Blain
Well Known Member
RV-8, Sensenich FP, Vans spinner. Quick search doesn't return any recent threads on the topic.
Vans says use a 2" diameter washer under bolt head and trim them to clear spinner bulkhead. I have a set of these from another builder. It just doesn't seem like the thing to do. An email to Sensenich got me "Do what Vans recommends".
![](/community/proxy.php?image=http%3A%2F%2Fi265.photobucket.com%2Falbums%2Fii232%2FBStumpf%2FIMG_20160531_211344543.jpg&hash=a7d31771a28d4893b5fd0cb2c76acd9c)
The only reason I can see to use this size washer is for the increased clamping area on the forward bulkhead.
As usual I may be over thinking it but I find a couple of drawbacks to this.
The trimmed washer will still turn when applying final torque until it hits the step in the spinner. Seems like that will create a stress zone.
Another issue which is probably easy to cure is the imbalance between the weight of the trimmed washers. I found 0.1 OZ difference. Even though they have a short arm to the center of rotation it must contribute to a harmonic imbalance.
Then the stack weighs 7.4 OZ, standard diameter washers only 1.8 OZ. that is rotating mass about as far forward as you can get.
![](/community/proxy.php?image=http%3A%2F%2Fi265.photobucket.com%2Falbums%2Fii232%2FBStumpf%2FIMG_20160531_211456143.jpg&hash=2d17a6ff02cb20b4fad50fc5df1f908c)
I've learned over the coarse of this build what looks improper usually has a reason. Am I missing something?
Vans says use a 2" diameter washer under bolt head and trim them to clear spinner bulkhead. I have a set of these from another builder. It just doesn't seem like the thing to do. An email to Sensenich got me "Do what Vans recommends".
![](/community/proxy.php?image=http%3A%2F%2Fi265.photobucket.com%2Falbums%2Fii232%2FBStumpf%2FIMG_20160531_211344543.jpg&hash=a7d31771a28d4893b5fd0cb2c76acd9c)
The only reason I can see to use this size washer is for the increased clamping area on the forward bulkhead.
As usual I may be over thinking it but I find a couple of drawbacks to this.
The trimmed washer will still turn when applying final torque until it hits the step in the spinner. Seems like that will create a stress zone.
Another issue which is probably easy to cure is the imbalance between the weight of the trimmed washers. I found 0.1 OZ difference. Even though they have a short arm to the center of rotation it must contribute to a harmonic imbalance.
Then the stack weighs 7.4 OZ, standard diameter washers only 1.8 OZ. that is rotating mass about as far forward as you can get.
![](/community/proxy.php?image=http%3A%2F%2Fi265.photobucket.com%2Falbums%2Fii232%2FBStumpf%2FIMG_20160531_211456143.jpg&hash=2d17a6ff02cb20b4fad50fc5df1f908c)
I've learned over the coarse of this build what looks improper usually has a reason. Am I missing something?