Hossackviffer Mkii

[redmarque]

Progress...more tubes! Strangly simular to the last pic but with a theme of grey and rust.

I will need to re-cut and profile the rear ones for a better fit, but otherwise coming together. :biggrin:

btw. 4130 tube works out at $45 per metre. What i bought was shipped from the US so could be cheaper for you!

[SEBSPEED]

Great stuff Red! I'd be interested in knowing what the frame weighs by itself once it's finished. :warranty:

[redmarque]

Thanks Seb!

I've calulated the weight of main frame with both stearing subframe and rear subframe in 4130 1.5mm tube at 7.3kg.

I'd planned on the rear subframe to be made from 6061 T6 ali tube so 'should' be a bit lighter than that still. Forks are currently 3.5kg but with the front arms and part of the shock weight to add to that, maybe another 2kg. Apparently one cbr1000rr 06 fork leg weighs 3.35kg (7.4 lbs) an ohlins one is heavier at 8.4lbs.

[SEBSPEED]

Thanks Seb!

I've calulated the weight of main frame with both stearing subframe and rear subframe in 4130 1.5mm tube at 7.3kg.

I'd planned on the rear subframe to be made from 6061 T6 ali tube so 'should' be a bit lighter than that still. Forks are currently 3.5kg but with the front arms and part of the shock weight to add to that, maybe another 2kg. Apparently one cbr1000rr 06 fork leg weighs 3.35kg (7.4 lbs) an ohlins one is heavier at 8.4lbs.

Does the calculation include the weight of material added by welding?

And do you know what the stock frame weighs?

[redmarque]

Seb, that doesn't include rod used in welding.

Had to search the forum: Stock 5th Gen frame weighs 7.6 kg without lower bearing race.(thanks tok tokkie)

[redmarque]

Update time!

After re-checking dimensions: the frame is nearly ready to be fully welded. The front and rear shock mount tubes need to be bored though on the mill. cleaned the tube ends with scotchbright and acetone to de-grease.

I've bought a 5 spoke 2005+ R6/R1 front wheel and axle plus 320mm Galfer Wavy discs to fit. This has ment re-designing the forks for the correct offset and new disc diameter.

Next job building the fork jig/fixture.

[magicman]

Now that's just fantastic.

[dutchinterceptor]

Well how cool is that! :cool:

What the Whyte PRST 4? yeah I want one! You can't pedal standing up (honk) very well but they 'float' over anything rough x-country. have a look at the new whyte bike's rear quad-link/tara swingarm works. Whyte was a ex-F1 benetton suspension designer. Done rear's for Marin bikes too. :laugh:

Friend of mine has one. I've had to service it a few times which meant riding it. There is no comparison to a conventional forked mtb. As you mentioned it does "float" over the rough stuff and it's still as light if not lighter than the standard design.

[magicman]

Well how cool is that! :cool:

What the Whyte PRST 4? yeah I want one! You can't pedal standing up (honk) very well but they 'float' over anything rough x-country. have a look at the new whyte bike's rear quad-link/tara swingarm works. Whyte was a ex-F1 benetton suspension designer. Done rear's for Marin bikes too. :laugh:

That totally just reminded me of that Turbo Encabulator video...

[redmarque]

That totally just reminded me of that Turbo Encabulator video...

Thanks for the complement Magicman!

Ah the turbo encabulator...classic technogobble.

http://en.wikipedia.org/wiki/Turboencabulator

[eviloppressor]

Nice. What are you going to do for steering links? IIRC, they are the most, uh, entertaining part of doing a Hossack (unless you're doing parallel, equal length links, and where's the challenge in that?).

With equal length wishbones, steering links can be really simple as long as the steering arm is parallel to the wishbones and the steering axis intersects the wishbone axes. For example, see this (non-Hossack) FFE -- two ball joints.

[redmarque]

Nice. What are you going to do for steering links? IIRC, they are the most, uh, entertaining part of doing a Hossack (unless you're doing parallel, equal length links, and where's the challenge in that?).

With equal length wishbones, steering links can be really simple as long as the steering arm is parallel to the wishbones and the steering axis intersects the wishbone axes. For example, see this (non-Hossack) FFE -- two ball joints.

James Parkers FFE Has an interesting linkage setup. Here's an article from the UK 'BIKE' Magazine from last year. He uses a telescopic tube to connect the upper wishbone to handlebars

www.redmarque.com/gsxrradd.zip (6MB 5 pages)

The Journo's comments about 'front end feel' are encouraging. Part of why I believe that FFE's haven't been accepted in racing is this 'lack of feel' of what the tyre is doing or hopefully a more realistic view the un familiar feel compared to telescopic forks.

[2fast2young]

The article you posted explains the advantages of other types of front ends really well. I think that allowing prototype chassis w/ production motors at the GP level will do heaps for getting something other than forks onto motorcycles. As my Mech Engineering friend says "Telescoping forks are just an accident of history."

That being said, I'm waiting for the RedMarque 5th Gen Hossack Kit :D Have you allowed room in your frame design for a Torocharger? :laughing6-hehe:

[redmarque]

What's interesting about James Parker's new FFE design mentioned in the article is the No 1 local club racer could brake deeper into the corners than on his race bike even though he's used to Telescopic forks! Maybe we'll see something in the Moto2 class at some point??

As to hossackviffer frame kits and torochargers we will have to see.... Its early days whether the design will 'handle' yet. but if it goes well then it's a possibility. :biggrin:

[eviloppressor]

Redmarque, I sent Norman Hossack a link to this thread and the old Mk I thread.

He replied attaching this powerpoint file, in which you may be interested:

http://www.bikeme.tv/hossack-2009-report.ppt

[Guest vfrrider]

I'd take that K bike anytime, one of my favorites.

Ride on Norm! :biggrin:

Larry

VFRrider

[redmarque]

That's great! show's his design stands the test of time. Amazing how light/stiff the fork is too.

[Guest heng47]

Hi, I'm also doing a hossack conversion on a firestorm right now and have read both of your threads in interest. How did you decide what shock to use for the front?

I'm not sure what's a good way to pick and am thinking of just using the same shock as in the rear.

[redmarque]

Hi, I'm also doing a hossack conversion on a firestorm right now and have read both of your threads in interest. How did you decide what shock to use for the front?

I'm not sure what's a good way to pick and am thinking of just using the same shock as in the rear.

The advice I’d give is to pick a rear shock that acts in the same way as you plan to implement.

I.e. direct attached to the swingarm or using some type if rising rate linkage

Another consideration would be the suspension travel of your hossack fork, choosing a rear shock that has the required travel i.e cbr954 as I’m using has 63mm of travel and the fork moves 120mm.

If you haven’t yet bought it Tony Foale’s FFE software is invaluable in calculating the detail for this aswell as the path and anti-dive information. http://www.tonyfoale.com/

I’ve picked the cbr954 shock because of it’s short overall length. This helps with packaging, so that the shock top mounting doesn’t have to be so high.

Apart from the BMW duolever, shocks aren’t specifically designed for hossack use: you will probably have to get any shock you purchase re-sprung and re-valved to suit the weight and damping required.

I’ve planned on using the stock shock as a template for a Nitron one that’s going to be specifically made and setup by PDQ in the UK ( The owner Larry Web worked with Norman Hossack when he did the original Hossack road conversions)

Here’s a link to shock overall lengths and travel for various bikes

http://www.vfrdiscussion.com/forum/index.php/topic/53111-honda-kawasaki-yamaha-and-suzuki-shock-lengths/

Also remember that shocks have bump stops which you’ll want to hit before the fork touches any steering linkage.

Hope this helps. Red

PS Do you have any pictures or design sketches of your project you could post? It’s always good to see how someone else looks at the design!

[Guest heng47]

Wow, that was alot of info, thanks! Definitely a great help.

The bump stops you mentioned, are they similar to steering stops?

Basically something to stop the forks from moving if the shock bottoms out?

Speaking of that, where did you place your steering stops, on the upper tripple or in the forks?

I was thinking of putting them in the forks, figured that would be safer if it somehow started to tankslap.

The weight and damping required, will Tony Foale's software produce those figures too?

I've seen his website before but had always found it confusing. The information's all over the place. Informative but disorganised.

I'll probably use some CBR shock both front and back as the stock firestorm shock is just made of rubber. Probably with linkages too for a more compact packaging.

I'm still kind of muddling my way through things now, haven't had too much stuff figured out yet. I am planning to get some sketches out next week as I'm tied with other stuff at the moment. Need to work out some rough dimensions too.

BTW, how did you get the dimensions for the motor in your model?

Did you download it somewhere or did you make it yourself?

I'll be pulling apart the firestorm this weekend to make some measurements for the mounts and will also use this opportunity to measure the engine and mock up a quick model in Google's sketch up.

Edited June 17, 2010 by heng47

[redmarque]

The bump stop in a shock is a hard rubber ring that is fitted around the shaft. At the end of stroke it takes the final impact once all the travel is used up. My point was to make sure that when the forks move up the bump stop is hit first not the fork hitting steering linkage!

In Tony Foales FFE software you can add in the weight on front and rear, but you'll have to guess what they are until the finished/complete bike can go on the scales. You'll also have to add the weight of the rider! Once these final weights are set the shock's springs/damping can be altered to suit. hence why i'm getting someone else who knows what the're doing to change this for me. both front and rear sag will need to be measured and possibly ride height front rear will need adjustment too.

As to the engine model - i spent many a fine hour measuring and re-measuring the motor and all parts before designing the frame. getting everything to fit together correctly is No1 priority! leant the hard way on Mk1

[Guest heng47]

Hey red, did you calculate the torque values for the various mounting bolts on your Mk.I frame?

If so, how did you do it?

[redmarque]

Bolt torque really depends on application

For engine bolts, shock mounts and linkages use the service manual values for whichever model the parts are from.

I'd recommend using loctite high or medium strength and put nylock nuts on everything else that might vibrate loose!

Red

[SEBSPEED]

Bolt torque really depends on application

For engine bolts, shock mounts and linkages use the service manual values for whichever model the parts are from.

I'd recommend using loctite high or medium strength and put nylock nuts on everything else that might vibrate loose!

Red

Honda actually had a torque value chart based on bolt & thread size in most of the earlier shop manuals. Nowadays they've incorporated them into the operation text at each step... I believe the 3rd & 4th gen manual has the chart - and it's available for download here if you want to check it out!

Should give a nice head start, but use discretion based on the material you are torquing into(like a big bolt into aluminum, for ex...)

[redmarque]

Small update! :491:

Here's the 10g 6061 T6 subframe ready to be welded. battery and ECU will hang inside here.

Lower suspension arm sitting in it's fixture. Currently not happy with the join beween the bearing holder turned part and main tubes. Needs to be stronger as will take entire front end load under braking. :scratches head: emoticon