Rotax 912 ULS exhaust nuts. Where to buy?

[danny_galaga]

And what is the part number if original? And for the future, what would be the best link to a parts list that you use?

[skippydiesel]

You can get these heat tolerant  lock nuts from any good nut/bolt supplier 

[danny_galaga]

Thanks. I felt I should be able, but thought I'd better ask. My local bolt place will have them. I just don't tell them it's for an ultralight anymore. One of the staff gets funny about it. I just say it's for a boat 😃

[Blueadventures]

From memory they are a copper vw exhaust nut, and need to get the 12mm spanner size as some are 13mm spanner fit and need the smaller size to fit as some close to header pipe.  May be incorrect of the spanner sizes, but you can get two sizes and need the smaller.  Cheers

[danny_galaga]

Thanks for the heads up on the 12mm size. Hadn't thought of that. The nut and bolt shop didn't sell exhaust nuts, full stop. But a few hundred metres away I went to an exhaust shop. They had just got some for a BMW car. They looked they would do, so I got them to order ten more. Spares because sure as eggs I drop one somewhere 😅

[RossK]

2 hours ago, danny_galaga said:

Thanks. I felt I should be able, but thought I'd better ask. My local bolt place will have them. I just don't tell them it's for an ultralight anymore. One of the staff gets funny about it. I just say it's for a boat 😃

Tell them it's for a snowmobile engine 😁

[skippydiesel]

2 hours ago, Blueadventures said:

From memory they are a copper vw exhaust nut, and need to get the 12mm spanner size as some are 13mm spanner fit and need the smaller size to fit as some close to header pipe.  May be incorrect of the spanner sizes, but you can get two sizes and need the smaller.  Cheers

I don't think they are copper Blue - neither my old 2000 912ULS or my 2019 ULS use copper nuts. They may be an alloy of something but they look like plain steel - There are at least 3 types - could only find two pics:

 

[skippydiesel]

[facthunter]

They won't be copper and the brass ones easily shear the points off the Hex. Exhaust nuts and studs are a problem on motors generally. You'll often shear them off trying to undo them. Some kind of good anti seize helps. Some use locktabs or a special like what skippy has shown.  Nev

[Blueadventures]

1 hour ago, skippydiesel said:

I don't think they are copper Blue - neither my old 2000 912ULS or my 2019 ULS use copper nuts. They may be an alloy of something but they look like plain steel - There are at least 3 types - could only find two pics:

 

Copper colour, the ones I got a couple of years ago are copper coloured and have a split part way around to keep tensioned.  I got them for my 80Hp UL Rotax.  Don't want ones that bind with corrosion to the stud.  These copper ones hold on and allow undoing without damaging the stud thread.  I carry two in my field kit and one head nut; as seen them crack and be missing.

Edited March 20, 2023 by Blueadventures

[facthunter]

It will be some sort of corrosion proof coating, Nev

[Blueadventures]

5 minutes ago, facthunter said:

It will be some sort of corrosion proof coating, Nev

Agree Nev,  knowing how copper and aluminium react.  Meant to say copper colour special nuts for exhaust of aluminium engines.  (Bit like the copper coloured clecos used to hold aircraft sheet in place.) Cheers.

Edited March 20, 2023 by Blueadventures

[danny_galaga]

I knew what you meant Blue. The ones I'm getting are not that, but they were available locally and will do at least for engine testing. It's funny, now I live in a fairly large city (Brisbane), it seems to harder to find unusual things. Whereas when I lived in Darwin, maybe the tyranny of distance meant people stocked up on stuff that otherwise might take a week to get there. Or I could be having a 'mothers cooking' moment 😄

Edited March 20, 2023 by danny_galaga

[facthunter]

A lot of "SHOWS" these days only carry fast moving stock.  Nev

[IBob]

I'd have to say mine look very much like copper, and I don't think it's a protective plating. Could they be bronze?
They have the fine cut part way across them, like the small nut in the first illustration above.

[facthunter]

Nuts to be any good must be high tensile and a good thread fit.  Copper is not very suitable on many grounds. Easy to check if it's a coating. Cadmium is now prohibited in most countries as it's highly toxic. Nev

[old man emu]

Aren't Rotax engines used in things like jet skis and those three-wheeler bikes with two wheels at the front? Maybe you could source the nuts from a motorcycle shop.

[Blueadventures]

Copper coated steel.  Their anti-seize method.  (I got my T'shirts for removing stubborn exhaust nuts and their studs in my early years.)

[facthunter]

You can plate alloys these days. Zinc-nickel has replaced Cadmium on some aero stuff., Nev

[spenaroo]

1 hour ago, old man emu said:

Aren't Rotax engines used in things like jet skis and those three-wheeler bikes with two wheels at the front? Maybe you could source the nuts from a motorcycle shop.

BRP own Rotax, BRP also own can-am, sea-doo, ski-doo

but its a bit like Kawasaki manufacture motorcycles, as well as ships and aircraft.
reality is the divisions are mostly separate just sharing a name.

[Thruster88]

Rotax make all the engines for BRP products plus kart, aircraft and some OEM motorcycles.  

[danny_galaga]

You know, I hadnt even thought of a bike shop!

[skippydiesel]

I have always assembled my exhaust system using the Rotax recommended anti seize - liberal applicator on all joints & studs. Goes together/lines up perfectly and the nuts never seize/gall the studs.

 

[Blueadventures]

46 minutes ago, skippydiesel said:

I have always assembled my exhaust system using the Rotax recommended anti seize - liberal applicator on all joints & studs. Goes together/lines up perfectly and the nuts never seize/gall the studs.

 

Skip lube only goes on the ball joints of muffler (100 hrly).  Never on header pipe flange to head or the stud nuts that hold the header plates at the attachment to the heads.

[Marty_d]

I bought some from Bert Flood in 2020.  On the invoice the part number is 842950 - Lock Nut M8-SW12, at that time they were $3.01 each.