Thanks Thanks:  0
Likes Likes:  0
Results 1 to 24 of 24

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

  1. #1
    Iflylower's Avatar
    Join Date
    Aug 2008
    Location
    Memphis, TN
    Posts
    1,350
    Post Thanks / Like

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

    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?
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	ImageUploadedByTapatalk1312346495.901230.jpg 
Views:	74 
Size:	692.7 KB 
ID:	3207   Click image for larger version. 

Name:	ImageUploadedByTapatalk1312346519.951128.jpg 
Views:	48 
Size:	985.1 KB 
ID:	3208  
    Last edited by Iflylower; 08-03-2011 at 12:00 AM.

  2. #2
    www.SkupTech.com mike mcs repair's Avatar
    Join Date
    Aug 2004
    Location
    chugiak AK
    Posts
    10,197
    Post Thanks / Like
    eeeeek!!!!!!!!

  3. #3
    aktango58's Avatar
    Join Date
    Aug 2004
    Location
    18AA
    Posts
    9,045
    Post Thanks / Like
    Do you want normal, or do you want correct?
    I don't know where you've been me lad, but I see you won first Prize!

  4. #4
    SteveE's Avatar
    Join Date
    Feb 2006
    Location
    Jenks, OK
    Posts
    4,197
    Post Thanks / Like
    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.

  5. #5
    Steve Pierce's Avatar
    Join Date
    Mar 2002
    Location
    Graham, TX
    Posts
    18,426
    Post Thanks / Like
    40 inch pounds or 1.84".
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  6. #6
    Iflylower's Avatar
    Join Date
    Aug 2008
    Location
    Memphis, TN
    Posts
    1,350
    Post Thanks / Like
    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 . 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

  7. #7
    Iflylower's Avatar
    Join Date
    Aug 2008
    Location
    Memphis, TN
    Posts
    1,350
    Post Thanks / Like
    P.S. Vans web store doesn't carry conical mounts. (anymore?). Will be looking for a source

  8. #8
    Steve Pierce's Avatar
    Join Date
    Mar 2002
    Location
    Graham, TX
    Posts
    18,426
    Post Thanks / Like
    I get the factory Lycoming ones from Avial with no problems. I can get you a set or you might check with Linda Lou.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  9. #9
    Iflylower's Avatar
    Join Date
    Aug 2008
    Location
    Memphis, TN
    Posts
    1,350
    Post Thanks / Like
    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!

  10. #10
    Steve Pierce's Avatar
    Join Date
    Mar 2002
    Location
    Graham, TX
    Posts
    18,426
    Post Thanks / Like
    Ha, at the Drm getting the wing splint removed.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  11. #11
    Gordon Misch's Avatar
    Join Date
    Dec 2003
    Location
    Toledo, Wa (KTDO)
    Posts
    3,281
    Post Thanks / Like
    I see that Spruce has the Lycoming P/N 71032 also. $9.25 ea. http://www.aircraftspruce.com/catalog/eppages/enginemountbushings.php

    I had installed the silicone ones because they sounded "new and improved". But maybe should replace them with the Lycoming bushings while it's easy - before the engine is all cowled in. Thanks for the heads-up.
    Gordon

    N4328M KTDO
    My SPOT: tinyurl.com/N4328M (case sensitive)

  12. #12

    Join Date
    Nov 2002
    Location
    Fargo
    Posts
    638
    Post Thanks / Like
    I think your manual is wrong it is 40 inch pounds not foot pounds that could be your problem.

    Chuck

  13. #13
    Iflylower's Avatar
    Join Date
    Aug 2008
    Location
    Memphis, TN
    Posts
    1,350
    Post Thanks / Like
    Here is the torque values from table III on l-21 build.

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

    Wrong?
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	ImageUploadedByTapatalk1312397032.980733.jpg 
Views:	85 
Size:	54.6 KB 
ID:	3211  

  14. #14
    Steve Pierce's Avatar
    Join Date
    Mar 2002
    Location
    Graham, TX
    Posts
    18,426
    Post Thanks / Like
    Yes, Wrong. 40 inch pounds or 1.84" per the Piper drawings.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  15. #15

    Join Date
    Apr 2007
    Posts
    8
    Post Thanks / Like
    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.

  16. #16

    Join Date
    Jan 2003
    Location
    nd
    Posts
    3,163
    Post Thanks / Like

  17. #17

    Join Date
    Jan 2003
    Location
    nd
    Posts
    3,163
    Post Thanks / Like
    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.
    Last edited by tempdoug; 08-03-2011 at 05:44 PM.

  18. #18

    Join Date
    Oct 2010
    Location
    okeechobee,fl
    Posts
    41
    Post Thanks / Like
    ditto tempdoug 2 years no prob, only small superficial cracks.

  19. #19
    Darrel Starr's Avatar
    Join Date
    Jan 2003
    Location
    Plymouth, MN
    Posts
    2,524
    Post Thanks / Like
    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.

  20. #20
    Iflylower's Avatar
    Join Date
    Aug 2008
    Location
    Memphis, TN
    Posts
    1,350
    Post Thanks / Like
    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.

  21. #21

    Join Date
    Mar 2003
    Posts
    495
    Post Thanks / Like
    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

  22. #22
    behindpropellers's Avatar
    Join Date
    Feb 2003
    Location
    NE Ohio
    Posts
    6,671
    Post Thanks / Like
    Quote Originally Posted by Iflylower View Post
    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??

  23. #23
    Kub18's Avatar
    Join Date
    Jan 2011
    Posts
    25
    Post Thanks / Like
    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
    $31.50

  24. #24

    Join Date
    Jul 2016
    Posts
    1
    Post Thanks / Like
    Sent from my iPhone using SuperCub.Org

Similar Threads

  1. Silicone Cowl Seal Thickness etc.
    By Darrel Starr in forum Tips and Tricks
    Replies: 25
    Last Post: 03-25-2009, 06:03 PM
  2. Silicone Rocker Gaskets
    By Jerry Burr in forum Member to Member
    Replies: 10
    Last Post: 11-10-2007, 10:06 AM
  3. J-3 eyebrow cracking
    By JimC in forum Super Cub Sick Bay
    Replies: 8
    Last Post: 06-20-2005, 04:21 AM

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •