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Wobble and bounce

OK, Folks. I am new to sidecar business. I purchased a used motorvations Formula 2 car. put it on a 2012 HD Road Glide. Getting totally frustrated. Harley shop has put it ondone a lot of work. Bike has a front end wobble and if you go over 55 it will start bouncing up and down like crazy. First, I kept telling the dealer it was taking me to the ditch. Finally when I had had it, drove in, they looked quick. Well axle was broken. Feeling like they are not listening to me and have made mistakes putting car on wrong. Seems to far out from bike. If I have the lever to almost center it will ride truer down rode. but gods forbid, don't let go of handles and don't go very fast. Any suggestions? Jean :o:-( :o:-(

Jean,

First, contact Motovation. Did you use their mount hardware? They are very helpful folks and may be able to give you some good ideas.

Generally, if you have head shake we start out by telling you to make sure you have your front tire fully [if not over] filled and check the tightness of your steering head bearings. Both these are known to contribute to head shake.

The lever you reference is is there to compensate for crown in the road. If you drive on roads with a lot of crown having the lever half way up isn't really out of line.

Good Luck!

The head shake can be mostly eliminated by snugging up the steering head. What I used to do (K1100 BMW/Motorvation Formula) was to jack the bike up so the front wheel was off the floor and tighten the large nut at the top of the headset until the front fork would fall slowly to one side or the other. Don't go too tight. You will dimple the bearings. This method eliminated my head shake.

First, if your front end is bouncing "up and down" more then likely the sidecar has nothing to do with this. Usually this is a tire issue, either out of balance or out of round. It can also be exacerbated by issues with the forks not dampening well often due to low fluid level.

Usually if you are having a head shake at higher speeds there is a lot of flex in the mounting system. We find that the 1 1/4 inch diameter tubing that Motovation (and others) flexes a lot which is why when we mount these sidecars we make the tubes that slide into the sidecar frame called clamps double walled and then we step up to 1 1/2 inch for the "boss" that slides into these tubes. This is much stiffer and as such along with stout hardware on the bike goes along way to addressing head shake. We have also found flex in the Motovation swing arm / torsion system that makes it hard to keep from having a front end shake. Usually the up grades on the mounts is enough. Motovation pretty much always has a steering damper to "hide" the flex in the system. A damper from a VW beetle is often used. Harley with their sidecars used a VW bus damper that they put in a Harley box and marked the price way up. As your sidecar is an older one the bushings that the suspension mounts in could also be showing wear causing issues. We do not make a damper for your bike as we have never found a need with our sidecars and hardware.

Head shake at low speeds especially on deceleration is not uncommon and usually can with proper adjustment be so little that as long as you keep one hand on the handle bars it is not an issue. A damper will hide this however we try to avoid dampers as they make your steering effort harder all the time which is the last thing you need.

People will often tell you to change the "rake" on the front end to fix this. What they are usually speaking of are triple tree's that change the angle of the forks to reduce trail on the front end. This looks like changing the "Rake" but does not actually change the rake, it does reduce trail making for easier steering. In general this will not fix a front end shake it can however make the shake so much easier to control and as such easier to live with that people think they have made the shake go away. We offer these triple tree's for $695 to USCA members and we have them in stock.

Alignment can also make a huge difference, you say you think that the track width may be to great, narrower track widths tend to have less influence on front end shakes then wide track width. Wheel lead can also effect a front end shake, the more wheel lead the more likley you are to have a front end shake. We like to set wheel lead to 10-15% of the wheel base of the bike. Motovation calls for less. We have also found changing toe settings by as little as 1/8 of an inch can make a huge difference in front end shake. While we never would recomend riding hands free once over about 20 mph your rig if set up well should not have any tendency to have a front end shake.

When speaking of the "lever" I assume that this is one of their older sidecars that has a manual lever for changing the ride height of the sidecar to trim for load and road conditions. When setting sidecars up from scratch we like to have adjstable leveling (we do it electricly and call it electric trim) such that you have very little down adjustment and lots of up as you will seldom need to lower the sidecar from its base set up. As such I suspect you do not have enough lean out on the bike.

You can check the alinment your self. It is not all that hard to do. I have attached instructions. On our web site are three video's the first tells you about us, the next two show how to install and align a sidecar. http://www.dmcsidecars.com/sidecars.

Hope this information helps you straigthen things out. Sidecars are a blast to ride once set up correctly.

Jay G
DMC sidecars
866-638-1793

Attached files

BASIC SIDECAR INSTRUCTIONS.doc (389.5 KB) 

Jay G DMC sidecars www.dmcsidecars.com 15616 Carbonado South Prairie RD Buckley WA 98321 866-638-1793 Hours Monday - Thursday 6-4:30