[alpinelakespilot2000]

Went to do the final torquing of my exhaust system and noticed that I have a stainless lock washer under the stainless nut on the stud of the exhaust ports, but no flat washer . Normally, lock washers are used over a regular flat washer. However, my initial install did not have them, leading me to believe that I must have had a reason for omitting them, but I can't find anything in my documentation from Vetterman about the washer combination that should be used on the studs. The only thing I seem to vaguely remember is that the studs, as they came from Aerosport Power, are not really long enough to get an additional flat washer in there. Perhaps that's why I left one off. Should I have a stainless flat washer under the lock washer or does this particular installation allow for only the lock washer?

 

[flion]

This is one I have no engineering background to fall on but it seems to me that a flat washer under a lock washer would negate the locking properties of the lock washer.

 

[Walt]

Flat washer and internal lock washer is correct.

 

[LifeofReiley]

I personally prefer a flat washer and a locking nut but the lock washer and nut combo will work just fine without a flat washer. FWIW, my Vetterman exhaust did not come with flat washers.

You could use a lite (thin) washer.

 

[alpinelakespilot2000]

Thanks for the replies. I was able to get a hold of Larry Vetterman on the phone. As Reiley mentioned above, Vetterman exhaust kits do not come with flat washers. This is, I just found out, because Larry Vetterman is adamant that a flat washer should NOT be used in this situation. He said something along the lines that, while normal to use the combination elsewhere, using them here would facilitate a loosening of the torque given the extremes of heating and cooling. Lock washer and nut (with no flat washer) is the way to go according to him.

Hope this helps the next person.

 

[Neal@F14]

The Vetterman 4-pipe exhaust system we got for the RV-8 also came only with internal star lockwashers and nuts, no flat washers.

 

[Walt]

Thanks for the replies. I was able to get a hold of Larry Vetterman on the phone. As Reiley mentioned above, Vetterman exhaust kits do not come with flat washers. This is, I just found out, because Larry Vetterman is adamant that a flat washer should NOT be used in this situation. He said something along the lines that, while normal to use the combination elsewhere, using them here would facilitate a loosening of the torque given the extremes of heating and cooling. Lock washer and nut (with no flat washer) is the way to go according to him.

Hope this helps the next person.

Larry has more experience with exhaust systems then anyone I know, so in this case, I will yield to his vast experience and supreme knowlege and say go with the lock washer/nut combo as he recommends!

 

[LifeofReiley]

I'll yield and say...

Larry has more experience with exhaust systems then anyone I know, so in this case, I will yield to his vast experience and supreme knowlege and say go with the lock washer/nut combo as he recommends!

A side locking nut has been the best in my application, no worries ever. The internal lock washer is a plus. I've flown aircraft when the exhaust came loose and it is no fun! And Vetterman is THE MAN! A Thick Flat washer has never been used in any exhaust install that I know of, seen Thin washers.

 

[Flying Scotsman]

Oh, great...now I have to go back and take all those nuts and washers off and reinstall them! Yes, I installed the system with the "standard" nut+lock washer+flat washer combo...

 

[az_gila]

Oh, great...now I have to go back and take all those nuts and washers off and reinstall them! Yes, I installed the system with the "standard" nut+lock washer+flat washer combo...

There are thousands of test cases flying around with that Lycoming approved combination...

I'd leave it alone and just change when you have the system off next if you must.