Cable vs Hydraulic

[crawsue]

Apologies if this has been kicked around before but I’m interested in learning the views of you knowledgeable people……I am fortunate to have 3 modernish bikes, 2 Triumphs (1050st & T100 Bonnie) both have cable clutches and perform well with no noticeable “heaviness “…..my Evo has a hydraulic action. My mates new Hypermotard is hydraulic but another pal has a modern Supersport, which I think has a similar engine to the Hypermotard, the clutch on the SS is cable. Today I joined a pal on his brand new GSX”S”…..1000cc supernaked…..with a cable clutch.
To my nonengineering brain it would appear that cable should be cheaper to fit….so what advantage does hydraulic have on a motorcycle application ?

[jerry]

All 4 of my ducatis from 1991 to the 2001 model have Hydraulic , some times they are glitchy
my 2022 Z900 is cable as is my Daughters 2019 Z650 both are very sweet ,, my old HD is cable but even with so called light clutch set up its heaavy

Crawsue does your T100 Bonny have any engine braking because every Hinkley Bony from 2016 to now that I have ridden had zero engine braking and I have tried every model

[Nickj]

Might be 6 of one and half dozen of the other..

In the very late 60's honda bought out the CB750 with hydraulic brakes, it was a bit techy, a bit flash AND suddenly every bike manufacturer had to add them or they'd be seen as a bit old fashioned.
It is undoubtedly easier to set up hydraulics than a 2LS drum of even a 4LS but much more difficult to strip and rebuild a hydraulic system.

I suspect that as a good 2LS or a 4LS can be a very effective system that on road bikes it's more about style than anything else. On dirtbikes definitely more fashion, on a sandy enduro most disk pads were toast after a few short hours at a wet sandy venue the rear drums kept on working though.
Modern race bikes where the disks can be seen going a dull cherry red it's more about having a working system.

I'd blame Honda

[dunf]

Originally Posted by Nickj

In the very late 60's honda bought out the CB750 with hydraulic brakes, it was a bit techy, a bit flash AND suddenly every bike manufacturer had to add them or they'd be seen as a bit old fashioned.


I'd blame Honda

Pretty sure Lambretta brought out a production disc brake before Honda. I'd blame them

[Luddite]

Originally Posted by dunf

Pretty sure Lambretta brought out a production disc brake before Honda. I'd blame them

If we're talking early disc brakes, how about this from 1906? It's an Imperial 500 - note the scissor type 'caliper'. Still a disc though.

[350TSS]

From the manufacturer's viewpoint cable operation will be a cheaper option and possibly lead to either a better margin or a more competitive retail price.
Most clutch actuating mechanisms operate via a push rod through the main shaft of the gearbox which means a cable clutch has a cable routed across the top of the gearbox or a cranked pull from the front, the cable can suffer with a tortuous route to the LH lever, particularly around the headstock. Hydraulics have less of a problem with sharp corners on route between the master and slave cylinders and are easier to route away from excessive heat which might adversely affect a cable. Manufacturers, I suspect, would prefer a hydraulic operation when designing a bike platform as it would be easier to accommodate a multitude of handlebar positions , instrument clusters, exhaust routings across a range of types of motorcycle.
From a reliability perspective my experience of both cable and hydraulic I have never had a cable break but on 3 occasions have had hydraulics misbehave

[Mr Gazza]

It's all about friction with a cable.
Maybe they have improved over the years and are made with better friction reducing materials, but will still be prone to sudden catastrophic failure, in other words they snap or a nipple pulls out!

Some interesting observations here; http://www.ukmonster.co.uk/monster/s...spring+balance particularly on post #15 comparing hydraulic and cable.

The comparison doesn't take mechanical advantage into consideration, but highlights how the friction increases dramatically with each deviation from a straight cable route. No such friction with hydraulic and the mechanical advantage can be manipulated with various piston sizes. With modern radial masters this can even be manipulated via adjustable lever fulcrums.
With a cable you're pretty much stuck with what you've got unless you can somehow alter lever lengths, and that's after all the cable drag!

[Nickj]

Like the hydraulic brakes introduction the hydraulic clutch took off and one of the given reason was easier pull than cable-actuated clutches. It was also a new and exciting selling point. As Mr Gaza says the cable is the weal part of the system and the liners no matter what they are wear and get glitchy.
A side effect of the easier pull allowed the use stiffer clutch springs, making the clutch stronger and handling more torque. Given the power outputs of modern engines you'd need a more complex arrangement that a long lever at one end or the other to give you a good chance of pulling the bar lever in.
They are also able to provide a more consistent feel than cable-actuated clutches and they do simplify the manufacturing process though I'm not sure how but KTM for one says that they do. Instead of a cable pulling on an arm to actuate the clutch, the hydraulic system obviously uses a clutch slave cylinder and a push rod, and they can be tucked inside the motor casings.
The hydraulics do need bleeding but once set it stays pretty much the same and doesn't need to be tweaked as the clutch wears or the cable stretches.
And you can change the slave or master to tweak the hydraulics feel and pull weight.

Also as Mr Gaza noted you won't get your nipples pulled off, possibly the best advantage as it's potentially painful ..

[crawsue]

Interesting points, I suspect that from a purely
engineering led perspective then hydraulic is the “ go to “ solution…..and I understand the friction argument of cable routing and also the ability to build in stronger clutches……BUT, my two Trumpets have sweet, easy to use cable operations + the T100 is 19 years old and 36 k mls….on the original cable….the ST produces around 130 bhp and the clutch copes fine.
And so far no response to Ducati using both cable and hydraulic on similar engines…..?

[Kato]

Hydraulic clutches are generally easier to modulate and have a lighter, more consistent lever pull since there's a master cylinder and a slave cylinder amplifying your grip strength
In general sport bikes / Race bikes use cables in preference to hydraulic, as they are simple and can be adjusted easily.
Hydraulic clutches are more complex and require more maintenance compared to clutch cables. They are also more prone to leaks and other issues that can affect their performance, require more regular maintenance to ensure proper performance and longevity.

[Nasher]

Originally Posted by Kato

Hydraulic clutches are generally easier to modulate and have a lighter, more consistent lever pull since there's a master cylinder and a slave cylinder amplifying your grip strength

What he said.

Originally Posted by Kato

In general sport bikes / Race bikes use cables in preference to hydraulic, as they are simple and can be adjusted easily.

Yep, far more difficult to adjust a Hydraulic Clutch
I've often thought an adjustable length push rod or screw in the slave piston would be useful, but then think that if the rest of the system is working as it should there is no need for adjustment.

Originally Posted by Kato

Hydraulic clutches are more complex and require more maintenance compared to clutch cables. They are also more prone to leaks and other issues that can affect their performance, require more regular maintenance to ensure proper performance and longevity.

And there lies one of their problems
With no external adjustment or obvious maintenance regime too many assume they are a fit and forget maintenance free system

Some of us for example change our brake fluid every few years, and adding the Clutch fluid to that is natural.

Those that don't change their brake fluid get away with it a lot because the action of pushing the Caliper pistons back when new pads are required at least moves the fluid about a bit and frees off the pistons.
That just doesn't happen with a clutch.

[jerry]

I bleed my Hydraulic clutches every few months and change the fluid at most in 2 years but as my recent issues with an oberon unit proves they can be fickle

[Dukedesmo]

Originally Posted by jerry

I bleed my Hydraulic clutches every few months and change the fluid at most in 2 years but as my recent issues with an oberon unit proves they can be fickle

I've got an Oberon slave on the Monster, works fine but the fluid turns black in a matter of weeks whereas, my 916 has an Evoluzione slave cylinder which also works fine (for 20+ years) but doesn't turn the fluid black at all, not even after 2-3 years without changing fluid.

I know most Ducati owners say their clutch fluid turns black over time but, it makes me think Evoluzione had a better design WRT to seals? Shame they're not in business anymore.

[jerry]

Originally Posted by Dukedesmo

I've got an Oberon slave on the Monster, works fine but the fluid turns black in a matter of weeks whereas, my 916 has an Evoluzione slave cylinder which also works fine (for 20+ years) but doesn't turn the fluid black at all, not even after 2-3 years without changing fluid.

I know most Ducati owners say their clutch fluid turns black over time but, it makes me think Evoluzione had a better design WRT to seals? Shame they're not in business anymore.

Oberon claim the new seals used in last few years dont turn the fluid black ,, ????? not sure about that yet ???

[velosam]

Followed this thread and thought I should bleed my clutch. Easy enough with a vacuum bleeding kit. Now I have lovely clear fluid... until next time. First time I have done it, didn't take too long at all.