Modern Vespa

If you are running these, how did you do it? I think these can work in both 7 spring and Cosa clutches - there's some good info on YouTube. I just ordered some of these after helping Falcon modify a set for his stock Cosa basket.



He also has the complete BGM version w/ wider slots that can accept unmodified corks. We will have a chance to compare homemade to the overall heavier BGM setup. If you've got the BGM, how's that working for you?



Gaging the width.

I've got my sweaty mitts on a cossa clutch (nearly) and i've a set of cr plates in my basement...... dun dun dun dun. and i'm diggin' the tree stump work bench.

I am running the BGM Superstrong with the CR plates, 10 stiffer springs and an MRP clutch arm and I am really happy with it. I previously had a reinforced 7 spring clutch, with 4 plates and reinforced springs / cir-clip. Unfortunately it couldn't manage the torque of my setup (Malossi 221) and I had a lot of dragging and jumping. BGM has changed the basket in the latest revision. I believe they shaved a bit of weight. It now has some kind of triangles all around the outside of the basket...

So the results are in after a good 40 mi jaunt around town. I have the new cr 80 clutch plates in a stock cosa basket with bgm springs and steels. THe fourth plate of the cr plates you have to shave of the cork on one side and then sand it flush, to get your last plate in and have it fit correct with the circlip. We decided it was best to grind the plates all of one one side of the tab - if u are looking at a slot facing you on the clutch basket we figured from observation and reasoning that the left face took the brunt of the clutch foces so we grinded the right side. I put a dot of marker on the side of each clutch plate to keep track, after i did that i still had to dress the other side with a hand file to get the angle correct for a smooth fit.

Voo doo was instrumental i should add in all this figuring ,,,!!! suprised ...? heheheh

So to say the least this is a great mod. The upgrade in my LML cases with this cosa clutch - bgm springs - bgm plates - and cr corks i fashioned to fit is really smooth and works like a charm ! When I did this mod I also added the 22 tooth clutch gear cog and with my stock LML gearing its awesome . I am running a Malossi 166 btw. people get your dremels out the next time you have to do your clutch and give this a whirl!

Glad it worked out well for you!

I'm using this basket, so don't need to resize the tabs.
http://www.mp-maschinen.com/omgshop/ersatzteile/kupplung/926/kupplungskorb-px200-fuer-hondabelaege


I'm using stock springs. It works fine.

The disappointing thing is about a great clutch is it just works... not like a great cylinder or great exhaust.

What I am looking forward to however, is not replacing beat-up plates all the time.

What is the advantage to these plates?

John, I think that's the key question and why the thread. We are finding out a few things already and will hopefully will learn more. So far I believe they'll handle more power and perhaps last longer as well as maybe being a tad lighter.

I am interested in BOTH 7 spring and Cosa conversions as many ppl don't have a Cosa or want to buy a new one if they have a good 7 spring. The Cosa is already a better piece, but how much improvement will it get and what might we see in a converted 7 spring? The old 7 spring won't pull any easier but will it clutch 'better'?

I see that you are in for a clutch job on your project. How about trying the CR80 plates in your 7 spring and reporting how it compares to stock? They are a cheap upgrade you can easily change if you don't like. I found eBay the only easy source, but lot's of choices. This one appealed to me with the heavier full corks like BGM, good price for 5 instead of only 4 and seems a good shop w/ hi rating although it's in England & shipping will take longer: http://www.ebay.com/itm/New-Clutch-Plates-for-Honda-CR-80-Set-of-5-Plates-1984-2004-/351771949394?_trksid=p2385738.m2548.l4275 . It's where I got the pic at the top of the page, compare the corks w/ Falcon's. These are like BGM's and only 15 bucks.

I got a lot from FreakMoped's videos, here's one for those thinking about trying this on a 7 spring. He has widened the slots here, but I believe trimming the tabs* is far easier and makes sense for ppl w/o machine shop access:
*there must be a hundred ways to approach this, I am looking for the easiest and most accurate ghetto approach. I am thinking now of finding a way that will reliably locate from a stop against the back side of the tab repeatably, and indexing on the ID. Set the stop right & you have the dimension you want every time.

Interesting, but I've already bought my plates, so I will await your discoveries.

It seems to work amazing - I would suggest anyone with a LML or similar engine go with the cosa / cr80 upgrade and use 22 TOOTH gear cog if kitted- this was one of the best mods I have ever done .My scoot is running like a dream! The power band is shifted a bit but I can now cruise 60 ish with hardly any effort and that is nice! The clutch is smooth like buttah!

Edit - I guess really tho time will tell. Make sure to get the plate style that Voodoo shows if you do this . I ended up with some knock offs that donts seem as well made (they are working fine after a good 40 mile trip ). Look carefully at pics of product before you purchase ...

But what is the fundamental advantage? More surface area of cork? More plates in the same height? I'm just asking how it is better, and not saying it isn't.

I don't really know other than the cork is concentrated to the outer perimeter where it can transmit the most torque and that the materials may be more technically 'modern' like any hi end replacement Vespa corks. The tabs are fatter and they're aluminum, so they won't hammer the basket like steel tabs would - will be interesting to see how aluminum tabs hold up in the long run but Honda obviously likes them.

Keep in mind that a bad cush will likely hammer ANY tabs and also that it's important to get the new width as close as possible while avoiding dragging because the less backlash you have tab to slot, the less room there is for the tab to accelerate, then hammer the slot edge when you get on or off the gas. That make sense?

I have PM'd FreakMoped and asked him to spill his guts here, he seems to know a lot about this modification and his advice & vids was one of the incentives for doing this. Doing it for science to answer YOUR question, it's kinda fun, Falcon is over the moon and it's dead cheap! Then I can tell you what we did & what happened and not just what I read on the internet.

There is actually less surface area! They are definitely lighter, being based on aluminum rather than steel. Not entirely sure if that's an advantage? They are cheap for a good quality product, as well as having all sorts of options of friction materials. Pretty much the same design is used in a number of models, some of course which transmit over 100hp.
The big deal as I see it is that the tabs are much thicker... you know how you pull out your clutch and the sides of the tabs are literally hammered? Well hopefully these will address that issue, as well as being gentler on the basket as there is greater contact area.

That's what I was thinking - less surface area is what it looks like and that doesn't seem to be a win. The tab durability is for sure a positive, especially if you are putting out big torque, but I wonder if it outweighs the loss of surface area.

So 5 of those Honda CB corks fit in place of the 3 in a stock P clutch?
And there's less total surface area?
You sure?

No only 3 fit in a 7 spring, 4 in a Cosa. But as Terry just pointed out to me, the smaller area means that the pressure per square mm is greater.

That might be true, but if you cut the surface area in 1/2 again, the pressure per square millimeter will double, but I wouldn't expect your holding force to.

In the end, what makes a clutch work is friction, and spreading that over more area with more force is the typical approach. Thus, the temptation always to squeeze in one more plate and up the spring rate in most performance clutches. The limits are that the steels get too thin when you fit the extra cork plate and thus get beat up, and the springs get too thick and bind up, leaving you with clutch drag.

Thanks Ginch, I counted 5 and was wondering how they all squeezed in there

Last edited by SoCalGuy on Fri, 02 Jun 2017 03:20:25 +0000; edited 1 time

I'm still using the same number of plates and original steels and springs.

Look, it's cheap to do and the plates can handle more power that we'll ever see (even considering we're using less plates), so why not? My friend's 4 plate Cosa above had the sides of the basket openings chewed out so was scrap metal. For not much money and a bit of grinding he has a better clutch.

Well that alone might make it worth doing - longer service life. So realize I'm not down on your project, I'm just wondering what's better, what's the same, and what you might be giving up. I'm an engineer, I like this stuff.

Ginch, you know anybody running these in a stock 7 spring clutch? Or links for more info? Does your custom basket 7 spring 'feel' any different?

i think the big advantages are lighter weight and fatter tabs to hit the basket. Also as was pointed out these same corks are used in engines that greatly exceed our power outputs so I am assuming they are more bulletproof - time will tell. So far I can say i don't feel any slippage and I am quite happy.

hi mates
Vodoo called
Where do u need help?

I am.using teninch (former ddog) cnc baskets for 11y now
From the very first version on. (somewhere in a video there is the history of these basket, at the end) in many dozens engines. All fine, never had a prob

With honda linings there are 2 options:
1) uses cnc machined or adjust it by yourself (just fid it yesterday for cosa with ring) In the normal basket no matter if cnc or original
(px7 spring, cosa 8 spring)
2) buy a basket for honda linings
Teninch, bgm, lth (=mmw="bgm")

1) is kind of.more charming as u can use the existing basket aaand the diameter doesnt get soo big. The space is limited

There is quite some work to do that a bgm.cr clutch
Fits and works, see here:
In general
2 advantages if honda linings:
1) no damaged flaps anymore
2) way smoother engaging of the clutch
Original: rough gravel.road in the forrest
Honda: hughway with

Once felt and driven, no way back
All! My engines i service and tune get honda plates
Its state of the art.

There is a tgird one!
3) u avoid those dry running linings that pop up from.time to time
(guess wrong glue so they get oilresistant)

Ps. Bgm superstrong is not superstrong currently
But on its way. Honda linigs was a VERY important change
(unbelievable using thr orignal 50ies kids linings for a strenghtened clutch... Common sense? Missing.)

The bad toothing of the inner part with the metal.plates
Is still an issur. Even oiginal 125 and 200.engines do damage
The toothing after some km's

Hey FM, thanks for the scoop.

I was discussing this stuff w/ my pal Doc and we were debating the advantages of opening the slots in the basket vs trimming the tabs. Modifying the basket would be harder to do accurately w/o a machine shop, but would allow you to use stock CR80 disks. But d oing the tabs accurately should be easier, you only risk ~3 bucks if you screw one up and you can use any Vespa corks if you want or need to go back.

And we thought of another issue. Does anybody know if the slot edges are hardened or have a way to measure hardness? If they are, I'd be wary of opening the slots.But d

Exactly for that reason i wouldn touch the basket..

Btw
Hardened teninch px 7spring groundplates announced
With own german bearing but hardened surface.where it sits
The pinasco clutchbslider damages the groundplates within a few 100 km's

And a very very special brandnew clutch no one ever thougt of

Thanks for the insight freakmoped and Voodoo.

Brownie's got a 7-spring and is due for a clutch overhaul. I'm willing to give the Honda plates a go and see how they do.

I am here to learn and this bargain clutch upgrade is a perfect example. It was Ginch that first told me that ppl were doing this and got me curious. I am discovering new info as we go. Here's the latest and something else to think about when wondering why they work so well for big Honda power. Divot pattern in the steels:


So John, you are doing a 7 spring rebuild right now... Maybe you could send me your old steels?

Funny thing is I am replacing that piece because of the pock marks. I was thinking about those yesterday in that the pock marks will retain some oil. I couldn't decide if that was a plus or a minus, though. And here you go showing me someone doing it intentionally! I've definitely heard of the same approach being done in 2 stroke honing to help with ring wear, but not in a clutch before. Hmm!

Once my clutch is up and running I might be able to donate the steels to the cause. Are you thinking to create the divot pattern on them?

friction is a funny thing, where the area of the contact patch falls out of the equations and does not have any effect on the force. It does factor into the rate of wear, but if they don't slip then that's not a big issue.

by reducing the size of the pad at the inner edge you remove the part that has the least torque and concentrate the pressure to the outside where the clutch has the most torque.

The three things that make a difference in the holding capability of a clutch (not counting springs or material) are:
1. the average radius of the plates
2. the number of plates
3. the primary gear ratio (N/A for large frames as it's on the crank)

There are two advantages the CR plate offers: better lasting friction material and being softer material than the basket, tabs won't create grooves and, subsequently, jerky plate movement.

The only way CR plates can match hold of plates that are twice its width is by using much stiffer springs or more springs. There is no other way around less surface area.

Example, Yamaha RD250/350/400, R5, DS7 use rubber dampening rings on the inside of friction plate (around the clutch hub). On my tuned DS7 I was getting slippage and only way around that was to install stiffer Barnett springs, but with that came unwanted wrist strain. I then noticed that Yamaha FZR1000 clutch doesn't use rubber dampener rings thereby making those plates wider. So I threw away the dampening rings, installed the wider FZR plates and didn't have to use stiffer springs, while gaining better hold on plates and rectifying slippage.

The Honda CR clutch uses 8 friction plates. That's how you get hold with narrow plates.

oopsclunkthud, regarding primary gear ratio, in the case of large frame the number is 1:1

yup, started to write it that way but thought it would be confusing.

oh, just going to leave this here

if I was good at hyperlinking I'd leave one too where it states that maximum pressure occurs at inner radius, so in my real life example, and not internet musing, the increased hold occurred because I changed inner radius area.

when talking about the vespa clutch we can wax and link all we want but the CR plate halves the size of an existing design! talking about theoretical design is fine, but how is it not obvious that the narrow plate, designed for an 8 plate and not 3 or 4 plate clutch, is not a good alternative?

few plates = wide lining. many plates = narrow lining.

Yup, all good points. And again, why I started this thread is to find out. Shouldn't work so well but it does according to everybody that's using them, kinda like how bumblebees fly I guess. Would BGM use them if the physics are wrong and this is all hype?

You mention a link where "it states that maximum pressure occurs at inner radius", but it seems the pressure should theoretically be the same everywhere unless something is slightly conical, but now I'm curious. Can you copy & paste the link?

I think it has to do with friction material, surface area(3000 sq mm CR vs 4665 or about 1/3 higher for Vespa), pressure(about 1/3 higher psi w/ CR), so those just offset, and also how far from center on average this all takes place(CR wins hands down w/ 100.5mm avg diameter vs 90mm).

Also with the stock Vespa corks and the large uninterrupted areas of contact on shiny steels at lower pressure, it just seems like it might be easier to get them to start sliding with the oil having to travel further to 'escape' after you've released the lever.

Hmm. The only thing I could find that refers to the difference between narrower vs. wider friction material -

http://www.raybestospowertrain.com/techtip-tech-tip-mean-effective-radius.aspx

regarding inner radius.

http://www.tech.plymouth.ac.uk/sme/desnotes/desclut.htm

this discussion thread is using a lot of terms and i don't think we are all on the same page, really. radius, diameter, torque, hold, pressure etc..

i'll admit i never gave clutches this much thought but since i'm curious i started to. and what i found that there is no consensus on whether clutches wear evenly or unevenly and there are different formulas for each. i've spent years using different two stroke simulators and calculators and most of that is based on assumptions. as one famous tuner (designer of Aprilias gp125 engine) said, how many races did Gordon Blair win with his machines? And all the computations in commercial software was based on his wining-less engines.

why would BGM use this clutch? because it's something different to try and to sell, would be my guess? but BGM would not be first to sell hype. motorcycle world is full of hype products. and why does it work? probably because most vespas make so little power that it doesn't matter. cork has lousy friction coefficient when oily and material used on CR plates is better so the smaller plate area is offset by its better friction.

like I said, larger plates, like on vespas, are designed for clutches with few plates. and smaller plates are designed for clutches with 6-8 plate systems.

this conversion seems more suitable for the cosa because you can use at least 4 plates but on stock 3 plate clutches? no way.

i gave an example of how bigger FZR plates worked to fix clutch slippage in my DS7. that's a tangible result, not academic armchair speculation. there was a discussion here on suitability and I gave my input. i'm not discouraging anyone from spending money.

As a matter of fact, Ray McCullough won quite a few Ulster GP races on Blair-designed 250cc engines. Just sayin.

Winning a few races proves what? Nicky Hayden won a GP championship with only 2 first finishes to Valention's 5 that same season. So did that make him the best that year or was it a very strange anomaly?

So the QUB engine won a few races... hahah, big deal. Overall Blair's design didn't win a singe GP championship or anything significant.

I am about 200 miles in now . It is a cosa clutch with BGM springs. I am not a technically minded person per se so I wont bother with all that. But in seat of the pants riding it feels great. Very smooth gear changes and need hardly any pressure on the lever to pull it - at first after the malossi 7 spring 4 plate set up i wasn't sure it was engaging lol - that was extremely stiff ! And i fucked those corks in a few thousand miles - the edge of the plates are so thin that 3 of 4 were badly deformed and probably going to fail soon.

Voodoo is going to build a 7 spring clutch set up soon so we will see if that works as well. I am going to rebuild the engine I put this clutch in at some point this year so then we can see how it held up - albeit the cr plated i used I think were inferior repops so the OG ones would be even better I presume.

I personally think this is promising~~~ check it out ...

I will!