Engine mounts sagging

[mike.smith]

Hi , has anyone had success with polyurethane engine mount bushes for a aerovee .

I did when I had someone else make them for me. Whatever polyurethane was used worked well. When I tried to make them myself the urethane I used didn't hold up 10 hours before beginning to fall to pieces. So be very careful about what urethane you use. And monitor your mounts often and carefully for a while after. I'm using stock AeroVee mounts at the moment.

[bvolcko38]

Does anyone have the physical dimensions of the rubber shock mounts?

[bvolcko38]

I bought a polyurethane round bar from McMaster Carr, 80 durometer, just like the factory bushings. I made 8 bushings to the same dimensions as the factory's. They have been installed and flown with for over 2 months now and zero sag. Vibration seems normal. The original bushings started sagging the day i mounted the engine. It took about 2 weeks to fit the cowl after mounting the engine and I noticed the creepage. 2 years later the bottom bushings were worn through and just started to get metal to metal contact between the backplate and the motor mount.

[pappas]

I had to replace motor mount bushings once on my 3300 powered Waiex in 2007. I went with the harder ones from sonex and did not have any additional sagging at the time I sold it in 2009.

However, because I am aware of the sagging issues everyone has; when I built my current Waiex Turbo in 2019, I simply wrapped hose clamps around the bushings and tightened them down like usual. 2 1/2 years later and 125 hours and my engine is in the same place it was the day I hung it.

I don't know if that will last, but my cowl spacing is the same as when originally fitted. Of course, now that I have spoken about it, I expect to find my motor on the floor when I get back to the hangar.

[bvolcko38]

I did the hose clamp thing as well, to no avail. The rubber compound is not right. It flows over time. So far the polyurethane seems to be working nicely. Time will tell. That's why they call this "experimental"

[pfhoeycfi]

I had to replace motor mount bushings once on my 3300 powered Waiex in 2007. I went with the harder ones from sonex and did not have any additional sagging at the time I sold it in 2009.

However, because I am aware of the sagging issues everyone has; when I built my current Waiex Turbo in 2019, I simply wrapped hose clamps around the bushings and tightened them down like usual. 2 1/2 years later and 125 hours and my engine is in the same place it was the day I hung it.

I don't know if that will last, but my cowl spacing is the same as when originally fitted. Of course, now that I have spoken about it, I expect to find my motor on the floor when I get back to the hangar.

Did you use 1/2" band clamps or something less?

peter

[Bryan Cotton]

Five years static, an hour of ground running, and 1.7 hours in 3 flights so far. Poly bushings seem good.

Edit: these are Super Pro SPF2092BK bushings. Available in the US and Australia it would seem. Some of the old links are broken but if you search for "Super Pro SPF2092BK" you will find their USA or Australia website, plus ebay sellers and so on.

[Bryan Cotton]

Five years static, an hour of ground running, and 1.7 hours in 3 flights so far. Poly bushings seem good.

Edit: these are Super Pro SPF2092BK bushings. Available in the US and Australia it would seem. Some of the old links are broken but if you search for "Super Pro SPF2092BK" you will find their USA or Australia website, plus ebay sellers and so on.

43.6 hours and I'm still happy with my Super Pro bushings.

[tps8903]

Five years static, an hour of ground running, and 1.7 hours in 3 flights so far. Poly bushings seem good.

Edit: these are Super Pro SPF2092BK bushings. Available in the US and Australia it would seem. Some of the old links are broken but if you search for "Super Pro SPF2092BK" you will find their USA or Australia website, plus ebay sellers and so on.

43.6 hours and I'm still happy with my Super Pro bushings.

Was there a change in engine position when you swapped from factory rubber to the Super Pro Mounts?

[Bryan Cotton]

Was there a change in engine position when you swapped from factory rubber to the Super Pro Mounts?

I went right to these mounts during the build, based on this thread. I tweaked the engine into alignment by adding washers and turns on the nut.