Well if some of you remember, I stumbled across this new Ural Car. Not really in a position yet to buy the bike I want, I have attached it to my old CX650E. Now I set some criteria before I started. Use Material I have on hand, (read Cheap), Don't modify either the bike or the car, meaning "be able to take mounts off leaving the original. Planning on being able to ride this beast and learn what I am doing, before I get it properly mounted to a better bike. I am not going to show any of my fab as I have just read through Zipper's thread(Winter Build) and am a tad embarrassed of my fabrication skills. I am an Auto Tech, not a Welder/ Fabricator. I have made my mounts adjustable but not so much for fore and aft. Rethinking on how I will redo it but I have to buy stuff. My lead is right on "about" 15 % of the wheel base and the track is 54 inches. Wheel base of 58.5 inches So I finally got the bike running Yesterday and was able to take my first rides around the Cul-de-sac. Gets going nicely and turns both ways fairly even. Damn near ran the car into my truck :huh Newbe !! Here is the Issue, I have a head shake of enormous proportion. Starts at about 15 MPH and gets worse. Too scared to go faster:eek1 I tried a few things, Played with lean out and toe in, tire pressure and I can adjust air pressure in both the front and rear suspension, nothing seems to change it. I am thinking I have the weight distribution off. If I put weight in the front of the car that should put more weight on the front wheel ?? The Unit seems to turn left easier than right, so I don't want to increase the lead. I also gave it a bunch more toe in, hence the easier left turn, but the head shake is the same. I think my mounts are strong enough so flex shouldn't be the issue. I know a steering dampener will help but I would like to kind of solve the problem then use the dampener. Any Ideas to point me in the right direction?? https:// https://
Just install a steering damper. Headshake on a sidecar is normal, but annoying. It is the sidecar pulling and pushing on the front fork. It is usually at low speeds. When you hold the bars and pull it over 40Mph it will vanish.
Important stuff first ... please tell me that is an MGB-GT in the garage. Head shake at that speed is normal , you'll get used to it and will not even notice after a while. Much like steering away from the chair when you take off ... it's a sidecar and that's just how it goes. The next time you are unfortunate enough to have to go shopping and use a shopping trolley watch the front wheels on the trolley when you start moving. They'll get head shake. The cause is the amount of trail. A damper just masks the problem which at this point is set up. Trail reduction with the use of a damper helps to take away that light headed sensation from having so little trail. Without seeing a clear frontal picture from near ground level it's hard to pick but you appear to have too much camber on the chair. Beautiful chair by the way . The color suits it. .
I understand that a bit of head shake is normal but this is tank slapper stuff, to the point that I can't hold it. The picture is a bit off, the car wheel is vertical as best as I can measure on a level floor and I have tried 1/2 inch to 1 inch toe-in Thinking from what I have read that lean out just effects pulling one way or the other. Was going to play more today but Daytona 500 is on right now Yes that is an MGB GT-- there are actually two in the shop, both Race Cars that take up way too much time and money Both are HIllclimb/Solo cars. Brian
No I didn't, working by myself, it is kind of tough to do. I did check with no weight and exactly zero on the car and about a 1/2 inch with the square against the rear wheel of the bike measured at the length of the square. Will get Kathy to sit on the bike with a sack of Cement in her lap, Hmmm maybe not!!! Going to reset things to see if it changes. As I have learned with the MGB, make big changes, record what happens then go the other way. I am kind of a trial and error guy-- mostly error Brian
I placed 2- 80 pound bags of sackcrete on the seat, which is with in 4 pounds of my weight, while I set up lean and swingarm height. You also could try wider bars for more leverage.
Just finished my Dakar Hack and I have the same problem. Tank slapper so bad it feels like the rubber is going to rip off the rim. I am paying close attention to suggestions on how to solve the problem on your rig. Good luck.
Some reading also :http://www.sidecar.com/mbbs22/forums/thread-view.asp?tid=7036&posts=4&mid=42681&highlight=wheel+bearing+&highlightmode=1&action=search The Heckler may have a point ! If only his explanations where a little more concise. I believe what he's saying is your sidecar wheel is not straight up and down,it may be leaned out at the top(away from car and bike). You may want to get that wheel straight up and down or slightly in, while the bike leans out (away from the car unloaded) then recheck your toe (always the last thing) you most likely will need a steering damper anyway.When I'm having a bad day I always wish mine was a Mini Cooper,since your a wrench we'll assume your steering head bearings are tight and in good shape.DB
I'm inclined to think at this stage he has too much lean out. As the rig moves forward the forks due to trail ( reduced or not ) are trying to swing around the head stem which itself is inclined and not perpendicular to the ground. As the forks swing one way the natural trail characteristics ( self center the steering ) are then swinging the forks violently the other way ... and so the cycle goes. Ask TouringDave to post up a picture of his sidecar axle. The same style can be bought for speedway bikes. When I built my first one I was in a major hurry due to time constraints. One of the , what I thought at the time , bloopers was that the axle was not square to the swingarm. What I found in use was that as the wheel moved up in compression it also added more toe in and kept the outfit on a straight course ... a very neat by product. .
The Heckler may have a point ! If only his explanations where a little more concise. I believe what he's saying is your sidecar wheel is not straight up and down,it may be leaned out at the top(away from car and bike). You may want to get that wheel straight up and down or slightly in, while the bike leans out (away from the car unloaded) then recheck your toe (always the last thing) you most likely will need a steering damper anyway.When I'm having a bad day I always wish mine was a Mini Cooper,since your a wrench we'll assume your steering head bearings are tight and in good shape.DB[/QUOTE] Thanks for the ideas, and I checked and tried several different settings. I did check the steering head bearings, they are fine. The best I could come up with was about a 1/4 inch of toe and about an 1" of lean out on the bike with me sitting on it. I also put about 75 pound of lead in the front of the car. Got it to about 25 mph before I scared the Shit out of my self. The car wheel is straight up and down, checked with my camber gauge. Of course not with me sitting on the bike. Remember I can adjust ride height on the bike with Air pressure to compensate for my weight. Tried lots of combos, Stiff, soft, in-between, nothing seems to reduce the tank slapper. After thinking about it and rolling the bike around I think I have the lead screwed up. The car moves a lot fore and aft when I turn the handle bars, and if I understand Pete Smith's summery on Scrub on the Side Car wheel in the Design forum I must have it wrong. Both the head shake and the car are working together to intensify the head shake until it is uncontrollable, or at least I don't have the strength. I am going to have to redo my mounting set up so I can adjust it better. Obviously there is more to this than I thought, Who Knew Brian
Would that be 8-9" of wheel lead ? 1" of lean out ? How would you measure that ? The Heckler may be right that you have too much lean out. Possibly straighten the bike up and try again, I personally hope Claude notices this thread and offers an opinion.My rig which hasn't much in common with yours(mines big and heavy) is almost straight up and down static or unloaded and just a hint of lean out when loaded.Depending on who you would be inclined to do business with in the future you may want to call and ask for assistance, I'm one of Claude's customers cause he was helpful before I spent any money with him.DB
Also lower the fork legs as in raise the fork legs through the triple tree by about 5mm. This will decrease trail slightly. Might help, certainly did on my bike. Makes the steering sharper. Unless you put a leading link on you will need a steering dampner. 3legs
You can give me a call if you like and I will see what I can do to help. BTW, I use to be an auto tec. (ASE master automotive as well as medium and heavy duty truck) Bet your MGBGTV8 is faster then the MGCGT my wife and I had for many years. Jay G DMC sidecars 866-638-1793 866-638-1793
Just a guess but with 92% of your wheelbase hanging out there on the end you may have the tub pushing the tug around. That's a pretty heavy wing (with a fuel cell) to be throwing on a fairly light fuselage. I dunno, seems to me when your lateral almost equals your longitudal things could get squirrely. Don in Nipomo
Again thanks for the ideas I may have been a bit off on some of my dimensions. Between measuring, changing and riding, then posting here, a few numbers got skewed. My track is actually "about 50 inches", it changes with the toe I set. I have a lead of 9.5 inches give or take an 1/8th My wheel base is 58.75 inches which puts the lead any where between 8 3/4 and 11 3/4 if my math is correct I picked 9.5 to start with ( guessing) but didn't really build in any adjustment. My bad. I didn't even think that the head shake would be an issue just pulling or turning issues. I did notice in my circles I did out front of the house. ( the Neighbours get quite a kick out of me, MGB testing you realize) That it really changed how the unit felt after each change, kind of what I expected to deal with. (Notice how the name has changed to Unit) I was quite careful to make sure the Car frame and wheel were level and vertical after each change I made. I have re-thought my mounts and can invest a bit more time in this project before I give up, ( It took 20 years with the Old MGB before we broke the hill record where we run ) Unless I find the perfect GS in the next week or so Then I will bundle the whole shabang up and take it to some one who knows what they are doing. Baring that I will also plan on a steering dampener. I believe that the car is pushing the tug around and due to the lightness of the bike, there is just no mass to counter act this action, with the trail of the bike also reacting to the push of the car. It just becomes more than I can control. Can you say Shopping cart:eek1. Thanks for the offer Jay I may be in touch. I also took all the ASE levels, no real need for me as I am a Red Seal Mechanic here in Canada but it was offered and I wanted to test my self. And Yes the B GT is quite a beast, 450 hp in a 2200 lb chassis, No head shake but the rear wants to pass the front when you get on the gas Brian
One other thing you might want to consider in the equation, Brian: many people have claimed somewhat amazing differences in handling and shake by juggling tire pressures. A major change higher followed by a similar amount of change to lower pressures may be worth looking into. In any event, the higher pressure on bike front tire may make steering lighter. Also there's 3 tires to play with independently so that broadens the possibilities.
Thanks I have read that but didn't think to try it. Caught up in the mechanical aspect. Speaking of which, what year, type of VW does the dampener come from, I am assuming older beetle. Year?? 90 degree plain from the fork?? I was also thinking, :eek1 even though I have jumped on, tugged, pushed etc. my mounts on the bike, that flex there could be a culprit. I do have them separately built and they are solid to look at but once the force of the car is against them. hmmm so many things to think about, finding it a bit of a fun exercise but it is taking a bit too much of my time. Brian
