Thinking the Unthinkable - Auto Clutch on a Competition Trials Bike

[Motobene]

When I was doing loop trail development on my property, I was using my `17 Sherco 250 Factory as transportation. Of course there were a gazillion get of then later get on, with same number of engine stop and starts. At least it's a 250, and the previous version of the carbureted Sherco 250 is one of the easier starting bikes on earth very light sweep-through kick does it... every time. What I found more a pain was trying to find neutral before I rolled to a stop. Not that I HAD to be in neutral, but it would be nice.

Anyway... I kept thinking how nice a capable electric bike would be for this kind of work, or my TRS 250 electric start. Now combine the TRS 250 with an auto clutch and I'd be there! My 250 is also a RR-model-based X-Track model, but all that X-Track stuff - the seat and larger tank and plastic over frame came off when I assembled the bike from the crate and it hasn't been touched since. I should have instead bought a Gold model to get the big Reiger shock. Lesson learned :-(

I still have the option to let EFM have a crack at stacking a ball-ramp mechanism on top of a TRS clutch (see the second post in this thread). I would not need the clutch slave cylinder in the clutch cover then, and I bet a cover spacer would be required to make room for the ball-ramp pack. The jury is still out on ball-ramp-style applied to a 3-fiber-plate, 2-steel-plate 'diaphragm' clutch with much higher net spring clamping force. Could require lots of tungsten carbide balls to get enough 'centripetal' force to attain the required clamping force at a low enough rpm.

Maybe I should finally give Gary a ring? The project cost to me would be buying and sending him a whole new TRS clutch:

Some design collaboration, and time in testing beta and then prototype. I know it can be done, the question is only how, and how tick a spacer on the clutch cover would be required to give room for a ball-ramp pack.

These-type clutches have steel clutch baskets with tiny tangs too small to thread into. But the backer part of the ball ramp could be machined in steel, adding the rotational inertia to the TRS motor that is so needed to get rid of stalls
(though going auto usually cures the stalling problem 100%). The steel part would have a boss to precisely fit the tangs and we'd use spot tig welding instead of fasteners. Hmm....

I just reached out to Gary at EFM. I'll let you all know what comes of that.

 

[Motobene]

Forgot to post this earlier, apparently, when asked about oil.

I talked one of the Rekluse engineers years ago, engineer-to-engineer, about Rekluse and tribology and clutch behaviors I had experienced on a more difficult Rekluse implementation. Out of that conversation
came the admission that "Shell Rotella T4 is a near equivalent to our branded oil" (wonder who supplies that to them?) Their oil could be a touch better than what I have long used, but I've had no reason to find out, as I went with
Rotella T6 long ago and it has worked marvelously with the Rekluse auto clutches.

Shell Rotella is a diesel (more stressed) engine oil that also happens to have the additives conforming to JASO MA2, which is: for modern 4 stroke (gasoline) motorcycle engines that shares engine oil with a wet friction clutch.
There are three Rotellas, varying in base stock. T4 is all mineral or petroleum base stock, T6 all synthetic, and T5 in between maybe half and half. The more the synthetic base stock thew higher the price.
Being a diesel oil gets a really robust anti-wear additive package and longer range. Not that I put long miles between motorcycle oil changes, but I had the stuff around anyway and long used it in all my 4-stroke motos
and ranch ATV.

Those SAE numbers we all know so well - but don't - aren't units of viscosity, but rather represent a range of viscosities reflecting actual viscosity with respect to temperature indirectly. The broader range of the T6 synthetic's
5Winter40 versus the T4's 15Winter40 very indirectly highlights the a higher VI or viscosity index of the synthetic base stock, as in changes in viscosity less over the full operating temperature. Strange, yes? But that's the
bizarre SAE system for describing oil.

SAE number, code for specifying the viscosity of lubricating oil, established by the U.S. Society of Automotive Engineers a long time ago has the numbers for crankcase lubricants range from 5 to 50, and for for transmission
and axle lubricants they ranging from 75 to 250; the lower the number, the more readily the oil flows. Other than that, the system is, well, confusing, and why you should not buy suspension oils that don't show actual
viscosity at cold and hot temperatures, for example SUS (Saybolt universal seconds).

The 5W part of the oil isn't thinner in viscosity when it's cold than when it's at 100 degrees C and supposedly a 40. It's actual viscosity is the opposite, as in thinner when hot. Anyway, if an oil does not provide a specific
viscosity at both cold and hot temperatures, you can't know the viscosity other than some rough idea from the SAE numbers. 0W20 is thinner than 15W40, but like so many things, it complicated. And I've measured 7W fork oils
that were thicker at room temperature than 10W fork oils.

I don't back off from this thicker diesel oil even in the cold season, as the bike will warm the oil quickly to where it isn't too thick. I've had the clutch on the Beta not release when the bike got cold soaked being pulled on a trailer in 20-degree air.
At the trailhead, I started the bike and let it idle for a minute, then rolled down hill and snicked it into 1st gear and rode it around until the engine warmed the oil enough to let the clutch release at idle by tapping the brakes.
Within an hour the New Mexico sun had raised the ambient temp by 20 degrees anyway.... Great to live here!

 

[Motobene]

Repeating what I am trying to achieve: I want to bring my personal competition trials bike in line with my other bikes, an auto clutch allowing loss of the manual clutch (and I mean no clutch lever at all), which
allows me to plumb the rear brake direct to any DOT-fluid based clutch master cylinder for a 1-finger strong rear brake. This in turn allows me to lose the foot brake.

The result is an extremely simple controls scheme. Mentally easy to handle and reprogram to, and as my experience has show, increasing both control, confidence, and safety. And zero stall potential!

Both brakes available in an instant, no matter where one's feet happen to be, excellent clutch slipping performance by throttle only that rivals manual control - especially when one gets tired. And this was unexpected:
The rear brake is connected to the 'brain bone' in the same spot as the clutch, and releasing the brake is just like releasing the clutch on an auto clutch bike. Throttle pulse, release clutch (er, um brake), hop
the front wheel or pop up on a step... amazing really.

The only thing missing is no longer important to me: massive-throttle splatters. Can still do them but don't want to. Not needed at the local expert level down.

UPDATE - THIS PROJECT (which was on hold a long while)
Garry Buzelli at EFM auto clutch has experience adapting to conventional helical coil springs clutches, and the newer so-called 'diaphragm' springs clutches are different in significant ways,
like less than half the clutch plates and much higher spring clamping force from the single Belleville spring. A problem, an advantage? I will explore this further.

There is a 2023 Montesa Cota 301RR (blue/white) sitting at the local Honda dealer that I have been eyeing. I know the 4RTs well as I have worked on a number of them from 2005 on. Every time I
ride one I find them weird. I know I could reprogram my soul to one, but don't know how long that would take. A risk that I would not fully mesh with one.

Certainly the engine characteristics of the 301RR would suit auto clutch adoption. And having a conventional clutch lowers implementation risk.
But the cost of commitment to this project going new is steep: A new 2023 301RR in the below color I prefer, sits near me at a Honda dealer of repute $13,500!
$2,000 MORE and one model year older than a new TRS Gold!

One concern I had about the 4RT is that unlike the former 315R, the clutch slave cylinder is in on the clutch cover, requiring a 'push in' rather than 'push out' pressure plate, and that require flipping around the clutch hub.
And that I think might complicates auto clutch implementation. If it does, I recently discovered that the the pre-4RT 315R was 'push out' on the pressure plate from the slave cylinder being on the left center case, resulting
the more common 'right side out' clutch hub. Below you can see both the 315R clutch hub and the 4RT clutch hub in their orientations as you would see them looking in. Both appear to have the same 19-tooth spline and spline
diameter, and in the same place relative to the driving transmission shaft. I will find out from Gary if the 315R part would ease auto clutch implementation. At 76 Pounds, worth the buy risk.

Will update y'all as I know more. For now, I have a major trials event to go back to working on.

 

[Nhuskys]

Beta not a consideration?

 

[Motobene]

BETA QUESTION
Beta is a fine machine, and a successful auto clutching of a Beta would take away the reason I have had to avoid the Beta historically: the two stroke trials Betas being the only modern
trials bike and the only Beta two stroke to retain the old European format of right side drive, clutch on the left. Every other two stroke on earth, including all the bigger Beta's is now Japanese-format left-side drive, clutch on the right.
Fitting a left-side foot brake has been a must for me since the `80s, and the Beta 2-stroke trials bikes were and remain too busy on the left side to do that. The kickstart is there. The shifter is there. The clutch is there. The muffler is on that
side too. So I went elsewhere over the years. As for their 4-stroke trials bike, it's never been a favorite.

The Beta has had ONE advantage for me, being left kick. Starting a kick trials bike for me is also left kick, and on all the Japanese left-side drive format bikes I kickstart standing on the right side, before I mount the bike.

Now an auto clutch would mean that I can lose the left-side brake. My goal goes beyond that - no foot brake at all, so the brake-on-left objection to the Beta goes away, and the probability of success is higher with a pre-Rekluse EXP-type
auto clutch and Beta's (or Honda's) conventional clutch. But I have been a TRS man since RYP went poof and the new administration made a series of unfortunate mistakes. The TRS I have found to be very high quality in design. The clutches
the power spunky and smooth, and the handling right on, for me. And what can I say? Electric start has been a dream for me and always worked flawlessly. Not having to kick a bike a hundred times in an event save a lot of energy over a typical event weekend.

OVERALL PROJECT TURN
A major question for me has been WHO to partner with to do an auto clutch for a trials bike as like it or not, it would be a development project. I've done a lot of design development and know what it takes to iterate designs before ANY metal
is cut so you only have to cut one time without a complete redo.

I turned to the engineers at Rekluse first because I found them very sharp on past projects, and significantly, their EXP-based clutches come at the get-go set up 'right' with the engage/disengage versus RPM characteristics that would make
for a successful competition trials bike implementation. Unfortunately the Cota clutch is based on legacy Honda street bike parts that Rekluse has no economic incentive to make and EXP packs and clutch plates for.

I turned to EFM with several inquiries over time as I was musing over this project and in a kind of probing about a working relationship. My last email where I proposed the 315R clutch basket to make implementation easier for him, and asking a critical question, "Please tell me your confidence at being able to achieve a clutch with my preferred characteristics for this application. And being able to do so in, say, no more than three iterations? I need to know what I'm getting into as this project would cost me around $15k" got me the following response. Hmm.

315 is more of a standard type hub.

Thank you for the interest in EFM Auto Clutch Inc.

Garry Buzzelli
EFM Auto Clutch Inc.

WHICH BIKE & WHOM CO-DEVELOPMENT
Gary might still help me out, but we shall see. I already like the TRS, a lot, and the fact that the local small dealer is a friend and a sharp professional engineer. When I discussed my project he was enthused and responsive, volunteering co-development time and resources, like his RP and CNC machines. Of course he wants me to remain in the TRS fold and not see me wandering off into Cota land. My TRS 250RR is a great platform for auto clutch development and - this is an update - I have figured out HOW to pull off an auto clutch on a diaphragm-clutch bike. Now I'm doing sketches as a first step to fleshing out a design in CAD.

I could have justified a 280 Gold, but the drop-dead ordering date for one of the 150 to be produced this year is well past. Not only was the major 2-day trials event in the way, but I engaged another major and immensely expensive project right at decision time. Mr. Gold became too much to think about for now :-0

 

[Motobene]

Last post updated.

 

[Motobene]

Just got a text inquiry from a friend who apparently also has a TRS and would like to do auto clutch on a trials bike.

I've long been a 250 man, as that size in the more spunky 250 bikes affords many advantages to the common man, not the least of which is
taking fewer points in competitions when 'bigger is better' and an over-spunky 300 repeatedly breaks traction. I passed up ordering that 280 Gold
so it may be past time to do so. The development work will thus take place on another bike. Maybe my 250.

On an auto clutch bike more displacement works auto clutches, as does also running tall in the final drive, and the greater torque from a touch more
displacement will go well with both. I just rode a new Vertigo 300 and that engine was the first 2-stroke 300 I'd not mind owning. It felt neither high inertia
(heavy), nor abrupt. Strange to have 4-stroke-like engine braking on a 2-stroke bike owing to FI setup. In the spunky TRS the 280 is a good engine size compromise.
And that magic button is, well, where they all should go.

When doing research on auto clutches recently I hit the following article on the former Rev-Loc clutches wherein there is 'getting it' regarding
how the controls can be simplified and how that simplification can enhance control for the majority of riders, as in those NOT doing super cross
or other extremes where departing from one's longstanding habits is deemed to risky to mess with success.

Interesting comment on moving the rear brake!

Those riders who tend to have the most problem with auto clutches and moving the rear brake tend to be those who over use the rear brake, under use the front brake (because it can be 'scary') and it's scary because those same riders also tend to sit or stand on bike un dynamically, like a sack of potatoes, and don't selectively weight the front wheel as they could. I've noticed they also tend to lean body with bike. That poor technique one can get away with riding big bikes off road or on, but in extreme situations that's dangerous, and in trials it leads to limiting out in the lower classes (who will volunteer for an ego killing flailing and dabbing away on a higher line?)

The most important factor in testing and adoption of something new is ones psychological flexibility, which even very smart people can fail at.

I found big advantages in safety and confidence on off-road bikes with auto clutch and only hand brakes. I talk about that as few listen or get it. That's entirely fine. The few will go there and like me, stay there or want to be there even in trials competition.

In trials it took me a long time to accept letting of of a manual clutch to gain the same whole package I discovered elsewhere. I'm dying to go there, but it will take maybe the rest of this year to attain, what with all my other grand projects That I chose to 'go there' with a bike with a fully modern clutch presents technical challenges which will take time to sort our, but I relish just that sort of thing.

 

[Motobene]

Want is subjective and right front rear brake and manual clutch? I don't understand.

If you reprogram to clutch by throttle and brakes on the two index fingers and nothing else, whether that comes out was want will depend on a number of variables.

I had a friend who went back on one bike. I have yet to ride with him after he converted back to foot brake to observe differences, which might not be easy to discern because the only change was how the rear brake is engaged. He'll still be auto clutch, with a return to a mostly useless cable-clutch lever where the rear brake master cylinder used to be. I barked out, "You F'd up the brakes!" He just looked sheepish.

Maybe it was the foot brake addiction. I get it. A foot is more powerful. As a trials rider, breaking traction at all, especially on the rear, is deeply programmed in. Heck, it took a while to program OUT of this former cross-country racer.

On my converted bikes the only time I lock up the rear wheel is for fun, such as say unloading the rear end a bit and sliding into a turn. That takes 2 fingers instead of the usual one. A long trials habit has me with the index fingers always resting on each lever, ready for a near-instant response.