582 High Vibration

[Av8r_Sed 82]

I have a problem with vibration on my grey head 582.  It has never run very smooth but recent attempts to dynamically balance my prop lead me to believe I have a rough running engine that needs to be addressed before I can properly balance the prop. My goal is to get it smoothed out at 5800 RPM so I can balance the prop for cruise.  I'm looking for help getting to the bottom of the issue.

 

I've tried both a Dynavibe and an ACES ProBalancer and I get average readings of around 0.70 IPS and the phase tends to wander around a bit.  Worse, as I've tried adding test balance weights, the readings don't improve much and certainly don't converge.  The vibration sensor is mounted firmly to the top of the gearbox in vertical orientation using a steel plug threaded into the gearbox vent hole.

 

Symptoms:

- It can idle between 1600 and 2000 RPM.  The RPM tends to wander and it doesn't purr like a kitten.  I've always thought that with no load due to the clutch at idle it will always be a bit rough, but maybe I'm mistaken.

- Seems to make good power.  With the ground adjust I can dial in the 6300 static RPM no problem.

- RPM always seems to wander at a fixed throttle setting.  If I'm targeting 5800 RPM static it can vary from 5730 to 5860.

- Vibration levels seem to vary over a fairly short time span.

 

Engine: 582 model 90, C 3:1 Gearbox, RK400 clutch, oil injected, 105 hours TT, rebuilt by L.E.A.F. about 4 years ago to meet Rotax time limits.

 

Carbs: dual Bing54 with HacMan system installed, choke installed and no primer

           everything clean - no debris, newer style floats and proper float level verified, mechanically synced

           idle jets: .45

           currently running .190 main jets with needle clip in 4th position (bottom) HacMan allows me to dial in 1150 EGT at 5800

 

Mounts: Side mount system with Lord 150PD-30 replaced 3 years ago and torqued down pretty tight.  The rubber seems pretty pliable because I can easily deflect them up and down by pulling on the prop hub.

 

Instruments: MGL E1 monitor for RPM, EGT's and water temp.  Also TinyTach for RPM which tracks the MGL readings.

 

Prop: 70" 2 blade IVO medium ground adjust for now, soon to go to IFA.

 

Ignition: Standard Ducati CDI.  I do have the ignition wired to an ACS key switch instead of the individual toggles.  

[wypaul 448]

I suggest using a CarbMate  or the likes to get the carbs balanced pneumatically. My 912 was not close by doing the mechanical balance job and would not run smooth at higher RPM.

 

The other Paul S.

[akflyer 1427]

If you have a clutch, it should be smooth as a babies butt at idle. I too would look at a carb mate. I can loan you mine if you would like to try it. For what ever reason mine would not balance perfectly at idle and at full rpm. Mine is off just a tad on the bottom end, but dead on at 3500-6800 rpm.

With a 2 stroke, unless you in dead calm air, your not gonna have a constant rpm. With up n down drafts, even very slight ones, it will gain n loose rpm.

[Mendlerr 4]

Mine 582 with a clutch idles so smooth at 1,500 you literally cannot tell its running if you are wearing any kind of hearing protection. Engagement is smooth and it has no vibration issues all the way to 6500. Something is definitely going on. I would look at carbs. My engine ran rough until I synced the carbs up

[Av8r_Sed 82]

OK, It sounds like the consensus is to try to sync the carbs, especially at my target RPM.  I've got a plastic U tube water manometer set up that I can attach to the unused (and normally capped) primer ports on each carb.  Will this do the same job as the CarbMate?

[dholly 718]

Was the gearbox rebuilt at the same time as the engine?

[Bandit 286]

I ran my 3 blade IVO prop with 2 blades for a while. It ran so dam rough that a engine mount bolt broke and the rivets were popping out of my skylight.

[Av8r_Sed 82]

Doug, no rebuild on the gearbox. I had it apart earlier this year to replace the rear oil seal and didn't notice any issues. Are you thinking bearings? Any good way to check?

Bandit, during the summer I was running a borrowed Ivo 3 blade ultralight ground adjust and it was smoother, but I still couldn't dynamically balance it. The guy I borrowed it from said he had it nicely balanced. Jury is out on the 2 blade medium but I should be able to get it balanced somewhat.

[Av8r3400 1178]

A rebuild on the gear box is what I am about to do to track down a vibration problem.  The bearings are not necessarily the problem.  The Bellevue washers that make up the spring that holds the upper gear in place can relax over time and cause very irritating and seemingly unfixable vibrations.  This can be exacerbated by the use of a heavier prop, like my 3-blade warp with nickel leading edges.  (The 912 'box is very similar in design to the 2-stroke 'boxes.)

 

After doing everything possible to my carbs including electronic syncing and Dynavibe balancing the prop, the gearbox is the last option...

[Mendlerr 4]

That's unfortunate.  I hope it doesn't end up costing you too much.  I recently had my gearbox apart and everything looked good.  Good bit of information you posted also

[dholly 718]

Paul, I'm not sure which bits inside caused the problem(s), but I remember a thread where someone went through the entire engine, carb, prop related process of elimination only to remain stumped. At another members suggestion who experienced the same unresolved symptoms, he had the gear box rebuilt and it solved his vibration issue too. Matronics list maybe?

[Av8r3400 1178]

There was one like that on TeamKitfox.  It was dealing with a 912...

 

My washer replacement job is only going to cost a few bucks for the washers, retaining clips and gaskets.

[Av8r_Sed 82]

I'm going to do the pneumatic balance then look into the gearbox if it's still rough.  First though, I've got to replace the original throttle cables which are anything but smooth even though I've lubed the heck out of them.

[Mendlerr 4]

I just replaced my throttle cables and it helped my idle, they were not allowing the carb pistons to go all the way down evenly.

[Av8r_Sed 82]

Next chapter in running down my vibration problem: I've now installed nice new throttle cables and done a pneumatic sync.  It's not perfect, but it balances nicely between carbs at 5800 RPM which is my reference for prop balancing.

 

I tried it with the Dynavibe and got the same bad results I had previously.  With my two blade 70" IVO ground adjust, at 3200 RPM the phase angle on the Dynavibe wanders around and never settles.  At 5800 RPM I get a steadier phase reading but the IPS reading is a little over 2.0!  I switched out the 70" IVO blades for a new to me set of 72" blades.  The tracking and pitch on these blades are very close as is their weight.  Still the same results.  I did apply some test weights to counter the readings I was getting but didn't see improvement.

 

So...I guess it's gearbox rebuild time.  I review the Mike Stratman articles on the CPS site regarding the C gearbox but didn't learn much of use.  I've looked at the C gearbox exploded diagram and I don't find any belleville washers or other thrust washers to replace.  All I see are roller bearings and ball bearings plus some shims.  My inclination is to have it done by LEAF since I don't have the fixtures or special tools it seems to require.

 

Before I pull it apart and take it in for a rebuild, does anyone have any ideas on how to check for bad C gearbox bearings?  If I pull forward or back on the blade tips I can't detect any play.

[JustNorm 14]

Just a thought,  do you know if the motor has a hydro dampner.  The old grey heads did not originally have them.  When I finally got a grey head with the dampner I could not believe the difference.  There are reports of grey heads blowing up because the the lack of a dampner.  My new grey head sure runs nice.

Norm 

[ChrisBolkan 130]

Hi!

 

_{Post a picture of your engine install. I have an idea what could be going on, but need to see if you have the motor mount setup that can cause the problem.}

 

_{Both my 582 mounts had to be re-worked (simple spacers installed) to prevent the top hat shaped brackets that screw to the engine from interfering with the engine mount under load.}  

 

_{That probably didn't make a bit of sense, but if you post a pic I can see if you have the mount type that has the problem.}

 

_{Basically under load, the rubber mounts flex and as the engine twists slightly the part of the engine mount that is attached to the engine binds and touches the part of the engine mount that is attaché to the firewall and vibration is transferred directly metal to metal into the airframe.}

 

_{If you look close you will see tell tale metal on metal contact evidence. It then becomes clear how to fix it.}

 

_Chris

 

[LSaupe 123]

I know this is old, but did it ever get sorted out?  If so, what was the culprit?  Chris, any chance you can post a pic of what you are talking about?

Edited 2 Apr 2016 by LSaupe

[Av8r_Sed 82]

As far as I know, the culprit was trying to idle a 582 smoothly with a 70" medium 2 blade Ivo. The mass moment of inertia is pretty high  I finally installed a RK400 clutch which works great. I've inspected my gearbox a couple of times since and all is well there. 

Strangely, I've been unable to dynamically balance my prop, even with direct help from a Dynavibe rep. Their analysis is the clutch is slipping but I sure can't detect it from the performance I get. I just periodically inspect the clutch and go fly.