Gracie's Hack... DR650 sidewalk chalk build

[gogogordy]

As a DR650 owner and "hacks" lurker/fetishist I am watching this with great interest. Good going, I think you're onto something here!

[CAVEboy]

This update is in spite of my friend who has been trying to find time to help me with my swing arm. The last time I went over with everything ready one of the acme threads on his tool bench stripped and we couldn't make the part. It has been very frustrating but none of it has been his fault. He is really trying to help me out. Once the bearing journals are cut the swing arm can be installed and then I can start working out the bugs. This should have been a relatively quick fab job, but has been sitting in my shop unfinished for way too long. I should have known.

Anyhow... here are some pictures of the mostly finished sub frame. I didn't make many changes other than reinforcing the upper frame mount so it will bolt to the oil cooler and sandwich the frame. Should be much stronger. I didn't come up with a satisfying way to mount the rear upper mount higher without sacrificing strength so it will be mounted a little lower. Although not ideal in location, I think it will be much stronger than the rear sub frame of the bike (up near the tail rack). I hope all will work out. I did get a little more width out of the lower mounts where the car frame will attach.







I spent some time rebuilding the car frame also. I shortened it and built in the swing arm mount instead of adding it to the outside of the frame like I've seen on many other builds. I don't know that this is better, just that I like the look of it more.







The width shown is narrower than actual width. I should be around 45-46" track width. Currently it is sitting at about 12" of wheel lead. How does this sound? I can drop down to probably 10" or go up another inch or so if needed.

[MotoJ]

Originally Posted by CAVEboy

This update is in spite of my friend who has been trying to find time to help me with my swing arm. The last time I went over with everything ready one of the acme threads on his tool bench stripped and we couldn't make the part. It has been very frustrating but none of it has been his fault. He is really trying to help me out. Once the bearing journals are cut the swing arm can be installed and then I can start working out the bugs. This should have been a relatively quick fab job, but has been sitting in my shop unfinished for way too long. I should have known.

Anyhow... here are some pictures of the mostly finished sub frame. I didn't make many changes other than reinforcing the upper frame mount so it will bolt to the oil cooler and sandwich the frame. Should be much stronger. I didn't come up with a satisfying way to mount the rear upper mount higher without sacrificing strength so it will be mounted a little lower. Although not ideal in location, I think it will be much stronger than the rear sub frame of the bike (up near the tail rack). I hope all will work out. I did get a little more width out of the lower mounts where the car frame will attach.







I spent some time rebuilding the car frame also. I shortened it and built in the swing arm mount instead of adding it to the outside of the frame like I've seen on many other builds. I don't know that this is better, just that I like the look of it more.







The width shown is narrower than actual width. I should be around 45-46" track width. Currently it is sitting at about 12" of wheel lead. How does this sound? I can drop down to probably 10" or go up another inch or so if needed.

I've bookmarked your thread- it will help me out immensely when I get around to hacking my KLR250. I'll have a lot of fab and welding practice to get through to start approaching your skills, though.

I have the wheel lead on my airhead rig at 9", which is about 12% of the wheelbase, from contact patch to patch. Everything I read prior to that build recommended wheel lead at 10-20% of wheel base, so I split the difference, but was also limited by the Dnepr mounts and subframe I used.

I think a touch more wheel lead might have allowed for left handers with a little less car nose dive. It's fine empty but with a passenger it dips a little. My car nose extends just past the plane of my front wheel axle, though, which looks farther forward than your setup.

[CAVEboy]

Picked up this 17" wheel to use on the car. It was a spare tire wheel from some SUV so already measures 4" wide. I know that a lot of people want car tires on their sidecars and bikes, but I wanted to be able to recycle my used tires from the DR by running them on the sidecar for a while. Yes, the profile of a tire on the stock 2.5" rim compared to the 4" rim is much different, but really they will still mount up and run down the road without any problems. I mounted up a 120 today to check it out and it fit so my 130s left over from the DR should work fine.

The backspacing was all wrong for the swing arm setup so I had to massage it a little.

Not the best looking wheel, but for $20 and free tires I'm happy.

[JoeyBones]

[CAVEboy]

My friend came through. Swing arm is done and mounted. Initial measurements are made with lead at 11" and track width at 46". I am ready to put this thing together with final gussets and welding but need a few more things from you experienced guys.

I am worried about the strength of this mounting system on the side car frame. With clamps for the lower mounts, the side car relies entirely on torsion of the car'sinner frame for support. Every time the car hits a bump, the upper frame mounts will be trying to rotate on the inside frame tube. Will this tear the tabs from the sidecar frame in time? I have seen similar setups and not heard of any failures, but my guts keep telling me to double check. I hope my questions make sense.



This picture shows the intended lower mounts of the diagonal struts. The blue tape is where the tabs would actually go. You can also see the lower frame clamps. I am worried about this tube on the car frame trying to rotate and ripping the tabs off. What do you think? Is this fear unrealistic?



Finished swing arm (minus suspension of course).

[CAVEboy]

This is one possibility to counteract some of that torsion. I can add some triangulation to the frame and mount the diagonals to those parallel to the new tubes. The tape shows the new bars. It would spread out the force a little better.

I could also mount the front diagonal as far forward and outboard as possible as shown by the actual strut in the picture. The rear diagonal can't go that far back to do the same so it would have to stay mounted to the inside tube of the car frame.

The reason for all this is clearance for the tub mounting. I don't have a lot of room to play with and even with the added bars (tape) I would have to mount very near that inner frame tube.





Happy with the ground clearance.



Happy with the stance.

[Motoblag]

I'm no engineer type but the front upper strut solution appears solid. I would assume the closer you get to square on the strut to frame angle, the less forces are acting to tear the tabs off.

The upper rear strut on Abenteuerfahrer's rig, as seen here, is close to square but not quite square. The front is square on the sidecar side.



iHop has these photos of what happens when the tabs, or in this case welded boss, fails:


More photos and discussion can be seen in the thread: http://advrider.com/forums/showthread.php?t=601636

[lemieuxmc]

I had slippage on my Velorex lower rear clamp on mount. I made a new mount from a single length of tubing that u-bolts to the inner and outer sidecar tubes to eliminate the torsion force, but still allow lead adjustment.

[CAVEboy]

I still don't have a spring/shock for the suspension. I was thinking about an air shock from a harley so I could mess with pressures a little. I found this cheap coilover on ebay. What do you think?
http://www.ebay.com/itm/11-Air-Shock...ht_2518wt_1163

[CAVEboy]

Thanks for the links. After a fair amount of reading this is what I settled with. I think this should do. I rigged up a rigid suspension and rode it around the neighborhood today. Interesting... I need to figure out what to use as a shock and then I can actually set it up and ride it with a little less sketch factor.

I read some interesting stuff about making the side car suspension height adjustable. Seems like it could be helpful for different weight loads. I like the idea but it will set back my timeline even further because I would need to order some more rod ends for the adjustable link. Thoughts? Lots of views but not a lot of weigh in. Thanks to those that have spoken up. I need the info.

[Kyler]

Originally Posted by CAVEboy

what is the diameter of the tubing on your swing arm and would you post a pic of the axle setup?

[CAVEboy]

All materials are 1 3/4" .120 tubing. The only piece that is different is the hub of the swing arm. It is schedule 80 pipe.. I think 1 1/2 but don't remember. The bearings of the swing arm are just some sealed bearings I picked up online with an ID of 3/4" and an OD of 1 1/2". The axle is simply a 3/4" bolt. I don't have any pictures of the bearings and such as I am at work today, but the journals were machined on a lathe for a pressed fit. It is a very simple and basic set up, but should do the trick.

Now for some info from you all on shocks.. please.

[Kyler]

Originally Posted by CAVEboy

Now for some info from you all on shocks.. please.

can't help much there - I had a shock made for my Wasp (Works Performance) and they were very helpful.

[lemieuxmc]

Originally Posted by CAVEboy

Thanks for the links. After a fair amount of reading this is what I settled with. I think this should do. I rigged up a rigid suspension and rode it around the neighborhood today. Interesting... I need to figure out what to use as a shock and then I can actually set it up and ride it with a little less sketch factor.

I read some interesting stuff about making the side car suspension height adjustable. Seems like it could be helpful for different weight loads. I like the idea but it will set back my timeline even further because I would need to order some more rod ends for the adjustable link. Thoughts? Lots of views but not a lot of weigh in. Thanks to those that have spoken up. I need the info.

The problem that you may have to address here is that the lever forces from the sidecar wheel are turned into a torsional force being resisted almost totally by the clamping ability of those two bolted clamps. The diagonal threaded struts are barely providing any assistance by triangulation.