Securing downpipe to manifold.

[Paul Amey]

I've used brass long brass nuts to secure the downpipe to the manifold. Now, I haven't bothered with spring washers. I'm not sure if I should have but seem to think there not needed. Any ideas?

[Colin Lindsay]

The early 1200 catalogue shows them (5/16 spring washers) so accordingly I used spring washers on both my 1200 and 13/60. 

[Paul Amey]

Argh right, thanks for that. I'll add spring washers.

[Pete Lewis]

after much trial and tests we dumped spring washers as pretty useless and easy to loose torque

so back in the 80s all truck chassis fixing were  replaced with plain washers 

and toque control became far more consistent 

Pete

[Paul Amey]

Did that include changing to nylock nuts as well? Which of course would be as much use as a chocolate fire guard on an exhaust manifold.

[PeteH]

The answer to that are "aerotight" nuts. All metal stiff nuts.

Pete

[Peter Truman]

2 hours ago, PeteH said:

The answer to that are "aerotight" nuts. All metal stiff nuts

Are those the locknuts with no plastic parts having a deformed top lip, ie 3 dimples in? I've learnt something today, thanks.

[PeteH]

Hi Pete. Google:- https://www.google.com/search?client=firefox-b-d&q=Aerotight+nuts Fill yer boots!.

They where regularly used in the aero industry. I think I still have some as small as 6ba. From back when Model Aircraft engines would shake the mounting bolts loose in no time flat. 26000rpm single cylinder, glow plug engines.

Pete

[Peter Truman]

Yep have a selection of those slotted head locknuts in the smaller sizes, never knew their specific name! I got them from my son 20 plus years ago when he was an apprentice aircraft mechanic, they appear to be a special material. The car ones I have seen have 3 dimples in the top ring which crimp on the male thread.

I flew RC Helicopters 30 years ago and I think the handful of lock nuts I brought for the heli cost a small fortune, the construction instructions advised thread lock but with the vibrations involved I wanted something better! Adding a gyro to the heli made life a lot easier to fly! I still have an uncompleted 1mt wingspan Spitfire RC plane in the garage and have all the gear to finish must do it!

Thanks for the info.

[PeteH]

Still got 3 of those engines, somewhere?. Including one with a Water jacket, which one time powered a Scale model of on MTB. later converted to Electric. Before being sold. Model making kept me off of the "booze" during long voyages. I bought one of the small Helio`s a few years back, problem is, being small it`s not often there is a low enough wind level to fly it. Sad Really. Flew it in a barn once, it survived being flown into a stantion!!. Friend of mines FIL built the Spitfire, about 15 years ago now, in his case it was remenicence too, as he actually few them in WW2.

Pete

[JohnD]

There must be dozens of different designs of locknut, the Aeronaut being just one.  When so many are available for one purpose it usually means they all work as well, although some may be specialised.  See https://uk.rs-online.com/web/generalDisplay.html?id=ideas-and-advice/locking-nuts-guide

[PeteH]

On 08/03/2022 at 09:18, JohnD said:

There must be dozens of different designs of locknut, the Aeronaut being just one.  When so many are available for one purpose it usually means they all work as well, although some may be specialised.  See https://uk.rs-online.com/web/generalDisplay.html?id=ideas-and-advice/locking-nuts-guide

The marine enviroment being what it is, eg: can be 3K miles to the shops. We sometimes (very often) had think laterally. A saw cut half way through a nut and then squeze it was one way of encouraging them to stay put in a high vibration situation.

Pete