SO i had my front forks rebuilt and new wheel bearings installed in both wheels. I replaced the rear shocks with progressive replaced steering stem bearings with tapered bearings. Now i have a weird wobble in turns. to the point where i dont want to ride the bike. Any info someone can give me as to what im doing wrong. the bike didnt have these issues before however before the rear shocks were like 10" long now the progressive i replaced them with are 12 or 14 I think. Im thinking this has something to do with it but not sure just looking for some direction.
After replacing suspension wobble in turns
- Thread starter AJWatUC
- Start date
How about more info on the changes? If you raised the rear two inches then youll have changed you steering angle and that can cause what you described. Put he stock shocks back on and see if the problem goes away or decreases.
The springs, progressive or otherwise, are not in themselves likely to be an issue. Ride height at either end definitely is. If the springs were the same (likely the new springs are stiffer than the stock ones regardless of the shock which would amplify the problem) , 2 inches extra at the back can be a LOT. 4 inches? The ride height, that is how high both ends of the bike sit with you and your gear on it, is important because it controls the steering geometry of your bike. Raise the back, or lower the front, and you can easily see how the entire frame rotates down at the front. The steering neck of course rotates along with it, and the rake is more vertical. This makes it much easier for the steering to turn away from straight ahead. This also decreases the trail, which is the distance between the center of rotation of your steering and the contact patch of your tire. This controls the castering effect of your steering - the larger the trail, the stronger the force created that pushes your steering to center and the more your bike wants to track straight ahead. Decreasing the rake by raising the back decreases trail and reduces straight line stability. Obviously these effects also affect behavior while turning.
Put the stock shocks back on and the stock springs back in the forks and ride the bike around to determine if the problem goes away. Presuming it does, measure the ride height front and back with you and your gear on the bike. Measure from the ground to some fixed points, like the tail light and headlight - anything that is easy and repeatable. Get a friend to hold you up balanced vertical but not impacting the height. Bounce the bike up and down to get an accurate and repeatable measurement. This is your base line for making changes. If you like the way it handles now, you want to keep these measurements the same after you change the springs. The handling I am talking about here is on a perfectly smooth turn with no bumps so the suspension does not come into play. You are interested in ride height and the resulting geometry so you want the smoothest test turn(s) possible so shocks and springs are minimized as a variable. Once you have a ride height you like, you can change the strength of the springs to change how your bike reacts to bumps, accelerating and braking. Whether you make them stronger or weaker rate, you need to adjust them so the ride height is not changed, otherwise you will change the geometry as well. For instance, you may want stiffer springs in front to reduce the impact of diving under braking and be willing to sacrifice some compliance and the resulting rough surface traction to get it. You will still want to set up the stiffer springs so that the ride height is maintained by adjusting the preload, otherwise the geometry will be changed affecting the handling - for the worse if you have already determined the ride height that gives the handling you like.
After you get your benchmarks for ride height, put your new springs back in and the new shocks back on and repeat your ride height measurements and compare. If you can not adjust to get close to your old measurements you can expect your bike to drive noticeably differently.
Making suspension changes is relatively complex. Part of that complexity is based on rider perception. For example, most riders will report that their bike handles better with stiffer springs. Mostly this is not actually true, but stiffer springs give crisper feedback to the rider which instills confidence in the rider but doesn't necessarily make the bike actually work better. No doubt, if you are more confident you likely will be able to drive better/faster, but all things being equal you will be fastest on the best handling hardware. Overly stiff suspension does not follow the road as well as a more compliant one, and affords less traction. How it feels to the rider is another element altogether, but it is as important as getting the right geometry and suspension (springs and shocks). Since each element (rider, geometry, and suspension) has an effect on the other two, optimizing the system is tricky.
So how does one logically approach trying to improve how their bike drives? Try looking at your chassis and suspension as two separate elements. One is the geometry which is all the fixed (assuming you maintain some particular ride height) parameters like rake, trail, wheelbase, swingarm length, fork offset etc, etc. The other is the springing and damping. If you like how your bike drives, you want to keep the geometry. You can adjust the road holding by adjusting the springs (that would be the spring rate, and adjusting the preload to maintain your ride height), shocks (and their damping) and tires (brand and type of tire and inflation pressure.) If you don't like how your bike drives, you then likely want to change the geometry - for instance if your bike speed wobbles or is twitchier than you would like at high speed, you might think of increasing the trail. This all requires quite a bit more expertise and there are a number of great books on the subject if you really want to go deeper. For most of us though, we want to stay very close to what the manufacturer came up with as far as geometry and limit our experimental adjustments to changing the ride height of the front or back (or both).
Put the stock shocks back on and the stock springs back in the forks and ride the bike around to determine if the problem goes away. Presuming it does, measure the ride height front and back with you and your gear on the bike. Measure from the ground to some fixed points, like the tail light and headlight - anything that is easy and repeatable. Get a friend to hold you up balanced vertical but not impacting the height. Bounce the bike up and down to get an accurate and repeatable measurement. This is your base line for making changes. If you like the way it handles now, you want to keep these measurements the same after you change the springs. The handling I am talking about here is on a perfectly smooth turn with no bumps so the suspension does not come into play. You are interested in ride height and the resulting geometry so you want the smoothest test turn(s) possible so shocks and springs are minimized as a variable. Once you have a ride height you like, you can change the strength of the springs to change how your bike reacts to bumps, accelerating and braking. Whether you make them stronger or weaker rate, you need to adjust them so the ride height is not changed, otherwise you will change the geometry as well. For instance, you may want stiffer springs in front to reduce the impact of diving under braking and be willing to sacrifice some compliance and the resulting rough surface traction to get it. You will still want to set up the stiffer springs so that the ride height is maintained by adjusting the preload, otherwise the geometry will be changed affecting the handling - for the worse if you have already determined the ride height that gives the handling you like.
After you get your benchmarks for ride height, put your new springs back in and the new shocks back on and repeat your ride height measurements and compare. If you can not adjust to get close to your old measurements you can expect your bike to drive noticeably differently.
Making suspension changes is relatively complex. Part of that complexity is based on rider perception. For example, most riders will report that their bike handles better with stiffer springs. Mostly this is not actually true, but stiffer springs give crisper feedback to the rider which instills confidence in the rider but doesn't necessarily make the bike actually work better. No doubt, if you are more confident you likely will be able to drive better/faster, but all things being equal you will be fastest on the best handling hardware. Overly stiff suspension does not follow the road as well as a more compliant one, and affords less traction. How it feels to the rider is another element altogether, but it is as important as getting the right geometry and suspension (springs and shocks). Since each element (rider, geometry, and suspension) has an effect on the other two, optimizing the system is tricky.
So how does one logically approach trying to improve how their bike drives? Try looking at your chassis and suspension as two separate elements. One is the geometry which is all the fixed (assuming you maintain some particular ride height) parameters like rake, trail, wheelbase, swingarm length, fork offset etc, etc. The other is the springing and damping. If you like how your bike drives, you want to keep the geometry. You can adjust the road holding by adjusting the springs (that would be the spring rate, and adjusting the preload to maintain your ride height), shocks (and their damping) and tires (brand and type of tire and inflation pressure.) If you don't like how your bike drives, you then likely want to change the geometry - for instance if your bike speed wobbles or is twitchier than you would like at high speed, you might think of increasing the trail. This all requires quite a bit more expertise and there are a number of great books on the subject if you really want to go deeper. For most of us though, we want to stay very close to what the manufacturer came up with as far as geometry and limit our experimental adjustments to changing the ride height of the front or back (or both).
What bike are we talking about?
As others have said, raising the rear that much has steepened your steering angle and is making the bike unstable. 2-4 inches (why don't you know if it's 2 or 4 inches?) over stock on the rear is a big change.
Just wondering what the stock bike is so we have a frame of reference. Is it the 1973 CB500 in your sig? If so, the stock shocks would have been around 12 inches if I recall mine.
As others have said, raising the rear that much has steepened your steering angle and is making the bike unstable. 2-4 inches (why don't you know if it's 2 or 4 inches?) over stock on the rear is a big change.
Just wondering what the stock bike is so we have a frame of reference. Is it the 1973 CB500 in your sig? If so, the stock shocks would have been around 12 inches if I recall mine.
So I finally got around to working on the bike I replaced the progressive shocks with factory it made no difference other than ride height dropped a little bit. I took the forks out and found one of the forks was totally empty the other had maybe an ounce of oil. Pretty confident this was my problem. If I don't post up here again consider this solved!
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you still have the stock shocks ? the springs being cut doesnt do anything to the shock ,measure it fully extended to see what length it is
just putting the bike up on the centerstand should allow the rear wheel to be hanging then measure eye centers but really this is so simple anybody should be able to figure that one out
dont ever ride a motorcycle so horribly molested ,deathtraps ,built by morons,go back and visit ,find the molester and kick the shit out of him or beat the dicklik to a pulp ,please
who pui the bearings in the wheels and why ? 99% of the time they do not need replacing and damage can be done just swapping out good bearings for good bearings
whoever did the job could have ruined a bearing or gotten something haywire with the axial bearing spacers
and funny feeling wobblies could be a resuelt
the steering head tapered bearings must be adjusted correctly with some preload ,very slight resistance ,no slack
was there anything done to the forks ?were the stanchion tubes slid up into the triple clamps ?
you need to post up some good clear straight on sideview images of the bike you are lost you shouldnt even be working on it until you know what you are even looking at
read some books this winter thats the only way besides long term exposwure and partical experience
just putting the bike up on the centerstand should allow the rear wheel to be hanging then measure eye centers but really this is so simple anybody should be able to figure that one out
dont ever ride a motorcycle so horribly molested ,deathtraps ,built by morons,go back and visit ,find the molester and kick the shit out of him or beat the dicklik to a pulp ,please
who pui the bearings in the wheels and why ? 99% of the time they do not need replacing and damage can be done just swapping out good bearings for good bearings
whoever did the job could have ruined a bearing or gotten something haywire with the axial bearing spacers
and funny feeling wobblies could be a resuelt
the steering head tapered bearings must be adjusted correctly with some preload ,very slight resistance ,no slack
was there anything done to the forks ?were the stanchion tubes slid up into the triple clamps ?
you need to post up some good clear straight on sideview images of the bike you are lost you shouldnt even be working on it until you know what you are even looking at
read some books this winter thats the only way besides long term exposwure and partical experience
