Reinforcing engine mounting holes

[FrankFuss]

Is it a good idea to reinforce the firewall around the engine mounting holes, like with CF dowels, so as not to crush the plywood, or am I just being anal, or both? :25:

[66stang]

Use a nice size washer!

[jlb]

Washers work fine if you're using nuts and bolts but I prefer using blind nuts (or T nuts as some call them) which eliminates the loose nuts and simplifies things somewhat.

[sweetpea]

I do this on all my aerobats.....probably overkill.

I use a holesaw and drill out some plywood. Then I put the blindnuts into that. I then glue them to the inside of the firewall. I then take a 1/8 flat piece of alum and cut it in 2 strips. 1 goes on the top and one goes on the bottom of the motor. This spreads the load across the motor box.

228912

228913

[classclown]

Use a nice size washer!

+1 on the washers = LESS WORK!!!!

[bodywerks]

All you really need to do is not over-tighten the bolts. Many people crank the bolts down in an effort to keep them from coming loose, but crush the wood in the meantime. They only need to be torqued to 50 inch-pounds or so. then safety them with safety wire or simply put a bead of silicone around the head of the bolt(assuming you use blind nuts on the other end) to secure it to the surface.
What you want to do with the CF stuff is a good idea, but 1/8" hardwood dowel works better. If you're going to do the fender washer technique it is a good idea.

[bodywerks]

+1 on the washers = LESS WORK!!!!
MORE WEIGHT!!!!!

[classclown]

Sure its more weight, if you use those grade eight nuts and bolts.

[66stang]

You could also use the nylon nuts, or thread locker.. But don't use thread locker on a nylon nut!!

[Fade2Black]

I am doing the same and came to the forum to see if there was any answers.

88" WH Edge 540 with a DA 50 going onto it.

The firewall was in good shape, but the guy that i brought it from had a G62, so he put a wood block on the front as a stand off. I tried like hell to get the wood block off without damaging the firewall, but it cracked.

I replaced the firewall with aircraft quality 4 ply, plywood. Used 30 min epoxy to hold the sides and the firewall in the joiners, and the clamped it down. I took it one step further by drilling 1/16th holes in the side of the motorbox into the actual firewall, and epoxying 1/16th carbon fiber pins in. I have heard of a varity of hold downs, but I think I may go with the fender washer way. My only problem now is getting the fender washers to fit with the tristock in the way. :211:
Any ideas?
http://i89.photobucket.com/albums/k224/Mariotango/Stuff/P1010421.jpg

[sinergy]

MORE WEIGHT!!!!!


Where did you get those blind nuts?

[Tired Old Man]

Grind off the side of the fender washers to fit the tri stock. Requires a little more effort to hold them in the correct position as the nuts are tightened up but only for a moment.

[Fade2Black]

Grind off the side of the fender washers to fit the tri stock. Requires a little more effort to hold them in the correct position as the nuts are tightened up but only for a moment.

Thanks for the info. What it did was just the opposite as I didn't see this post. I sanded down the tristock to fit the washers, the
n applied thinned epoxy over the tristock to harden it to he corner.

I think it may hold up.

[crazyjoe]

Where did you get those blind nuts?

True Value, Lowes, Ace hardare, Home Depot

[classclown]

True Value, Lowes, Ace hardare, Home Depot

You forgot to add Uncle Bob's house of nuts.

[sinergy]

thanks!