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This can't be good... Exp. Conical silicone bushings cracking

Iflylower

Registered User
Memphis, TN
I'm working firewall forward.

These silicone bushings are from aircraft spruce listed as experimental lycoming conical bushings. They are new and unflown, on the plane six weeks torqued properly to 480 in. pnds. called for in the piper manual. They seem slightly oversqueezed if you ask me. I referenced a video that says 400 in. pnds. and about 3 threads showing on the bolts. That checks here.

I don't like the cracks. Looking into replacements or Lycoming bushings tomorrow.

Advice from those who've done a few mounts? Can't be normal, can it?
 

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Cal,,, new and unflown ? could be, ,, looks like to me someone had them on the shelf for a long time,,, but could still be used and unflown, just old.
 
40 inch pounds or 1.84".
eng_mt_bushing.jpg
 
I looked it up again in the L-21 install manual... Said 40 ft. lbs, which I take to be 480 in. lbs.

I'm going with new Lord mounts as soon as I can find them. Maybe Jesse at Aero-in-stock.

I wish I had read this before I ordered.... Spruce will definitely hear from me on this. These mounts didn't even make one flight.

Copied from the Vans builder website...

Quote:
Originally Posted by LOCKNUT
Has anyone used the Conical Lycoming Engine Mount Bushings sold by Aircraft Spruce P/N 08-00662?
That is pure junk. You get 8 of those, 8 big washers and smash them down to an inch of their life. They isolate vibration like (fill in bad word here). They also don't last and wear and sag very quick. You want a LORD mount.

Get the LORD engine mounts. They are expensive but worth it. I think van has them for sale ($75). The part number I recall is J-1552 ($34.95 each, you need 8). The alternative part number is J-6230-1 and they are sold in pairs for $78.95, you need 4.

The temptation to go with a $8 bushing is high, but you will not be happy. You will be replacing them and unless you have a wood prop chance is you will be unhappy with the vibrations. The "Homebuilders conical Lyc engine mount bushings that Spruce sells cost $40 for the whole set. Yoy will need 8 large washers at $7 ea, or $56. These are larger dia and thicker than plan old AN washers. So you are into it for $100. For less than $300 you can get REAL engine vibration isolation mounts.


The LORD vibration isolators are like a Dynafocal design for the conical mount. Trust me, done that been there. Call LORD at Customer Support Center +1 877 ASK LORD (275 5673) to confirm part numbers. If you buy form Van's make sure they are LORD brand. I am not getting anything from this, but I have tried all brands and types and the LORD cost a few pennies more but are well worth it. The cheap "Bushings" are just squashed down. There is no torque because all you do is smash the bushing out from around the washer. IT SUCKS.

The Lord Conical mount has built in washers and spacers so they are easy to preset and not over crush. They are just a world apart. I had a vibration problem with my RV-4. I tried evey thing. My extend hub hartzell was balanced several times but was never quite right. Going from bushings to the LORD mounts was like going to calm sea's.


The bushing deal with conical mounts is a weird things. Back 60 years ago they used them for shipping. The bushings are good for shipping but not aircraft use. Bite the bullet and pony up the better part of $300 for the real deal. The bushings and the proper washers would cost you only about 1/5th of that, but if you have to replace them all the time and rattle you fillings out, it is not a deal.
__________________
George
Raleigh, NC Area
RV-4, RV-7, ATP, CFII, MEI, 737/757/767
 
P.S. Vans web store doesn't carry conical mounts. (anymore?). Will be looking for a source
 
I get the factory Lycoming ones from Avial with no problems. I can get you a set or you might check with Linda Lou.
 
Thanks Steve. I tried to ring you, no answer. Just missed you at Oshkosh.

I ordered 8 Lycoming #71032 from Linda Lou. She knows me well.

Thanks.

Beware all of the junk experimental conical mounts from spruce!
 
Here is the torque values from table III on l-21 build.

Last line of the list. Whole list in foot pounds.

Wrong?
 

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IFLYLOWER

I tried the silicon conical eng mount bushings on my O-320 two years ago and they are still fine. I used 40" lbs of torque on the bolts to draw them up, its not much.
I think maybe the manual you referred to gave you the improper torque value. The pictures you showed are bushings that look like they are crushed.
 
Search engine mount bolt torque, some good info on this. Thanks steve p. I think the small continentals are 7 ft lbs. now i got to check again.
 
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Be sure to measure the mounts when you get them. The first time I ordered the 0-320 mounts from Aircraft Spruce, I discovered that they were 1/8 smaller diameter ones for an 0-290. Apparently someone at Aircraft Spruce had dumped the wrong ones in the bin. Since they do not have a part number molded into them, no one figured out the error. I called them to alert them to the error and got another set also from Aircraft Spruce and this set measured correctly -- the OD of the straight length was 1 inch, the 0-290 ones are 7/8 inch OD.
From an earlier thread on this site, I wrote down these comments from others -- I haven't verified any of these statements, just passing it along from others on Supercub.org:
1. 1.75 sometimes works better than 1.84 inches.
2. 80 in-lb works better than 40 in-lb.
3. Torque the nut -- not the bolt head.
4. Tighten until the rubber mount slightly bulges is another method.
 
Thanks Steve P and everyone for the info. Guess you can't trust the piper manual. I'm glad I saw those cracks before it flew. Sounds like there would have been some vibration....

I was quick to call those spruce experimental bushings junk based on the cracks and the vans post. But, it appears I crushed the ever living snot out of em at 40 ft lbs. Guess I can't bash them personally.

New ones on the way, God Bless the help on this site.
 
I've had the same mounts in Cuzoom for five years when we run the engine on the test stand hit the nitrous the torque goes to slightly over 700 ft lbs it really squeezes the bushings but no issues on the plane with my new Catto three blade it will pick the left wheel off the ground if your not careful I've cracked an broken the engine mount but no bushing problems. Mikeo
 
Thanks Steve P and everyone for the info. Guess you can't trust the piper manual. I'm glad I saw those cracks before it flew. Sounds like there would have been some vibration....

I was quick to call those spruce experimental bushings junk based on the cracks and the vans post. But, it appears I crushed the ever living snot out of em at 40 ft lbs. Guess I can't bash them personally.

New ones on the way, God Bless the help on this site.

I don't think you were quick to call them bad. If they crack during static loading what happens when you have a much higher dynamic load on them??
 
I used these from Wagaero and sold the plane after 10 years without issue. Have another set not yet installed for my new build.
31.50 for 8.... less than $4.00 a piece.



Engine Mount Bushings, Lycoming, FAA Approved
Model:
SKU: I-982-000
Lycoming; Replaces P/N 71032. FAA Approved for the following engine models: 0235-C1, 0290-D2, 0320-A2A, 0320-A2B, 0320-A2C, 0320-A3A, 0320-A3B, -A3C, 0320-B2A, -B2B, -B3A, -B3B, -B3C, IO-320-E2A. Code 4



Engine sagging? Vibration chattering your teeth? Replace your engine mount rubber bushings and restore that vibration-free flight. For conical mounts only. Sold in sets of 8. Code 4
image.php
$31.50
 
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