Upper firewall retrofit to camlocs questions??

I want to eliminate the 2 piano hinge upper wires on my 4. Skybolt offers a kit to do this procedure ....but no instructions. Do the cowl and boot cowl piano hinges need to be completely removed? Would someone please detail the installation process for me. I understand that a receiver strip needs to be somehow installed on the firewall side for the 4000 series camlocs to be riveted to.
Thx in advance for all help in explaining how it's done.

Marvin

I did the same thing on my -4 some years ago. Skybolt included a pretty good instruction set. In short, however, a strip is rivet to the firewall to receive the Camlocs. In order to install this strip, it is necessary to remove the plate nuts that hold the forward fuselage skin in place. Some careful hole duplication is required to ensure the skin fit nicely again. I switched to floating plate nuts at this time to provide a little more forgiveness.

Next, you need to remove the old hinge strips from the upper cowl. I also replaced the original formed hinge (between the upper and lower cowl section) with extruded hinge with wider flanges to provide better bonding surfaces. (Why Van's provided that roll-formed hinge stock I will never understand.) I had to do some fiberglass work, but cannot recall if it was dictated by the Camloc installation or for the hinges. I do recall, however, that the Camloc instructions recommended the addition of a fiberglass stiffener along the curved portion of the upper cowl, just forward of the Camlocs. This is to eliminate/reduce puckering between the Camlocs while in flight (due to the ram pressure of the cooling air). I skipped this step, but wish I had complied as I do see some minor puckering in flight.

You will need to re-paint your cowl once you are done. I did this task about 10 years ago, and it all still works and looks great. I would call Camloc they must have these instructions.

Good luck.

autoglide said:

I want to eliminate the 2 piano hinge upper wires on my 4. Skybolt offers a kit to do this procedure ....but no instructions. Do the cowl and boot cowl piano hinges need to be completely removed? Would someone please detail the installation process for me. I understand that a receiver strip needs to be somehow installed on the firewall side for the 4000 series camlocs to be riveted to.
Thx in advance for all help in explaining how it's done.

Marvin

Click to expand...

Good luck. Skybolt's instructions didn't match the fasteners they sent me and requests for support went unanswered.

Blog

There a couple of photos of this process on page 2 of my blog.


I used 40 thou strip riveted to the firewall. 60 though would be better. I drilled pilot holes in the centre of where the fasteners were to fit. Then a strap duplicator to get them in the same place on the cowl.

Then drill out the pilot holes to the scene fastener size, put them in upside down an mount the receiver on top to drill the holes for the rivets which hold the receivers. Dismantle an countersink for the flush rivets then you can rivet the receivers in place.

It's really straightforward.

Blog

There a couple of photos of this process on page 2 of my blog.


I used 40 thou strip riveted to the firewall. 60 though would be better. I drilled pilot holes in the centre of where the fasteners were to fit. Then a strap duplicator to get them in the same place on the cowl.

Then drill out the pilot holes to the scene fastener size, put them in upside down an mount the receiver on top to drill the holes for the rivets which hold the receivers. Dismantle an countersink for the flush rivets then you can rivet the receivers in place.

It's really straightforward.

The strips that hold the Camloc (or similar) receptacles, that get riveted to the fuse/firewall, can be purchased from either Spruce or Vans in .050 thickness. As I recall they're 3" wide and 3' long ... Saves a ton of time cutting thick stock into long strips. IMO, .050 is the absolute minimum for thickness to get the Camlocs to work dependably in all conditions. Any thinner and they'll flex when you try to quickly fasten the Camloc when they're not lined up just perfectly.

oops

I just checked the Spruce part number (04-01993) for the aluminum strips on their website. It appears they no longer offer them.

RV-4 Skybolt Fasteners

In the last year I installed new upper and lower cowls on my RV-4 and decided to use the Skybolt (quarter turn) fasteners. I did order the V-lock tabs to attach to the curved firewall for the upper cowl, but didn't use them. I found it much easier to use two separate strips of .063 soft 6061 aluminum(close to 3 inches wide) , using the provided v-lock tabs as a pattern to draw the pattern onto the 6061 strips at your chosen spacing (I used 11 fasteners). One strip would have 6 fasteners, the other 5. You attach the the two strips to the firewall. Don't drill any holes in the projecting tabs. Install the upper cowl, with bottom cowl in place, hopefully your fit at the firewall is acceptable. After careful measuring drill 1/8th inch holes in the fiberglass into the hidden tabs, enough to mark the hole location on the hidden tab. Remove the cowl and finish drilling the 1/8th inch hole through the aluminum tab. Finally enlarge the tab hole to the size to match the hole size on your pattern tab, including the holes that hold the fastener. Also enlarge the hole in the cowl as recommended in the instructions. Just under 1/2 inch.

I did the Skylocs on the initial build and had no problems. They work great and are installed according to plans. I have the piano hinge only between the top and bottom half of cowl. Pretty east to do.