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Sidecar Shock

 
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Bandit Bill



Joined: 31 Jan 2005
Posts: 202
Location: Hamilton, Ontario, Canada

PostPosted: Tue Feb 07, 2006 4:57 pm    Post subject: Sidecar Shock Reply with quote

I'm entering a definite gray area of personal knowlege in regard to shocks used on a sidecar rig.

At present, the shock i thought i'd use (Bandit 1200 rear shock, 11 3/4" long, eye mount top, rigid forked mount bottom for a suspension dogbone) doesn't appear that it'll work without busting out a heavy duty (read expensive) engineering solution to deal with the fact that i'm putting a shock in on the suspension that needs to lay at an angle. The bottom forked mount of the shock, I don't think will have the flexibility necessary to deal with the 2-3 degrees of side deflection that the shock unit will have to deal with in the 2" of suspension travel without running the risk of stress fatique.

This leads me back to step 1:

a: Either find a shock, heavy enough for the dynamics of a 300 lb sidecar, with flexible rubber grommeted eye mounts top and bottom, to deal with the sideways stiction forces of the shock as it is compressed, and it's angle relative to the swingarm is changed.

b: Recycle the original volkswagon air shock (ugh)

c: Suggestions, brilliant ideas i've overlooked?
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Homebrew '99 Suzuki Bandit 1200 / '88 Hannigan Comet
'78 Honda CT70 playbike
http://www.chairintheair.ca
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bmcsheehy



Joined: 22 Jan 2005
Posts: 972
Location: Massachusetts USA

PostPosted: Tue Feb 07, 2006 5:55 pm    Post subject: Reply with quote

Could you space the bandit shock on the top or bottom to make it perpendicular to the axis of the swing arm and alleviate the side angle.
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Bill
High Performance Sidecaring... ...There is nothing "HACKED" about it.
2006 ZX-14 / HANNIGAN HP.
2011 Concourse / California Friendship III.
1936 Ford Fordoor Humpback
www.Yankee-Engineering.com
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Bandit Bill



Joined: 31 Jan 2005
Posts: 202
Location: Hamilton, Ontario, Canada

PostPosted: Tue Feb 07, 2006 6:13 pm    Post subject: Reply with quote

bmcsheehy wrote:
Could you space the bandit shock on the top or bottom to make it perpendicular to the axis of the swing arm and alleviate the side angle.


Thats the major weakness of my design, i guess. My dimensions are less generous to work with as compared to what your photo's show on your frame, related to the existing sidecar frame as it is.

At the top, between sidecar body, to tire sidewall, I have ~2" total clearance in which to shoe-horn the top shock mount in place. The bottom portion of the shock needs to be inset, relative to the top mount, 1 3/4" from centerline, into the recess created by the inside of the rim to clear the sidecar frame rail. The swingarm actually overlaps the sidecar frame by 1/2" just to make it work

I can minimize the overall angle of lean, but not eliminate it entirely. The shock needs to be mounted at an angle to fit, no way around it, short of chopping the sidecar frame itself (ain't happening).

I've got a set of Progressive Suspension 418's i can pull out of the crawlspace of reject parts, which have the rubber suspended eyelets - My concern is the shock spring weight isn't adequate to the task - and getting replacement springs for this set of shocks ain't easy - i went through a nightmare with them last project season (bought for the LL front end) before i found out that the shocks were a discontinued design series of the 418 and ended up buying the updated design of the 418 series to have upgradeable springs.

At this point, i'm thinking of hacking together a bolt-on adapter to the shock bottom mount, with a center post pivot hole attaching it to the wheel backing plate.. allowing it to pivot at the bottom, in two axis.. IF i chose to go with the stock shock - a lot of work, and no guarantee it will work.
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Homebrew '99 Suzuki Bandit 1200 / '88 Hannigan Comet
'78 Honda CT70 playbike
http://www.chairintheair.ca
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Bandit Bill



Joined: 31 Jan 2005
Posts: 202
Location: Hamilton, Ontario, Canada

PostPosted: Wed Feb 08, 2006 12:01 am    Post subject: Reply with quote

Hiem joint end.. if i made an adapter block to fit the forked section of the shock, and bolt the hiem joint eye to the bottom of the shock with a pass-through bolt (5/8 or 3/4" all the way), and used the threaded portion to bolt through the spindle backing plate, this would give me the range of motion required - BUT is a hiem joint end, even a larger 1/2" or larger eye bore, strong enough to take this sort of abuse?

I'm reaching here.. The one's I'm using for the swaybar linkages, as well as the main hiem joint i use for my bottom rear sidecar mount are all holding up beautifully.. but i don't know if it's wise to experiment with something this 'mission critical' using a hiem joint.. a shock mount involves more 'shock load' stresses than anything else being used on my rig using hiem joints.
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Homebrew '99 Suzuki Bandit 1200 / '88 Hannigan Comet
'78 Honda CT70 playbike
http://www.chairintheair.ca
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Bandit Bill



Joined: 31 Jan 2005
Posts: 202
Location: Hamilton, Ontario, Canada

PostPosted: Wed Feb 08, 2006 2:17 am    Post subject: Reply with quote

Using a rod end like this, perhaps a 3/4", sleeved down through the eye to span the full 30 mm between the shock mount forks, and use the stock 10 mm bolt.

http://www.racerpartswholesale.com/roden1.htm


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Homebrew '99 Suzuki Bandit 1200 / '88 Hannigan Comet
'78 Honda CT70 playbike
http://www.chairintheair.ca


Last edited by Bandit Bill on Sat Feb 11, 2006 10:12 pm; edited 1 time in total
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Moike the Squid



Joined: 14 Jun 2005
Posts: 123
Location: Santa Cruz, CA

PostPosted: Thu Feb 09, 2006 1:09 am    Post subject: Reply with quote

You want the stock SV-650 rear shock that's laying in my garage? It's pretty much spanky new. Came out of RyanB's bike ages ago.

-Mike-
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Bandit Bill



Joined: 31 Jan 2005
Posts: 202
Location: Hamilton, Ontario, Canada

PostPosted: Thu Feb 09, 2006 4:48 pm    Post subject: Reply with quote

Moike the Squid wrote:
You want the stock SV-650 rear shock that's laying in my garage? It's pretty much spanky new. Came out of RyanB's bike ages ago.

-Mike-


Thanks for the offer, Moike - but the SV650 shock has the same bottom forked mount design issue.

I got sitting on my desk here, a $104.45 piece of hardware in the form of an aircraft grade 3/4" rod end - This thing is very rugged. If it fails as a shock mount - I don't know what would make the grade..
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Homebrew '99 Suzuki Bandit 1200 / '88 Hannigan Comet
'78 Honda CT70 playbike
http://www.chairintheair.ca
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Bandit Bill



Joined: 31 Jan 2005
Posts: 202
Location: Hamilton, Ontario, Canada

PostPosted: Sat Feb 11, 2006 5:53 pm    Post subject: Reply with quote



My solution to the technical problem, i hope it works.

Rod end, 3/4" eye bore/shank, greasable fitting, sleeved down through the rod eye to 1/2", then a SS liner sleeved down to the stock 10 mm Suzuki bolt. Looks like it should work.. This bolts directly onto a 1/4" plate extension to the spindle backing plate.
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Homebrew '99 Suzuki Bandit 1200 / '88 Hannigan Comet
'78 Honda CT70 playbike
http://www.chairintheair.ca
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