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Sidecar Setup
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shoelu
Posted 5/10/2016 12:04 AM (#89055)
Subject: Sidecar Setup



Regular

Posts: 51
2525
Location: Saint Paul, MN
I recently installed a Cozy Rocket Sidecar on my 1970 BMW R60/5 utilizing a DMC subframe. This is the third rig I have set up over the years but I always have questions for the experts out there that either do this for a living or have done it many more times than myself.

Currently I'm very happy with the rig set up but am trying to decide if I should strive for better or just realize that it is probably as good as it is ever going to get. The rig is golden in straight line unaccelerated travel. I can ride virtually hands off while traveling with enough throttle to maintain current speed. During acceleration I get a slight pull to the right as expected with any sidecar rig. During deceleration I experience a noticeably stronger pull to the left than the force needed to counteract right pull while accelerating. My past experiences have shown a very symmetrical pull force left or right under similar acceleration/deceleration rates.

Currently I have the rig set up with a small toe-in and the cycle has a slight lean out with the rider on the cycle. The hack is set up to be level on each axis when the rider is on the bike. My question involves determining if there an adjustment I can make that will attempt to minimize the left pull on deceleration without adding additional right pull during acceleration (which is currently minimal)? Do i adjust toe-in or lean out or neither and just leave well enough alone since It rides great in unaccelerated travel which is where I spend the vast majority of my time on the bike?

Thanks for your input.
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jaydmc
Posted 5/10/2016 10:21 AM (#89063 - in reply to #89055)
Subject: Re: Sidecar Setup


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How is your tire wear? Can you reduce the track width?
Jay G
DMC sidecars
www.dmcsidecars.com
866-638-1793
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shoelu
Posted 5/10/2016 12:09 PM (#89066 - in reply to #89063)
Subject: Re: Sidecar Setup



Regular

Posts: 51
2525
Location: Saint Paul, MN
jaydmc - 5/11/2016 9:21 AM

How is your tire wear? Can you reduce the track width?
Jay G
DMC sidecars
www.dmcsidecars.com
866-638-1793

I've probably only got 100 miles on the combo so far so no noticeable tire wear to speak of yet. I have the car as close to the cycle as the attachment hardware will allow, but the current width is larger than I would like. I had considered modifying the both lower mounts to allow the sidecar to be moved closer to the cycle but that would be a process of shortening both the front curved mount (not that difficult, just shortening the length by cutting a piece off) and shortening the straight adjustable rear mount. The rear mount would need to have a section removed from the center and then welding the strut back together. In your opinion is the track width most likely the problem? Would the track width cause asymmetrical pull during acceleration and deceleration? Currently the width from rear cycle wheel to sidecar wheel is 48 inches.



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jaydmc
Posted 5/10/2016 12:19 PM (#89068 - in reply to #89055)
Subject: Re: Sidecar Setup


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Posts: 1513
1000500
The rig should pull to the right when speeding up and push to the left when slowing down. Having the sidecar in closer while it will not change this, will lesson the effect.
I would pull the sidecar in as tight as practical.
Jay G
DMC sidecars
866-638-1793
www.dmcsidecars.com
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Hack'n
Posted 5/10/2016 12:20 PM (#89069 - in reply to #89055)
Subject: Re: Sidecar Setup



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Posts: 4833
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Location: Boise, Idaho
You have an asymmetrical vehicle. With the extra weight and drag on the side, the car will lag behind the tug upon acceleration and inertia will keep it going at the same approximate speed when slowing or braking the tug. A slight counter pressure on the bars takes care of this problem. This isn't something that different alignment will cure. It's common physics.
This is the same reaction that will cause harmonics and the undesirable nose wiggle that many rigs experience during slow speed acceleration or deceleration.
It sounds like you are pretty well aligned at present.

The wider the rig the more tendency for this phenomenon to occur.

Lonnie
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Hack'n
Posted 5/10/2016 12:37 PM (#89070 - in reply to #89055)
Subject: Re: Sidecar Setup



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Posts: 4833
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Location: Boise, Idaho
I see you have the car about as far from the bike as the mounts will allow. This also makes the setup less rigid.
I usually setup rigs at near 12" from bike frame to hack frame as a rule. The mounts aren't overextended and turns are about even in needed pressure.

Lonnie
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shoelu
Posted 5/10/2016 1:40 PM (#89072 - in reply to #89070)
Subject: Re: Sidecar Setup



Regular

Posts: 51
2525
Location: Saint Paul, MN
Hack'n - 5/11/2016 11:37 AM

I see you have the car about as far from the bike as the mounts will allow. This also makes the setup less rigid.
I usually setup rigs at near 12" from bike frame to hack frame as a rule. The mounts aren't overextended and turns are about even in needed pressure.

Lonnie

Actually, the sidecar is as close to the cycle as the mounts will allow. Currently the bottom front curved mount is slid as far in to the receiving tube as possible. I could easily cut off a portion of the front curved mount which would allow it to slide further in to the receiving tube before it bottoms out. The limiting factor I believe is the rear mounting strut. It is 8 inches long and is currently adjusted as far in as it will go. To get the sidecar closer to the cycle, I would need to shorten the rear bottom strut to allow it to move closer. I had both the sidecar mounts welded to the sidecar frame and I chose the the placement of the rear mount for strength, but it is sticking out a bit further from the frame than the standard mount would have. Does anyone stock a very short adjustable strut, perhaps 3 or 4 inches? That would allow me to snug the sidecar closer to the cycle and also allow the top struts to adjust to a shorter length.
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jaydmc
Posted 5/10/2016 1:48 PM (#89074 - in reply to #89072)
Subject: Re: Sidecar Setup


Expert

Posts: 1513
1000500
One of our male eye's with one of our female eyes gives you a strut that is in the 3-4 inch range, it would be the same type of eyes as on our mounts.
Jay G
DMC sidecars
www.dmcsidecars.com
866-638-1793
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shoelu
Posted 5/10/2016 2:24 PM (#89076 - in reply to #89074)
Subject: Re: Sidecar Setup



Regular

Posts: 51
2525
Location: Saint Paul, MN
jaydmc - 5/11/2016 12:48 PM

One of our male eye's with one of our female eyes gives you a strut that is in the 3-4 inch range, it would be the same type of eyes as on our mounts.
Jay G
DMC sidecars
www.dmcsidecars.com
866-638-1793

I don't believe the eye to eye set up would work. The subframe mounts are lower than the mounts on the sidecar frame. Currently I am set up to have the sidecar frame level on each axis with my weight on the cycle. If I move the sidecar closer to the cycle, it will cause the lower rear strut to move to a nearly vertical position. It seems that a vertical rear strut setup would reduce the rigidity of the setup as a whole.



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jaydmc
Posted 5/12/2016 5:35 PM (#89119 - in reply to #89055)
Subject: Re: Sidecar Setup


Expert

Posts: 1513
1000500
When we do a Cozy sidecar we convert it over to boss and clamp type mounts as I really do not like the idea of using struts for lower mounts. At this link you can get an idea of what we do. http://www.dmcsidecars.com/the-result-of-improper-sidecar-mounting-...

Jay G
DMC sidecars
866-638-1793
www.dmcsidecars.com
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