Announcement

Collapse
No announcement yet.

Cantilever Suspensions 101

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Cantilever Suspensions 101

    I am building this KL powered Triumph Sptifire in another thread and I have been on a severe learning curve for cantilever suspensions -since that is what I have chosen to go with -due to limited space in those small cars.

    However -they are not just for small cars -as many people build these suspension systems for show cars. Since I am learning at a crazy rate -I figure I would put all the cantilever stuff here as I learn it -so that if anyone else ever wanted make a cantilever suspension -they can come here for info and ideas.

    I started at first trying to figure out a spring rate that I would need and quickly ran into so many walls that I gave up on trying to do it mathematically. I know it can be done -but even a typical suspension car is very hard to calcuate for spring rate -and when you throw cantilevers into the mix -it goes 100 calculations beyond that.

    So I desided to just do it the old fasioned way by experimenting until I get something I like.

    My first step was to purchase lots of different "dog bones, or knuckles" as the motorcycle guys seem to call them. It seems that they cannot decide which name they want to call it. To me -knuckles is what has already been established as the spindle assembly. So it just doesn't seem right to call it a knuckle. When they refer to a spindle on a 4-wheeler -they also call it a knuckle. So perhaps we need to teach them how to be consistent with their naming conventions.

    And there is a dog-bone in the linkage systems -but it is exactly what it looks like and is what I have always called a dog-bone. It is a linear link with ball joints on both ends. So they call this piece a dog-bone and some others call the other piece a dog-bone as well.

    So -for us I will define the linear rod with Heim ball joints as a dog-bone or a push-pull tube with Heim joints.

    I will define what they sometimes call the "knuckle" as a fulcrum arm or pivot arm. These are on most all motorcycles as I have discovered and there is a huge variety of sizes, ends (clevis or pivot bearing) and ratios. There are also cast versions and CNC ones. Four our purposes of discussion here -the ends with two "ears" is called a "clevis" end. And the single pivot end that goes in between clevis ears is called an eye or pin-eye.

    So below are a few of the samples that I purchased to figure out which would work best for my purposes:



    From top left clockwise: 1985 Yamaha XT350, 1984 Yamaha TT600, 99-07 Hayabusa 1300, 02-05 Kawasaki ZZR 1200, 02' Honda Goldwing 1800, 07' Yamaha YZF R1, 06' Honda CBR1000RR.

    My personal favorites are:

    1) 84' Yamaha TT600 -because of extreme beefy-ness and clevis ends on both ends so that a shock pin eye can go in one end and a Heim push-pull tube on the other -extending down to where the shock pin eye would normally attach on the lower "A" arm. The Heim ends allow the linkage to have misalignment that you cannot have without the spherical ball end. And this can be a very good thing when arranging the cantilever layout.

    2) 85' Yamaha XT350 -again because of beefy-ness and clevis end on one end. I could probably get around the pineye end -since I have not decided which shock to go with. Some of the motorcycle shocks have pineyes that attach to the fulcrum arms and others have the clevis end. So the choice between these two depends upon which shock set-up I choose.

    3) is the 06' Honda CBR1000RR again -because of beefy-ness -but this one would require clevis attachments on both ends. Using this one would require strict alignment. If you are not trying to offset the shocks up top so that they lay side-by-side and have room to mount them end-to-end -then this might be acceptable.

    4) 07' Yamaha YZF R1 -because it is CNC machined 6061 billet aluminum. Cast will never be as strong as CNC billet. This one also has clevis ends at both ends.

    But the down side of this one is that it is smaller in size. It might still work for my purposes -because the car is not likely to be much heavier than 1600 lbs -or be an all-out race car. There may be larger examples similar to this one used on larger cycles -but I just haven't looked in-depth enough into it to find out.

    All of these examples seem to be decent castings (other than the CNC) and can probably be polished to a high shine chrome-look finish. Most of the eyes on these fulcrum arms are needle bearing assemblies. Some have grease zerks as seen with the Kawasaki ZZR 1200 example above. There are probably hundreds more of examples of these fulcrum arms (other makes/models and changes in years). So there is no limit to the choices on these.

    In my opinion -these are the most ultimate fulcrum arm that you can use in a project car. They will do the job very well, they can be polished to make look like a show piece, relatively inexpensive and most of all -almost unlimited choice for the application.

    I will continue to add to this thread to make it a comprehensive source for cantilever suspension. -Sticky?

    Superb Pinterest pages of Cantilever stuff:

    https://www.pinterest.es/pin/361132463855878191/

    https://www.pinterest.es/pin/302515299940010117/

    Link -to get an idea of how much math is involved if you wish to do it the long way:

    https://www.race-dezert.com/forum/th...lcrank.105586/

    Designing a cantilever system:

    http://www.super7thheaven.co.uk/glos...nk-suspension/

    Standard suspension spring rate calculator:

    https://www.hypercoils.com/spring-rate-calculator/

    Wicked cantilever system:

    https://photos.smugmug.com/Event-Cov..._6291adj-L.jpg
    Last edited by KLZE Porsche; February 3, 2018, 09:14 PM.
    Success is a measure of determination!
    Bonneville Dreamer-(AKA Purple Pimp Mobile)
    $500 Gas-Electric-Gas Reconversion/Restoration
    Mini-me & 500k "Old Gal" RIP
    Restoration of a legend

  • #2
    That's several more tabs that will be open for awhile on my browser. Definitely suspension pron.
    Probe out for Harambe
    94 PGT KLZE http://i882.photobucket.com/albums/a...psr6dk8q1m.jpg
    https://www.youtube.com/watch?v=aauXMeITcdM

    Comment

    Working...
    X