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Hopefully you haven't put your order in yet. I would like to get a set of the -14's as well if you would like to go halves in the shipping.

Phone you tomorrow Murray.

Have local supplier, going to give me a quote on the 14's, when he gets back from annual holiday.

1. "To try & preserve as much of the Sonex recommended system (22001-13) I will start by replacing the lower donuts with the 14 donuts and see if that has the desired effect."

As a first step, I think the above is small, therefor may not result in sufficient movement reduction, so planning for the future (if needed);

2. The lateral movement, viewed from the cockpit, is to the left. With this in mind, could step two be replacing the two - 13 mounts, on the left side only, with the stiffer -14's. What might be the negative effect of mixing two diffrent mount stiffness (Note: All 22001 mounts have the same dimensions)???

3. It seems that the rear/aft mounts are being subjected to more movement that the front two - Should I consider replacing the aft mounts with -14's leaving the front two -13's? As in 2, what might be the negative effects??

4. I will be purchasing 4 X - 14 mounts, so if step two/three don't have the desired effect OR are skipped (due to advice/reflection) I will just replace all -13's with -14'. Aside from checking for desired movement reduction, I would appreciate any advice on what I should monitor ??

So I now have the Hutchinson/Barry Controls 22001-14's fitted.

In my last post I had planned to substitute bits & pieces of - 14' s only going to fully replace the -13"s as required, however the suppliers of the mounts advised that I just replace the -13's completely. They seemed to know what they are talking about (30 years in the vibration control business) so went with their advice.

My Sonex is based on a grass strip, very wet at the moment, so no flying but hoping for hot dry weather over the next few days, to dry it out and then I will test/report back on the -14 mounts.

I have just done 1.4 hrs (2 engine starts) with the new Barry 22001-14 mounts (with my Cupped Snub Washers) in place .

Did not notice any major change in vibration/noise - possible very small increase in HF vibration through control stick.

Significant improvement (reduction) in lateral movement but still just marking witness tabs.

Next step - add the Sonex supplied spacer washers ACV-P54 -06 & -07 .

Have done 2.4 hrs with the new Sonex spacing washers (FYI: - they have a larger OD & are better machined, than the original supplied - they actually fit without further adjustment).

Again some improvement BUT still getting a touch, between rear right exhaust header and engine frame.

Options;

Go another step stiffer with the Barry Controls engine mounts to part number 22001-15

OR

Have the offending exhaust header reworked/new build, with slightly wider clearing curve - this last is possibly the best solution, as preserves the engine mount(s) vibration control while allowing damping movement BUT as is often the case, the most costly and time consuming

It has been suggested, on another Forum, that making a strategic dent/depression, in the existing & offending exhaust pipe, to enhance the clearance between it & the frame, would have little impact on the cross sectional area of the pipe and therefore be unlikly to result in any engine performance loss - what thinks the Brains Trust??

If you agree with this proposal - how would you go about it? eg would you heat the pipe to plastic stage & then press/hammer in the depression, fill the pipe with sand to reduce unwanted distortion, do the aforementioned cold, etc

It has been suggested, on another Forum, that making a strategic dent/depression, in the existing & offending exhaust pipe, to enhance the clearance between it & the frame, would have little impact on the cross sectional area of the pipe and therefore be unlikly to result in any engine performance loss - what thinks the Brains Trust??

If you agree with this proposal - how would you go about it? eg would you heat the pipe to plastic stage & then press/hammer in the depression, fill the pipe with sand to reduce unwanted distortion, do the aforementioned cold, etc

I will need a dent of about 10 mm in depth (in a 25 mm pipe) to be assured of not contacting the frame, in a poorly executed engine stop.

Have a look at this automotive experiment, to assess the effects of denting the exhaust system:

https://www.facebook.com/watch/?v=152724102049876

Update!

Finally bit the bullet and had my right rear exhaust header remade/adjusted, to give about 12mm extra clearance to the engine frame - seems to have done the trick. No evidence of brushing/touching in about 3 hrs of flying.

I have added one additional washer to the front two rubbers. This is to slightly change the prop thrust line, to reduce the amount of up elevator in cruise - seems to have worked. Carrying weight (max 18KG) in the luggage compartment behind the seat, has a similar effect.