I want to replace my old Dzus fasteners on my cowlings with stainless steel ones prior to painting. Has anyone done this? I would appreciate any and all advice on how to do this without damaging the fiberglass surrounding the grommet.
Help Curt

I just replaced all of mine with camlocs. Start from behind and meticulously crush all of the retainers (the swollen portion of the dzus) holding the fasteners too the cowl. This enabled me to have more room under the head of the fastener and more play all around. Now take a thin piece of solid metal (thin enough to place between the fiberglass and head of the dzus) and firmly push towards the fiberglass and with on swift hit of a wooden mallet from behind they literally just pop out. There is a good video on YouTube that explains my method just slightly different. Also I am way happier with the camlocs. Something to think about. Goodluck

To do camlocks didn't you have to change the receptacle and do fiberglass work on the cowlings?

The hole diameter went up for the camloc and the rivet mounting holes were the exact same spacing to just rivet on the camloc receptacles on the female side. I didn’t have to do glass work for the camlocs to work but I did redo my cowl due to some cracks and separation. I guess the variables in camloc and dzus fasteners could change the outcome for individual aircraft and maybe I got lucky.

Thanks for the great info!

You should remove the grommet prior to paint. Then reinstall new grommets after paint. You should be able to do both without any glasswork assuming eveyis in good condition to begin with.

What is the best way to remove the studs and grommets?

A modified C-clamp works well. The fasteners will press out reasonably well most of the time. Then you can use a counter sink bit to cut the back of the grommets so they slip out from the outside. If you are patient, they should come out without any trouble or damage to the cowl and existing paint.

My worry is that the grommet would come out with the stud and mess up the 3/8" hole in the fiberglass. I thought about the cutting the stud or at least grinding it down a bit with a diamond bit so it would slide out easier. I like the counter sink idea. I was thinking of using 3/8" of slightly smaller drill bit through the grommet.

Did you use fixed or floating receptacles, and also can you tell me what length studs you used and in what locations? The sides of the lower cowling should be the shortest, the sides of the top cowling where it mates to the lower cowl should be a medium length, and the ones across the top rear of the of the top cowling are the longest. I talked to Maule and they said most of them are 40S5-6S studs, but is kind of trial and error to get the best fit.

I used the factory installed clips as mine were in good condition. All of my studs on the M4 were identical in length.