Cupped Washers for Turbo Exhaust Manifold

Hi all,

I am installing a 90+ manifold on a B21FT, and I am trying to decide what hardware to put on the car. It looks like the car has non locking nuts with washers. I can't tell if they are the stock cupped washers or not. My question is, are the cupped washers seen here, what people use between the turbo manifold and the nut? And if so, what nuts do you use with them, because it looks like you cannot use a flanged locking nut like this, because the flange is large than the recessed area for the nut in the washer?

Or do people just say the hell with it and just use normal locking flanged nuts with no washers.

Thanks for the help!

I've used these with good result.





https://www.mcmaster.com/wedge-lock-washers

I have always used the OE turbo studs, OE turbo cup washers, and new copper coated locking nuts every time it's assembled. 100% success rate, never had one move and never had one seize.

The 419401 washers are specified for turbo applications as well as the push rod engines going back to B18.

The recessed area faces the manifold, not the nut. If you look closely, the washer is stamped UT which means 'out' in Swedish.

Copper coated steel lock nuts like this are what most people use. The washer is curved so the flanged lock nut doesn't do much.



FYI, I have the nuts and cupped washers in stock.

I've always assumed that the cupped washers, with manifold contact just on the edge of the cup, allow the manifold to move around a bit (over many heat cycles) if it's stressed. IIRC, there are 7 big holes and 1 smaller locating hole in the manifold.

Great, thank you all for the information. I'll have to pick up some fresh hardware, maybe from Eric.

hiperfauto said:

The 419401 washers are specified for turbo applications as well as the push rod engines going back to B18.

The recessed area faces the manifold, not the nut. If you look closely, the washer is stamped UT which means 'out' in Swedish.

Copper coated steel lock nuts like this are what most people use. The washer is curved so the flanged lock nut doesn't do much.

FYI, I have the nuts and cupped washers in stock.

Click to expand...

Those copper coated nuts look stock for VWs.