Bagger wobble exposed!
Thread Starter
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Club Member
Joined: Jun 2007
Posts: 45,429
Likes: 2,898
From: Bedford UK
Been there and done that! I have since further upgraded my suspension to Ohlins at both ends. Ohlins and T-T are complimentary and both provide benefits in my experience.
Road Captain
Joined: Oct 2012
Posts: 520
Likes: 37
From: houston, tx
CCE Mad Dog kit is $850, anyone tried it? Looks like it would improve things a bit???
Am running Howard's (RIP) 49mm GP front fork kit with a little tighter neck bearing adjustment, factory front cylinder brace, aftermarket lower brace for the front of the engine, a brace for the rear of the engine that is next to the starter, and another brace under the back of the engine. With the mad dog kit I could probably remove the two rear engine braces. (Tried the GlidePro, but the bushings don't last and they charge a pretty penny for replacements.). Some RPS adjustable M2 shocks are on order but preventing swingarm/rear motor mount movement would make things handle better.
Am running Howard's (RIP) 49mm GP front fork kit with a little tighter neck bearing adjustment, factory front cylinder brace, aftermarket lower brace for the front of the engine, a brace for the rear of the engine that is next to the starter, and another brace under the back of the engine. With the mad dog kit I could probably remove the two rear engine braces. (Tried the GlidePro, but the bushings don't last and they charge a pretty penny for replacements.). Some RPS adjustable M2 shocks are on order but preventing swingarm/rear motor mount movement would make things handle better.
Club Member
Joined: Apr 2016
Posts: 11,576
Likes: 8,405
From: Inland NW
Agreed, even on the newer ones. Every little bit helped, but the Ohlins front and rear, and the TTs was finally what got rid of mine on 90+ sweepers. It may be a bandaid, and I may do the whole spherical swing arm bearing solution someday, but for now, I am happy.
Supporter
Joined: Dec 2020
Posts: 1,410
Likes: 4,861
From: Colorado
On another thread, the wobble was mentioned and there was posted by another member linking to this thread. It is a wonderful thread.
I have experienced no wobble on my 1998 FLHTCUI but I ordered a True-Track stabilizer. Before receiving this stabilizer, I have done quite a bit more reading/on-line-videos and am now convinced that I need to replace the bushings on the swingarm cleve blocks with metal bushings (also from True-Track) and the front motor mount.
This is all for prevention. With me supplying the parts, what should I expect to pay as labor to my indy for:
1. the removal and install of my swingarm bushing parts,
2. install of the front motor mount
3. alignment of the rear tire to the swingarm,
4. align of the rear tire to the front tire,
5. vertical alignment of both wheels, and finally
6. the install of the rear stabilizer?
(Have I forgotten anything?)
Would anyone venture a guess as a ball-park figure for labor? (If it matters as to cost, my indy is in the Denver area.)
I have experienced no wobble on my 1998 FLHTCUI but I ordered a True-Track stabilizer. Before receiving this stabilizer, I have done quite a bit more reading/on-line-videos and am now convinced that I need to replace the bushings on the swingarm cleve blocks with metal bushings (also from True-Track) and the front motor mount.
This is all for prevention. With me supplying the parts, what should I expect to pay as labor to my indy for:
1. the removal and install of my swingarm bushing parts,
2. install of the front motor mount
3. alignment of the rear tire to the swingarm,
4. align of the rear tire to the front tire,
5. vertical alignment of both wheels, and finally
6. the install of the rear stabilizer?
(Have I forgotten anything?)
Would anyone venture a guess as a ball-park figure for labor? (If it matters as to cost, my indy is in the Denver area.)
Last edited by Evo-Wes; Jul 4, 2022 at 07:45 PM.
Tourer
Joined: May 2011
Posts: 469
Likes: 158
From: Alberta
I've always noticed a hinged in the middle feeling on my 98 Ultra Glide Classic when at highway speeds, in sweepers and also when hitting some dips in the road at speed. It doesn't like to be pushed and quickly tells you what it doesn't like doing. I've had other bikes in the past, early gold wings, 1000 & 1100 cc bikes, VT1100T that exhibit the same behaviour. The effect is not noticeable in slower twisties, 25-30 mph range. Any of the sport bikes or adventure type bikes I've owned didn't exhibit this behaviour. My 08 Heritage Softail ( solid mount ) also was good in this area. So this is my two cents to the conversation.
I decided to try fix the problem on my harley. I've read quite a bit about the wobble, not only on harley's but other bikes as well. I replaced the rear shocks to a non air suspension and installed a bagger brace. I won't waste anybodies time with brands or how I installed it. Installation was fairly straightforward and I had to remove the left muffler and part of the header for the rear cylinder, right muffler and loosen the header pipes at the heads to get enough slack. If you can follow directions, have patience and are reasonable good with a wrench, it can certainly be done by the average DIY.
Note: The newer shocks didn't change the wobble issue. I had put them on about 2000 miles before I installed the brace. The ride was better and I had better damping along with being able to adjust the sag for the weight on the bike. I had also replaced the front fork oil as it was due. No other mods to the bike. Tires are new and balanced.
With the brace installed the bike is much more solid feeling. It holds a line better in curves, less disturbed by bumps in corners etc. In fact enough that I will be changing the preload on the rear shocks for solo riding. Some have complained about an increase in vibration. In my case it just seemed to move the vibration to a different part of the bike. Less on the floorboards and more on the seat. ( Seeing as the brace's attachment point is located directly under the seat that kind of makes sense to me.) I find that my bike has kind of a harmonic vibration around 2500 rpm. It has made that a bit more noticeable, but at 2800-3000 rpm on the highway it is smooth and the vibration is gone. Some of this is road surface related. Also no more/less vibration at lower rpms.
My initial feelings are positive and the brace is money well spent. It does change the handling of the bike in subtle ways that are hard to explain but you can feel them when you are going down the highway. I like the brace and look forward to my next trip to the sweepers.
I decided to try fix the problem on my harley. I've read quite a bit about the wobble, not only on harley's but other bikes as well. I replaced the rear shocks to a non air suspension and installed a bagger brace. I won't waste anybodies time with brands or how I installed it. Installation was fairly straightforward and I had to remove the left muffler and part of the header for the rear cylinder, right muffler and loosen the header pipes at the heads to get enough slack. If you can follow directions, have patience and are reasonable good with a wrench, it can certainly be done by the average DIY.
Note: The newer shocks didn't change the wobble issue. I had put them on about 2000 miles before I installed the brace. The ride was better and I had better damping along with being able to adjust the sag for the weight on the bike. I had also replaced the front fork oil as it was due. No other mods to the bike. Tires are new and balanced.
With the brace installed the bike is much more solid feeling. It holds a line better in curves, less disturbed by bumps in corners etc. In fact enough that I will be changing the preload on the rear shocks for solo riding. Some have complained about an increase in vibration. In my case it just seemed to move the vibration to a different part of the bike. Less on the floorboards and more on the seat. ( Seeing as the brace's attachment point is located directly under the seat that kind of makes sense to me.) I find that my bike has kind of a harmonic vibration around 2500 rpm. It has made that a bit more noticeable, but at 2800-3000 rpm on the highway it is smooth and the vibration is gone. Some of this is road surface related. Also no more/less vibration at lower rpms.
My initial feelings are positive and the brace is money well spent. It does change the handling of the bike in subtle ways that are hard to explain but you can feel them when you are going down the highway. I like the brace and look forward to my next trip to the sweepers.
Tourer
Joined: May 2011
Posts: 469
Likes: 158
From: Alberta
I have basically the same bike. Depending on how you ride the bike you may or may not ever experience the wobble. If you ride aggressively in sweepers etc at higher speeds then you will notice it. Same goes for hitting bumps dips etc. Higher mileage bikes are going to be worse.
As to cost. Your list is pretty extensive and it won't be cheap. As an example it probably took me 2 hours to install the brace alone. Installation time depends on how much you have to mess around with the exhaust. I've never installed a brace before but am pretty good with a wrench and have been doing all of my own work on my bikes for years. I had to remove quite a bit of exhaust and loosen headers etc to get enough slack. Type of brace will also determine installation time. Generally if the bike is out of alignment the brace won't line up properly so you likely won't have to do the alignment stuff unless you have a problem. If it was me I would just have the brace installed and then see if you have to do any of the other things on your list.
I would treat the installing swingarm bushing parts and new motor mount as a separate issue and do them only if you have an issue after the brace is installed. Likely the majority of wobble is directly related to the swing arm anyways. Bikes with swingarms with bearings rarely have any wobble issues.
Not really what you asked as to cost, too many variables. Your indy will be able to give you an accurate quote on installing the brace of your choice on your particular bike.
As to cost. Your list is pretty extensive and it won't be cheap. As an example it probably took me 2 hours to install the brace alone. Installation time depends on how much you have to mess around with the exhaust. I've never installed a brace before but am pretty good with a wrench and have been doing all of my own work on my bikes for years. I had to remove quite a bit of exhaust and loosen headers etc to get enough slack. Type of brace will also determine installation time. Generally if the bike is out of alignment the brace won't line up properly so you likely won't have to do the alignment stuff unless you have a problem. If it was me I would just have the brace installed and then see if you have to do any of the other things on your list.
I would treat the installing swingarm bushing parts and new motor mount as a separate issue and do them only if you have an issue after the brace is installed. Likely the majority of wobble is directly related to the swing arm anyways. Bikes with swingarms with bearings rarely have any wobble issues.
Not really what you asked as to cost, too many variables. Your indy will be able to give you an accurate quote on installing the brace of your choice on your particular bike.
Grand HDF Member
Joined: Sep 2010
Posts: 3,580
Likes: 215
From: Illinois
Good question. I would like to know some feedback from M8 owners on this.
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Seasoned HDF Member
Joined: Dec 2005
Posts: 19,921
Likes: 8,026
From: poway
Absolutely. All bikes do it to some extent. Bikes need to be properly maintained. My 17 RK M8 would do it when certain tires were 1/2 worn..
Grand HDF Member
Joined: Aug 2017
Posts: 3,586
Likes: 889
From: Nowhere
Introduction:
OK chaps, sit up straight and pay attention, we’re going back to school! There will be coffee and cake for those who stay the course.
I’ve lost count of how many times I have answered questions about ‘bagger wobble’ on HDF, so this is a description of the rubber mounting system in our Touring bikes, from an engineering perspective, in the hope of improving understanding of what the wobble is and why it happens. I make no apology for this being a long thread, but you can always print it out and read it in bed or in the small room!
It goes without saying that the following assumes a bike in tip top shape. Let us also be clear that many Harley owners have probably never experience the so-called wobble and are blissfully happy with their ride, so for them there is no problem. If you read this and are wondering what on earth it is all about, do not allow yourself to be suddenly gripped with fear!
Let us start with the original rubber-mount system introduced in 1980 and cover the 09-on bikes later.
Wobble 1:
Evos and early TC bikes not only had rubber engine mounts, they also had rubbery swingarm bushings, called ‘cleve blocks’. Some of the bagger wobble reported on these bikes can be blamed in part on them, as they allowed a degree of sideways movement of the rear wheel and swingarm, relative to the rest of the bike. They were dropped by Harley in 2002 and replaced with steel bushings, which cured that aspect of the handling problem. After-market bushing kits are available to replace them on older bikes still fitted with cleve blocks.
Why Rubber Mounts?
Over the decades our bike engines have become progressively bigger in capacity and more powerful. As a consequence the forces inside the engine have become greater, causing more vibration, which in turn is more uncomfortable to us riders and more likely to damage parts of the bike. Norton tackled this challenge back in the 1960s with their Commando, a watershed design, partly because parallel twins are more prone to vibration than our V-twins. In 1980 Harley introduced the FLTs, with their own design of rubber mount system, credited to Erik Buell, which we have all come to know and love!
The approach Norton used in the Commando was to isolate the engine from the frame, using concentric rubber mounts. That system is far from perfect, in part because it didn’t allow the engine to actually move very much. Essentially they addressed high frequency vibration, but not the engine speed ones so well. The beauty of the Harley system is that our engines are allowed to shake, which helps deal with engine speed vibrations, but are also rubber mounted, which helps dampen higher frequency vibrations. That gives us a more comfortable ride, but also has the potential benefit of providing high quality handling at the same time.
Comfort:
Humans are sensitive creatures, despite the tough and rugged image we riders like to have! When man started to employ science in the design of engines and vehicles, we soon learned that if we are going to sit on top of one, the least unpleasant form of vibration is up and down. So our bike engines, solid or rubber mount, are designed to shake that way. When you watch your Harley engine bobbing up and down at idle, that is deliberate! You are watching the laws of physics at work, in perfect harmony with engineering, under man’s control. All is well with the World.
Description:
The engine and trans are bolted together, and the swingarm is mounted directly onto the rear of the trans. Along with the rear wheel this makes up a substantial single Assembly, which is mounted into the frame at three points, of which more shortly. The swingarm axle not only allows the rear wheel to move relative to the rest of the bike, but doubles up as part of the rear mounting.
I will continue to use the word ‘Assembly’ to refer to the combined engine/trans/swingarm/wheel.
Kinematics:
Take a deep breath, we are about to dive into the bowels of your bike!
Wobble 2:
The lack of a rear stabilizer is IMHO a serious flaw in the way Harley introduced this design. That comment is entirely justified as every Buell has one, as do all rubber-mount Sportsters, so Harley knows how to do this. It is a mystery why our Touring bikes don’t have one.
This omission is the main source of the infamous ‘bagger wobble’. Lateral forces compress those rear rubber mounts and cause momentary misalignment of the rear wheel relative to the front wheel. The rubber used is stiff and only yields a little. It also is only able to compress to a small degree due to the design, but it is significant and too much.
2009-on:
While Harley continue to use a similar design of rear rubber mounting on their latest bikes, the old single front mount has been changed to a pair that are similar in design to the rear mounts. There are now four rubber mounts instead of three, but instead of leaving only the rear mounts without lateral support, neither front nor rear have a stabilizer.
Frankly, from an engineering perspective, Harley appears to have abandoned the fine principles of the original design. There are many reasons why Harley changed the frame, of which the engine mounting system is only one, however they could have retained the original design and simply added that vital rear stabilizer.
If you sometimes wonder about the handling of your lovely new bike, you have every right to. If you changed from a pre-09 bike to a post-09 one, to get a better handling bike, you simply jumped out of the fire into the frying pan!
Wobble 3:
It cannot be denied that the 2009-on set-up gives improved lateral stability, but it doesn’t cure it. Both front and rear rubber mounts can compress under lateral loads, although the degree of misalignment this causes is improved over the older design.
Stabilizer Kits:
Harley inadvertently created a market opportunity for the custom market, which many brands have filled. The better designs provide lateral support to the rear rubber mounts on earlier bikes, and both front and rear mounts on later bikes would be nice. By providing suitable lateral support, the kinematic principles of the original design are fulfilled.
On both versions of bike, the steering is made more accurate, improving the steering and feel of the bike even at slow speeds, as well as giving better handling at higher speeds. The improved stability improves the riding experience throughout the speed range. The benefits of stabilizers are for all of us, not just those who want to ride fast. However, not all kits are created equal and some designs are superior to others.
Summary:
The original rubber mount design is excellent, but was compromised by the factory, by leaving off the rear stabilizer link, for reasons we may never know. Rubber squashes, which is why we make much use of it in so many aspects of our lives. It squashes on the original bikes and it does on the latest ones as well. Both sets of bikes will ride better with suitable lateral stabilizers.
Finally:
I hope that goes some way to improving understanding of the way our rubber-mount bikes work and why the original design is actually a very good one, only let down by leaving out a vital part. Later bikes are also flawed, so none of our rubber-mount Touring bikes are perfect, or as good as they could be.
Any questions?!
Added later:
If you are looking for the silver bullet, the product I use and recommend is True-Track.
There is also further reading at post #49, for those keen to learn even more!
OK chaps, sit up straight and pay attention, we’re going back to school! There will be coffee and cake for those who stay the course.
I’ve lost count of how many times I have answered questions about ‘bagger wobble’ on HDF, so this is a description of the rubber mounting system in our Touring bikes, from an engineering perspective, in the hope of improving understanding of what the wobble is and why it happens. I make no apology for this being a long thread, but you can always print it out and read it in bed or in the small room!
It goes without saying that the following assumes a bike in tip top shape. Let us also be clear that many Harley owners have probably never experience the so-called wobble and are blissfully happy with their ride, so for them there is no problem. If you read this and are wondering what on earth it is all about, do not allow yourself to be suddenly gripped with fear!
Let us start with the original rubber-mount system introduced in 1980 and cover the 09-on bikes later.
Wobble 1:
Evos and early TC bikes not only had rubber engine mounts, they also had rubbery swingarm bushings, called ‘cleve blocks’. Some of the bagger wobble reported on these bikes can be blamed in part on them, as they allowed a degree of sideways movement of the rear wheel and swingarm, relative to the rest of the bike. They were dropped by Harley in 2002 and replaced with steel bushings, which cured that aspect of the handling problem. After-market bushing kits are available to replace them on older bikes still fitted with cleve blocks.
Why Rubber Mounts?
Over the decades our bike engines have become progressively bigger in capacity and more powerful. As a consequence the forces inside the engine have become greater, causing more vibration, which in turn is more uncomfortable to us riders and more likely to damage parts of the bike. Norton tackled this challenge back in the 1960s with their Commando, a watershed design, partly because parallel twins are more prone to vibration than our V-twins. In 1980 Harley introduced the FLTs, with their own design of rubber mount system, credited to Erik Buell, which we have all come to know and love!
The approach Norton used in the Commando was to isolate the engine from the frame, using concentric rubber mounts. That system is far from perfect, in part because it didn’t allow the engine to actually move very much. Essentially they addressed high frequency vibration, but not the engine speed ones so well. The beauty of the Harley system is that our engines are allowed to shake, which helps deal with engine speed vibrations, but are also rubber mounted, which helps dampen higher frequency vibrations. That gives us a more comfortable ride, but also has the potential benefit of providing high quality handling at the same time.
Comfort:
Humans are sensitive creatures, despite the tough and rugged image we riders like to have! When man started to employ science in the design of engines and vehicles, we soon learned that if we are going to sit on top of one, the least unpleasant form of vibration is up and down. So our bike engines, solid or rubber mount, are designed to shake that way. When you watch your Harley engine bobbing up and down at idle, that is deliberate! You are watching the laws of physics at work, in perfect harmony with engineering, under man’s control. All is well with the World.
Description:
The engine and trans are bolted together, and the swingarm is mounted directly onto the rear of the trans. Along with the rear wheel this makes up a substantial single Assembly, which is mounted into the frame at three points, of which more shortly. The swingarm axle not only allows the rear wheel to move relative to the rest of the bike, but doubles up as part of the rear mounting.
I will continue to use the word ‘Assembly’ to refer to the combined engine/trans/swingarm/wheel.
Kinematics:
Take a deep breath, we are about to dive into the bowels of your bike!
- Statement: kinematics is a branch of engineering that deals with the geometry of motion of moving parts.
- Question: what on Earth does that mean and how does it affect your Harley?
- Answer: it is at the very core of it and is the basis of the original Harley rubber mount design.
- The rear rubber mounts serve several purposes. The ends of the swingarm axle are fastened to those mounts, which are retained in the frame by the passenger footboard mountings. They support a large part of the weight of the bike; locate the Assembly in the frame, both laterally, vertically and fore and aft; also allow it to rotate up and down, or pitch.
- The front rubber mount supports the front of the Assembly and allows it the freedom to move up and down, rotating on the rear mounts. It is laterally supported by a stabilizer link, which prevents the unit from moving sideways at that point, or yawing.
- The top support is a simple stabilizer link, which also has several purposes. It doesn’t bear any weight, but allows the Assembly to rock up and down, also back and forth, while preventing it from moving sideways, or rolling.
Wobble 2:
The lack of a rear stabilizer is IMHO a serious flaw in the way Harley introduced this design. That comment is entirely justified as every Buell has one, as do all rubber-mount Sportsters, so Harley knows how to do this. It is a mystery why our Touring bikes don’t have one.
This omission is the main source of the infamous ‘bagger wobble’. Lateral forces compress those rear rubber mounts and cause momentary misalignment of the rear wheel relative to the front wheel. The rubber used is stiff and only yields a little. It also is only able to compress to a small degree due to the design, but it is significant and too much.
2009-on:
While Harley continue to use a similar design of rear rubber mounting on their latest bikes, the old single front mount has been changed to a pair that are similar in design to the rear mounts. There are now four rubber mounts instead of three, but instead of leaving only the rear mounts without lateral support, neither front nor rear have a stabilizer.
Frankly, from an engineering perspective, Harley appears to have abandoned the fine principles of the original design. There are many reasons why Harley changed the frame, of which the engine mounting system is only one, however they could have retained the original design and simply added that vital rear stabilizer.
If you sometimes wonder about the handling of your lovely new bike, you have every right to. If you changed from a pre-09 bike to a post-09 one, to get a better handling bike, you simply jumped out of the fire into the frying pan!
Wobble 3:
It cannot be denied that the 2009-on set-up gives improved lateral stability, but it doesn’t cure it. Both front and rear rubber mounts can compress under lateral loads, although the degree of misalignment this causes is improved over the older design.
Stabilizer Kits:
Harley inadvertently created a market opportunity for the custom market, which many brands have filled. The better designs provide lateral support to the rear rubber mounts on earlier bikes, and both front and rear mounts on later bikes would be nice. By providing suitable lateral support, the kinematic principles of the original design are fulfilled.
On both versions of bike, the steering is made more accurate, improving the steering and feel of the bike even at slow speeds, as well as giving better handling at higher speeds. The improved stability improves the riding experience throughout the speed range. The benefits of stabilizers are for all of us, not just those who want to ride fast. However, not all kits are created equal and some designs are superior to others.
Summary:
The original rubber mount design is excellent, but was compromised by the factory, by leaving off the rear stabilizer link, for reasons we may never know. Rubber squashes, which is why we make much use of it in so many aspects of our lives. It squashes on the original bikes and it does on the latest ones as well. Both sets of bikes will ride better with suitable lateral stabilizers.
Finally:
I hope that goes some way to improving understanding of the way our rubber-mount bikes work and why the original design is actually a very good one, only let down by leaving out a vital part. Later bikes are also flawed, so none of our rubber-mount Touring bikes are perfect, or as good as they could be.
Any questions?!
Added later:
If you are looking for the silver bullet, the product I use and recommend is True-Track.
There is also further reading at post #49, for those keen to learn even more!
Was this corrected on latest models as I noticed this is quite an old post.
Last edited by Burbur2; Jul 28, 2022 at 11:36 PM.