaman
The 6volt, 1200 cc VW (OLD) Beetle uses a 180mm Sachs clutch disc.
so potentially a 1200 or 1100 (180mm) but no 1150 (165mm) compatibility.
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Old 10-28-2008, 09:18 PM   #47
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7500 km on a clutch!!!

Two personal BMWs and three work bikes.... Not one has ever had a clutch replaced. I slip my clutch all the time, but I believe most people over rev when slipping(or stand on the rear brake). The BMW twin produces enough torque at low speeds to pull you up anything you will go up. It pulls enough to pull an fully loaded RTP up a set of stairs without issue!
I'm sure a ceramic clutch has its advantages, but there has to be a reason BMW does not use them.
I would be weary if the clutch reduces the amount of friction, and thus requires higher rpms to put the power to the ground. I would also weary if it could not endure the "shock" that a standard clutch could.
my .02
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Old 10-28-2008, 09:25 PM   #48
bonox
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Quote:
Originally Posted by motorfiveo
I'm sure a ceramic clutch has its advantages, but there has to be a reason BMW does not use them.
I would be weary if the clutch reduces the amount of friction, and thus requires higher rpms to put the power to the ground. I would also weary if it could not endure the "shock" that a standard clutch could.
my .02
as outlined above, they are harder for the average joe to use. Thus one of the main reasons why manufacturers don't install them as standard equipment. Secondly, the normal use of a GS (and in fact all of the R series bikes) is on road - there isn't a need for a clutch that will withstand a lot of abuse without dropping in friction coefficient much. At that is the reason to install a ceramic clutch - to deal with high temperature abuse. (As one might find when hauling full loads through sloppy terrain by someone without helge peterson experience levels). The stock clutch will put up with an amazing amount of abuse anyway. You would only want a ceramic model to ensure you could keep it up for a long time without needing replacement. At any rate, something in the system has to wear, and if it isn't the friction disk, it'll be the pressure plate and flywheel. Just as with brakes, the more aggressive the pad, the quicker the rotor wears.

Shock loading is mostly taken care of by the spring elements and not the friction face, but the same applies to both organic, sintered and ceramic clutches, so isn't really any measure of comparison. Those
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Old 10-28-2008, 09:31 PM   #49
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IMO there's more BS in most of these ceramic clutch threads than honest information from people who have used both. Please take the "information" from people who have never used them with a grain of salt.
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Old 10-28-2008, 10:49 PM   #50
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Quote:
Originally Posted by bonox
You would only want a ceramic model to ensure you could keep it up for a long time without needing replacement. At any rate, something in the system has to wear, and if it isn't the friction disk, it'll be the pressure plate and flywheel. Just as with brakes, the more aggressive the pad, the quicker the rotor wears.
Makes sense. So do these ceramic models require a stronger clutch spring to make up for the lower friction?
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Old 10-28-2008, 11:05 PM   #51
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Quote:
Originally Posted by motorfiveo
Makes sense. So do these ceramic models require a stronger clutch spring to make up for the lower friction?
i'm sure configurationspace will say I don't know anything because he's the only one in the world who has ever used a ceramic clutch, but here goes:

1. if your reason for the ceramic was to make a smaller clutch diameter (for a racing design, say), then unless the friction coefficient goes up, yes you will need heavier springs. On the other hand, if your torque output goes up a lot, you'll need stronger springs even for the same diameter regardless of clutch friction type.

2. You don't have to have a lower friction coefficient. Like all composites, their properties can change with a small change in the components. Generally though, the harder the material, the lower the friction coefficient. THere are micro-mechanical properties as well - sintered metal brake pads and clutches are harder than the green (organic) types, but give higher friction coefficients owing to how they interact with the rotor (especially when wet). This is potentially one of the things that causes the 'grabbing' drivers report of ceramic clutches.

3. The clutch available for the GS (from the 1150 I rode with one) seems to be a bit of a hybrid. It appears to exist only for high temperature longevity. It isn't anywhere near as aggressive as the ones i've used in formula ford racecars for example. As configuration says of his, it behaves more or less the same as the original. From my experience of the 1150 it needed a bit finer control than a mates 'normal' 1100 I used to swap with, but not much)

This clutch will probably last longer than the organic original and will probably put up with more abuse (although I didn't abuse the one I had which just came with the second hand bike - i didn't install it for a reason).

If you don't upgrade the clutch springs you probably won't notice much of a difference in behaviour, nor are you likely to destroy the splines or hub. My experience from the small race-cars however says that if you put in a ceramic clutch, you will usually uprate the springs (there has to be a reason for installing a high temperature clutch after all) and with no additional work, the fords used to strip the splines more regularly. (the organic clutches would just slip - the uprated springs plus slick tyres was probably way more than the designers of the original (road car) 1.6litre ever imagined).

Edit: as a point of interest, the literature suggests that relative speed of the friction surfaces plays a bigger role in heating than the power being transmitted - ie more torque but lower speed gives less heating than the other way around. ie more throttle and lower engine speed when using the clutch is less likely to make it overheat. Clutches are sized for about 1.5 to 2times the peak engine torque as a general rule (to account for heating under repetitive use as you would get crawling along in traffic) but they will eventually give up - even a ceramic model.
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bonox screwed with this post 10-28-2008 at 11:27 PM
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Old 10-29-2008, 04:58 AM   #52
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Quote:
Originally Posted by bonox
...

Edit: as a point of interest, the literature suggests that relative speed of the friction surfaces plays a bigger role in heating than the power being transmitted - ie more torque but lower speed gives less heating than the other way around. ie more throttle and lower engine speed when using the clutch is less likely to make it overheat. Clutches are sized for about 1.5 to 2times the peak engine torque as a general rule (to account for heating under repetitive use as you would get crawling along in traffic) but they will eventually give up - even a ceramic model.
Exactly why motocops can slip their clutch a lot with minimal damage. If you learn to slip your clutch at low revs you will find it does little or no damage, and you can work the tight slow speed stuff.

Jim
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Old 10-29-2008, 07:47 AM   #53
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We've installed Touratech Ceramic clutches on all of the BMW R12S/HP2 S race bikes we've put onto the track, additionally I have had one on my R11S for quite some time and just installed one on my HP2 last month. If I could get it from the factory with the Ceramic, I would. If I were taking a trip around the world, or anywhere for a prolonged time the Ceramic Clutch would be on the mod list before I left on any BMW Boxer. It's all pluses in my book and no where near as harsh as ceramic clutches I've had in performance cars/trucks, it's very easy to modulate on the BMW Boxer.

As for the bevel spring for the clutch plates, it is very difficult to upgrade this as it is part of the pressure plate assembly and not a separate piece, nor a traditional spring/pressure plate setup.
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Old 10-29-2008, 10:43 AM   #54
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True...But

Quote:
Originally Posted by JimVonBaden
Exactly why motocops can slip their clutch a lot with minimal damage. If you learn to slip your clutch at low revs you will find it does little or no damage, and you can work the tight slow speed stuff.

Jim
Do agree about why it is best to use low revs when slipping clutch is required..BUT off road on dirt, going up a steep grade if I must go slow and spinning the rear wheel is not a viable option, I am faced with either lugging the engine all to hell, rattling the shit out of it, or increasing throttle and slipping clutch to gain momentum...this is very rare, but it does occur..and the blessed mother of boxer torque has saved me several times, even when lugged unmercifully..

I guess for my use, off road, the ceramic might be the ticket however what I hear is discussion of race/track bikes where RPMs are up..

Has anyone used these ceramic clutches in a boxer used mostly off road?
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Old 10-29-2008, 11:04 AM   #55
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I'm planning another leg of my RTW tour, and I'm thinking I'm needing to upgrade to the ceramic. I almost did it in Panama, and at the last minute I only replaced my clutch with OEM. I have some questions-

Once, being an idiot, I was revving my engine very high, and suddenly smelled the worst burning clutch smell. Will this still happen with the ceramic?

For example, in Panama when I was stuck in mud, I was trying to not spin the wheel. I don't know how else I could have tried to get up the mud hill without slipping the clutch. I was doing it at idle-rpm, and I still got the burning-clutch smell. Will this still happen with the ceramic? I was abusing the clutch terrible. By the time I got the bike out of there, I felt that I'd probably worn the clutch down to nothing. When I took the bike apart, the clutch was, indeed, almost worn-out.



Would the ceramic last longer? This was at only about 30,000 miles, of which about 7k were mine, and all I know about the previous 23,000 was that someone had ridden it to Alaska.

I'm sure I'll have at least one more tough-tough day, a day where I'll have to abuse my clutch. Will the ceramic really be better?
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Old 10-29-2008, 11:11 AM   #56
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Quote:
Originally Posted by bananaman
Once, being an idiot, I was revving my engine very high, and suddenly smelled the worst burning clutch smell. Will this still happen with the ceramic?
Nope. Instead of burn, the ceramic clutch becomes a bit more "grabby" but only while it's overheated.

Quote:
Would the ceramic last longer? This was at only about 30,000 miles, of which about 7k were mine, and all I know about the previous 23,000 was that someone had ridden it to Alaska.
Yup. At some point the ceramic requires some maintenance though. When it is half worn you need to remove the spacers. But for this you don't need to pull the tranny off -- you can get at them via the opening at the starter.

Quote:
I'm sure I'll have at least one more tough-tough day, a day where I'll have to abuse my clutch. Will the ceramic really be better?
It is for me.
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Old 10-29-2008, 12:20 PM   #57
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I'm almost qualified to do the install myself... but what a waste of time it would be if I got the whole thing back together, only to find that I'd missed some little nuance. Therefore, I'll want to have a pro do this job. Other than Atlanta BMW, where else can I get this done? Or should I ride down to Atlanta? I know that "insurance regulations" usually prohibit customers in the shop, but for my intended use, I feel like I really need to, at the very least, be an active observer for the entire operation. Suggestions?
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Old 10-29-2008, 12:45 PM   #58
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Quote:
Originally Posted by bananaman
I'm almost qualified to do the install myself... but what a waste of time it would be if I got the whole thing back together, only to find that I'd missed some little nuance. Therefore, I'll want to have a pro do this job. Other than Atlanta BMW, where else can I get this done? Or should I ride down to Atlanta? I know that "insurance regulations" usually prohibit customers in the shop, but for my intended use, I feel like I really need to, at the very least, be an active observer for the entire operation. Suggestions?
It really is not that hard. Just pay attention when you remove things, take digital pics if you tent to forget, and reinstall the parts as you took them off.

Jim
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Old 10-29-2008, 01:00 PM   #59
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Quote:
Originally Posted by JimVonBaden
It really is not that hard. Just pay attention when you remove things, take digital pics if you tent to forget, and reinstall the parts as you took them off.

Jim
Is there a video constructed anywhere of any GS being disassembled to the clutch?
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Old 10-29-2008, 01:19 PM   #60
JimVonBaden
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Quote:
Originally Posted by Mago
Is there a video constructed anywhere of any GS being disassembled to the clutch?
There was one of the R1150RT, same principles, but none of the GS that I am aware of.

This link shows many of the basics: http://www.advrider.com/forums/showthread.php?t=314290

Jim
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