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KLR Sidecar Rig Is Sagging

I’m mounting a lightweight utility/cargo sidecar to my 2013 KLR.  This is my third rig, but the first time I have tried to fabricate a mounting system for a car.  So, please don’t laugh too hard at what I’ve already done or tell me how stupid I am.  I just need your help and I’m sure there are plenty of you out there who can help me.  I bought this rig already “set up”, but the PO knew nothing about sidecars.  He made the sidecar and did a pretty good job, in my opinion.  But he mounted it with two solid pieces of square tubing bolted directly to the KLR frame.  I have since undone that, cut off the two pieces of tubing and installed a KLR sub frame I bought from Claude Stanley at Freedom Sidecars in Pennsylvania.  I welded and bolted 4 eye bolt mounts to the car frame, as you can see in the pictures and installed the two upper and two lower struts from these eye bolt mounts to the bike sub frame eye bolt mounts.  I have adjusted and tighten all bolts and mounts at least 4 times.  I’ve put a long cheater handle over my ratchet handle to tighten everything almost to the point of stripping the bolts or nuts.  But, after adjusting everything and doing a test ride something is slipping and the bike wants to lean into the car. What am I doing wrong or not doing?  I will be glad to post or send you more pictures if needed.

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Try rotating the two lower eyebolts connected  to the bike frame so that the hole is on a flat plane with the ground and the bolt is going thru vertical to the ground instead of parallel to the ground.  

I used typewriter correction fluid to mark all my connections so that if they sag, I know which connection are the culprit. Some people use paint or some other method. 

Quote from John Holbrook on April 3, 2021, 6:13 pm

I used typewriter correction fluid to mark all my connections so that if they sag, I know which connection are the culprit. Some people use paint or some other method. 

Thanks John.  I'll try both suggestions this week and let you kow how it comes out.

John Holbrook has reacted to this post.
John Holbrook

My guess is that where you have the struts going to tabs that are bolted to the frame, the tabs are pivoting around the bolts. It would only take a few degree's of movement at these points for this to happen. I know you say you welded these down and I can see welds on some but not on the front one.

While many sidecars use "struts" for their lower connection mainly on the rear I have never liked this set up. I much prefer some thing that does not pivot on both end of things. Just to many places for things to move.

This is one of the reasons when we do Velorex, Cozy and similar sidecars we change them over to "boss and clamp" type mounts. You can see how this works at this article. Sidecar Mounting | DMC Sidecars

Another point that this could be happening is the way you made your rear strut, the flat part where you are running the all thread through could be twisting. In any event it is more then likely flexing a bit while riding which would change your lean out a bit.

The upper mounts on the sub frame could also be moving, you do not show how these were done. I know on our KLR sub frame which runs a frame clamp for the upper rear if this is not tight, things will move. If tight no issues at all. On our upper front we clamp around the spine of the bike under the fuel tank and then support the mount at two other points about 14 inches apart forming a tripod. We do this as we found that the down tube on the KLR is weak as such not a good place to clamp onto.

One quick way to do a very limited assessment of everything which is what I use to do when teaching the sidecar class if some one wanted to uses their own bike is to vigorously shake the bike. You should see the sidecar moving exactly the same as the bike with nothing flexing and no sounds from bolts sliding in their holes and bottoming. Everything should be absolutely firm and quiet.

As this is a cargo sidecar, while it would add a little more aerodynamic drag, why not attach the upper front strut to the far side of the sidecar frame? This would stiffen it up considerably. 

Jay G
DMC sidecars

866-638-1793

http://www.dmcsidecars.com

Monday - Thursday 6-4:30

CCjon has reacted to this post.
CCjon
Jay G DMC sidecars www.dmcsidecars.com 15616 Carbonado South Prairie RD Buckley WA 98321 866-638-1793 Hours Monday - Thursday 6-4:30
Quote from jaydmc on April 6, 2021, 8:53 am

My guess is that where you have the struts going to tabs that are bolted to the frame, the tabs are pivoting around the bolts. It would only take a few degree's of movement at these points for this to happen. I know you say you welded these down and I can see welds on some but not on the front one.

While many sidecars use "struts" for their lower connection mainly on the rear I have never liked this set up. I much prefer some thing that does not pivot on both end of things. Just to many places for things to move.

This is one of the reasons when we do Velorex, Cozy and similar sidecars we change them over to "boss and clamp" type mounts. You can see how this works at this article. Sidecar Mounting | DMC Sidecars

Another point that this could be happening is the way you made your rear strut, the flat part where you are running the all thread through could be twisting. In any event it is more then likely flexing a bit while riding which would change your lean out a bit.

The upper mounts on the sub frame could also be moving, you do not show how these were done. I know on our KLR sub frame which runs a frame clamp for the upper rear if this is not tight, things will move. If tight no issues at all. On our upper front we clamp around the spine of the bike under the fuel tank and then support the mount at two other points about 14 inches apart forming a tripod. We do this as we found that the down tube on the KLR is weak as such not a good place to clamp onto.

One quick way to do a very limited assessment of everything which is what I use to do when teaching the sidecar class if some one wanted to uses their own bike is to vigorously shake the bike. You should see the sidecar moving exactly the same as the bike with nothing flexing and no sounds from bolts sliding in their holes and bottoming. Everything should be absolutely firm and quiet.

As this is a cargo sidecar, while it would add a little more aerodynamic drag, why not attach the upper front strut to the far side of the sidecar frame? This would stiffen it up considerably. 

Jay G
DMC sidecars

866-638-1793

http://www.dmcsidecars.com

Monday - Thursday 6-4:30

Jay - Thanks so much for your lengthy and helpful reply and suggestions.  I also read your article, "The result of Improper sidecar mounting and the proper fix"  Do you sell any hardware similar to what is in that article that would solve my problem, with some minimal cutting/welding/fabrication with what I've done up to this point?  Also, I assume from other information I've read while trying to research this problem, the main culprit for this sagging problem is with the lower struts and not so much the uppers. Is that correct?  If so, if I changed the eye bolt mounting points around on the bike sub frame and on the sidecar frame so that the bolt that goes through the clevis portion of the strut is perpendicular to the ground instead of parallel, would that help the situation.  It seems to me that would keep the strut from pivoting up and down.  if it did tend to pivot it would need to pivot forward and backward, but the upper struts would help to eliminate that.

Again, I'm a novice at this, but having fun learning and I really appreciate your help as well as other suggestions I've received.  Also, I'll be glad to send additional pictures if that would help.

Quote from fredtman on April 6, 2021, 3:54 pm
Quote from jaydmc on April 6, 2021, 8:53 am

My guess is that where you have the struts going to tabs that are bolted to the frame, the tabs are pivoting around the bolts. It would only take a few degree's of movement at these points for this to happen. I know you say you welded these down and I can see welds on some but not on the front one.

While many sidecars use "struts" for their lower connection mainly on the rear I have never liked this set up. I much prefer some thing that does not pivot on both end of things. Just to many places for things to move.

This is one of the reasons when we do Velorex, Cozy and similar sidecars we change them over to "boss and clamp" type mounts. You can see how this works at this article. Sidecar Mounting | DMC Sidecars

Another point that this could be happening is the way you made your rear strut, the flat part where you are running the all thread through could be twisting. In any event it is more then likely flexing a bit while riding which would change your lean out a bit.

The upper mounts on the sub frame could also be moving, you do not show how these were done. I know on our KLR sub frame which runs a frame clamp for the upper rear if this is not tight, things will move. If tight no issues at all. On our upper front we clamp around the spine of the bike under the fuel tank and then support the mount at two other points about 14 inches apart forming a tripod. We do this as we found that the down tube on the KLR is weak as such not a good place to clamp onto.

One quick way to do a very limited assessment of everything which is what I use to do when teaching the sidecar class if some one wanted to uses their own bike is to vigorously shake the bike. You should see the sidecar moving exactly the same as the bike with nothing flexing and no sounds from bolts sliding in their holes and bottoming. Everything should be absolutely firm and quiet.

As this is a cargo sidecar, while it would add a little more aerodynamic drag, why not attach the upper front strut to the far side of the sidecar frame? This would stiffen it up considerably. 

Jay G
DMC sidecars

866-638-1793

http://www.dmcsidecars.com

Monday - Thursday 6-4:30

Jay - Thanks so much for your lengthy and helpful reply and suggestions.  I also read your article, "The result of Improper sidecar mounting and the proper fix"  Do you sell any hardware similar to what is in that article that would solve my problem, with some minimal cutting/welding/fabrication with what I've done up to this point?  Also, I assume from other information I've read while trying to research this problem, the main culprit for this sagging problem is with the lower struts and not so much the uppers. Is that correct?  If so, if I changed the eye bolt mounting points around on the bike sub frame and on the sidecar frame so that the bolt that goes through the clevis portion of the strut is perpendicular to the ground instead of parallel, would that help the situation.  It seems to me that would keep the strut from pivoting up and down.  if it did tend to pivot it would need to pivot forward and backward, but the upper struts would help to eliminate that.

Again, I'm a novice at this, but having fun learning and I really appreciate your help as well as other suggestions I've received.  Also, I'll be glad to send additional pictures if that would help.

Jay - Attached are a couple pictures of the sub frame on my KLR

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  • Subframe-1.jpg
  • Subframe-2.jpg

Jay may not see this. Best to contact him directly.  Search for DMC sidecars ,and  contact him there 

Your sub frame should be fine, while it is getting into "who designs the better stuff" I prefer our mounts as the upper mounts end up much higher up on the bike. The higher up and further apart the better triangulation you are going to get.  The better triangulation, the stiffer the mounting system will be. I have attached information on our mounts for the KLR however I am not recommending you change what you have.

People will often rotate the eye bolts on the bottom such that they are not trying to pivot. As you read in the linked article we actually use hiem joints here which have a bearing in them such that brute force is not what holds things together rather proper triangulation.  I like the Hiem joints as they are easy to work with and make it such that it you change your alignment you are not forcing stress into the mounting system. Just a different philosophy then others use. Not going to go into which is best as legitimate arguments can be made for both philosophy's 

One sidecar shop that was around for many years in California that the owner has now passed they would put it all together then  when things moved he would weld the eye bolts together. We had one Watsonian sidecar he mounted that had no fewer then 5 different "universal" type clamps for just the upper front mount. Welding eye bolts together works but it is not some thing I would ever do.

If you had brought us your sidecar to do what we would have done to the sidecar is weld two pinch clamps under the sidecar frame for boss and clamp type mounts. Depending on how well built the sidecar is we might have these pinch clamps long enough to weld to both sides of the frame, in essence adding to cross tubes to the frame. We would cut holes all the way through your sidecar frame with a one inch hole saw then drop in sleeves welded on both ends so that the frame will not collapse when the eye bolts we use for the struts to attach are tightened.  Then use our eye bolts on the frame and our struts to the upper mounts. This allows us to set wheel lead, toe and lean out and once done if latter you want to move the sidecar to a different bike, you do not have parts that were dedicated to the specific bike it came off of.  Another advantage to this is when people are paying us shop rate to do the work, this goes much quicker and while we are using hardware that we pre-build, we are not using up a bunch of shop time figuring out one off solutions. This is also some thing that we can send out to people doing their own work that we know will work every time. If you email me direct I can give you pricing on all of this jay@dmcsidecars.com people will be reading this thread long after I am gone, often not looking at dates and wanting the pricing in the posts so I try not to post pricing. I still get people asking about tires that we use to stock that sold out 19 years ago. Not trying to sell you anything, just giving you some different options as to how to do what you doing.

Jay G

DMC sidecars

http://www.dmcsidecars.com

866-638-1793

Monday - Thursday 6-4:30

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Jay G DMC sidecars www.dmcsidecars.com 15616 Carbonado South Prairie RD Buckley WA 98321 866-638-1793 Hours Monday - Thursday 6-4:30