For those who wish to know, drive on a flat surface at around 2~3 MPH, turn handlebars radically like making a turn than jam on the brakes and watch the horable fork flex and tweaking. What do you think happens at speed?

Duck tape or make a clamp to fasten a set of good & powerful LED flashlights onto your forks than go down the road watching how your forks react and how they twist. Any discerning rider should notice this characteristics on their own or once being pointed out. Do it yourself. The question is why:

If anyone has ever done their own work and pulled their forks on their bagger they would have seen this POS system HD uses. I am sure their thought would be that you are not suppose to go over the speed limit, a touring bike is not a sport bike, or a touring bike is not made to handle. I say that this product (HD Motorcycles) is made only to maximize profit and not put out an American product that we as Americans were use to producing in the past. It takes money and knowing what to do to make this a motorcycle that it sould have been as sold to the public.

The 1 5/8" (wrongly AKA: 41mm) fork tubes are held into the triple trees by clamping around the lower tree and pass through (slip fit) the top tree a fork tube bolt and is held into place by a bolt. This is unacceptable and can not hold the fork tubes stably in place. Here is what you have.



For anyone that can say it is not necessary, just think about it.

In all sport bikes have a top tree that clamp around the fork tubes or sliders (inverted) to make the steering rigid. Below is a top tree we make (not for baggers) for racing and street applications for our R&T Ohlins forks.



1 5/8" (wrongly AKA: 41mm) fork tubes:

These forks have a small cross section but very thick wall. They bend at speed and are not as stable as larger diameter forks with correctly sized wall thickness for the application. The ID of these OEM 1 5/8" forks do not allow enough room for proper internal hydraulic control for the weight and size of a bagger. I use to make 20mm cartridges with externally adjustable rebound but is discontinued as just not good enough with the options available today in other offerings.

If you are satisfied with what you have than there is no need to upgrade, if not than wait and see what happens next. If your life is not worth the aforementioned triple tree upgrade made by the company featured above, than you have just put a dollar value on your life. I get asked a few times a year to testify against the MOCO by different lawyers in lawsuits which I refused every time. People do get hurt and killed with this wobble and the family wishes justice. Maybe if those who ride might have exercised proper judgment in the product they ride and how they use the product under what conditions there would be far fewer mishaps. Ride the Bagger in conditions they were designed for. Personal accountability helps in these situations.

 

fabrik8r is a very knowledgeable person and a good asset to this forum. I do not wish to challenge him but I would prefer he is still around to ride tomorrow. Please, I am asking you fabrik8r, personally to please take the aforementioned test. Have a few friends stabilize the bike when you turn and feel/watch the forks. Do it a few times. I personally know and have spoken to fabrik8r so maybe you members can understand where I am coming from. I **** off enough people unintentionally and feel no need to do it unintentionally to a friend.

I rode a friends 2009 FLHTCU and as soon as I turned out my driveway and stopped to get my mail I felt it immediately. That is where the investigation started.

 

Thanks Howard, I appreciate the vote of confidence. I did a similar test like you mentioned and it definitely illustrates the flex in the fork tubes and trees that influence undesirable handling. With my front wheel nested in a locking chock, I just applied a little turning pressure to the handlebars and I can clearly see the trees and tubes flex out of alignment while the wheel stays fixed. I understand that clamping on the upper and lower tree is a better design for overall holding force. However, the OEM fork top cap head is larger than the bore in the upper tree, so once assembled its like bolting the tube through the top tree, so the fork can not slide out, and the fork plug bottoms out in the top tree so it can't slide upward either. The tube plugs slip into the upper tree, but they aren't exactly sloppy, maybe a couple thousandths clearance, so not much movement potential there. When disassembling the front end, you can loosen the lower tree pinch bolt, but the tube cannot be removed from the top tree until the tube top cap is removed. Without conducting any type of testing or dedicated observation, I just don't see any deficiency in the OEM tree’s ability to hold the fork tubes, and I don't see the performance potential of changing the upper tree fastening design to a pinch bolt application. I don’t think the OEM cast steel upper tree itself flexes, requiring a heavier construction, but rather it rotates on the stem out of alignment with the lower tree. I guess what I would like to know, with the CCE tree, where exactly is the measurable performance improvement over OEM. I notice the CCE upper tree tube clamp area extends a little lower than the OEM tree, this will shorten the distance between the upper and lower clamp area, creating a little potential for increased stiffness between the upper and lower trees, but doesn’t most of the tube flex occur below the lower tree? I also noticed that the CCE kit comes with new tubes, is it possible that’s where the magic lies. I would love to make or buy some stiffer tubes for the purpose of comparison. Last observation, Why do lighter weight Dynas have 49mm tubes and heavier weight Tourers have 41mm tubes, maybe all we need is a conversion tree set that will accept Dyna forks. It just doesn’t make sense to me to spend big money on a heavy-duty top tree only, which still utilizes the same weak component in the system, undersized tubes. Great, now I gotta build something to mitigate my fork flex, already got some ideas. Unfortunately, work has been getting in the way of my machine shop play time, it might be a while.

 

Is there gunna be that much noticable improvment for $845?

 

>>> "OEM fork top cap head is larger than the bore in the upper tree"
<<< As you stated but the wondering your front wheel does is caused by the flexing of the top triple tree connection.to fork tube. If your fork tubes are not stabel your wheel will move in an unwanted direction. If you go into a high speed wobble with the wheel out of control, you have a situation you may not get out of. If your fork/wheel/triple tree assembly is not very stable the problem logarithmically increases (movement/deflection) as speed increases. Reasonable speed there is no problems. Fork movement up and down is not a issue. Forget about that, only focus at deflection of the wheel.

>>> I don't see the performance potential of changing the upper tree fastening design to a pinch bolt application
<<< Reduction in wheel isolation and the movement between top and bottom trees. You have a very heavy bike but your heavy wheels, like a gyroscope, will tend to resist change in direction, the one saving factor with this design.

>>> I just don't see any deficiency in the OEM tree’s ability to hold the fork tubes
<<< If your wheel is not firmly connected to the same plane as the two triple trees which need to be parallel at all times. The bike will not handle as it should and will not go in the direction imputed by the handlebars. If our suspension is loose, handling will suffer. Remember: slower speeds, this system is acceptable. Highway speeds I believe the situation can be compounded.

>>> cast steel upper tree itself flexes
<<< It does not. The reason why the aftermarket top tree is made on the CNC is because of costs. Aluminum is quick to mill, cheap set up charge, billet material is strong compared to some aluminum cast material. In both cases, oem & aftermarket, flexing is not a problem and not an issue.


>>> CCE upper tree tube clamp area extends a little lower
Fork tubes are longer to go through the triple tree clamp. Racing triple trees are only 3/4" thick but too thin for the street but you get the idea. If you made a "gull wing" type so the fork tubes need not be longer but the fairing mounting system would be wrong. The design below works well and a few racers use this system.



>>> Why do lighter weight Dynas have 49mm tubes...conversion tree set that will accept Dyna fork
<<< The new dyna's have them but the wall thickness (0.100") is much thinner than the 1 5/8"/41mm fork tubes. Cross section does make the 49mm fork tubes stiffer but an engineer and testing would be needed to deturmine the final 49mm FLT conversion fork tube thickness.

>>>It just doesn’t make sense to me to spend big money on a heavy-duty top tree only, which still utilizes the same weak component in the system, undersized tubes.
<<< I agree. In place of what you have, how about imagination:

1. Bottom 49mm triple tree made from chrome molly 4041 with a chrome molly 4041 hollow steering stem than heat treated which makes this component bullet proof.
2. Aluminum 49mm top tree that clamps around the fork tube, naturally.
3. Ohlins 30mm cartridge system with externally adjustable: compression, rebound, and spring preload.
4. Direct bolt up so the fairing, wheel, rotors, fender, and calipers fit without issue.
5. 4* raked trees which are a replica of the 2009~current OEM style. All 1980~2008 appear to have the same 4.5* rake in the trees but I have not measured them all, just the 2000 that I have. I do know that all FLT from 1967 have the same center to center measurement on the fork tubes. This would theoretically mean that a 2009~current OEM fork would directly drop into a 1980~2008 FL. I am sure there are some differences but without close inspection on all trees no one can say for sure. The purpose of #5 is to demonstrate that possibly all may fit. Why: reduce your trail from 6.9" to 6.69" as all of the 2009~current are.

There you have it, my reasons, and my investigation. Would this be a good upgrade? Only if you wish the most advanced suspension ever made for a FLT. If you are satisfied with your suspension than the aforementioned is just a case of speculation and an exercise in thought. My purpose in all of this.

 

Looks like a great design, for an unneeded and expensive item if you ask me.


Oh wait, you didn't ask. Never mind.

 

I appreciate all the input. I make a living as an engineer, so I realize that this system will definitely add more strength to the front forks. I had my front forks off my bike today and the top tree is not securely fastened to the forks. The only thing holding the forks to the top tree is the filler cap. The lower tree is provides the only clamping power to resist twisting. My inverted forks on my softail has clamps on the top and lower trees. I agree with most in the fact that this system is very expensive, but if it will improve the stability of the bike then it is money well spent IMO. I asked if anybody had installed the system to see how much improvement they may have experienced.

Howard - how far away are you from a design that can be installed?

 

The front fork issue can be more accurately described as a connection issue. You have three types of connections: hinged, pinned and fixed. Fixed offers the most secure connection while hinged offers the least. At the same time, fixed can induce higher moment arms through the supported structure while hinged will induce less. The connection at the top tree is most definitely hinged. Since the forks are short - as compared to other large structures - one can see how a fixed connection will provide more stability. The question for this system is how well is it designed and how much of a difference will it make?

 

Sweet, that is a very accurate technical description, thank you. In simpler terms, the upper and lower trees are free to swivel independently of one another on the tree stem. So when more or less force is applied to one or both of the fork tubes, a sort of scissoring action takes place, with the two trees rotating on the stem in opposite direction. If the upper and lower trees utilized a fixed stem alignment design to ensure synchronized motion, i.e. key, spline, setscrew, this particular handling issue would be nearly eliminated, baring the remaining tube flex. The OEM tubes aren’t necessarily weak; they are just too weak to keep the trees in alignment in the current set up. So from a discerning engineering viewpoint, what mechanical advantage do you see employed in the CCE top tree/tube kit that provides more resistance to the rotating motion of the hinged top tree.

 

I believe the value of this OP triple tree design is determined by the skill and riding level, as well as the limits the individual rider demands. I tried to explain the value as well as my own personal experience of the type of system requested. I have nothing for sale, just information gathered by doing and observing.

Several years ago I have welded two "donuts" onto a top triple tree (mild steel sand cast OEM tree) and machined a clamping system in it. I than bored it for the fork tube(s) so it would align with the bottom tree but did not waste any time on the nacelle/bat wing mounting found on a OEM tree. This exercise was only for investigation and never made to go on the road. I purchased a set of fork tubes that is longer to go through the top tree and assembled on my 2000 FLT. As with the unknown, if you want to know things, you have to first do it than observe as theory only is that, just a guess. Who would have second guessed photos would be relevant/useful back than?

Note to the OP: You will only receive an improvement with higher speeds or in transitioning at speed. If you ride your bike slowly, always blocking traffic on the highway and make square turns, this upgrade is unnecessary. It is up to you to decide what is important and what you use your bike for. If you are just some newbee bouncing down the street with no riding skills and a armed only with a big mouth than this upgrade is a waste of money. If you are someone who actually rides your bike at greater than highway speed or enjoys turning in at curves at speed, than you should take a closer look at this or similar products.

A note to those who post their negative comment, quite possibly can you back up your opinion by fact? I am open to listen, please enlighten me with what your study/findings contain and why you made your comment(s)?

My own bike has an inverted hand made fork with steering stem behind with no rake. 26* neck and 4" of trail. I have no interest in owning a bike with 6.6" or 6.9" of trail.