Modify flap handle spring results in too short actuator tube?

In Van's Notification 15-10-01 the flap actuator force can be reduced by trimming the VA-114 spring by 0.5".
When I cut F-1260A to length of 10 13/16" as described in Section 32, I didn't remember that I already had trimmed the length of the spring. So I ended up in a too short F-1260A flap handle tube.
No big deal to replace that tube, but I am wondering if the KAI should have been updated or why the notification does not mention anything about the fork assembly.
Do I miss anything here?
Thank you !!

Suggest that you replace the spring, not the tube. A longer tube will defeat the purpose of cutting the spring, which is making the button easier to push. Maybe you can stretch the spring. Some builders have replaced the spring with a weaker one such as Century Spring part number 72160S. Unfortunately Century has a $50 minimum order.

Using Joe's experience with springs, I opted for the spring he noted above. It was the most single improvement to the flap handle.

Yea, you're right Don. Shortening a compression spring is not the most effective way to reduce tension. If the material is the same, and the OD is constant, you really need to change the wire size to effectively change the tension. However, you will get some tension change by altering the length.

Springs have a parameter called "RATE", defined and the force in pounds required to compress the spring 1 inch.
Van's flap handle springs have a rate of 10
Century Spring part # 72160S has a rate of 2.9
Century Spring part # 72144S has a rate of 2.1
I put part number 72144S in my flap handle and believe that is what Don used.

Regardless of the rate value, length of a spring being used is also a design factor.

The spring originally used was chosen because it was already in inventory, but it retrospect, it probably should not have been since the length required that it already have quite a bit of pre-load even without the button pressed.
Shortening the spring by .5 inches reduces the pre-load to the point that the system then works very nicely.

magiccarpet said:

In Van's Notification 15-10-01 the flap actuator force can be reduced by trimming the VA-114 spring by 0.5".
When I cut F-1260A to length of 10 13/16" as described in Section 32, I didn't remember that I already had trimmed the length of the spring. So I ended up in a too short F-1260A flap handle tube.
No big deal to replace that tube, but I am wondering if the KAI should have been updated or why the notification does not mention anything about the fork assembly.
Do I miss anything here?
Thank you !!

Click to expand...

Have you talked with anyone at Van's tech. support about this?

You are the first I am aware of to mention a problem since the CN was released (quite a while ago) so I think it is likely caused by one of your parts not being to proper dimension. It should work with the 10 13/16" dimension.

rvbuilder2002 said:

Have you talked with anyone at Van's tech. support about this?

You are the first I am aware of to mention a problem since the CN was released (quite a while ago) so I think it is likely caused by one of your parts not being to proper dimension. It should work with the 10 13/16" dimension.

Click to expand...

No I haven't talked to Van's customer service, since it's only a minor issue for me. I doubled checked the dimensions of the tube and it appears ok.
(If the spring was originally too short, that would explain the problem)

Once installed, the lower part of the flap actuator button goes inside the flap handle tube and the remaining travel distance to release the handle from the notch is too short.

Thanks for all your ideas and comments here. I easily could stretch the spring to get to proper distance or doing another work around, but I hestitate doing that, because I prefer to stick with the Van's assembly instruction.


P.S. Quite a long post for describing a rather easy thing. I am curious what happens when I will have reached engine installation ;-)

Problem solved

After painting the detent bracket assembly, the MS20392 pin of the fork assembly didn't go anymore fully into the notches of the F-1266A.
I didn't noticed that first and blamed the shortened spring for that. Smooting out the notches with a fine file solved the problem instantly. So, the dimensions given in the KAI are perfectly correct.

Once more, if anything doesn't fit on that kit, it's likely the builder who did something wrong.
Thank you everybody for your valuable comments.