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Motor mount torque?

K

ksecub

Registered User
Portland, OR
Does anyone know what the proper torque is for the (4) carry through bolts on conical rubber engine mounts (150-180hp)?
 
Torque

It is not a torque value it is a compression measurement. The rubber mounts should be compressed to 1.840 between the mount washer and engine mount pad. This is measuring the rubber only and not the washer or mount pad. Crash
 
Where did you find the compression measurements? The old L-21 manual actually says 40 FOOT pounds.
 
Compression measurement

I got the compression measurement off of a Crosswinds STOL blue print for their O-320 conversion. Crash
 
For the 40 INCH-POUND ref, see Piper Service Letter No. 349 dated Dec 14, 1960 and/or Piper Service Aid MISC/TP-1001A. For the measurement specification, see virtually ANY Lycoming Four Cylinder Engine Operators Manual. There are lots of other places these specs show up, but these are certainly "Official". When using the torque method, you MUST find an accurate "running torque" for each bolt first -what it takes to just turn the nuts on the bolts under no load, then add 40 inch-pounds. When done this way, you will get within a Frog's Whisker of the measurement at that torque if you have everything in perfect alignment when you do each bolt. The measurement method has seemed to work the best for me over the years. Forty FOOT-POUNDS is a scary number (12X what two other documents say) and makes the mounts WAY TOO stiff! You can feel the engine running sitting on the seat. That HAS to be a misprint (or a missed rememberance).
 
From the Piper engine installation drawing for the O-235-C1 in the PA16.

eng_mt_bushing.jpg
 
C90 -8 or -12 --------- 60 to 80 Inch pounds Tq at the Nut

C90 -14 or -16 or 0200 with Lord Mounts ---180 to 190 Inch pounds Tq at the Nut

Source: Form X30010 Section VI
 
rising this thread from the dead. I am finishing up my engine install and looking for the torque value for the engine to the mount. I have read anything from 40 in/lbs to 50 ft/lbs. Does anyone have the correct answer? With the rubber mount it seems that 50 ft/lbs would crush and ruin the new mounts.

Thanks guys
 
Ditto. 1.84 inches. From what I remember the last time I replaced mine, it only took a few lb/feet to reach the compression spec. 50 lb./ft. would be absurdly over tightened.
 
Last edited:
Lycoming Installation drawing for O-360-H requires 40 in-lb for 1.63 Max Dia Lord conical rubber mount bushing. No compressed bushing dimension is given.
Piper Powerplant drawing for O-290-D/-D2 requires 1.840 compressed for rubber bushing and washer supplied with engine.
 
I used the 1.84 measurement for my 0-360 and it works just fine.
 
I might add, my previous post was based on old data, The Lycoming drawing was at Rev. C, dated 1976, and Piper drawing at Rev. BW, dated 1955. I will be changing my bushings soon and will use both the torque value and dimension as Steve Pierce does. No one has specified whether they are using Lycoming conical bushings or not. I understand that Lord still makes a conical bushing, but do not know whether it is approved for an O-360.
 
Is this measurement with the mount bolted to the airframe or doesn't it matter?


Sent from my iPad using Tapatalk
 
Thanks to everybody who contributed to this thread 8):howdy I bolted in the replacement engine to my 12 on Thursday and yesterday and used the 1.840" mounting rubber to mounting rubber overall length measurement and the split pin holes in the castle nuts depth lined up perfectly in all 4 cases!!!!!

THANK YOU!!!!
 
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