Leading link forks

[hagon_84]

I need to build a leading Link front end for my dirt track sidecar project I'm starting before I do I was wondering if anyone on here has any expert advice on the way to go about it? Basically what would be the best to use bearings or bushes on the bail pivot point and should I make it adjustable trail through axle slots in square bail tube or keep it round bail tube fixed axle with adjustment on the pivot point?
Al.

[Michael Moore]

Al, I recommend you get a copy of Tony Foale's FFE (funny front end) software

www.tonyfoale.com

You can model LLFs in it (and I've been doing so the past couple of days for some 7" travel solo forks) and it will let you work out the geometry, suspension and dive/antidive characteristics.

There are also photos of various LLFs (mostly not outfits though) on the graphics pages of my website, and reviewing those may be of some use to you.

http://www.eurospares.com/newadd.htm

and go on to the next two pages via the links.

If you look in this folder:

http://www.eurospares.com/graphics/chassis/

you can find patent documents for Ribi and some others that may be of use to you.

I've seen both types of trail adjustments.  The moveable axle will have a bit more effect on unsprung weight but may well be easier to do.  Sliding blocks in rectangular tube like on some rear swing arms would be easy to build and pretty stiff if you use 1" x 1.75" or 1" x 2" tube.  Remember that an outfit puts a lot of side load on the wheel attachments so I'd recommend something more than flat axle plates like a Hodaka.    You want to be able to clamp up the axle nice and solid.

I just uploaded this so I don't have it linked from the website yet so here's a picture of Vic Willoughby looking at the Reynolds fork on Bill Boddice's outfit.  Note the adjustment at the link pivot:



Here's a nice LLF done by Kelvin Blair for a track outfit.  Note how it uses rubber springing:



Either sealed rolling element bearings or bushings can work at the link pivot.  The bushings are more "dirt proof" and can be more compact.  Taper roller bearings, angular contact ball bearings or standard deep groove ball bearings should all be fine too -- the important thing is to do a good design job for whichever one you will use.

I'll have to try and get around to making an FFE page for my website to pull all the scattered links together in one spot.  Maybe soon . . . . .

Please post a photo of what you build when it is done.

cheers,
Michael

[VMX247]

Hagon 84 on third page of Britush Marque topics are pages on "Ribi Forks" hope that can help you out.
Cheers

http://forum.ozvmx.com/index.php?topic=17623.0

[firko]

I've got a pair of these Swenco leading link forks made for a DT1 Yamaha. I eventually hope to find the time to fit them to my DT1 dungracer.
                                                                                 

[davidmc]

The Forks of Kelvi Blair are made by Paul Pinfold, worked for Rob North.
They are Speedway set up, different spec required for Dirt Track.
Paul can make as required.

[Mike52]

This one has rubber bushes like PE swing arm .

[Michael Moore]

. . . made by Paul Pinfold,

Thanks, I must have misunderstood Kelvin when he sent the photo to me many years ago.

cheers,
Michael

[hagon_84]

Thanks for the info I'll go thru all of it be for I start building them so I make sure I've made the right!
Al.