Posted 7/4/2014 6:07 PM (#78627) Subject: Handling at speed
Since I changed cars to a heavier Ural car the rig had developed a bad wobble from 15 to 25mph I changed the tire on the car it was an old russian tire even full of air you could flex the sidewall by leaning on the car. I also replaced the shocks on the bike and replaced the springs and put heavier oil in the forks. The bike used to sink 3 inches when I sat on it now only 1 inch. The low speed wobble is gone! yay, however now at 40 to 55 ( I haven't gone past 55) it will occaisionally oscilate as though letting off the throttle and rolling back on. It isn't really pulling but wondering if it could use more toe in? It is a 2000 883 hugger w/ural sidecar 3/4 inch toe in 1 degree leanout right now.
Posted 7/5/2014 3:43 PM (#78634 - in reply to #78627) Subject: Re: Handling at speed
Posts: 4833 Location: Boise, Idaho
The toe -in seems OK, probably near max.
Lean out wouldn't cause the oscillation, unless you are quite heavy, or the mounts are flexing.
One way to check if the toe-in is correct, is to check the sidecar tire tread for smooth wear without any sign of scrubbing.
One side of the tire tread may have a rounded edge on one side and the other a sharp (perhaps feathered) edge.
A rounded edge on the bike side indicates not enough toe-in.
A rounded edge on the outside indicates too much toe-in.
I assume this is a right side mount sidecar.
Posted 7/6/2014 3:32 AM (#78637 - in reply to #78627) Subject: RE: Handling at speed
It is mounted right hand side. I am 200 lb. dont think the mounts are flexing seem pretty stout, also didn't mention this has an 8 inch lead.I tried adding more toe in to 7/8ths inch now actually felt a little better but still got the oscilation. I checked end play on the the tugs wheel bearings all in spec but did find the sidecar wheel can rock back and forth with an audible clack. Haven't found a spec for end play on this only that they are tapered bearings so I know they are too loose but not sure how tight they should be. I suspect this may be a contibuting factor in the handling.
I will keep an eye on the tire to see if it feathers towards or away from the bike once I adjust the bearing end play(good info thanks).
Posted 7/6/2014 11:46 AM (#78643 - in reply to #78627) Subject: Re: Handling at speed
Posts: 4833 Location: Boise, Idaho
Shouldn't be an audible clack when rockng the wheel.
Another culprit could be the bike swingarm bearings.
Edited by Hack'n 7/6/2014 12:04 PM
Posted 7/6/2014 3:55 PM (#78651 - in reply to #78627) Subject: Re: Handling at speed
Found a write up on adjusting the sidecar wheel bearing, got 3/4 turn on the compression nut. It has no noticable play now and spins free. I really want to go for a spin and try her out but its 105f here now and wont be getting any cooler till sundown
Posted 7/6/2014 7:39 PM (#78655 - in reply to #78627) Subject: Re: Handling at speed
Ok its not sundown yet but couldn't resist at least going out and staring at the rig. Anyway got to shaking the pusher wheel back and forth and with a finger on the pivot point of the swingarm can definitley feel movement. Man 2000 seems like yesterday but I guess it was 14 years ago. Thanks for the suggestion Lonnie, guess I'll be getting a swingarm kit and throw that in. Thinking maybe the improvement seen after increasing toe in was just from opposing force between the car wheel and the pusher, I'll readjust later after reading the tire.
Posted 7/7/2014 11:12 AM (#78670 - in reply to #78627) Subject: Re: Handling at speed
Is your wheel straight on the sidecar? Is the tire round and balanced?
Posted 7/7/2014 12:10 PM (#78672 - in reply to #78627) Subject: Re: Handling at speed
I checked runout on the rim when I changed the Russian tire out, it was out of spec with some loose spokes. I have all spokes torqured and got it down to .040 have checked it again after running and still good. I balanced the tire when I changed it, removed 9oz relocated 2oz (the old tire was not round).
On another note your 70 degree boss and Hiem joint connectors make adjustments on this car a snap! It will be a week before my parts come in but there is plenty of lateral movement on the swingarm so I'm thinking this should make a difference. I will check runout on the pusher once I get it removed. Thanks for your help.