Clutch Pack Weights

In the process of taking my primary off my 850, I reassembled the clutch pack to keep everything together (it has the bronze plates). And of course was stunned by how much it weighs. This is not a new discovery. I wish I would have weighed my 750 clutch when I had it out of the bike as it has Barnett plates in it. I am pretty sure the weight difference is significant.

Does anybody have data at hand as to what different clutch sets weigh? Might as well throw belt drive units into the mix if anybody has information on this.

I went on to place all the bits from the primary back inside the case and put the bolt through to close it up so that the pieces are stored as a unit. Holy smokes! It doesn't look all that heavy bolted to the bike!

I know there are threads that have talked about this, but I was driving myself crazy trying to weed through it. Any info appreciated. I also noted that Ludwig mentioned in another thread the idea of turning the clutch plates down to remove weight. Any additional information on this idea would be great as well.

Russ

If no one pipes up I've got factory 750 primary all apart on hand and same with belt drive with Barrnett plates/Al pressure plate, which I too want to know what the difference is on scale. Definitely more responsive with lighter kit. Plus no oil mass in case. One way I assess mass difference is holding items and flinging back/forth or twisting back forth to feel the ease to do so or not. Hope my battery in still good in beater bath room scale. There are plastic primary covers available too.
Belt drive come in steel or alloy pulleys btw.

Belt drive with lightweight basket and aluminum plates in free air versus full OEM bronze plate stack = well over 10# weight savings I would guess.

That is SIGNIFICANT.

I happen to have one of the 3 Carbon Fibre primary cases that Kenny Dreer had built, they only weight a couple of ounces. Trick stuff!

Just weighed my collection for both of us.
Factory 750 triplex chain, basket, crank sprocket, clutch pack = ~12.75 lb.
Belt drive, Al basket/crank pulley, belt, Barentt plates, Al press plate, ~5 lb.

Minus the diaphragm spring, [still in puller]
All factory numbers complete clutch stack innards, ~3 lb.
Fancy after market clutch stack ~2 lb..

Okay then, a total trick kit with CF caase would be over 10# savings, plus better performace by a good bit.

I will weigh my stuff this evening and post weights for the complete clutch assembly and the entire primary. I am not worried much about the static weight but that rotational stuff that is subject to shock loads as well is something to worry or at least wonder about. Jeepers, I was wondering if I should rig up an outboard bearing for that poor main shaft!

grandpaul said:

Okay then, a total trick kit with CF caase would be over 10# savings, plus better performace by a good bit.

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The chaincase is not a rotational weight and doesn't have any bearing on the effects of a spinning clutch.

swooshdave said:

grandpaul said:

Okay then, a total trick kit with CF caase would be over 10# savings, plus better performace by a good bit.

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The chaincase is not a rotational weight and doesn't have any bearing on the effects of a spinning clutch.

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But it is less weight the engine has to pull around.

bwolfie said:

swooshdave said:

grandpaul said:

Okay then, a total trick kit with CF caase would be over 10# savings, plus better performace by a good bit.

Click to expand...

The chaincase is not a rotational weight and doesn't have any bearing on the effects of a spinning clutch.

Click to expand...

But it is less weight the engine has to pull around.

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Righty-O.

Less weight to move around equals more HP available to propel you forward faster, and less weight to deal with in flicking the bike around in the tight stuff.

Its said average pilot can feel 10% difference in mass or power or traction. Best can feel way less than that. 4.5 lb = 1 hp acceleration. Commandos are mass biased to the DS, so good'r place to remove over all mass. I got stated on adding mass when pre-Peel Combat 8# center stand fractured so removed it and noticed a bit more ease and safety to make it to pavement. Wheels and flywheel pay back most for the bux on mass loss. Primary spinning mass is next. Lightest race Commando
reported so far is just under 290 lb. A Commando at planning speed on THE Gravel can feel the benefits of just drilling the snot out of factory foot supports and kicker and side stand. So 'sliding' scale of who and where mass most noticed. Greg's fork kit is noticeable lighter than factory kit. Save up adding lightness costs.

..what is 10# ??[/quote]


4.535 Kg

My racing buddies tell me that one pound of rotational weight equals 8 pounds of static weight. I will accept that as a truth (even if it is over simplified). I know I brought up the weight of the entire primary and mentioned belt drives, but my focus is really just on the clutch pack. I was really thinking more about that poor mainshaft supporting all that weight outboard of its bearing. But any reduction in weight in the clutch assembly would also yield positive results in power delivered to the rear wheel, so it seems like a good spot to work on.

The average guy could make some decisions about what he puts in there for friction plates to reduce the weight some. I weighed one of my bronze plates and it is .5 pound or about 230 grams. The steel plate weighed in at 6 ounces or about 170 grams. The entire clutch assembly is whopping 11.5 pounds or about 5.23 kg. The primary with all of its components and cases weighs 27 pounds or 12.27 kg. So yeah there is the possibility to reduce some weight there.

But getting back to that clutch. What I would like to find out is how much do different friction plates weigh, as this is a choice that can be made without modification. If you put on a belt drive how much of that 11.5 pound clutch assembly can you kiss goodbye. (We can do the chain vs the belt easy enough.) As for the steel plates, Ludwig, I was thinking that you had proposed reducing the weight of those by enlarging the center hole on a lathe. It looks to me like there is part of the plate that doesn't come into contact with the friction plate. Is this what you mean by cutting it 5mm narrower? (Removing some of the plates and cutting a new groove is in the advanced course.)

Russ

# is the symbol for pound (of weight)

So, 10# is "shorthand" for 10 pounds.

If I ever have to retype this, I will have saved nothing by using the "#" symbol about 10 times instead of simply typing the word "pound" those same 10 times...

Sorry, thought # was universal known symbol on phones and key boards and in various shipping notation. But 10# could also be read as number ten - No. 10. ugh.
Barnett friction plates are composite on Al platters. I'm always on alert to add lightness so getting more educated following this post. In Peel's case I'm trying to figure out how to add more plates, sheeze.

FWIW Barnett plates for the 850 weigh 62 grams each. So a stack of 5 would save 540 grams! That alone is about a pound a quarter. Anybody have access to a Surflex friction plate? For that matter does anybody know who carries them? Are there other brands lurking out there?

I just got a confirmation on availability of 4 sets of Surflex friction plates for the 750; works out a bit different for the 850...

rvich said:

FWIW Barnett plates for the 850 weigh 62 grams each. So a stack of 5 would save 540 grams! That alone is about a pound a quarter. Anybody have access to a Surflex friction plate? For that matter does anybody know who carries them? Are there other brands lurking out there?

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I have some, but they are buried in the clutch. They are very light, when not soaked in oil...

http://www.oldbritts.com/ob_clutch_info.html

They are vague on which plates they have.

They do list the Solid Fibre Clutch Plate, 750 061339 so perhaps drop Ella an email to confirm? Betcha she'd also confirm the non-oiled weight...

According to their parts list they have the Barnett.

http://www.oldbritts.com/alt_063741.html

More data:

Bronze plates (5) = 1150 grams
Surflex plates (5) = 853 grams*
Barnet plates (5) = 310 grams*

*these weights reported from distributors.

From Joe Piska in NY working up a '71 modeled my Ms Peel features. I left him with my own down/dirty clutch stacking no measure method for sweetness, mix and match plates and pressure plate thickness so diaphragm spring just does slip into its groove w/o slack or force to fit. Al press plates available in various thickness or can DIY.

Grams / 28 = Ounces / 16 = pounds

1150 / 28 = 41.071 oz / 16 = 2.566 lb
853 / 28 = 30.463 oz / 16 = 1.904 lb
310/28 = 11.071 oz / 16 = .691 lb

..so a Barnett set is 431% lighter than a Bronze set?
One bronze plate is 383.33 grams or 14 oz.
barnett is 62 grams each or 2.21 oz

Big spinning inertia difference, with all that talk of crankshaft
inertia, I'd bet ( a small amount) that a spinning clutch pack has a
bit of effect on an EngineCycle.

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