Dubro anti vibration Motor Mount
 

A fellow flier suggested to replace the stock mount on my GP Extra 300SP with the Dubro mount with elastomeric inserts that absorb vibration. I had read somewhere that these mounts twist on application of power to the engine. This model is particularly suseptible as it is built very light. Wanted to know what is everyone's experience with them and whether I should retain the stock once or replace with the Dubro mount

Ameyam

RE: Dubro anti vibration Motor Mount
 

I use them all the time in Sport planes and they work well. Have to replace the rubber every couple years, but they do the job quite well.
SIG SE
4*40 & 60
Midstar
60 size Corsair w/YS110
Hog Bipe
Some others-can't remember

RE: Dubro anti vibration Motor Mount
 

I fly 3D and am not comfortable with the twisting, if it does occur

Ameyam

RE: Dubro anti vibration Motor Mount
 

I wouldn't expect much twisting per se, since the mount bolts go all the way through to blind nuts just like any other mount. In the one I've seen used I've never seen any twisting. Was on a super stick.

RE: Dubro anti vibration Motor Mount
 

i personally dont like them.... and definitely wouldnt use them in IMAC, pattern, or 3D style planes either

RE: Dubro anti vibration Motor Mount
 

Requesting to make a note of why you like or dislike them. That is the entire reason behing posting

Ameyam

RE: Dubro anti vibration Motor Mount
 

There are a lot of anti vibe mounts on the market and I like some better then others. In this case you are asking about the Du-Bro 682 beam mount. I have used them quite a few times, most the time for my small gas engines more so then my glow engines. Everything has it's place with me and these mounts I like for bigger engines. Last one I used in a plane was with a 2300 or G-20 Thunder Tiger glow engine. They do tend to torque but I haven't noticed it in the planes I have used them in, a 3-D pilot may notice it more then I do. I have used them in Extras and a Decathlon. I just used one last week to mount a YS 1.20 on then put it on my run in stand. No torquing was noticed. They are easy to mount onto a fire wall and allow you to move the engine forward and back with room to spare to fit your plane. They work, if something works then I like it.
I found the anti vibe mount from Jtec better for removing any vibration but they are harder to mount on the fire wall. I can also find the Du-Bros at almost any hobby shop.
It's another one of those choice things.

RE: Dubro anti vibration Motor Mount
 

I use those mounts every chance I get. Sometimes the extra length is a problem, epically with a big four stroke. Ihad one occasion of movement of the engine when given full power. It wasn't twisting along the crank axis, but was kicking the engine changing the thrust angle. It turned out to be that one of the aluminum spools that the rubber mounts on was about a 16th shorter than the rest. That set up the mount with a short leg and under a sudden acceleration, the engine would pull down the high leg. When I replaced the aluminum spool, all was right with the world again.

As a side note, those mounts, along withthe spinner collapsing when hitting the ground probably saved me a few engines. The little extra cushion softens the sudden crash blow. I've only damaged one engine using those mounts, and on that one, the rocker cover was the first contact with the ground and it just exploded the engine. Any other mount would have shown the same results.

Don

RE: Dubro anti vibration Motor Mount
 

From my experience, it reduces vibration in the fuselage. I did a test between a regular mount and a dubro ant vibration mount. I'd do with dubro anti vibration mount. Make sure everything is secure, or it will shake apart, happened to me, luckily on the ground.

Cheers!

RE: Dubro anti vibration Motor Mount
 

I used the Sullivan soft mount and it seemed to do just fine. I also used a different form of soft mount on my original trainer, the NexSTAR. It was an RTF and came with the engine mounted in a somewhat soft mounting system, although it was somewhat stiffer than the Sullivan mount was.

CGr.

RE: Dubro anti vibration Motor Mount
 

So then, is the mount recommended or not?

Ameyam

RE: Dubro anti vibration Motor Mount
 

I use Hyde Soft Mounts on all my fuel planes.... a little pricey but I find them much better for reducing vibration than most others. I have since switched my pattern planes to electric so not as much of an issue for me anymore.

RE: Dubro anti vibration Motor Mount
 

I don't know what engine your using, but try it.
I like them for most applications. If you don't like it change it.
My .02 is like everyone elses on here-just .02!

RE: Dubro anti vibration Motor Mount
 

Like that french guy said, try it, I like them and they work, if you don't like it then try another one. I have no idea what engine you have or how bad it vibrates but there are a lot of other reasons why you get vibration. I use a lot more of the GP adjustable mounts then any other. I just don't seem to ever have a bad vibration problem. I use almost nothing except four strokes or gassers if that says anything??

RE: Dubro anti vibration Motor Mount
 

From what I understand it won't do much to kill the vibration from an unbalanced prop or spinner, but it does smooth out the torque pulses from your engine. If you are having vibration problems, have you checked out the other solutions like balancing first?

RE: Dubro anti vibration Motor Mount
 

I like these type mounts because they absorb some vibration. Although they do not reduce vibration coming from any source, they do reduce the amount of vibration transferred to the airframe.

Some Engine torque, when the throttle is advanced, gets absorbed by these mounts and there will be some power lost due to this event. The amount of "twisting" is very little, as is the amount of power loss.

Sport flying aircraft should see no adverse effect. However, for an Extra 330 or performance type aircraft, IMO the engine should be bolted directly to the airframe, to ensure there is NO lag between throttle input and how the aircraft responds.

Why did your friend suggest switching to this type of mount?

RE: Dubro anti vibration Motor Mount
 

I prefer the two piece Hangar 9 mount any time I can use it. Most of my planes are set up so the engine is all the way forward in the mount and the bolts are tight enough but not cranked down. It's saved an engine before being able to slide back on impact. My Mustang (60 size Marie version with OS 120 pumped) is 7 years old with no problems with that setup.

RE: Dubro anti vibration Motor Mount
 

Actually, he just suggested it. Also he did so some time back. I got into it again lastweek after I balanced my prop (12x8) and set a temporary dubro spinner on my 55AX. When at absolute idle, the engine would vibrate a bit. But when I gave couple of cliks of throttle, the engine stopped vibrating. Spinner would continue to vibrate however. Since I was running at home, I couldnt open the throttle for fear of irritating the neighbours.

Ameyam

RE: Dubro anti vibration Motor Mount
 

An out of balance prop or trying to get too low of an idle will cause vibration. If your spinner isn't straight and true it too will cause it. To date i have never bothered with an anti vibe mount on any engine that small. That would have been an instant Great planes mount. I use the Du-Bro anti vibe on engines like the 1.20 four strokes or something like my G-20 two stroke or RCS 1.40 gasser. I have just never had a need for one on a small engine?? Then again, sitting here in my living room I can't see your engine vibrating but it sounds like you have something wrong and the mount isn't the best answer. It may help but finding the problem would be a better cure.

RE: Dubro anti vibration Motor Mount
 

For those that have used these, are they effective at quieting an airplane?

RE: Dubro anti vibration Motor Mount
 

With regard to engine maximum decibel's reduction...no, IMO.

Some planes (mostly arf's) are constructed in such a way that the airframe and covering act like an echo chamber or speaker box, and resonate like crazy, or at least, more than others do. This is an application where the rubber mount might lessen "noise", due to the fact that they absorb some vibes, therefore pass along slightly less to the airframe.

Just my .02$

RE: Dubro anti vibration Motor Mount
 

That's where I was going actually. I got a new OSMax 1.20 two stroke I'm going to put in a second Venus II and I know it'll be borderline noisy for our club. The other Venus II is okay with a OSMax 1.20 four stroke and APC prop.
Knowing some of the noise from a plane comes from vibration noise I'm thinking if I use a quieter prop like an APC along with reducing some of the vibration noise by using rubber in the mount, I might be okay for the club's standards. I also don't expect to use full throttle much if at all as the four stroke already seems to offer almost unlimited verticles at less than full throttle and this should be even more powerful, so throttle management will also help.

RE: Dubro anti vibration Motor Mount
 

These are excellent engine mounts especially for 4stroke or gasoline engines.

they will only move due to torque if the mounting bolt torque is not even across all fourbolts so installation with a torque wrench is advised or if the elastomers have gone soft.

to correct any thrust issues you will need to shim from behind the engine mount against the firewall as per any other engine mount.

Many of the PAttern guys use these but most pilots simply use the suplied plastic mounts in the box of the ARF since the plastic is a pretty good damper of vibration anyways.