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M1Combat
12-25-2015, 02:40 PM
I'm thinking we can get a 3D scan of a front sprocket then get them made? Any other effort on getting sprockets made? I saw something from a while back on the facebook list but it seems nothing came of it?

Please advise.

d_adams
12-25-2015, 09:26 PM
Vortex makes the sprockets, just need to order it by part number. PN 821-xx where xx = tooth count, ie; 44 teeth.

http://www.ebay.com/itm/Vortex-821-44-Road-44-Tooth-520-Rear-Sprocket-Silver-/271787665194

M1Combat
12-26-2015, 04:31 AM
That looks suspiciously like a rear sprocket :)

d_adams
12-26-2015, 04:45 AM
Whoops, my bad. Didn't read the part about the front sprocket.

M1Combat
12-26-2015, 04:59 AM
It's ALL GOOD :).

As I understand it the front sprockets will be difficult to replace going forward? I'm assuming we'll have a non-cush alternative but IMO the best solution would be to retain the cush drive. Have I missed any efforts in that direction?

d_adams
12-26-2015, 05:00 AM
I do have a new one sitting here, but I do not have the cush parts for it. I'll see if I can find a way to get it scanned, but it may be a bit.

Doosh
12-26-2015, 08:59 AM
New front race sprocket or one for the cush drive?

I'm looking into getting a bunch of the race style front sprockets cut.

Mike
12-26-2015, 01:37 PM
M1 -

An OEM (that is, yes on the original design) version is a very good idea. Though doing the layout, design check and the first few will be expensive. Hopefully you can make them inexpensive enough (notice I didn't say "cheap" enough !) to come close to the Buell price.
If this "deal" goes the wrong way, new stock front sprockets will sell, maybe just not right away.

Mike

Doosh
12-26-2015, 02:57 PM
I'm not making stock ones. It's a terrible design with that huge cush rotating up front like that. The race sprockets are a lot lighter and there's not really a consequence to them in practical terms.

Mike
12-26-2015, 06:37 PM
Not racing, don't need a few oz. less weight. Would rather have the drive train protection.
Would still like to have the availability of an OEM style front sprocket if they (a well designed one) were to become available.

Mike

M1Combat
12-27-2015, 02:09 AM
I'd rather keep the OEM design as well. I'm not too interested in trying to produce them myself but if we can get a good 3D scan of one that's brand new we'll have something to work from later. 3D printing is coming along in LEAPS AND BOUNDS. Who knows... maybe some day we will be able to 3D print them. I understand they would be "quite a test" of 3D printing tech at this point but maybe one day.

When that day comes.... We'll need a 3D model of it :). Failing the 3D printing maturing far enough... A 3D scan would allow us to approach someone with a better idea of exactly what we need.

Doosh
12-27-2015, 06:57 AM
Not racing, don't need a few oz. less weight. Would rather have the drive train protection.

It's more like 5 lbs. That cush is ridiculously heavy.

I'm not sure what you are protecting, to be honest. I've been racing these bikes for years with direct drive and never had an issue.

M1Combat
12-27-2015, 01:38 PM
But have you ever tried to put 150K miles on one with the direct drive?

Doosh
12-27-2015, 01:51 PM
Lol, no. But have put more than 100 hours on one that way.

Its fine.

1313
12-27-2015, 09:51 PM
The only dog I have in this fight is trying to keep my 1190RX on the road as long as feasibly possible, taking into consideration the unknown of EBR - and it being unable to provide replacement parts - at the present time. Below are some data points - feel free to draw whatever conclusion you feel comfortable ending up with.

Data to support Doosh (nice username, BTW...):
Pretty sure that all of the racebikes - even up to WSBK - had the direct drive front sprocket.

Data to support 'conventional thinking':
The PVM rear wheels used on those machines had cush drive.

Has anyone ever put serious brainpower to answer why NONE of the EBR racebikes used the OE EBR rear wheel and they ALL used the PVM rear wheel?

Like I said, feel free to draw your own conclusions (as I know what mine are as I do have a complete, brand new, unused 1190RX front sprocket with all the compensating parts as a back up - just in case)...

Mike
12-27-2015, 11:48 PM
Doosh -

I've drag raced some form of car for most of my life. From 13 second to 7 second cars.
I know "exactly" what sudden shock can and DOES...to the surrounding parts.

I'll stick with the softer hit thanks..!

Mike

M1Combat
12-28-2015, 01:56 AM
So... Now that that's taken care of...

How do we solve our problem?

3D scan and machining?

3D scan and hope 3D printing matures enough for a part like that (My guess... 6-10 years maybe?).

Design a new cush that can be mated to a non-cush front sprocket?

Find a way to re-engineer the sprockets we do have to replace the sprocket section?


How about the rubber parts? How long should they last?


I'm serious here. Lets figure this out. Personally I'm leaning to the last choice... We may be able to mill the old sprocket section off and replace just that section with a conventional sprocket. I'll have to take a look at one.

Any good ME's here ;) ?

Doosh
12-28-2015, 09:09 AM
Data to support Doosh (nice username, BTW...):
Pretty sure that all of the racebikes - even up to WSBK - had the direct drive front sprocket.

Correct. And, all during the DSB era the 1125r bikes were run without cush on either end.


Data to support 'conventional thinking':
The PVM rear wheels used on those machines had cush drive.
Has anyone ever put serious brainpower to answer why NONE of the EBR racebikes used the OE EBR rear wheel and they ALL used the PVM rear wheel?

Faster/easier gearing changes.

Doosh
12-28-2015, 09:14 AM
Doosh -
I've drag raced some form of car for most of my life. From 13 second to 7 second cars.
I know "exactly" what sudden shock can and DOES...to the surrounding parts.


1. Drag racing isn't road racing.

2. The clutch has a cush built in, btw. I think a lot of guys forget that. The chain and AL rear sprocket are quite a bit different than a rigid drive linkage, too. So, that all plays in.

The OEM sprocket is large, heavy and unusual. It's going to be a hard find, and when you DO find it, it's going to be expensive compared to a conventional sprocket. It has a needle bearing in it, for goodness sake. The size of the drive spokes makes it impractical to machine one (IMHO) meaning you are looking for cast parts now. Ugh.

So, keep the cush if you like. My bike will be back on the track using the race sprocket. After literally YEARS of racing these bikes, and having done so to the point motors are simply worn out, I can tell you the top end is what needs love, not the transmission.

The ordinary guy out riding the street trying to keep his bike isn't going to suffer motor damage during the service life of the vehicle dropping the cush. Chains and sprockets will wear a bit faster, for sure, but that tranny will be fine.

M1Combat
12-28-2015, 03:30 PM
I'd prefer to find a solution to keep the cush drive. Do you have any ideas pointed in that direction Doosh?

I think most of us are smart enough to understand the benefits and drawbacks of a cush drive. You've decided you don't want one on your race bike. Fine. I've decided I want one on my street bike.

Willing to help?

Doosh
12-28-2015, 03:53 PM
Honestly, no, because the stock front sprocket is a needlessly complicated affair that's going to be expensive to manufacture compared to an ordinary front sprocket design and offer nominal advantage, even for the street rider.

Early next year I'll pull the trigger on a minimum order of 100pc of a race sprocket design that compensates for the 1190rx chain offset (vs. the 1125) and move on with those. It will be a very good solution for what you are trying to do -- keep your bikes on the road. And even after I mark them up to help pay for the carrying cost of ordering roughly 95pc more than I need, probably cost less than 1/3rd per unit what you are proposing.

The OEM piece is such a one-off design. When made in quantity, they still managed to retail for $150 a pop instead of the $20 a typical front sprocket sold for! It's going to be a real PITA to make. It's only advantage is not needing a crazy broach to cut the drive splines that's apparently unique to the 1125/1190 motor.

yamatr3
12-28-2015, 03:59 PM
On the rear wheels, the WSB's had JB Power Magtan wheels. I have not seen any pics of the PVM's. Does anyone have a pic? The Magtan's look like they have a cush set up on them.

Doosh
12-28-2015, 04:14 PM
On the rear wheels, the WSB's had JB Power Magtan wheels. I have not seen any pics of the PVM's. Does anyone have a pic? The Magtan's look like they have a cush set up on them.

This is correct to my knowledge. I believe the PVMs were used in AMA.

This one is in hero livery, but has the PVM:

https://cdn.rideapart.com/wp-content/uploads/2015/04/10313834_10152501489216782_6921987859319264683_n.j pg

M1Combat
12-28-2015, 04:16 PM
Ahhh... so you'll be selling sprockets. It all makes sense now. I was wondering why you were railing so hard against anyone trying to find a solution to keep a cush drive... Seemed really odd to me until just now.


So if you're unwilling to help find a solution to keep the cush drive (which is what this thread is about) would you mind not trying to derail the thread so you can sell non-cush sprockets? Thank you kindly.

I assure you if we don't find a solution I'll happily buy some sprockets from you... but in the mean time I'd rather try to find a way to keep it.



Soooo....


Back on topic.


I'm thinking that the idea of milling the sprocket off and adding splines that will then accept a different sprocket might be a worth approach. The issue becomes finding a sprocket that mates to a much larger spline and finding a way to secure it. I suppose adding threads and a spline might work and then secure the replacement sprocket with a nut but I don't know how much room we have to work with on the trans side of the sprocket. Doesn't look like much but I haven't actually removed the front sprocket to take a real look at the situation yet.

Obviously having a shop mill the original sprocket, cut splines and then add threads wouldn't be cheap :)... but maybe cheaper than not having a cush. Maybe...

M1Combat
12-28-2015, 04:19 PM
You say there's a cush in the clutch though??? Like an actual cush or what? Lemme go take a look...


Hmmm.... Not exactly seeing a cush drive in the clutch. At least not one that I can identify via the parts manual...


Are you just referring to the clutch allowing smooth gear shifts like clutches tend to do? Is that what you mean?

What about clutchless shifting? Wheel hop? Curb Jumping? Pot-holes?

yamatr3
12-28-2015, 05:47 PM
This is correct to my knowledge. I believe the PVMs were used in AMA.

This one is in hero livery, but has the PVM:

I just e-mailed PVM to see if you could special order a wheel. It looks like the they might have a cush too. I also texted the guy that bought Larry Pegram's race bikes to see what rear wheels he has.

Mike
12-28-2015, 09:31 PM
M1 -

Don't think you can cut splines on a modified, stock cush drive. No room for the cutter to run out without cutting into the hub itself, which you wouldn't want to do.
BUT...machining the center out of the stock cush drive, cutting splines into the I.D. of the now...just a cush drive "hub", finding a sprocket would be much easier to have machined, because you can make a "splined sleeve" of whatever diameter suits a good diameter for making off the shelf sprockets work. And done right, it should be plenty strong enough.

I'd buy into a design like that.
Original cush drive hub, a splined sleeve, and a modified off the shelf sprocket. The only problem "might" be the hardness of the off the shelf sprocket. There's always EDM (Electrical Discharge Machining) machining for hard materials..!

Mike

Doosh
12-29-2015, 08:17 AM
Ahhh... so you'll be selling sprockets. It all makes sense now. I was wondering why you were railing so hard against anyone trying to find a solution to keep a cush drive... Seemed really odd to me until just now.

Jesus, **** no. I'm not trying to sell you sprockets. I'm trying to illustrate the problem with the front-cush design.

Here's how this plays out:

If EBR comes back or liquidates, we both buy up enough sprocket inventory to last us how long we think we will keep the bike. Let's say that's 8 fronts for me, and maybe 4 for you. I'm paying $20-$30 for the race sprocket, you are paying $150 a pop for the OEM. We are both happy. For both of us, this is the best possible outcome.

If this issue lingers on, and we are both forced to paddock the bikes, now we have a choice.

I will do this order of 100pc to make it worth while for this sprocket guy to tool up to make race-style sprockets. It's a custom broach mainly, about $1200, and all the other tooling required is completely ordinary sprocket manufacturing stuff. So, I'll cough up $2,000 - $3,000 up front for this initial run, and I will resell the sprockets I don't need to racers and said sprocket company will also sell individual pieces to anyone who calls and orders. Probably around $40 a pop to buy direct from them, given the limited runs, but still, a good solution now available for EVERYONE to keep these bikes spinning wheels. Case closed.

You will chase this cush problem. First of all, you don't need some 3D scanner or anything that complicated to reverse engineer the part. It's a sprocket with a back plate and drive spokes. It's not complicated -- it's just big and expensive. To make one, find any competent machinist, hand them one, and say "make me another". Its relatively straightforward machine work.

Keep in mind, NO ONE is tooled up to make these. Everything is going to be a one-off because it's unlike any sprocket out there.

The machinist is going to have to start with, what, half-a-foot of 4-inch round for this thing? (it's not in front of me to measure). On the cush side, you have a ton of material removal work to do, so that's going to take a couple of hours. And, on the drive side it's an ordinary sprocket -- mostly. I doubt a typical sprocket grinder can deal with the integrated backplate, so you are going to be milling the teeth, which to get any durability in the part means you are probably cutting this from 4140 and then heat treating it to service hardness. There's another couple of hours.

Now, for this sprocket, you are 3-4 hours of machine time and probably $50 of raw materials in, and you still need to source that needle bearing that goes in the center of this thing!

I'll be stunned if you can get a part off the machine for less than $400. I just had some of these sprocket retaining cups turned, and 4 of them was $350 plus materials. Making parts for bikes NEVER makes out. Never. It's always better to buy mass produce, but because of the small numbers here we can't really place a big enough order to make a cast-and-machine operation worthwhile, which would be a good solution to this part. So you are looking at a material removal approach, and because it's such an oddball part you don't really get any of the advantages of it being an ordinary "sprocket" and something an ordinary machine shop is tooled up to make easily.

That's your problem.

The other proposal that's been kicked around is an ordinary sprocket that happens to have the right hole pattern to fasten the drive spokes that fit into the cush. I'm not an ME, but I would have significant concerns regarding the shear load on those fasteners, plus you still have to find a hollow-bore sprocket you can mill out to allow the drive crank to pass through.

You could, however, start with a part and machine-to-finish. For example:

http://www.mcmaster.com/#6793k171/=10g69uv

Take this thing, machine .063 off the drive teeth (ANSI50 -> 520 chain), and then machine the bore to accept drive spokes. I still think you are going to have a shear load problem and ultimately send a piece of 4013 flying into your boot, but it's a solution that won't cost as much.

Doosh
12-29-2015, 08:22 AM
I just e-mailed PVM to see if you could special order a wheel. It looks like the they might have a cush too. I also texted the guy that bought Larry Pegram's race bikes to see what rear wheels he has.

You can order a PVM with or without integrated cush. Even with a cush and in Aluminum, they are lighter than OEM wheels. I've owned one before, they are very, very, trick.

Doosh
12-29-2015, 08:29 AM
You say there's a cush in the clutch though??? Like an actual cush or what? Lemme go take a look...
Hmmm.... Not exactly seeing a cush drive in the clutch. At least not one that I can identify via the parts manual...


Part number CG2501.1B6.

Behind the clutch basket is a set of main drive springs.

M1Combat
12-29-2015, 08:25 PM
754

Are you talking about the set of springs in the middle of sub assembly 1? I don't see a part# CG2501.1B6 in my parts manual.

d_adams
12-29-2015, 08:29 PM
It's the set of springs in the middle of that pic, main section #7. There's 6 "sets" altogether.

M1Combat
12-30-2015, 12:14 AM
That makes me feel a lot better :). Maybe I'll be buying sprockets from you after all :). You wouldn't happen to have any pics of that cush drive?

Doosh
12-30-2015, 08:58 AM
Here's an exploded diagram from the RS parts manual. You can see how the sprocket doesn't get any drive from the motor, but instead the cush assembly has the drive splines and the sprocket is the driven "inverted" by those spokes on it. So, that's why this sprocket has the huge hole in the center, no drive splines, is absolutely HUGE because of the drive spokes that push into the cush, and has the idler bushing and needle bearing assembly to allow the drive shaft to pass through it.

It's ridiculously complicated. It's heavy. It's expensive. It's unnecessary.

755

mackja
12-30-2015, 09:53 AM
The front sprocket system is the same on the 1125 except for the belt pulley, the rubber cush bumpers are the same part, and a cheaper to buy. It was probably the easiest and least expensive way to design the system, being able to use existing parts keeps cost down, have not checked but I would not be surprised if the inner hub is not the same also.

M1Combat
12-30-2015, 04:06 PM
That's good to know... Would give us some more metal to work with in figuring a way to get splines for a different sprocket on there...

Doosh do you have a better pic/diagram of the cush in the clutch? By the pic I posted I'm pretty sure I'm understanding how it looks/works but I'd like more info if you have any.

Based on the design though if we were trying to get a spline and sprocket to work there's maybe not enough material between the bottom diameter and the bore diameter...

M1Combat
12-30-2015, 04:17 PM
Has anyone tried moving to the 1125 belt system?

M1Combat
12-30-2015, 04:45 PM
So to go the other way like Mike suggested...

If we could find something like 697950041346 or 697950010212 from http://www.martinsprocket.com that might do the trick? Martin was just the first place I looked. There may be better parts to base this design from on both a quality and starting part point of view.

756

We would first cut excess hub off, then spline the OD of the hub of this sprocket and bore+spline the center of the driven side of the current sprocket cush. Then bore the ID of this sprocket to the ID of the original sprocket. As far as I can tell this would also solve the issue of keeping the sprocket on the splines if they were on the other side yes?

Maybe not... What would keep the sprocket from working it's way toward the engine side? Looks like #9 in the diagram of the SX cush? That means one more cut to the sprocket.


Looking at the other side of the sprocket side of the cush though... It looks like we'd still run into available material issues.


Cost wise we would only do the machining of the driven side of the cush once, and we would order these from Martin as needed or in batches. We might even be able to get them to make a bunch and keep them in stock if we explain why we need them to and they have a soft spot :).

Doosh
12-30-2015, 04:59 PM
You are going to end up doing a lot of work to get a nominal advantage. I'm sticking by what I said earlier -- kill the cush, use an "ordinary" front sprocket.

M1Combat
12-30-2015, 06:27 PM
I understand your point of view... I'm not even sure I disagree with you exactly.

Do you have any better pics/diagrams of the cush in the clutch?

Doosh
12-30-2015, 08:40 PM
I'll get some this weekend I have mine apart

M1Combat
12-30-2015, 11:40 PM
Thanks a ton :).

yamatr3
12-31-2015, 12:43 PM
Hey Doosh, where can I get a rear PVM wheel from in the US? Ive e-mailed a few places with no response.

Doosh
12-31-2015, 05:06 PM
Special order from pvm only. Call them. They are probably on holiday. No one in Europe works this week

bairframe
01-08-2016, 06:59 PM
Just a public service announcement... I have a front and rear sprocket that I am going to be working on. I know Vortex makes the rears but I've had requests for a steel rear as well after i'm done with the front. I have the complete capability to manufacture replacements of the fronts as well as make any new design/ material improvements or cush-delete sprockets. I'm also working on an idea to retain the cush-drive and be able to swap sprocket sizes. I've been busy before the winter, otherwise it would be done by now. Feel free to ask questions or post requests.

Oh, and i'm not looking to make money on this deal - just support the cause. I also like a good project.

Doosh
01-08-2016, 07:31 PM
I can send you specs and dimensions for a proper front sprocket interchangeable between RX or 1125 applications.

bairframe
01-08-2016, 07:45 PM
Doosh - pm sent

M1Combat
01-09-2016, 02:06 AM
Just an idea I threw together the other day. Rough but just to get the idea out there. Hopefully if anyone can gain any ideas from it it might be useful. Feel free to use at will.

765

Doosh
01-09-2016, 06:55 AM
Doosh - pm sent

Check your email.

bairframe
01-13-2016, 09:07 PM
--Update on progress--
I have determined the original material of the front (4130 steel) and rear (7075 aluminum) sprockets. The front sprocket is cast which could explain the low OEM cost and the failures we've been seeing. I have a source for, what I'm hoping to be, improved material and I should start fab soon. I'm also making a prototype model for a cush-drive with changeable sprockets. I know everyone is going to be asking about cost but until I know I'm making something solid I won't be able to give that just yet.

AKA Marco
01-14-2016, 06:35 AM
Thank you bairframe, keep up the good work!

Doosh
01-15-2016, 08:33 AM
The front sprocket is cast which could explain the low OEM cost and the failures we've been seeing.

It's cast because it's a ridiculously huge piece to try and machine. You aren't going to use material removal methods of production and keep costs low. The part is just geometrically too large for that to be a successful production approach. Even the OEM part -- cast and crappy as it is -- is crazy expensive compared to the functional equivalent for any other motorcycle.

M1Combat
01-15-2016, 06:41 PM
There are other motorcycles with the functional equivalent of a cush drive in the front sprocket setup?

GJB
01-16-2016, 08:52 PM
I think my 1290 Superduke R has a cush drive in the front sprockt

M1Combat
01-17-2016, 03:23 AM
Oh really? I'll have to look into that :). Thanks for the tip.

zviadi
01-17-2016, 03:51 AM
I think my 1290 Superduke R has a cush drive in the front sprockt

Nope.
http://www.ebay.com/itm/FOR-KTM-SUPER-ADVENTURE-1290-2015-15-FRONT-SPROCKET-15-TEETH-SUNSTAR-PITCH-525-T-/121708933305?hash=item1c566af0b9:g:92MAAOSwLVZVrQr x&vxp=mtr

buell-fan
01-17-2016, 07:52 PM
Nope.
http://www.ebay.com/itm/FOR-KTM-SUPER-ADVENTURE-1290-2015-15-FRONT-SPROCKET-15-TEETH-SUNSTAR-PITCH-525-T-/121708933305?hash=item1c566af0b9:g:92MAAOSwLVZVrQr x&vxp=mtr

That manufacturer looks like it could make the sprockets these guys are wanting for a non-cush drive, interchangeable system.

darrenandrach1
05-03-2017, 02:35 AM
Just wondered how you went with the steel rear and new designed front sprocket that you were looking at at the end of last year?.

M1Combat
05-03-2017, 08:10 PM
Same here...

Elduche211
05-25-2017, 08:41 AM
Dosh any updates on the front sprocket....PM sent

Elduche211
07-06-2017, 04:24 PM
Doosh do you have the non crush alternative ? did you ever follow through your idea of producing some....I am desperate for some!
Thanks


New front race sprocket or one for the cush drive?

I'm looking into getting a bunch of the race style front sprockets cut.