Topic: Dry clutch on CB750

[voxonda]

Hey there,

Just checking if there is interest in a dry clutch for our beloved 750/836/850.............../1000.
It is for real, no kidding.

Cheers, Rob

[J.Webster Designs]

i thought that i saw one before... what would be the advantages for dry clutch over wet?

[MRieck]

Hey there,

Just checking if there is interest in a dry clutch for our beloved 750/836/850.............../1000.
It is for real, no kidding.

Cheers, Rob

Approximate cost Rob.....500.00, 1000.00 ....well....not that much It is very interesting and I'd like to read some details.

[andy750]

.. what would be the advantages for dry clutch over wet?

+1

[MRieck]

.. what would be the advantages for dry clutch over wet?

+1

Less drag but more importantly no clutch fiber crap in the oil

[voxonda]

Hey there,

Just checking if there is interest in a dry clutch for our beloved 750/836/850.............../1000.
It is for real, no kidding.

Cheers, Rob

Approximate cost Rob.....500.00, 1000.00 ....well....not that much It is very interesting and I'd like to read some details.

Will give some details, but it's early days yet. But all is looking good. Will post some pic's soon.

Rob

[mec]

indeed, there is interest in a dry clutch.

without having more infos on that project, think of the fact that it could be a benefit to build a slipper clutch as it is used in modern racebikes now.

mec

[voxonda]

It is never been the intention to make it like a modern (race)bike.

Rob

[kos]

While at Dennis Zickrick's (Greddie Spencer's engine builder 1979-1982) home three weeks ago, we were going thru his old DOHC Team Honda race parts and I came across one of his RSC dry clutch kits and found to my surprise that the clutch center was a "300" part numbers. As these engines (SOHC & DOHC) are very much alike... I would try looking for RSC made DOHC CB750/900/1100 dry clutch parts.  Would make your project a lot easier.


KOS

[voxonda]

While at Dennis Zickrick's (Greddie Spencer's engine builder 1979-1982) home three weeks ago, we were going thru his old DOHC Team Honda race parts and I came across one of his RSC dry clutch kits and found to my surprise that the clutch center was a "300" part numbers. As these engines (SOHC & DOHC) are very much alike... I would try looking for RSC made DOHC CB750/900/1100 dry clutch parts.  Would make your project a lot easier.


KOS

Thanks Mark, did that route but though they lookalike, not much is usable from that kit. Would make it even more expensive than it already is. They are pretty kit's though.

But there are others brands which can be very helpful, dare not to mention that name here.

Regards, Rob

[MRieck]

Hey there,

Just checking if there is interest in a dry clutch for our beloved 750/836/850.............../1000.
It is for real, no kidding.

Cheers, Rob

Approximate cost Rob.....500.00, 1000.00 ....well....not that much It is very interesting and I'd like to read some details.

Will give some details, but it's early days yet. But all is looking good. Will post some pic's soon.

Rob

Gives me something to look forward too.

[turboguzzi]

.. what would be the advantages for dry clutch over wet?

+1

Less drag but more importantly no clutch fiber crap in the oil

Not sure I quite agree with you on this one.... Racing engines get there oil changed often enough so that fibers oil the oil dont look like a problem to me. All current superbikes run wet clutches even at WSBK level without issues.

I think the main advantage is a relatively higher torque capacity in relation to size and weight. A dry clutch can in theory cope with more torque than a wet as there is no oil to "lubricate" the plates so the friction coefficient between plates is higher. Being exposed to air lets it get rid of the friction heat as well. 

[754]

Fluid cooling, is far more effecient than air, moreso when airflow is shrouded by the ignition bulge. That is of course provided the clutch can hadle the oil temps, seems to be the case in this instance.

 I ran Barnetts for years, no evidence of added wear due to clutch material being in the oil.. cant vouch for stock, but doubt it is an issue..

[voxonda]

We can discuss the pro's and con's of a dry clutch, in this case, or the 'need' for a 1000cc kit. Fact is we do what we do because we like it. To show our skills or just to show off in front off a crowd. All the things we do to our beloved SOHC will not make a modern superbike of her. Aim for that 100 rwhp with or without help from Turbo or whatever, put her next to whatever modern bike and it'll be a laugh. My sons Triumph Daytona with 130 bhp, only needs 3 gears to hit 130 mph!! And does everything better, steering, braking you name it.
Of course there is no real need for a dry clutch, though it has some advantages against the OEM one, less drag, better torque resistant etc..... it even has disadvantages like more noise, the plates wear faster etc..... but it looks COOL!!!!
During my scrutineering years seen a lot of wet clutches go up in smoke in Superbike racing, in the Moto GP all are dry clutches.

Rob.

[mec]

a dry clutch is for racing purpose mainly.
cause there is no lubricating oil i can be designed smaller, less rotating mass means quicker throttle response, better overall performance.
all the heat produced by the clutch does not affect the oil temp.

i think there is no MotoGPbike without a dry clutch. in WSBK the manufacturers a forced to use what they sell (ducati uses dry clutches).

biggest advantage: the racelike rattle and noise 

mec

[paulages]

i could have sworn i saw a slipper clutch conversion being developed by cyclex, but now i can't find it on their site. the "engine parts" page isn't opening for me, which is probably where it is. can't remember if it was dry or wet, but it looked to be a nice product.

[voxonda]

i could have sworn i saw a slipper clutch conversion being developed by cyclex, but now i can't find it on their site. the "engine parts" page isn't opening for me, which is probably where it is. can't remember if it was dry or wet, but it looked to be a nice product.

I think you mean their "lock-up" clutch.

Rob

[Terry in Australia]

Dry clutches are only for race bikes? Geez, I didn't realise my BMW K1100LT with 105,000 miles on the original OEM (silent) dry clutch was a race bike? How cool is that? 

[paulages]

i could have sworn i saw a slipper clutch conversion being developed by cyclex, but now i can't find it on their site. the "engine parts" page isn't opening for me, which is probably where it is. can't remember if it was dry or wet, but it looked to be a nice product.

I think you mean their "lock-up" clutch.

Rob

yeah, i think you're right. just had a memory in the back of my head, and remembered it as a slipper clutch.

[MRieck]

We can discuss the pro's and con's of a dry clutch, in this case, or the 'need' for a 1000cc kit. Fact is we do what we do because we like it. To show our skills or just to show off in front off a crowd. All the things we do to our beloved SOHC will not make a modern superbike of her. Aim for that 100 rwhp with or without help from Turbo or whatever, put her next to whatever modern bike and it'll be a laugh. My sons Triumph Daytona with 130 bhp, only needs 3 gears to hit 130 mph!! And does everything better, steering, braking you name it.
Of course there is no real need for a dry clutch, though it has some advantages against the OEM one, less drag, better torque resistant etc..... it even has disadvantages like more noise, the plates wear faster etc..... but it looks COOL!!!!
During my scrutineering years seen a lot of wet clutches go up in smoke in Superbike racing, in the Moto GP all are dry clutches.

Rob.

+1   You have the right idea.

[mec]

Dry clutches are only for race bikes? Geez, I didn't realise my BMW K1100LT with 105,000 miles on the original OEM (silent) dry clutch was a race bike? How cool is that? 

we are speaking motorcycles. never knew that BMW built bikes 

mec

[lordmoonpie]

I'm interested Rob for sure. I have dry clutches on my Ducatis and also on my 450 Honda racer. There are significant benefits in that the oil is less contaminated by clutch fibres, gets less broken down by the high friction action between the plates and that means proportionately longer oil life or more effective oil in the same timeframe.

Dry clutches keep clutch fibre and dirt out of the engine and it largely blows away in use. The major benefit though for me and I'm surprised no-one clocked this, is that changing and maintaining the clutch is as easy as pie. I can swap the clutch plates out on my ducati in under 2 minutes, which is a major help.

The other beneift of course is that with oil clutches, you do lose power in the lubrication system. Yes it's fractions of a horsepower but when you want every last ounce out of a race bike, you can see why Ducati and all Motogp bikes run dry clutches and the grand prix 125 and 250 machines all use dry clutches and have for years. On my 888 the estimate is that is liberates a further 0.5 bhp!

After all that the main benefit for me personally is that they look super cool spinning away in full view, they sound great and they make maintenance easy. Here's a pic of my 450 clutch....l-o-v-e-r-l-y!

So Rob, where can I get one

[Terry in Australia]

Dry clutches are only for race bikes? Geez, I didn't realise my BMW K1100LT with 105,000 miles on the original OEM (silent) dry clutch was a race bike? How cool is that? 

we are speaking motorcycles. never knew that BMW built bikes 

mec

Ha ha, well they've been building bikes twice as long as Honda mate, but why am I telling you? They're pretty common in your neck of the woods, ha ha! Cheers, Terry.

[voxonda]

I'm interested Rob for sure. I have dry clutches on my Ducatis and also on my 450 Honda racer. There are significant benefits in that the oil is less contaminated by clutch fibres, gets less broken down by the high friction action between the plates and that means proportionately longer oil life or more effective oil in the same timeframe. ...After all that the main benefit for me personally is that they look super cool spinning away in full view, they sound great and they make maintenance easy. Here's a pic of my 450 clutch....l-o-v-e-r-l-y!

So Rob, where can I get one

Hey LMP,

Great to hear of your interest, the one on your 450 is a Cappellini isn't it?

Rob

[lordmoonpie]

Hey LMP,

Great to hear of your interest, the one on your 450 is a Cappellini isn't it?

Rob

Hi Rob,
No it's a Nova dry clutch. It was actually a total pig to get working despite being sold as a kit to just bolt on. Took me nearly a year and lots more modification to the engine to get it sorted but now it's as sweet as a nut! I think it's based around an old Yamaha TZ clutch with obviously a custom cast crankcase cover. The clutch is very small but I'm hoping it'll solve the usual CB450 clutch slip or burnout problems...