theTRUTH

See cars and bikes being built for the salt

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harky
Posts: 252
Joined: Fri Feb 09, 2007 9:03 am
Location: Adelaide

Re: theTRUTH

Post by harky »

WE ALL still need trainer wheels
maybe we should call them low-speed stability wheels
that sounds and looks better
if any of these things we are planning ,fall over , it will take a crane to pick them up
Richard S weapon looked stable @ low speed , he is a very experienced operator
keep the ideas and pictures coming
it's nearly too cold to go out to the shed
harky
DLRA #643
so far 120mph for$2000---imagine how fast I can go for $20,000
russelllowe
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Re: theTRUTH

Post by russelllowe »

Hey Walkingpace,

Yes, been looking at every clutch I can find ... haven't seen a picture of a top fuel clutch from that angle before though. So are you saying the part I've circled below is a cylinder that slips over the central shaft and is splined on the end that goes into the clutch plate part? If so that's very similar to my drawing above, except I fix the plates directly to the cylinder. The reason I did mine that way is because I didn't think the center spline diameter of the clutch friction disks was larger enough ... the picture below suggests it might be.

I've just looked at it again and the central shaft seems splined ... it wouldn't need to be if it was like my drawing; I'd love to see a section drawing through this one.

(If the friction disks and sprocket were splined to the central shaft then you'd think there would have to be a bearing in between there somewhere; maybe that surface to the left of my red "circle"?)

Image

I took a look at the Quartermaster clutches yesterday too. Some look very much like the above, but with a diaphragm spring rather than the centrifugal arms. Much cheaper than the Crowerglides too ... I also like the NASCAR heritage/usage.

I found your Bike Engine Classes thread with Vinsky talking about the original TRUTH. Turns out Vinsky is John Hanson, who owned the original TRUTH in 2012. Really nice guy putting together a LSR Vincent.

Cheers
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walkingpace
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Re: theTRUTH

Post by walkingpace »

I'm not entirely certain on the identity of the piece you circled. These clutches often use a sliding sleeve to control progressive lockup so it might be to do with that....or it might not. Either way it is generally similar in concept to your drawing. There would have to be bearings in it but I've never seen one in pieces so I'd be guessing about where they are and what type are used.

You're right about the splined shafts ordinarily being too narrow to run as a sleeve outside a central shaft. The quartermaster ones and most crowerglides use various standard gearbox input shaft dimensions which wouldn't give you much room. The top fuel bike guys usually have access to some serious CNC equipment and make their own Crowerglide copies so they're all a bit different. There's even a pneumatically operated one out there. They work well but BIG dollars involved.

Have you looked at the old 'sidewinder' drag cars from the 60's? There's a few diagrams on the net showing how they ran crowerglides on a jackshaft.
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walkingpace
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Re: theTRUTH

Post by walkingpace »

Image

Theres quite a few bits missing in this pic but it seems to also point to a two piece jackshaft design. This seems to be a common thread amongst those wishing to use off the shelf clutches. The only one piece designs I've found after researching this for quite a few years are complete scratch builds, adapted motorcycle clutches, amd snowmobile drives but they are WIDE.
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walkingpace
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Re: theTRUTH

Post by walkingpace »

Found thesand drag pics. 2 piece shaft mounted on pillow blocks with an ordinary car clutch. He later changed to a crowerglide but kept the same shaft style.

Image

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Image

Image
russelllowe
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Re: theTRUTH

Post by russelllowe »

Hi Walkingpace,

Yup, found the Sidewinder drag cars after finding the Sidewinder V8 motorcycle ... the ones that use Harley clutches/gearboxes: http://www.v-8motorcycle.com/

Haven't seen that picture though, it's very cool. And yeah, does look like a two piece jack shaft design.

The sand drag pics are also very interesting (I've also not been able to find ones as good as these for jackshaft design). It looks to me that the first pic shows 3 pillow blocks with two closer together on the drive side. It suggests that there would be only one pillow block between the drive sprocket and flywheel/clutch pressure plate; putting a lot of bending moment through the pilot bearing on the end of the input shaft. It also looks like that was changed between the first pic and the last one; the flywheel and clutch pressure plate moving towards the output sprocket with another pillow block put in as well. Is that how you see it?

I guess my problem with the two piece design is keeping them aligned when you slide the whole lot back to correctly tension the primary chain. Alternatively a sprung tensioner might do the trick...

Here's another question for ya; will you be using pillow blocks (or pillow plates) for your setup ... and can you swap the bearings in them? I'm a bit concerned that they wont be up to the sustained high rpm we'll be expecting (in my case around 5500rpm, maybe more), but they are a nice solution for holding the bearings.

Cheers!
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walkingpace
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Re: theTRUTH

Post by walkingpace »

I won't be using pillow blocks. At least not the industrial type you see here. I've recently set up a furnace and associated equipment to start casting aluminium so I plan on making alloy housings to hold the bearings, as well as a small amount of oil. The idea is I can then move up to a two speed gearbox made from gears salvaged out of something else.

If that fails (because I can't make it properly) I'll be using sealed bearings (or maybe even ceramic) in simple custom housings. I also plan on spinning the jackshaft at 3/4 engine speed to lower the centrifugal load slightly with max engine revs for the current combination at 6000rpm.
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walkingpace
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Re: theTRUTH

Post by walkingpace »

I'm using a manually adjusted primary drive tensioner as well. Basically a cog on a little arm that swings on a hinge with a bolt and lock nut to adjust tension.

The jackshaft stays where it is once it's mounted.
russelllowe
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Re: theTRUTH

Post by russelllowe »

Hi Walkingpace,

Cool! The aluminium casting stuff sounds great, as does making your own gearbox. Keen to see that.

I wouldn't mind using industrial pillow blocks, or the flange type housings (plenty to choose from here: https://www.colliermiller.com.au/catego ... g-housings). But ideally I'd like to replace the standard bearing with something I know the speed rating on, or better, such as ceramic. First step is to figure out how their names relate to size I guess ...

Been learning Fusion 360 this morning. I've used Solidworks and Inventor before (inventor being a very thinly disguised version of Solidworks) and finding it very similar. I have a mate who does architectural facades who really rates Fusion 360 which is why I'm giving it a go. One of it's strengths seems to be integration with CNC and 3d Printing ... so will probably 3d Print the below next week some time. I think it should have some inbuilt pattern making tools too ... I'll let you know.

Anyway, here's my fork design so far ...

Image

The beautiful red bits are the spherical bearing/bolt at the top and the lower one is the horizontal arm that goes to the chassis at the bottom (on both sides).

Cheers
russelllowe
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Re: theTRUTH

Post by russelllowe »

Hi Everyone,

Version two of the front fork:

The main legs will be 75x50 RHS with a 3mm wall. All the plates will be 6mm thick.

I'm keen to see how the geometry adds up to a virtual steering axis ... when I do it with a pencil between my index fingers it seems like the center point (of the pencil) moves from side to side. Not a great test, so hopefully an assembly in Fusion 360 will confirm that it works as advertised.

Image

Any comments or advice much appreciated!

Cheers
russelllowe
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Re: theTRUTH

Post by russelllowe »

Another update,

In this version the fork is a little shorter at the top (so it will be lower than the top of the front tire), and the chassis is raised about 75mm with a tubular backbone (cos I have some tube that size handy). I'll also drop the motor about 75mm I think ... it'll make the chassis fab a little more convoluted and reduce my cornering angle (pretty sure I wont notice ...) but it'll lower the center of gravity, hopefully making it be more manageable at low speed.

As I write this it occurs to me that manageable at high speed should be my main concern. I don't think I'll be able to shift my weight around much in the reclining position, which means ... to be honest, I have no idea. I recon it looks better lower, so I'll go with that...

Anyway, here she is:

Image

Bones: it looks like I'll be using a modified stock single plate clutch (the motor comes with a flywheel and clutch), wouldn't want to push (excuse the pun) my luck with two rule changes in a year ...

Cheers
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BONES
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Location: Killara Sydney

Re: theTRUTH

Post by BONES »

Hey Russell
With the top pivot for the fork, I think the rod end would like it more if you screwed the shank into the main frame
and bolted the ball to the fork. Maybe a plate on top of the ball to make it in double sheer.
It could do with some triangulation from the steering head back to the chassis.

Remember Russell use the bussa :-)

cheers Bones
Hoofhearted
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Re: theTRUTH

Post by Hoofhearted »

Fascinating build idea, I was wondering why not use standard forks cut down to what you need? Front suspension is, as you already know, not necessary.
Don't cry because its over. Smile because it happened.
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walkingpace
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Re: theTRUTH

Post by walkingpace »

Hoofhearted,

I must say I was thinking the same thing. Look at the system used on the BUB streamliner. It does have suspension but is basically a very short conventional fork attached to a conventional steering head. Simple and proven. Not saying the proposed system won't work, just that there is enough wheels to reinvent on this as it is. Adopting a proven steering system just takes one out of play so you can deal with the others. It also allows the use of proven rake/trail geometry to provide stability at speed.

Just my two cents. A chassis or landspeed expert I am not. Just built a few custom bikes over the years.
russelllowe
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Re: theTRUTH

Post by russelllowe »

Hi Guys,

Bones, yup, will put a couple of diagonal 1" tubes for some lateral stability. Don't understand the difference between bolting the shank to the fork or the frame ... the spherical bearing will be in the same place ... on the bottom side between the fork and top of that strut; static gravity load will be completely in compression there.

Graham sent me the Tony Foale chassis design book which should help with figuring out the rake and trail numbers and hopefully what I should be aiming at. My previous understanding was that plenty of rake and trail will help with high speed stability but make it flop a bit at low speed. Keen to see if Mr Foale agrees with that ... I'm out of the office so progress is a bit slow!

Hoofhearted and Walkingpace, thanks for the comments
... My thinking is really driven by a desire to make it myself. But apart from that I like the idea it has a virtual steering axis (for no other reason than steering with "nothing" sounds like a cool thing to do), I recon it could be much stronger (finally a sensible reason!), and it should be lower than a conventional fork (to get a conventional fork that low I figure it would have to be tilted back so the rake would get pretty extreme), and finally ... related to the first point ... it looks pretty easy to make (and quite adjustable ... just in case things move during welding, which they have a habit of doing). I also learned what a big impact having the wheels perfectly aligned makes to going in a straight line ... my APSG1000 was fine at 140, scary at 185, and good fun spinning the back wheel at 195 after I did a wheel alignment with a piece of string robbed from my tent.

Bones, is using the bussa the same as using the force? I can buy into that!

My LS3 should arrive in a few days.

Cheers
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