Why is it doing this??

dumb question,..is there any loosness in the mounting of the tub's axel assembly itself? sounds like the bolt to the bike is secure, yet there is unpredictable loosness , wheel and hub mount all secure?,..just thinking out loud, my hack tire is towed and cambered in a bit heavy also, but no loose feelings anywhere.purhaps the looseness is only present with heavy road drag?...block up the rig and bar lift under hack wheel, same test for auto balljoint movement??? ..good luck and be safe, crawf.

Sounds like it is not being caused from the normal low speed front wheel shimmy (the LLs should remedy at least most of that) that can be controlled with wider handlebars and a steering damper.
Is it due to acceleration or braking? Being an asymmetrical vehicle the sidecar will lag when accelerating causing a pull to the right and pull to the left under deccelerating or braking. Quite normal and controllable.
A bit more toe-in may be in order if it is a wide track mounting.
The slight lean in of the sidecar wheel won't cause the problem you describe. Many set the sidecar like this purposely. The stock URAL is set up with the wheel side higher than the bike side.
Modifying the front URAL mount to raise the car to level isn't much of a job. Cut and insert weld a short section of tubing.
It almost seems like you don't have a rigid sidecar to bike mounting setup unless the LL's aren't allowing enough trail to maintain a straight path without constant steering correction.

Lonnie
Northwest Sidecars

Thanks for the responses.
The sidecar axle is not loose. And no, I am not talking about acceleration and braking forces.
I plan to weld in an adjustable sleeve and pinchbolts to the front car mount like the mount arrangement on my Hollandia (then I know I'll be able to adjust the chair level, even if I change to a different tire size).
As it is, everything on the rig seems perfectly tight... Yet, it keeps wandering...
I think I will move the earles swingarm back to the 'solo' position and see if that might make a difference... increasing the trail seems like a reasonable thing to try. Thanks.

Hack'n - 4/11/2011 3:00 PM

....unless the LL's aren't allowing enough trail to maintain a straight path without constant steering correction.

That was my first inclination as well. Please let us know when you figure it out.

Here's an Update:
Moving the front swingarm back to the 'solo' position, as predicted, made a good improvement.
I can now drive a straight line with confidence. The rig still exhibits the weaving behavior a bit, but much less of a problem. I seem to notice it now particularly while decelerating (slowing down without the use of my brakes), and also when the road slants away to the left. Could the tires cause such behavior?
Tomorrow I'll adjust my lean-out (as I stated before, it's a little too much presently) and see if that changes the behavior at all.
I'll be happy when this gremlin is gone for good.

How is your sidecar tire wear pattern? If unusual scrubbing is noticed one way or the other you may have too much toe -in if it has a tendency to pull to the left.
How are you measuring toe-in?

Lonnie

Lonnie, thanks.

I haven't run this rig more than a couple hundred miles so far. Can't see any evidence of scrubbing off the rubber yet.

I use strings to check the toe-in. I have a couple of long heavy pieces of aluminum angle which I place perpendicular to the bike at the front of the front tire and the rear of the rear tire. I stretch the string (with the help of my nephew, or my wife) to contact the edges of the rear tire and mark where the string crosses the aluminum angle with a sharpie marker. Same with the sidecar tire, then measure the distances on the aluminum angle pieces. I would be interested to hear how others check their toe-in. I seem to get good repeatable results with my method.

Pulling to the left is not the problem... It pulls to the right and the left alternately and unpredictably (what my Dad used to call "chasing rabbits"). I've seen old cars do this with the front wheels toed-out, but usually with some amount of lost motion in the steering. It's as though the weight shifts to the right wheel, causing the car to go right, then the weight shifts back to the left wheel causing the car to go left. The cure for old car steering is to take out the lost motion, and give the wheels a bit of toe-in so they both remain under a predictable side-loading (I know that newer cars have better geometry and work with Zero toe-in).

Now that you mention it, I think I may try ZERO toe-in and see how that works... Would likely improve my fuel economy and tire wear, if it doesn't make the handling worse.

Steve,
I use two 1"x1" lengths of square steel tubing for standards. On 4"x4" blocks. One placed against the REAR bike wheel only
(since many bikes have different sizes front and rear), the other against the sidecar wheel. Using a tape measure I check side to side behind the rear bike wheel to the sidecar wheel standard and ahead of the front wheel to the sidecar wheel standard.
Since bikes vary greatly in wheelbase I usually set toe-in between 3/8" and 1" for the initial toe-in setting.
The lesser amount for shorter bikes or close track rigs and the larger settings for longer wheelbased bikes and wide track setups.
After road testing final tweaking for the best tracking may be as little as 1/4" or up to 1 1/4" for some doublewides.

Lonnie

Just a thought -- maybe the issue isn't with the sidecar at all, but the motorcycle. You might want to check your rear subframe for cracks and swingarm for play. A futzed rear suspension CAN cause steering problems.

Ed Bianchi

Sounds like everyone is doing things right on the alignment issue. Here is a visual on the technique, as done by the #1 Rooskie worker at IMZWA. Hope it helps. Some folk use the 8' florescent light bulbs instead of the aluminum rails. Some use the aluminum electrical strips like used in shops and homes. My only worry over using strings is that string can possibly stretch and fool ya'.

Me, I am guessing it is more on the bike end than the hack and hack frame, but I am simply guessing. Ural tubs don't require dampners when mated to Ural motorcyles, but one never knows with a modified combo. I just met a fellow in Arlington who rides a BMW with a Ural hack that he bought from Perry's, in Ft. Worth. Wish I had seen this post first and asked him yesterday about his method of alignment and if he had any issues, as mentioned. I didn't look his rig over for that sort of thing, so I am not sure how that rig was set up for him. Heck, I didn't even look close enough to know what model BMW it was, as his rig was the same color as my Troyka and we mainly discussed my Ural Troyka, instead. Maybe I'll run into him in the near future again and get to ask him about the alignment and handling issues. His rig sure looked nice. It was actully a chance meeting at the local NAPA store, but he did tell a funny story about riding along with a friend who owned a Ural. He couldn't believe that the Ural owner couldn't keep up with him on a trip they took together. He actually had thought that because both bikes were of similar size, that they were of the same engine size. He kept having to slow down for the Ural at every hill. I laughed about that one. Yup, a 750 Ural is no speed deamon to compare with, especially when it drives like a brick in the wind. He thought the issue was that the other fellow was riding with his shields on his bike and hack. 🙂

how are the fork bearings ,swingarm bearings?

Nobody yet has asked if the wheels are true. If the wheels are not perfectly round and no side to side varience the machine will do exactly as described.
Put the wheels on a truing jig and true them all. Make sure all the spokes are tuned.

Phelonius