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I was slightly hesitant about starting this project for a couple of reasons, I already have more projects on the go than I can remember all at once, and also because weird front ends are really ol’ Robs bailiwick. Didn’t want to step on his toes!
There was a thread on here a couple of years back where Twizz & Rob were lamenting the fact that to get noticed in the major league show circuit you had to have a HD based bike to display.
I seem to remember suggesting to Rob that he might apply some of his radical ideas to a harley. But he’s not taken up this gauntlet yet, so I thought I’d do something of the sort.
Anyway, I’m sure that Robs take on things would be very different to what I’m doing here.

Many on here will be familiar with the Hossack front end design (if not have a look here: http://www.hossack-design.co.uk/php/page.php?p=4 ) But apart from Robs versions and the Chica one (which he got a bit wrong), I’ve not seen this concept applied to a chop before.

I decided that this needs to be a low buck project too; insofar as this is possible with a harley anyway. I scored an early evo lump last summer for £800 with the heads off. I already had a spare gearbox which only owed me £200 and I gave my mate Colin £250 for a complete primary drive from an ’02 Dyna. So I guess the whole drivetrain’ll owe me about £1500 when its all back together.

I decided on jap 3-spokes for the wheels. I know they’ve been done to death, but they’re the best bang-for-the-buck you can get. A Honda pan-european 18" one will go up front and a big Kwak one will go in back.

I actually did the frame back last September. I wanted a big tube rigid with oil in frame and battery under gearbox so the area under the seat would be empty.
A hossack front end has no headstock. Instead it has 2 pivot tubes for the wisbones to -erm- pivot on.
When I made the frame jig (30 years ago!) I made the headstock cradle using long studs to hold it in alignment while it was welded up. These holes now came in handy to locate the 2 pivot tubes:



The cradle tubes are 1.625” 14g. Quite a bit of careful de-burring & cleaning out are needed for oil-in-frame. Not to mention holes for circulation & return, breather etc:



Starting to come together on jig:



Off jig & wheel in. Trying to decide on a tank here, this ones wrong:



More later.

Cool project Briz, though i am biased now of course.
What sort of tank do you have in mind?

Lovely work Briz. Will be watching with interest.

Yep, from me too......................

and me

now this I rather like...........

Just out of interest what size battery is planned fro under the gear box

interesting.....
yeh, you did suggest a harley project to me, but i couldn't interest any harley owners in the idea, even with a 'cost price' offer, and i certainly can't afford a harley myself!!
have you ever ridden a hossack before? the handling's a revelation.
even on mine, which was certainly 'form over function', i was off the edge of the front tyre first time out.

put the fuel in a belly pan. if you're gonna have a hassack front, show it off!!!

shock position might be an issue for you, you don't want it looking like a bmw paralever, (bm waited for 'ol norms patients to run out, then copied it. bastards. mind you, they could've saved themselves millions in development cost if they just talked to him). and if you cantalever the shock back onto the top tube, it'll look a bit like mine!!

this will be good...I think I have to pop in for a cuppa

Looks to be good Briz, I've got an interest in hossack front ends too so will definitely be watching this closely.

Wow like the idea of this. Looks sooo different.

How practical is it if used on a Trike.

Bearing in mind the lateral forces on the steering neck would this need to be beefed up significantly.

I'll be using a stock size softail one which is 3.5" thick. Normally there isnt enough room, but this is why I chose a dyna primary, If you examine a dyna glide, you'll see that the engine is tilted back by about 4 degrees. So if you use a dyna inner primary on a straight-up solid mount engine, it raises the gearbox about 20mm. Makes centre tube clearance a bit tight:


Its also a right pain to do as none of the dyna gearbox holes line up except the starter mounting. I had to do quite a bit of welding on the inner primary and then remachine every surface due to (minimal) distortion.



Yeah, I bet Norman Hossack is spitting bullets! If it was me, I'd be torching BMW dealerships.

Shock pretty well has to go here:

Only other place is in the conventional girder position, but I dont want it to look like its just got a set of girders on it.
Wouldn't be room underneath now for a belly pan. I liked the look of a fatbob from the side but its too fat from the top.
So I thought I'd revive the 'Axed' fatbob, which is cutting & narrowing a pair into one.
All the 'bobs on ebay have been stupid money recently, but I grabbed a pair at the swapmeet for £45.
Wasn't a bargain - when I cut them apart, they turned out to be the most buggered pair I'd ever seen. Under the filler, whole chunks had been badly welded over with new bits of plate:

I was tempted to bin 'em. But didn't. Cut out the bodgery & formed up a new bit & hammer-welded it in. Then tig-ed the 2 halves together:



Should be well suited to trike applications; I'm using car balljoints ('59 Fairlane) in the wishbones which are obviously intended for sideloads. You can also greatly increase rigidity of the frontend by making the wishbone pivot points further apart. This is obviously limited by front-end length.

bloody hell Briz....you never do owt the easy way do ya

Thanks for the Reply Briz.

I thought it would be ok. As you say it is effectively a car double wishbone but at first sight it just looks a tad weak with the steering pivot so far out in the Hossack Graphics.

I know it's just a visual thing but when your not used to seeing it (on BMW's most of it's covered) it just looks kinda odd.

Love it though. The bike I'm sure is going to be a stunner and look forward to seeing it in the flesh.


I know what you mean about the tank prices.... Jeez they are stuoid money. I bought a Guzzi California Tank for £80 cos the the harley stuff was way over they odds but all parts seem overpriced. Ie £250 for a 20 odd year old pair of fork legs

Cool build. Alway liked the idea of a Hossack front end (maybe one day)

Petrol Tank looks familiar.

Going to be watching this one , love the work Briz

cool, this will be a very interesting build, i shall watch carefully never seen a hossack front end before but they look quite clever and tunable... will watch carefully

When I get a frame job finished on a friday afternoon, I can then easily justify spending saturday messing with my own stuff. Which is what happened last friday.
Thought I'd do the bottom wishbone. A steel bench is a great universal jig:


Balljoint is leftover from a kit for a '59 Ranchero which I had back in '92. Not absolutely ideal, but chunky & costs me nowt.

Mocked up on the frame. Fork clearance might be a bit tight - may have to alter it. We'll see. Not decided on the fork design yet anyway.

I know, you're gonna ask "whats with the spacers between the wishbone and the frame, Briz?"
If I say 'handlebars', you'll be able to figure out what I've got in mind, right?

Rear brake setup; some japanese 4-pot that cost me a tenner and a disc from a ZX10 on a carrier that I made 7 years ago & didn't use. Note the non-billet calpier bracket:

noted

yep.

what ratio is your suspension leverage?

Its 1.875:1 (7.5" long wishbone, 4" shock arm) I reckon I'll need about a 500 lb spring on the shock which will have 3" travel giving about 5.5" wheel movement.
I KNEW you'd be the first to get the handlebar thing.

i think i remember norm wrote that he used 1.15:1 after trying many variants, but he was on a track.

Worth remembering that when ol' Norm was figuring all this out, he didn't enjoy the huge range of available shocks & springs that we have today. Probably didn't want to be specifying a shock that would have to be made for the job, so went with a ratio that suited what was obtainable back in the late '70s.
At the end of the day, the leverage ratio isn't important, as long as the end result has the rate & travel needed.
Except (and this would be important to Norm), parts that dont have to handle heavy spring rates can be made a fair bit lighter.

As i am a self confessed fuck-wit can someone clue me in on the bars, ta

My 'guess' (in that it is what I would be doing with the layout) is that the spacers lie where the bars pivot. So they won't so much turn as push backwards and forwards. Not at the same time of course - elf tried that and the bike was described as pretty much unridable! Drag links go forward to tie bars on the steering. Relationship between the width between the drag links at the bars and at the steered part mean that you can 'gear-up' the steering by changing the leverage.
Easier to draw than to describe. For me at least.

Anywhere close, Briz?

Yep; you got it Myles. Push-me-pull-yous.
Tony Foale sez its easy to get used to. We'll see!
The alternatives are to have a mini-headstock for the bars to turn on and connect them to the forks with a kind of pantograph link which takes care of suspension movement. Works well - its what Rob, BMW and Norm himself did. But its a bit cluttered for my liking.
The last way (in both senses!) is to have the bars on the forks and have them bounce up & down with the suspension. Its what Chica did. Its not for me! Hands & wrists are buggered enough as it is.