Dry vs Wet Clutch

[ANDYVH]

I agree with most of the posts above, especially with Paul Glaves. I'm also an MSF instructor and have used my 94 RS for ERC classes with no detriment to the dry clutch. I too, hold the clutch in, and stay in gear, at a stop until I know fairly certain that nothing is happening behind that may need me to take off quickly.

I keep my clutch adjusted exactly to spec (I feel it does make a big difference), and check it a few times during my typical 10,000 mile riding season. I also make sure my clutch splines are clean and lubed with the tacky grease recommended by BMW. My RS has 140,000 miles on it, now on the 2nd clutch assembly, that I installed myself. It has great light feel to it with good lever travel. I replaced the original clutch cable at 115,000 not because I had to, I just did it to avoid a potential roadside issue.

I don't quite agree that a wet multi-plate clutch would be more reliable. A wet clutch requires a lot more friction surface to transmit the engine power, so you have multiple friction plates. But a wet clutch, again because of the multiple plates does tend to have easier/better feel and takeup, and a wider friction zone than a single plate dry clutch. Learn to make quick efficient shifts (each shift should take no more total time than a finger snap). And once the bike is moving, you really only need maybe 1/3 of the clutch lever travel to make an up or down shift. Preload the shift lever to take up the slack in the shifter, in prep for the shifts. In fact, less clutch lever travel is better than squeezing the lever to the grip every time.

 

[bikerfish1100]

I would never argue with Paul G [I'm afraid of his wife! <g>] but, I believe you will have good life from your clutch if you remember to put the bike in neutral as you roll to a stop. It is easier to put in neutral while still moving than it is to try to find neutral while stopped - which of course is heating up the clutch.

that statement makes no sense whatsoever. Heat/wear to the clutch discs occur when there is slippage between the pressure plate and the clutch plate, and that does not happen at a stop- unless you intentionally "play" with the clutch.

I can't be doing much wrong as I have never replaced a clutch in any vehicle, 2 or 4 wheels in my 50+ yrs of driving/riding.

Its pretty intersting to see bikes stopped at lights and the rider is holding in the clutch, gunning the engine, letting the clutch out a bit, then gunning some more. That will surely get you the smells, the heat, the worn clutch quickly.

again, if the clutch is fully disengaged, it matters not at all what the engine is doing- as the two systems (engine & trans) are fully isolated from one another. Gunning the engine does nothing to the clutch- the "letting clutch out a bit" and rolling back and forth does wear the clutch, but it's likely minimal, unless it's going on with lots of engine revving at the very same time

Have good and safe rides.

i wasn't going to comment, but i hate to see a noob get misinformed.

clutch wear happens when you ride the bike in the friction zone, period. dry clutch bikes are much less tolerant of living in the FZ than are oil immersed clutches.

as PG stated, there will be some slight wear to the throw-out bearing by leaving the bike in gear/clutch disengaged at a stop... but the wear is relatively insignificant.

continue doing as you were taught in the BRC- it's the safest advice.

the biggest advantage of a multi-plate wet clutch are two-fold. 1) more tolerant of slippage/FZ use. 2) relatively easy/cheap to replace, as the clutch pack is usually situated on the side or above of the transmission, rather than sitting in-line between the engine and trans as our dry clutches are.

 

[beemergirl]

Thanks everyone, I'm still listening.
In the few days I've had the bike I've become very conscious of the time I spend in the friction zone. Since of conscious of it, I can start working on lessening the time spent there.

Nancy

 

[Penforhire]

Some riders seem to need more time in the friction zone than others, especially starting from a stop. In that regard wet clutches are so much more forgiving. I am more conscious of getting quick engagement with my dry clutches.

I don't see a major drawback to wet clutches so I'd prefer one on my RT. Shared oil hasn't seemed to harm the many Japanese wet-clutch bikes I've had over the years. Of course, those were water-cooled so perhaps the oil allowance is different. OTOH, I do hear tales of individuals frying their dry clutches prematurely.

I haven't changed a throw-out bearing on a Hexhead. Is it significantly harder or more expensive than Airhead's multi-bearing disk? Otherwise I'd say let 'er fry because that part is cheap and easy to replace.

 

[darrylri]

I've owned lots of cars in the past 50 years. Most of them "stick shifts" with a manual transmission and a dry clutch. To my knowledge I've never seen a car with a multi-plate wet clutch.

My 1971 (?) Honda 600 car had a multiplate wet clutch. (That would be the really little bitty one, smaller than the original Civics.) It had "4 on the dash", as there was no room to put the stick on the floor.

 

[joelaw]

I've owned lots of cars in the past 50 years.* Most of them "stick shifts" with a manual transmission and a dry clutch.* To my knowledge I've never seen a car with a multi-plate wet clutch.* QUOTE]

There may have been others, but I know that 1941 and 1947 Hudson automobiles had wet clutches.

As has been note in other posts, HD uses wet clutches and porbably have for ever. On the HD the clutch shares oil with the primary chain drive, not the transmission or the engine.

In the nearly 30 years of riding BMWs and a little over 500K miles, I have had really good service from the dry clutches on these motorcycles. I have '91 K100LT with 104K miles and as part of some extensive preventative maintenance, I had the clutch replaced, it was worn but still had many thousands of miles of live remaining.

As several other repliers note, I too never put the transmission in neutral at red lights. The key, as has been pointed out by others, is to keep the clutch adjusted properly and get the clutch fully engaged a quickly as possible when getting underway.

 

[osbornk]

My 1971 (?) Honda 600 car had a multiplate wet clutch. (That would be the really little bitty one, smaller than the original Civics.) It had "4 on the dash", as there was no room to put the stick on the floor.

The the little bitty car had a motorcycle engine in it.

 

[paul_f]

U turn practise and clutch?

After having read all of these posts, I have obviously been putting too much strain on my clutch when practising slow speed U turns, with the throttle steady and the clutch regulating speed. Am I correct in assuming slow U turns with a beemer should be done with more trail braking to regulate speed rather than using the clutch?

 

[darrylri]

The the little bitty car had a motorcycle engine in it.

Yes, that's right, it had a 600cc water cooled twin and a wet clutch, all sharing the same oil with the transmission. It had a lot of motorcycle tech in it, and was surprisingly full featured, too. For example, it had a 3 range, fully variable speed setting for the windshield wipers. Heck, even BMW's Z3 didn't have that.

Mine was crushed by a speeding Chevy Nova that ran a red light and T-boned me as I was completing a left turn. Sounds like a motorcycle accident! The driver just didn't see me (or the other two lanes of traffic that were already stopped for the light).

 

[Motorwerk]

Am I correct in assuming slow U turns with a beemer should be done with more trail braking to regulate speed rather than using the clutch?

That's correct, it's more of an on/off accelerator than clutch-slipping exercise. A bit more difficult but quite managable.

In regards to pre-loading the shifter; while that was almost mandatory for a smooth shift in pre-Heaxhead transmissions it's not so necessary now but still helps a bit. The trannys are vastly improved. All the gyrations of managing the 1100 compared to the 1200 are a thing of the past.

Nancy, don't worry too much about it you will get better with practice. Just know not to linger in the friction zone. On occasion you will know you've been there too long and why and sometimes you may not have a choice.

 

[Tom K.]

Thanks for the replies. In MSF class they tell you to stay in first at stop lights....so that you can prevent getting rear ended. So I've always been one to hold the clutch in and stay in first while everyone else is handsfree. Guess it's time to join them and be handsfree.

Of course when I drive a manual transmission, I'm the one sitting there gunning the engine waiting for the light to turn too.....I guess I have some habits to unlearn.

So far I'm just trying to feel comfy on this huge thing. Only stalled once today. Trying to figure out what all the things on the computer are and I'm going to have to reset the clock as we silly Americans have to change the time twice a year.

My technique (in cage or on bike) at lights is to try to see when the cross traffic light turns yellow, at which point I shift from neutral into first.

I'd also mention that the RT has a very high 1st gear (about 53 mph @ redline), so co-ordinating throttle & clutch for a smooth start may require some practice.

Re changing clocks, for the first time, I managed to set the time in my car without resetting the trip odometer!

Enjoy your RT!
Tom

 

[mikeb921]

Dry clutch

Interesting thread. I'm surprised no one has mentioned the hydraulic aspect of our new hexhead clutches. I, for one, have grown acustomed to the feel and "take up" of the new system for normal starts but I can't seem to get a good feel for quick launches. I like the idea of it being hydraulic (been working for decades in autos) but I think BMW needs to continue experimenting with the size of the master cylinder and or the slave cylinder until they can get it to engage more like a cable operated set up. As far as wet versus dry, I can't imaging a "Boxer" with anything but dry. It's been working well for them for a very long time.

MB

 

[mpmarty]

Regarding the high first gear and dry clutch I find myself slipping the back tire instead of the clutch

 

[ragtoplvr]

Some other comments.

on a 1150, the Bosch 4417 4 electrode plug gives better low RPM (like at idle) then the OE or the autolight.

I set my idle a bit more than recommended at about 1200 to 1250 RPM, particularly in the winter. I can easily although slowly pull away and never touch the throttle, or pull away a bit faster and never slip the clutch above 1000 RPM, I can not do this on my bike using any other plug.

I have smelled the clutch before, particularly in a panic situation, stopped at the light and notice a HUGE ford truck grill gaining rapidly with MY name on it. But slipping at 6 or 7K rpm in a case like that is not only allowed, it is preferred, if I had stalled it I would not be typing this. BTW that truck continued right thru the intersection without hitting anything as I struggled to not drop mine on the shoulder after getting out of the way! Adrenalin is wonderful, and one leg was really sore from over straining the next few days.... Watch your 6 folks. One car actually circled around to make sure I was OK as I paced off the adrenalin in a parking lot.

Rod

 

[Polarbear]

Finding first gear!

Nothing is as important than your 6, when stopped or coming to a stop. I still always use neutral at most stop lights and never take my eye off my 6 as i'm doing so. Clutch use? Well, all must decide for themselves, but I can garantee my foot hits the footpedal and shifter at the same time, when pulling out. Its a bone chilling excercise to hear tires screeeching from behind as you sit at an intersection... Its good advice to always have an "out", when you do need it, so break all the rules to save your life when this occurs. Any rider, riding long will have this happen someday! Clutch in or out, just know how to find first and move quickly. For us neutral guys/gals, its a one movement excercise. Clutch, foot, throttle all come together in one motion in a split second. Thats how I see it and do it, Randy

 

[mpmarty]

There has been a whole bunch of construction work on the road from my home into the nearest town. Frequent flaggers stopping traffic. When I arrive at the tail of the line I pull over onto the right shoulder where possible and move up along side of the last vehicle. I still watch my mirrors. I got rear ended at a stop light in Florida in '85 on my Yamaha Virago 920 and got blown into the middle of the intersection. Fortunately I didn't end up getting hit by crossing traffic. 4X4 Pickup "didn't see me". Not something I ever want to repeat.

 

[169993]

HD Wet Clutches

I normally do not read this forum, as I do not own a Hexhead not do I know anyone who does. That said, I do know a little about clutches.

As far as Harleys having a wet clutch, the older ones do not. I can't speak on Evo engined bikes, but I know a lot about Harleys from 1982 and earlier.... Although they do have a multi plate clutch running in a primary case with a lubed (either oil drip or oil bath) multi row primary chain, the clutch itself is dry. What I mean by this is the clutch is not bathed in oil nor does it need to be to work properly. In fact, if enough oil gets on the plates it will lead to slipping. I have replaced the primary chain with a belt drive on many of these bikes and no modifications whatever are needed to the clutch. On the earlier tin primary bikes, one simply turns off the chain oiler. On the later alumimum primary HD's one runs without any oil in the case.

This same analogy is also applicable to earlier pre-unit construction Brit bikes. They are multi plate clutches and will operate quite happily dry. The main reason for multi plate clutches is to furnish an adequate surface area without having a large diameter clutch.

HD's also have a pressure plate with three studs holding it on. Thes studs are asymetrically spaced to give the pressure plate an inherent wobble. This greatly aids in a gradual engagement of the clutch rather than the sudden grab already spoken of here.

As far as the longevity of a dry clutch, think of a semi truck...They all (assuming a manual trans) have a large dry clutch and last for hundreds of thousands of miles trouble free.

 

[marchyman]

As far as the longevity of a dry clutch, think of a semi truck...They all (assuming a manual trans) have a large dry clutch and last for hundreds of thousands of miles trouble free.

And are only used for starting and stopping.

 

[PGlaves]

I have been pondering which is the least desirable: a wet dry clutch or a dry wet clutch. I haven't decided but tend to think the latter might be worse, but I'm not sure.

 

[mpmarty]

Worse! particularly in the old Hudson cars. their friction material was cork. No wonder they kept the clutch filled with oil.