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The Dreaded Strap Clamp Slip!
Quote from OldSchool_IsCool on August 17, 2011, 9:33 amHey All!
Rig: GL1100 tug with an Auburn Gemini (double wide) hack mounted with two lower heim joints and two angled adjustable struts. Frame attachments are made with strap clamps using eye-bolts that bare down onto the frame via a shim.
I recently took the Mrs on a camping trip. I expected my rig to behave differently what with the car and the bike being fully loaded with humans and equipment. But MAN! did it pull hard to the right! I made a few adjustments with the struts to change the lean out and even tried to toe in the sidecar tire by shortening the forward heim joint. Didn't help much.
I made it about 300 miles into a planned 1500 mile trip when I finally had enough and elected to dig into what was really going on. To make a short story long, I found that the REAR heim joint (mounted to the bike's lower horizontal frame) had slipped. Or more accuratly, the strap clamp rotated from a horizontal position (call it 3 o'clock) to about 5 o'clock. This made the rear of the car sag and made the sidecar tire tow out quite a bit!
I took things apart and remounted the car. I moved one of the rear angled strut to a more vertical position so that it was supporting the car's weight as much as the car's yaw and bike's lean out. I also used a U-bolt to umm, err, ah... fix the rear heim clamp to a foot peg to prevent strap rotation. (Forgive me Father for I have sinned!) Checking alignment, things seemed close 'nuf to continue on, but I elected to turn for home.
Now, to the question(s).
I've read a couple of posts here that suggest spot welding the strap clamps to the frame. Is that good advice? Shoud the strap itself be spot welded or should the shim? Both? I know a guy that welds a lot of cycle frames, so I'll farm the job out to him if this is the correct solution. I may also relocate the rear heim connection point to a frame member that isn't so horizontal. Been wanting to do this anyway since my car's lead is a little more than the suggested 20% of bike's wheel base.
Thanks in advance for your learned advice!
Hey All!
Rig: GL1100 tug with an Auburn Gemini (double wide) hack mounted with two lower heim joints and two angled adjustable struts. Frame attachments are made with strap clamps using eye-bolts that bare down onto the frame via a shim.
I recently took the Mrs on a camping trip. I expected my rig to behave differently what with the car and the bike being fully loaded with humans and equipment. But MAN! did it pull hard to the right! I made a few adjustments with the struts to change the lean out and even tried to toe in the sidecar tire by shortening the forward heim joint. Didn't help much.
I made it about 300 miles into a planned 1500 mile trip when I finally had enough and elected to dig into what was really going on. To make a short story long, I found that the REAR heim joint (mounted to the bike's lower horizontal frame) had slipped. Or more accuratly, the strap clamp rotated from a horizontal position (call it 3 o'clock) to about 5 o'clock. This made the rear of the car sag and made the sidecar tire tow out quite a bit!
I took things apart and remounted the car. I moved one of the rear angled strut to a more vertical position so that it was supporting the car's weight as much as the car's yaw and bike's lean out. I also used a U-bolt to umm, err, ah... fix the rear heim clamp to a foot peg to prevent strap rotation. (Forgive me Father for I have sinned!) Checking alignment, things seemed close 'nuf to continue on, but I elected to turn for home.
Now, to the question(s).
I've read a couple of posts here that suggest spot welding the strap clamps to the frame. Is that good advice? Shoud the strap itself be spot welded or should the shim? Both? I know a guy that welds a lot of cycle frames, so I'll farm the job out to him if this is the correct solution. I may also relocate the rear heim connection point to a frame member that isn't so horizontal. Been wanting to do this anyway since my car's lead is a little more than the suggested 20% of bike's wheel base.
Thanks in advance for your learned advice!
Quote from Hack__n on August 17, 2011, 10:32 amTHe practice of making a couple of small spot welds to secure the clamp strap has been used for a long time. Motorvation and other MFG'rs. have recommended this fix in the past for some odd angled mount positions.
I've used a small spot weld on both sides of the strap on some applications with no ill effects.Caution:If doing this fix, do not over weld as this will cause the frame tube to crack next to the weld some time down the road.
I know of one instance where URAL sidecar frame mounts were solidly welded to a Suzuki frame and it seemed to work fine for the owner for almost 20K miles till the frame tube cracked.
L.
THe practice of making a couple of small spot welds to secure the clamp strap has been used for a long time. Motorvation and other MFG'rs. have recommended this fix in the past for some odd angled mount positions.
I've used a small spot weld on both sides of the strap on some applications with no ill effects.
Caution:If doing this fix, do not over weld as this will cause the frame tube to crack next to the weld some time down the road.
I know of one instance where URAL sidecar frame mounts were solidly welded to a Suzuki frame and it seemed to work fine for the owner for almost 20K miles till the frame tube cracked.
L.
Quote from jaydmc on August 17, 2011, 12:19 pmIn general frame clamps should only be used when possible such that they are not trying to resist a twisting motion. When ever possible it is much better to not run frame clamps for several reasons, on the bottom as modern frames are not very long you end up with the front and rear lower mounts being to close toghether for good triangulation. (we do make a bike specific mounting kit for your bike) There are also vast differences in the quality of different frame clamps. One company simply supplies you with a piece of flat steel with two holes in it you wrap around the frame and then put an eye bolt in the holes and tighten it down, if need be adding washers to keep it from crushing the frame, These are the worst type of frame clamp as they almost always slip and often damage the frame. Another company (motovation) makes a clamp where the back side of the clamp has full contact with the strap part but the front only has contact at two points on the egde of the part being used to pinch down. These also tend to slip and crush the frame. Several companies make frame clamps simlar to the ones we make where you have a strap that goes around the frame that bolts to a block with the eye bolt (or clevis or ball) tightening down against a anvil. The most current clamps that California sidecars made, Champion sidecars and ours are pretty much the same and tend to work well if used correctly. Early California sidecar frame clamps that do not have cross bolts in them should not be used as they tend to fail. On the clamps we make the "U" part of the strap is bent over the clamping block such that the cross bolts do not take the load, they are there just to keep the strap from spreading. The Anvil is fairly thick on these clamps and has a flat machined into it for the eye bolt to push on. Velorex also makes a strap clamp that looks similar to ours however the "U" part is bolted to the block and as such the bolts are taking the load in a very small area of the strap and over time the holes tend to strech allowing the clamp to slip. The Velorex anvil is very thin and has a dimple pressed into it for the eye bolt to rest in and the eye bolts is tapperd to a point such that when you tighten the eye bolt down as the pressure is going through the point of the eye bolt to a thin anvil it tends to bend the anvil and or crush the frame.
It sounds to me that the real underlying problem is you are using frame clamps where you should be using sub frames and you may also have a fairly low quality frame clamp. I would rethink your entire mounting system if you are having to weld the frame clamp down then there is an underlying design problem and chances are you are asking the frame clamp to be used in the worst possible mannor that the clamp can be used in. You should never have to weld a frame clamp to the bike, not even a spot weld.
You are also running way to much wheel lead 20% of the wheel base of the bike is way to much for a street bike, we on some of our dual sport sidecars that run in the gravel and off road we will go as much as 20% of the wheel base of the bike however your bike is not likley to be ran off road, We would try to get closer to 10% of the wheel base of the bike. You will have better tire life, easier steering and less of a tendancy for head shake.
With a mounting system that can slip, chances are that there is also flex in the system and as such the rig more then likley does not handle as well as it could. You should be able to shake the bike vigorusly while looking at the mounting sytem and see little to no flex or movement.
Our mounting kit for your bike does use frame clamps for the upper mounts but as they are in line with the struts they are not trying to resist a twisting motion and do not tend to slip. Our front lower mount is a small sub frame that picks up the front engine mounting bolt and clamps to the frame tube with a thin clamp. In this area of the GL1100 frame the frame is not entirly round, it has a curve in it and also bends inward, A frame clamp is a very bad idea in this area, if you move the frame clamp back some then you are getting to close to the rear lower mount for good trianglulation. Our rear lower mount replaces the center stand, goes under the muffler and also attaches to the side of the bike. This allows us to move the mount rearward for better trianglulation and also moves the mount lower such that it is not higher then the front lower mount. If you clamp the rear lower mount simply to the frame on the GL1100 the rear lower mount ends up being higher then the front lower mount which makes it really hard to get the alignment correct as when you change lean out, it move the toe setting oppisit of the way you would want it to go. For example, if you have a pull to the right, you would fix it by leaning the bike to the left however with the rear mount higher then the front when you add more lean out you also end up with less toe in, less toe in causes more of a pull to the right.
I put over 150K on a GL1100 with a sidecar so if you have any specific questions at all I should be able to help.
Jay G
DMC sidecars
www.dmcsidecars.com
866-638-1793
In general frame clamps should only be used when possible such that they are not trying to resist a twisting motion. When ever possible it is much better to not run frame clamps for several reasons, on the bottom as modern frames are not very long you end up with the front and rear lower mounts being to close toghether for good triangulation. (we do make a bike specific mounting kit for your bike) There are also vast differences in the quality of different frame clamps. One company simply supplies you with a piece of flat steel with two holes in it you wrap around the frame and then put an eye bolt in the holes and tighten it down, if need be adding washers to keep it from crushing the frame, These are the worst type of frame clamp as they almost always slip and often damage the frame. Another company (motovation) makes a clamp where the back side of the clamp has full contact with the strap part but the front only has contact at two points on the egde of the part being used to pinch down. These also tend to slip and crush the frame. Several companies make frame clamps simlar to the ones we make where you have a strap that goes around the frame that bolts to a block with the eye bolt (or clevis or ball) tightening down against a anvil. The most current clamps that California sidecars made, Champion sidecars and ours are pretty much the same and tend to work well if used correctly. Early California sidecar frame clamps that do not have cross bolts in them should not be used as they tend to fail. On the clamps we make the "U" part of the strap is bent over the clamping block such that the cross bolts do not take the load, they are there just to keep the strap from spreading. The Anvil is fairly thick on these clamps and has a flat machined into it for the eye bolt to push on. Velorex also makes a strap clamp that looks similar to ours however the "U" part is bolted to the block and as such the bolts are taking the load in a very small area of the strap and over time the holes tend to strech allowing the clamp to slip. The Velorex anvil is very thin and has a dimple pressed into it for the eye bolt to rest in and the eye bolts is tapperd to a point such that when you tighten the eye bolt down as the pressure is going through the point of the eye bolt to a thin anvil it tends to bend the anvil and or crush the frame.
It sounds to me that the real underlying problem is you are using frame clamps where you should be using sub frames and you may also have a fairly low quality frame clamp. I would rethink your entire mounting system if you are having to weld the frame clamp down then there is an underlying design problem and chances are you are asking the frame clamp to be used in the worst possible mannor that the clamp can be used in. You should never have to weld a frame clamp to the bike, not even a spot weld.
You are also running way to much wheel lead 20% of the wheel base of the bike is way to much for a street bike, we on some of our dual sport sidecars that run in the gravel and off road we will go as much as 20% of the wheel base of the bike however your bike is not likley to be ran off road, We would try to get closer to 10% of the wheel base of the bike. You will have better tire life, easier steering and less of a tendancy for head shake.
With a mounting system that can slip, chances are that there is also flex in the system and as such the rig more then likley does not handle as well as it could. You should be able to shake the bike vigorusly while looking at the mounting sytem and see little to no flex or movement.
Our mounting kit for your bike does use frame clamps for the upper mounts but as they are in line with the struts they are not trying to resist a twisting motion and do not tend to slip. Our front lower mount is a small sub frame that picks up the front engine mounting bolt and clamps to the frame tube with a thin clamp. In this area of the GL1100 frame the frame is not entirly round, it has a curve in it and also bends inward, A frame clamp is a very bad idea in this area, if you move the frame clamp back some then you are getting to close to the rear lower mount for good trianglulation. Our rear lower mount replaces the center stand, goes under the muffler and also attaches to the side of the bike. This allows us to move the mount rearward for better trianglulation and also moves the mount lower such that it is not higher then the front lower mount. If you clamp the rear lower mount simply to the frame on the GL1100 the rear lower mount ends up being higher then the front lower mount which makes it really hard to get the alignment correct as when you change lean out, it move the toe setting oppisit of the way you would want it to go. For example, if you have a pull to the right, you would fix it by leaning the bike to the left however with the rear mount higher then the front when you add more lean out you also end up with less toe in, less toe in causes more of a pull to the right.
I put over 150K on a GL1100 with a sidecar so if you have any specific questions at all I should be able to help.
Jay G
DMC sidecars
http://www.dmcsidecars.com
866-638-1793
Quote from OldSchool_IsCool on August 22, 2011, 12:22 pmYes, I'm thinking I need to rethink my mounts. I'm not thrilled with welding, mainly because I can't do the welds myself. It would also mean that I would have to have the mounts in the right position to begin with when I tack 'em down.
Jay, your mounting system sounds like something I really need to look into. You mention that your kit has upper clamps, a forward lower sub-frame and a lower support that takes the place of the center stand. Does the kit include new bosses (the part between the sidecar frame that connects to the lower mounts via hiem joints, I think that's called the boss). Do the upper clamps include adjustable struts and the clamps to fix the struts to the sidecar frame? I also have non-OEM mufflers, so I'd need to measure to make sure they wouldn't interfere with the lower rear mont.
Please send me a PM if this is something you would rather discuss off-line.
Bruce
Yes, I'm thinking I need to rethink my mounts. I'm not thrilled with welding, mainly because I can't do the welds myself. It would also mean that I would have to have the mounts in the right position to begin with when I tack 'em down.
Jay, your mounting system sounds like something I really need to look into. You mention that your kit has upper clamps, a forward lower sub-frame and a lower support that takes the place of the center stand. Does the kit include new bosses (the part between the sidecar frame that connects to the lower mounts via hiem joints, I think that's called the boss). Do the upper clamps include adjustable struts and the clamps to fix the struts to the sidecar frame? I also have non-OEM mufflers, so I'd need to measure to make sure they wouldn't interfere with the lower rear mont.
Please send me a PM if this is something you would rather discuss off-line.
Bruce
Quote from jaydmc on August 22, 2011, 12:46 pmOur mounting kit provides only the 4 attachment points for the bike, The non-oem mufflers should not be a problem at all. We also do make the bosses, clamps and hiem joints but they are not included in the kit.
If you send me an email request to jay@dmcsidecars.com I will send you photo's of what comes in the kit.
Jay G
DMC sidecars
www.dmcsidecars.com
866-638-1793
Our mounting kit provides only the 4 attachment points for the bike, The non-oem mufflers should not be a problem at all. We also do make the bosses, clamps and hiem joints but they are not included in the kit.
If you send me an email request to jay@dmcsidecars.com I will send you photo's of what comes in the kit.
Jay G
DMC sidecars
http://www.dmcsidecars.com
866-638-1793
Quote from Doug Hasert on September 1, 2011, 9:06 pmMy lower rear mount has the eyebolt mounted on a 2" x 1/2" plate mounted on the driver and passenger foot pegbolts. I have used this on 3 different GL1100's . Easy to make. " And all ways proof read your answers before submitting. "
My lower rear mount has the eyebolt mounted on a 2" x 1/2" plate mounted on the driver and passenger foot pegbolts. I have used this on 3 different GL1100's . Easy to make. " And all ways proof read your answers before submitting. "