Nc backbox gasket(s)?

I finally found a backbox but it’s used and I want to buy the right gaskets for the job.

I have watched some US videos of backbox installed and I believe there is 2 gaskets?

A round seal, seems easy to find.

A aluminium looking gasket that goes on the 2 faces where the mid section and backbox meet. Can’t find much info on this one.

Any ideas?

Think it’s just a ring the flanges don’t meet just compress the ring when bolted together.Will double check tomorrow if no one responds tonight.


If you are talking about something like the Goodwin super q silencer it uses a flat sandwich type steel and paper gasket. I tried 2 options.

  1. Order a replacement through the racing beat europe website after contacting them on their enquiry form.
  2. Order a sheet of BGA Rpk 1 gasket material on ebay and make your own. Not as easy as it sounds as the metal and gasket layers tend to delaminate while cutting.

The bolt centre holes on the Goodwin flange are 41/2 " and the the centre hole about 61mm. This may be a common size in the US but I couldn’t find anything off the shelf from Walker exhausts catalogue.

If you use the original ring type gasket with a flat aftermarket flange be wary of distorting the flat flange when tightening the joint.

It’s for a Cobolt exhaust and the aftermarket sales for that stuff in the UK seems very poor at the moment. Probably just best to get it and measure up and go from there.

just fitted a cobra backbox, came with similar gasket thats in the photo above.

Also used a little sealant paste, no issues with blow

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I used the crush gasket linked to (Mx5parts) to fit my Cobalt back box. The flat washer type gasket that came with it didn’t seal very well.
Just offer up the back box first (fit to hangers) to make sure it sits square before putting the gasket in. The mid section pipe with flange has a protrusion, the gasket fits nicely over this, just clean it up so it sits flush, mine was a little made up with corrosion and muck etc

Okay that sounds simple enough.

The mid section is a bit rusty, seen a few snap :crossed_fingers:

I have some plus gas that I have been applying to the bolts so hopefully they come up without too much of a fight.

See if you can find some red rubber grease or silicon grease for the rubber hangers as it makes replacing and subsequent removal of back box much less of a hassle.

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I have some hunters silicone grease, it’s used for brake seals and plumbing so hopefully will help, thanks for the tip!

Standard box uses a ring, I just had mine off.

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