Holy cow, I have a couple of questions that I will break out into two threads, they are that different..
First off I went for a blast today to film a TV promo for the up-coming 7th Annual Western Maine European Rally that happens at Sunday River Ski Resort in Bethel, Maine... shameless plug. http://eurobikemaine.org
When I got back I measured for lead of the car to the tug.... !! Conservatively 13" ... !!!!! That is using a pretty well trigged out set up to verify that things were fairly square to be able to measure axle center to axle center.
So, think that has something to do with the tracking of this rig...?
I will need to contract the help of a decent sidecar set up type person to aide me with the fabbing of brackets or lugs, whatever may be needed.
It appears as though the person that set this up went with the easy way out which, as we know, is not always the best way.... and the front/lower mounts are using an existing frame bolt that while convenient, is wrong. That made the rig way too far forward.
Back to the drawing board...
Rob
13" is a lot of lead, and will contribute to heavier steering and perhaps a greater tendency to pull to the right or increased tire wear and higher fuel consumption, true.
But I think if your mounts are shifting the changes in lean out/in and toe in/out that are resulting are probably the source of any handling problems.
See if you can get your mounts solid and play with the alignment and see what happens.
if you can reduce your lead easily by about 5", fine, but my guess is your biggest problem is the mounts.
The thirteen inch lead won't hurt tracking of the rig. However it will cause quite heavy steering.
Sidecar lead is relative to the wheelbase of the bike. There is no single ideal lead in inches for all rigs. The 4" to 10", or 6" to 8" numbers that are floating around are just numbers someone has heard from someone else and passes on as gospel. It stands to reason that the steering of a shorter wheelbased rig would benefit from less wheel lead than a long wheelbased one.
Advice that was passed around in the past was: The less the lead, the easier the steering. More lead offers better high speed stability.
Maybe that was seat of the pants Trig. lol
Lonnie
Ok,
Red and Lonnie I will check on the clamps first and continue to analyze the steering, handling and general driveablitiy.
The theory about more lead equals more high speed stability is spot on. The rig seems fine at higher speeds, well all but the lack of being neutral in steering, still pulls right. Steering is heavy to the left taking off from a stop and in left-handers.
Yes it was seat of the pants Trig and I checked it many times before I was satisfied that the figure was 13".... !! lol
What happens to the other mounts when the clamp lets the rig sag..? Do the struts just rotate on down in the clevis...? I have noticed a slight bend in the front lower strut bolt... should I replace that...?
All right, I have some work to do.... I'll start with the mounts and go from there.
'preiciate it,
Rob
Hey Rob: I'd be happy to take pics of the mounts I'm using if that'd be any help. Can't remember, but did you contact Lee Bruns? I think he's made a set of Velorex to Guzzi mounts.
Rich
One way to think about lead is that the farther forward the sidecar tire is the more it shoudl be able to steer with the motorcycle. Think of driving a car with the right front tire not being able to be steered. Oversimplified? Maybe so but basically true.
Take that same car and remove the right front tire and the nose of it would fall down. So..we move the sidecar wheel forward to add support to the rig especially in left handers and sacrifice some steering ease etc as part of the compromise.
With too little lead a rig can be downright dangerous in left handers. This can be especially true with lighter bikes with soft suspensions.
When it comes down to it almost all of the figures talked about when talking about lead end up being seat of the pants figures anyhow. The 6 to 10 inches or whatever are good base lines but mean little until the rig is riddeen. Why is this? Lead really should be related to percentage of motorcycle wheelbase, track width and even how stiff or soft the suspension is on all corners.
Two things that may be interesting to some. With a steering sidecar wheel a rig can run more lead with much less ill effects on steering overall. With a swaybar a rig can run less lead and still be stable in the turns, left handers especially.
Hi Rich,
I have not talked with Lee as the rig was already set up and I did not realize that I was having this issue until just a couple of days ago. I'm going to run through all the mounts, clamps and bolts to be sure they are tightened against the frame or shims properly and eliminate problems as I go. The sidecar frame clamp seems to be the culprit just to start with. Then move on to the "Lead or not to Lead" issue... 😉
I'll let you know if I need the photos... thank you.
Speaking of photos... Have a good time at the Nat'l ...? Nice shot of you and Miss....???? Your outfit looks great... !!
Gettin' there...
Thanks,
Rob
Originally written by claude #3563 on 7/21/2006 7:18 AM
One way to think about lead is that the farther forward the sidecar tire is the more it shoudl be able to steer with the motorcycle.
With a swaybar a rig can run less lead and still be stable in the turns, left handers especially.
Claude,
The thing about this rig the way it is now is that the steering is very heavy... has to be that clamp slipping.
I am going to spend most of Saturday sorting things out.... Every morning in the garage, finishing my last cup before hitting the road to work (on a different Guzzi) I just look at things on the rig, that clamp slipping is hauling the top of the cycle toward the Hack.... I am getting anxious to get this dialed in.
Some of this is my own fault for not checking every bolt, nut and clevis before I started riding (driving..? ) the rig. I would never have done that on any other motorcycle that I have owned... especially if it had a few miles on it.
I may have to contact you about a sway bar as I move forward on this..
Thanks much,
Rob
