Vibration with new crush plate

rcfaubion · #1 01-26-2010, 11:44 AM

Made a change and looking for suggestions. RV-4, o-320, 160hp, Catto 2 blade, Landoll harmonic dampner, standard Saber alum 3/8 crush plate--ran smooth. Was looking for expanded c/g range so installed 1 3/8 by 7" steel Sabre crush plate (with new bolts) and now have a noticeable vibration in the 1100-1500 range, with a slight change at almost all other settings(imagination?) very noticeable with power off for landing.

n700jl · #2 01-27-2010, 06:50 AM

Check the blade track and prop bolt torque. if it is out of track more than 1/8th inch. shim with heavy paper shim under the prop. 1 shim will give you an 1/8th of an inch at the tip. Use manilla folder paper for the half moon shim. if you still have vibration have prop assembly dynamically balanced to .1 IPS or less. good luck!

rcfaubion · #3 01-27-2010, 08:09 AM

Thanks Jon, will check the track but don't think that is it. Track was fine before and just replaced thin crush plate with heavier steel plate. Had a good visit with Sam at Sabre Mfg. yesterday and he thinks it could be "sag" due to the 1/64 oversize bolt holes (can't put a 7/16 bolt in a 7/16 hole) and the much heavier weight of the steel plate so I will check that also after tracking.

rcfaubion · #4 02-02-2010, 02:45 PM

Track is fine, dynamic balance set up for Sat.