[dhawalmakwana99]

Originally Posted by ArizonaJim

Pardon me for saying so and it is just my opinion but I think adding a slipper clutch is a totally unnecessary addition of a complex, unneeded part which will only add weight to the motorcycle.

A slipper clutch serves to protect the engine and the rider if the rider improperly downshifts to too low of a gear ratio but that is basically just covering up for his/her poor shifting decisions and lack of skill when downshifting.

A good rider knows what gear their motorcycle is in, what gear will soon be needed and how to use the clutch and throttle to make the downshift smoothly, without over-revving the engine or causing the rear tire to break loose.

In other words, the slipper clutch is a crutch to help inept riders who make stupid mistakes.

For 90% of the riders and 99% of the riding conditions they face the additional weight and complexity of the device is totally unnecessary.

It does serve the sales department though.
It allows them to boast of the virtues of the unneeded gimmick (assuming they are smart enough to even know what it does).
They hope that this will make their machines seem to be far advanced over the competition.

Perhaps next we shall see something more valuable like LED lighting for all of the lights on our motorcycles? At least that would be something we all can benefit from.

ArizonaJim. Agreed that the slipper clutch increases weight of the motorcycle. But I see more advantages than disadvantages in having it.

Weight increase. Yes, but the Duke 390 is already a very light motorcycle in terms of power to weight. another 3-4 lbs wont really make that much of a difference.
Of course a good rider knows which gear is the motorcycle in. In fact he will know from the sound of the engine. In my opinion, the slipper clutch is something which is very useful when you are aggressively downshifting so it prevents wheel hop and rear end chatter. Not to mention the motorcycle stays more or less in a line under braking (read: does not back itself out vigorously) rather than making up for poor shift decisions/ lack of downshifting skill.

Slipper clutches are widely used on high performance motorcycles to prevent unwanted rear movement under heavy braking/ downshifting. MotoGP, WSBK, IDM, BSB, AMA. All of these racing classes have clutches with slipper action for added safety and added functionality. That is the reason why the technology has trickled down to road bikes. I would say it is just a welcome addition for road riders to taste 0.5% of technology of modern motorcycles.

I have used motorcycles w/ & w/o slipper clutches and you have to trust me when I say this: I would not like the feeling of the BMW S1000RR backing it out of control on my favorite twisty on a Sunday morning.

Having said this, I would personally not be a fan of slipper clutch on a motorcycle like the Duke 390 (read: love to back it in). Heck, I am even trying to find a way to disengage only the rear wheel ABS on the bike for all the sinful fun on this bike!

P.S LED lights for me too!

DM99

[ArizonaJim]

While the slipper clutch does have a useful purpose on a race track I'm not sure the roads or the riders in India really need it.

For instance, on a race track where the rider is approaching a hard turn at 140 kmph and will be leaving the turn at 60 it can be useful to be able to shift down two or even three gears so the maximum acceleration while exiting the turn will be on tap. The slipping clutch will allow the rider to concentrate on maintaining his line during the turn.

That said, how many riders in India will need to make use of this sort of feature, even on the high speed roads which seldom require such downshifting to exit a tight turn on a 40 horsepower machine like the Duke?

Speaking for myself, in over 300.000 miles (484,000 km) of riding motorcycles on the streets and interstate highways in the US I have never needed a slipper clutch (if one had been available).

I suppose having a slipper clutch also gives the owner some "bragging rights" but I think the added weight could have been put to a better use by increasing the strength of the Duke's cast aluminum rims or, as I mentioned above, something the average rider will use.

[ashwin1224]

@ArizonaJim +1 Brother

I think the slipper clutch, with all its benefits is just a marketing gimmick. All the 390 riders out there, When was the last time you locked your rear tyre while braking? In a year of ownership I can recall maybe just 2 or 3 instances when I locked mine, and those times I admit I was being stupid. Also, regardless whether the slipper clutch doesn't increase the cost of the bike or not, it will definitely increase the maintenance cost as it will wear off far more quickly than a standard clutch. And from what I understand, a slipper clutch will also reduce engine braking by a lot which by far is the only torture I put my bike through(downshifts at 9k rpm <3 )

The slipper clutch is great only on the spec sheet, or a track, not so much on the road.

[Sutripta]

Originally Posted by ashwin1224

When was the last time you locked your rear tyre while braking? In a year of ownership I can recall maybe just 2 or 3 instances when I locked mine, and those times I admit I was being stupid.

During normal braking, what effect does the slipper clutch have? And the ABS?

Regards
Sutripta

[ashwin1224]

My bad, I meant during aggressive downshifting, the rear tyre looses traction . ABS will certainly not let you slide.

[Beast_of_Burden]

The 390 has a really high effort clutch, KTM might be addressing that issue mainly as the new clutch has gone from 5 to 3 springs. Sure, it might be a marketing gimmick but I am really interested in knowing if the new clutch is easier on the knuckles. This was one of the big reasons I sold mine. Not that I am going to buy another KTM anytime soon.

[Sutripta]

Could someone explain this '3 spring' thing in a bit more detail.

Regards
Sutripta

[B O V]

The 3 springs through which the cap screws are bolted onto the hub via the pressure plate and clutch cap.

Part number 15 ( springs ) in the below image.

I do not understand however how this leads to a decrease in clutch effort, lesser springs lesser the effort?



Regards,

BOV

[Beast_of_Burden]

Here is a link that explains how clutch effort at the handle bar relates to those clutch springs.

http://www.google.com/patents/US8297425

We cannot ofcourse assume that going from 5 to 3 means a reduction in clutch effort if the 3 have higher stiffness. Someone needs to ride and find out.

[man_of_steel]

Originally Posted by B O V

I do not understand however how this leads to a decrease in clutch effort, lesser springs lesser the effort?

Generally depends on how strong the 3 springs are, but in 390's case pretty much thats the case it seems. The showroom guys are claiming that clutch effort with this 3 spring setup on the 390 is pretty much reduced to CBR's territory now!

[ebonho]

We have performance clutch springs set for tuned Bullets from Hitchcock's comprising of thre heavy and three light springs. I have the same on my Bullet 500 along with a few other parts from them. This new mod by KTM looks somewhat similar. Only they seem to have done away with some springs, instead of just making them lighter. I still have not heard any authentic confirmation about the slipper clutch incidentally. Anywhere. If its there, I'll get it retrofitted to my 390 and try it out.

[hiren.mistry]

Originally Posted by ebonho

I still have not heard any authentic confirmation about the slipper clutch incidentally. Anywhere. If its there, I'll get it retrofitted to my 390 and try it out.

Welcome back doc!
Can this be considered as confirmation for slipper clutch on the Dukes?
Link to xBHP 1, look at the third attachment
Link to xBHP 2

cheers

[nishsingh]

I got a call today from the KTM dealer at Kondapur,Hyderabad confirming that the 2015 Duke 390 does have the slipper clutch.The dealer also mentioned that the price for the new Duke hasn't gone up, and is still at 2.17 lacs.

The KTM guys at the KTM booth at Hyderabad Auto Expo (held last week) too had confirmed the slipper clutch for 2015 models.

[man_of_steel]

Originally Posted by ebonho

We have performance clutch springs set for tuned Bullets from Hitchcock's comprising of thre heavy and three light springs.

Welcome back Doc!

Did the clutch effort go up with the Hitckcock's kit?

[ebonho]

Originally Posted by hiren.mistry

Welcome back doc!
Can this be considered as confirmation for slipper clutch on the Dukes?
Link to xBHP 1, look at the third attachment
Link to xBHP 2

cheers

Thanks Hiren. Yup, slipper clutch it sure looks like. Let me make a call.

Originally Posted by man_of_steel

Welcome back Doc!

Did the clutch effort go up with the Hitckcock's kit?

Thanks buddy!

I have it on my Std 500 with the 4 plate clutch assembly which has been "Enduranced" (oil holes, de-burring, warp truing, basic blueprinting). I briefly tried the clutch rod, ball bearing mod and fit in 5 bonded Endurance plates in place of the thicker 4 cork standard lates, but there was very slight imperceptible drag (creep) so I returned to the 4 plate cork plates.

The action of the Std 500 clutch is anyways butter soft (compared to the LBs which give me forearm pump after a hard day in the hills up North) so it wasn't for that per se. Since my 500 is modded, I used to get a lot of clutch slip under power even with brand new perfectly set up lates. The performance springs cured that. Which means more available power to rear wheel istead of spinning the engine ineffectually.