I posted about this in another related thread, but no response- so I'm re-posting in it's own thread.
When I bought my 1953 C180, the seller included a set of aluminum firewall bushings to replace the standard rubber ones at the attach points for the engine mount. These are often referred to as "seaplane bushings".
They would be p/n 0751004-1 (bushing) and -751004-2 (pad), to replace the rubber units p/n's 0550155 & 0550154-2.
Unfortunately, I don't know for sure if they are genuine Cessna parts, owner-fabricated duplicates, or just what.
Can anyone furnish the dimensions of the Cessna aluminum bushings & pads?
I want to install the right stuff, but I don't wanna drop $275 for a Seaplanes West bushing kit if what I've got is good to go

I was in the opposite position a couple months ago. I wanted to get dimensions so I could fabricate my own. At that time, I was unable to locate any dimensions so I installed new rubber ones. I personally would would pull your existing bushings, measure the holes for diameter and proper length, then install what you have if it looks likes they will fit properly.

I have them but can't tell you how deep they are going through the firewall. Why not call Yingling or Seaplanes and get them to measure the official bushings to compare against your's.

Jeredp wrote:..... I personally would would pull your existing bushings, measure the holes for diameter and proper length, then install what you have if it looks likes they will fit properly.

Hoping to have my ducks in a row before I loosen up everything and pull out the old rubber bushings.
Don't want to have to do it twice, or be down a week or two waiting for the correct parts if mine aren't right.

180Marty wrote:I have them but can't tell you how deep they are going through the firewall. Why not call Yingling or Seaplanes and get them to measure the official bushings to compare against your's.

Thought about that, but then wondered how eager they would be to take the time to measure some parts so that I can NOT buy theirs. Probably not very.

Hotrod, I can tell you this much----the part on the front of the firewall that looks like a thick washer is 1 and 3/8 in diameter and 1/4 inch thick. Can't remember if they are the same front and back and meet in the middle---been a long time. I bet you have the correct ones since the guy also bought Monarch caps and didn't install.

The seaplanes west kit consists of three parts for each attachment.
There is an aluminum disk 1.25" in diameter by .250 thick.
There is an aluminum bushing that goes in the firewall hole, it is 5/8" diameter by .275" thick (the package says .250 but it measures thicker).
There is a hardened steel washer that is 1.0" diameter by .100" thick.
All the parts have a .375" id hole through them.
These fit an early 180. Not sure if later ones are different.
As I recall you'll need a different length bolt than for the rubber bushings.
Parts are easier to install than the rubber bushings as the mount does not need move out from the firewall more than just over .250"
A 3/8" drift may be useful for alignment.
Bottom two are pretty easy, top two are more of a challenge.
Of course your mileage may vary.
Two man job to tighten unless you have arms like a mutant orangutan.
Have pix of parts but not sure how to get them here.
ff

flyfish wrote:........There is an aluminum bushing that goes in the firewall hole, it is 5/8" diameter by .275" thick (the package says .250 but it measures thicker). .....

Thanks Flyfish.
I believe the bushing that goes through the firewall needs to be stepped?

I just sent you a PM.

No step in the bushing.
Radius on one end, but I think that is just for ease of install as there is no other reason for it.
ff

Pm sent also

Sounds like Seaplanes is different than what I have. I think I remember mine from Yingling being stepped down where it goes through the fire wall and one piece with what is visible on the firewall. Then just one piece on the backside.

That would make sense as it would mimic the rubber version.

That's how the ones I have are configured.
Flyfish sent me pics of his and they are as he describes.

Here's a photo of my firewall bushings (of unknown origin):



and a photo Flyfish sent me of his Seaplanes West bushings:

Right or wrong, this is what the backside of mine looks like. My friend and IA, who owned a 55 180 at the time, installed them in 1988 and over 1200 hrs ago. He did his also and I think we used the same bolts.