Taper Pin Question

SeanB · #1 10-31-2018, 09:41 AM

Hello,

I elected to install taper pins in the tailspring of my RV7. I am using the AN 386-9A pin for the forward pin (installs vertically) that holds the tailspring to the receiver. This pin accepts a 364 or 365-1032 nylock nut. I have the special cupped washer.

The Van's plans have you install an AN4 bolt and nut here. Knowing the tapered pin is a different animal, am I wasting energy thinking of the smaller threaded portion and associated nut being used in the tapered pin compared to original hardware?

Thanks!

Bicyclops · #2 10-31-2018, 03:56 PM

The bolt or pin will be mainly loaded in shear. If the pin is of equal or larger average cross section as the bolt, which one is stronger? Also need to consider edge distance. The nut size really doesn't have much to do with it.

Ed Holyoke

David Paule · #3 10-31-2018, 06:35 PM

Also be wary of torque. I haven't found anything about that with these, but I'd base it on the necked-down portion and use the smaller shear torque and call that a maximum. All we really want, I think, is to get the taper pin firmly seated and nothing more.

Same situation on my RV-3B.

Dave

scsmith · #4 10-31-2018, 07:03 PM

Quote:

Originally Posted by David Paule

Also be wary of torque. I haven't found anything about that with these, but I'd base it on the necked-down portion and use the smaller shear torque and call that a maximum. All we really want, I think, is to get the taper pin firmly seated and nothing more.

Same situation on my RV-3B.

Dave

Yes, you just want to torque it enough to keep the taper seated. I tapped my taper pins in with a plastic-headed mallet on the head end, fairly hard to be sure the taper was seated, and then tightened the nut so it was "thats about right". It has never needed any additional tightening. You should also get the special washers made for taper pins that are a cup that fits over the end of the taper pin. -- Oops, yes, I see now that you have those.

The pin is entirely in shear. Two taper pins is plenty. On the RV-8, the holes were drilled horizontal, side by side. I put one taper pin in from the left, one from the right, to maximize edge distances on everything.

This is really the way to go.

BillL · #5 10-31-2018, 07:36 PM

I just happened to discover some deadband in my tail spring and elected to install a taper pin in the forward tail spring attachment. I would recommend you have a diamond hone plate available and use it regularly to sharpen the tapered reamer every two revolutions or so. You will be much happier with the tapers and it will remain tight for ever.

I don't know about two though. I used just one in the forward position. If the tailwheel gets loose it will get the same solution

PS- I did not check your numbers, are you talking about the spring base or tailwheel attachment?

vfrazier · #6 11-01-2018, 10:15 AM

Blake has tech tips for the tailwheel here:

http://www.flyboyaccessories.com/Tai...nts-p/1109.htm

Included in the documents are part numbers and general techniques for maintaining your tailwheel system... including tapered pin discussion.

Tailwheel tech sheets

SeanB · #7 11-01-2018, 11:37 AM

Thanks everyone. Vince, I spoke with Blake yesterday. Great help!

SeanB · #8 11-06-2018, 12:22 PM

Reading the EXCELLENT post by Vince earlier in this thread, he calls out "AN365-832 or AN320-832 nuts" for these pins. I ordered those and they seem too small. -1032 nuts seem to fit correctly. Sound correct?

Also, confirming, the "cupped" washer has the larger opening facing away from the nut, correct? Flat washer not needed in addition, unless for thread spacing?

Thanks!

David Paule · #9 11-06-2018, 02:01 PM

That's correct. The cup is for the small end of the taper pin to protrude slightly.

Dave