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Discussion Starter #1
I am thinking that I would like to consider a girder front end on a cafe style 2 stroke single. Maybe the look of the older Brit stuff with the Villiers 2 strokes, but I would start with a Jap enduro as the basis. What does anybody know about girder front suspensions? Not springers, I hate springers.
HackA? What have you got laying around?

Ken
 

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the only thing I currently have in a girder is a 1935 Indian Sport Scout unit, it's been molested so I removed the huge stem and fitted a 1 incher to it, doubt I'll use it on the panhead it's on right now but it does look good there

funny thing is a guy had it fitted to a brit cafe bike and welded BSA axle clamp ends to make it accept a 190mm Goldie hub

the work was solid enough but ugly so I cut it all off and redrilled thru axle holes

I had been looking at these two and slept at the wheel

http://cgi.ebay.com/ebaymotors/ws/e...STRK:MEWA:IT&viewitem=&item=320228483386&rd=1

http://cgi.ebay.com/ebaymotors/ws/e...STRK:MEWA:IT&viewitem=&item=320228480175&rd=1

the old girders are cool to look at, they work ok

but one made with modern bearings which can easily be serviced by replacement

well they are nice

I've started one for a project here that is built that way, no bushing pressing/reaming/fitting required

and using a dual air chamber over hydraulic shock instead of just a spring

I do like girders and didn't snag either of the posted ones because I was busy in the shop

anyhow, I'll dig and see if I'm forgetting but some are definitely better than others

this sport scout unit is neat but like many period girders

to overhaul it...... is an expensive pita because of how it's made and how all the bushed pivoting areas work

you have to replace the studs, which are not simple hardware but actually a part

and bushings which also are not a standard bushing but actually a part

then ream or hone to fit

a rambling side note

Gambler, back when CK Spurlock owned it

made the first modern girder that used double angular contact bearings

they worked very well and economical to produce although the bearings weren't cheap
 

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Discussion Starter #3
I don't really know anything about the relative sizes of girders, but having seen pictures of some of them on the early BSA singles, they might look right on a 2 stroke single.
Any idea how rigid they are under side loads? Most of th ones I have seen seem to be triangulated nicely fore and aft for braking forces, but are only 2 dimensional for side loads. I like the looks of the ones built up from tubular stock.
Ken
 

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the original prototype of the confederate wraith used a girder with the shock and spring hidden inside the neck (actually the neck was the shock as it was fluid filled). JT is a freaking genius for designing that.
 

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you are asking the right questions to indicate your eyes are well calibrated to real world function of these forks

There have been various girder makers thru the years, and some have worked much better than others

some English makers were Brampton, Castle, Monarch (I think) and a few others

some of them were notoriously weak as far as side loads and some would break "hammer links"

that is what the English call the 4 dammits that control the up and down motion

if you look at many you can see why...... some are just plain flimsy

I think one found in the links I posted struck me as being very frail as far as the hammer links are concerned

and if they strong enough but still thin, the shear loads will be phenomenally high

then when you start looking at how they are bushed and pivoted

it becomes much easier to tell what's for real and what's weak as puppy piss

yeah the tubular girders are great and very light

the better designs are quite strong

poke about at some of the Indian girders, like the sport scout, and various girders found on many English bikes

a girder off a smaller Indian, like a 250-ish small bike

might be just what you need

stay away from the DKW-HD 165 rubber band stamped steel ones

they are kinda laughable
 

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Discussion Starter #6
well, I have ridden enough race bikes to be concerned about side deflection. But this would just be on a fun street bike. How hard would it be to just lay out a pattern and have some tubular girder legs welded up? Since I don't have a project bike yet to start with, I'll keep looking around.
Ken
 

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cake walk and really nothing much to it

My thinking is to use high grade "stripper or shoulder" bolts

good bearings precisely fit

and when a bearing wears

replace it and keep on going

the "hammer links" need to be robust enough to carry a moderate size bearing anyhow

I am thinking a 6200 series DA contact bearing should be quite adequate although the next size down (0.500" ID) is likely overkill

the 6200 series has a 0.625" bore

beats the daylights out of having to replace 8 inch studs and oilite bushings because both will wear at nearly equal rates
 
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