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-   -   Should there be pull on a leaner? (http://www.advrider.com/forums/showthread.php?t=812185)

BuiltnotBought 07-27-2012 08:12 AM

Should there be pull on a leaner?
 
Having no experience opperating sidecars yet, I'm wondering if any amount of pull is normal on a leaner (Kalich style) when adjusted properly? It makes sense to me that a properly setup rig should fly straight, but don't want to assume.

I'm working a leaner right now and hope to take it for a test spin by next week. I'm excited for the first ride, but dreading the setup. I'm hoping I have the toe-in and wheel lead at suitable settings now so that only minor adjustments will be needed. But hey, its my first time down this road, so I expect at least a couple setbacks.

leejosepho 07-27-2012 08:31 AM

When the drive and braking are not centered within the overall mass, the drive will always try to pass the offset mass and the offset mass will always try to continue on during deceleration or braking.

BuiltnotBought 07-27-2012 12:06 PM

Right, but the toe-in is to correct that problem right? My question is, with correct adjustment can you completly eliminate this effect while cruising, or will you always have to be pushing on the RH bar?

Mechanista 07-27-2012 03:31 PM

Quote:

Originally Posted by BuiltnotBought (Post 19226896)
Right, but the toe-in is to correct that problem right? My question is, with correct adjustment can you completly eliminate this effect while cruising, or will you always have to be pushing on the RH bar?


Wellllll...
In theory, yes, if it is adjusted correctly, and the rig design is stiff enough, the pull shouldn't be very discernable in a straight cruise. But wind drag and friction will cause it to pull at higher speeds, no matter what you do.
This effect can also be used to steer the rig to a small degree as well, without turning the bars on medium to small sweepers. Throttle on to go right, and throttle back to go left. (Assuming you are in N.A.)

BuiltnotBought 07-27-2012 05:31 PM

Ok, good to know, thanks.:thumb

BuiltnotBought 07-27-2012 08:44 PM

Well a bit of success tonight, I got enough finished to brave a bit of a test spin up and down the street.

I took it up to about 45-50mph without any real pull at all!:clap

Bad news is that at very slow speed, say 5mph turning around in a lot, or pulling out onto the street, put it into a very brief but very strong headshake.

Common trouble at that low of speed? Possible cause?

Seems too slow of a speed to warrant a steering dampener. I wonder if maybe I just need to limit the radius of my turns at slow speed with the sidecar on. Things to keep me up tonight an mull over I suppose. I want to get the frame finished up with a few more gussets before I put any more road time in, so that will give me some time to think on it.

Oh, and the shock I chose I'm sure is too hard too. I can jump up and down on the frame beside it and it won't bounce more than a quarter inch. Might have to look into atv or dirt bike shocks again.

Pete-NZ 07-27-2012 10:53 PM

I built a offroad cargo leaner.. It tracked straight with no pull..
There was no pull cornering till you run ot of lean..
I found a lead of 10% worked best "on my set up"
A leading link front end is not needed steering weight
did not change... when you set it up have the front mount
higher than the rear then the car will steer in the direction
you turn as the bike leans.. I had the front mount 75mm higher
than the rear.. A longer arc ratio on the front mount..
Have the mount points in line with the wheel centres
of the bike then as the bike leans its not trying to lift or lower
the car & the car weight is not trying to lean the bike...

The only issue with it was I didn't give the bike enough lean..
I'm building anther leaner for my XT660R at the moment...
The first one was really a trial to see if they were any good
offroad,,,,

leejosepho 07-28-2012 03:27 AM

Quote:

Originally Posted by BuiltnotBought (Post 19230211)
Well a bit of success tonight, I got enough finished to brave a bit of a test spin up and down the street.

I took it up to about 45-50mph without any real pull at all!:clap

Congrats! I had no idea what my first spin might reveal, then it went as well as yours.

Quote:

Originally Posted by BuiltnotBought (Post 19230211)
Bad news is that at very slow speed, say 5mph turning around in a lot, or pulling out onto the street, put it into a very brief but very strong headshake.

Common trouble at that low of speed? Possible cause?

You are pushing the front tire to one side to turn the rig and your trail is trying to pull it back straight. Mine does the same even though I would not call it "very strong", and my decision about trail will be made in relation to shake at higher speeds.

Quote:

Originally Posted by BuiltnotBought (Post 19230211)
Seems too slow of a speed to warrant a steering dampener. I wonder if maybe I just need to limit the radius of my turns at slow speed with the sidecar on.

I drive like an old man because I am one, and that gives me a right to take my time whenever I have to make a hard turn wherever!

BuiltnotBought 07-28-2012 05:04 AM

Quote:

Originally Posted by leejosepho (Post 19231400)
Congrats! I had no idea what my first spin might reveal, then it went as well as yours.


You are pushing the front tire to one side to turn the rig and your trail is trying to pull it back straight. Mine does the same even though I would not call it "very strong", and my decision about trail will be made in relation to shake at higher speeds.


I drive like an old man because I am one, and that gives me a right to take my time whenever I have to make a hard turn wherever!


Thanks! So then maybe this shaking is just something I will get used to and learn with experience how to avoid that "un-sweet" spot. I'm really looking forward to riding this thing some more!

leejosepho 07-28-2012 05:54 AM

Quote:

Originally Posted by BuiltnotBought (Post 19231620)
Thanks! So then maybe this shaking is just something I will get used to and learn with experience how to avoid that "un-sweet" spot. I'm really looking forward to riding this thing some more!

In an overall effort to leave a good impression of sidecar rigs, I actually enjoy driving mine in such a way that other people do not ever have to see any "shake" at all (like when I make a slow-speed turn) and then possibly end up thinking rigs might be dangerous. Rather, it is just a matter of an operator knowing his rig and keeping everything under control.

Leaf 07-28-2012 09:13 AM

Quote:

Originally Posted by BuiltnotBought (Post 19231620)
Thanks! So then maybe this shaking is just something I will get used to and learn with experience how to avoid that "un-sweet" spot. I'm really looking forward to riding this thing some more!

Is it bad enough that you can't make it stop?

Mine tries to wag at around 25 mph, but it stops doing it pretty as you please if I hold the bars a little tighter.

Back when I was talking to Claude about hooking the Velorex to the Hawk, he said that if you have tapered roller bearings in your steering head (but /not/ ball bearings), you can tighten the steering head down a little more than you're supposed to and it'll take care of the head-shake. Without having to install a steering damper.

BuiltnotBought 07-30-2012 01:03 PM

It wasn't too much to handle, it just surprised me quite a bit. I think I was maybe just trying to try to turn too sharp at too slow of a speed. It strikes me that as soon as I widened up my steering arc it stopped. For all the trouble it would be to install a dampener I might just do that if I have to.

Finished up some welding today, looking for a better shock to use, then I will start putting some more miles on it and hopefully be able to figure out a little better what is normal and what isn't. It was wierd enough just riding a motorcycle that was 52" wide! That alone will take some getting used to. :)

BuiltnotBought 07-31-2012 07:14 AM

Did a longer test ride last night, rode well but there is enough of a headshake problem that I think I will get a dampener for safety. I had some shake at faster speed, but I think that was possibly due to the cars suspension. I noticed on bumps that the whole car was jumping on me, which of course translated to some rough tugging on the undercarriage of the bike, causing headshake - thats my thought at least.

A softer shock is on its way this week, and probably a dampener as well, then we'll see how she rides. Might even be confident enough to post some pics of the rig then.

Leaf 07-31-2012 07:25 AM

If it's too bouncy, I wonder if the shock piston just needs rebuilt, and it's just riding on the spring at the moment without any hydraulic damping. :3

I am pretty sure that's why my Velorex is so sproingy. I don't think the Hawk outfit is worth putting much more money into, though, so I just throw some extra weight in the sidecar when I go on bumpy stuff, and that seems to calm it down a good bit....

If I have to put a damper on whatever tug the Ural chair goes on, I'm gonna to use a cheap VW damper. :clap

BuiltnotBought 07-31-2012 10:00 AM

I see old gixxer dampeners on ebay for $30 shipped...?

The 250 shock is meant to work with a linkage, not direct link, thats why I think it is too stiff. I'm getting a shock off a crf70 kids dirtbike, I'll try it, but really its going to be trial and error I think.


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