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Old 03-23-2015, 03:17 PM   #1
Ridn3 OP
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Steering damper to strong?

For the first week on my 2004 R1150RT rig I had a pretty strong wobble between 15 and 20 mph. It is rock solid at anything above that. We put a steering damper on it that was from a Harley/Hannigan rig and the wobble went away. Unfortunately a new problem cropped up. On straight sections of road the rig tends to wander or dart to the right or left requiring almost constant correction. It is bad enough that my passenger noticed it within a half mile stating "somethings wrong, this doesn't seem safe".

Today I* disconnected the damper and the headshake is back but the darting is gone. Our thoughts are that the damper is to strong and causing the darting, much like when steering head bearings are to tight on a 2 wheel bike. An any thoughts on this? Is the VW damper weaker? The 20 mph head shake is too strong to be able to control it even when applying a lot of hand pressure if that makes a difference.
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Old 03-23-2015, 03:45 PM   #2
offroad
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No expert here, but some recent experience:

What is the condition of your front tire? Has it been doing sidecar duty long enough to be worn more on the right (inboard) side because of lean in?

Also what air pressure are you running in aft, front and sidecar tires?

I ask because head shake was an issue for me until I changed out the worn front tire (which wasn't "that bad") and after the new tire, no head shake on my sidecar rig.

When some vehicles are perfectly aligned (i.e. manufacturer's recommended specs) the will exhibit "hunting" behavior at certain speeds. In the case of the 2000 Ford F350 experienced alignment techs will set the alignment off spec by 1 degree to eliminate the hunting the wheels otherwise do as they try to track straight going down the road if they are aligned to spec. It is nearly impossible to drive straight down the road without a slight feeling of the the tires searching from side to side for a straight path when aligned to spec.

It could be your steering damper is acting to offset some hunting behavior at speed and creating more of a problem than would otherwise exist, but I think alignment is going to be where you find your solution.

Good luck with your rig and let us know how you come out with a solution.

Jim
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Old 03-23-2015, 03:56 PM   #3
seekeronsaltspring
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have you adjusted it to an softer setting On an ural you change it until you find the sweet spot.
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Old 03-23-2015, 04:04 PM   #4
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Quote:
Originally Posted by offroad View Post
No expert here, but some recent experience:

What is the condition of your front tire? Has it been doing sidecar duty long enough to be worn more on the right (inboard) side because of lean in?

Also what air pressure are you running in aft, front and sidecar tires?

It could be your steering damper is acting to offset some hunting behavior at speed and creating more of a problem than would otherwise exist, but I think alignment is going to be where you find your solution.

Good luck with your rig and let us know how you come out with a solution.

Jim
The front tire only had maybe 200 two wheel miles on it when the sidecar was added. I started out with 39lbs in each tire as that is what a friend runs in his similar riig.
Thanks for the info.
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Old 03-23-2015, 04:05 PM   #5
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Quote:
Originally Posted by seekeronsaltspring View Post
have you adjusted it to an softer setting On an ural you change it until you find the sweet spot.
Unfortunately there does not seem to be any adjustment on the damper. If the URAL one has adjustments, has anyone successfully mounted one to a nonURAL?
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Old 03-23-2015, 06:05 PM   #6
claude
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Play with air pressure. Not gospel but more air in the sidecar tire can many times make a difference. Start high as you can always let some out. Front tire pressure may go up or down to make a difference.

Damper mounting position can also be critical. It the darting is related to hitting bumps and road conditions it may be a bump steer situation.



Make sure the pivot ball on the tele lever is tight!!

Do the easy things forst and see what effect It has.

I would begin by removing the damper and playing with air pressure .
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Old 03-23-2015, 06:09 PM   #7
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Might help to post a pic of your damper installation. Because the 1150RT has "right-side up" forks (the opposite of upside down forks) there really is no good place to install a conventional VW-style damper. If you clamp to the fork anywhere below the lower fork bridge you will experience bump steering. IMO, the only way to install a damper on your setup to avoid bump steering is to mount a piston damper from the fork to the A-Arm like this--

Or mount to the top clamp using a Scotts-type damper. Ralle-Moto sells a kit for that. Looks like this--


If neither of these are possible, I'd make sure my VW-style damper was mounted as close to horizontal as possible so that the movement of the piston is minimized when you go over bumps.

I'd also say that, yes, your damper may be too strong. If you go to eBay, you can find quite a few dampers. You could try to find a weaker one. When searching, try various misspellings of the word "damper" such as "dampner" and "dampener" and "stabilizer".
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Old 03-23-2015, 06:13 PM   #8
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Claude got his post in there while I was composing mine. He mentioned that you should check your ball joint. IMO, you should also look at the big bearing in the middle of the top clamp and make sure it's in good shape and torqued properly, then look at the bushings on the tops of your forks where they bolt to the top clamp. Those suckers are famous for turning to crap on sidecar rigs.
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Old 03-23-2015, 06:32 PM   #9
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Claude, I purchased the sidecar used so don't know the mileage but it seems almost like new. Not even and stone chips in the front paint. Believe that it spent most of it's life indoors. I have jacked it up and attempted to shake the wheel and there does not seem to be any play. If it was the swing arm, would it go away when the damper is removed?

The damper was mounted to the right caliber and to the sidecar frame which put it at about a 90' angle from the fork. I have been doing a lot of internet research on this and have found a couple of articles where you mention that you rarely use dampers anymore. I would like to reach that poi9nt. I will be trying different tire pressures and see where that gets me. I have the stock shocks and I feel that they are contributing to the problem. As soon as I can decide which shocks to go with, I will be ordering them. Any recommendations?
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Old 03-23-2015, 06:39 PM   #10
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Drone, As I replied to Claude, the damper was/is mounted to the Caliber bolts and sidecar frame. The bike only has 44k miles and being an RT, they are all on pavement. The sidecar has only been on a week and 300 miles so hopefully the bushings are still good but I will check. Really like the damper mounted to the lower A frame.
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Old 03-23-2015, 06:51 PM   #11
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Mounting to the caliper mounts is almost as low as you can go on those forks. (The only way to go lower would be to mount it to the axle! ) Which means you have the damper mounted where it will affect your steering the MOST! If I was trying low-cost solutions, (low-cost beats the hell out of high cost) I'd find a tube clamp (like in the above picture) that would fit the fork right above the lower fork bridge (like in the picture) and re-mount your damper up there. This will automatically reduce the force the damper can exert on the steering. Then I'd make sure the other end is mounted to whatever place you can find on the struts close in height off the ground as the fork clamp. But watch your plastic bits--you don't want the damper smashing into your fairing the first time you hit a big pothole! Mount it in such a way that when the front shock is compressed there's still clearance.
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Old 03-24-2015, 04:22 AM   #12
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No experience with dampers, but at the recommendations from Claude and Drone, I hade good luck playing with tire pressures.

On my GS rig, I had a tolerable wobble at 25-30 mph. It got worse when I switched to a 140-17 rear tire on the front. I dropped down to 30 psi in the front (rear and chair both at 35) and the wobble has completely disappeared. I don't know that I would recommend going down to 30 psi, but I am running k60 tire with real stuff sidewalls.

Good luck experimenting.
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Old 03-25-2015, 07:21 AM   #13
Ridn3 OP
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OK, adjusted the air upwards in front and sidecar tire and it does seem to help a lot with the damper disconnected. Looked at the rig and there does not seem to be an easy way to mount the damper up any higher. We used a DMC subframe which puts the upper front mount behind the cylinder so connecting to it is not practical. It did not look like there was much space under the fairing for a smaller damper mounted to the lower A arm. We are now going to try using a VW damper mounted where we had the Hannigan one mounted. After I get new shocks I may try again to do without a damper. We shall see.
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Old 03-25-2015, 10:55 AM   #14
claude
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Quote:
Originally Posted by Ridn3 View Post
OK, adjusted the air upwards in front and sidecar tire and it does seem to help a lot with the damper disconnected. Looked at the rig and there does not seem to be an easy way to mount the damper up any higher. We used a DMC subframe which puts the upper front mount behind the cylinder so connecting to it is not practical. It did not look like there was much space under the fairing for a smaller damper mounted to the lower A arm. We are now going to try using a VW damper mounted where we had the Hannigan one mounted. After I get new shocks I may try again to do without a damper. We shall see.
Not my personal preference but They can be mounted low and even off the front axle. Need to test it for no binds or over center situations.
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Old 03-25-2015, 11:24 AM   #15
redtails
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If there is no damping adjustment (weird), then the best alternative is to change the weight of the oil to a lighter viscosity.
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