To those of you that have installed DP's, talk to me about flanges

[Niart906]

To those of you that have installed downpipes or even installed cat back exhausts. Any idea if the studs can be removed from the stock exhaust flanges?

These flanges: https://www.ecstuning.com/b-genuine-...e/18327850430/

The OE hardware on my car now is so rusted I will most likely have to cut them off. My new VRSF downpipes came with fresh hardware, but only the shorter DP has a new flange. I'll need to reuse the stock one on the other side.

Has anyone tried to press these studs out of the stock flanges?

[TopJimmy]

I'm in PA too and noticed the flange bolts/nuts on my '18 F80 had rusted pretty good but WD-40 got me by. I bought new flange nuts from FCP so I can swap them with pipe changes. If they have the flange I'd get it there too.

Instead of pressing out the stud bolts I'd just buy the new flange and get a few tack welds added after installing on the VRSF. If you do press out the studs and try bolts it's likely to fit loose since the stud holes are bigger than the bolt threads. It's also a royal pain to get a box wrench up on the bolts…my ARMs mounted like that.

[1000hp]

Originally Posted by Niart906

To those of you that have installed downpipes or even installed cat back exhausts. Any idea if the studs can be removed from the stock exhaust flanges?

These flanges: https://www.ecstuning.com/b-genuine-...e/18327850430/

The OE hardware on my car now is so rusted I will most likely have to cut them off. My new VRSF downpipes came with fresh hardware, but only the shorter DP has a new flange. I'll need to reuse the stock one on the other side.

Has anyone tried to press these studs out of the stock flanges?

The flange for the longer downpipe (bank-1) is pretty cheap from the dealer. I got a new one when I put my midpipe on just in case of issues with the stock studs and nuts. I think it was $45ish.

Part number: 18 32 7 850 430

[Niart906]

Originally Posted by TopJimmy

I'm in PA too and noticed the flange bolts/nuts on my '18 F80 had rusted pretty good but WD-40 got me by. I bought new flange nuts from FCP so I can swap them with pipe changes. If they have the flange I'd get it there too.

Instead of pressing out the stud bolts I'd just buy the new flange and get a few tack welds added after installing on the VRSF. If you do press out the studs and try bolts it's likely to fit loose since the stud holes are bigger than the bolt threads. It's also a royal pain to get a box wrench up on the bolts…my ARMs mounted like that.

As it turns out, you can press the studs out of the stock flanges and the new hardware provided with my VRSF DP's fits perfectly into the stock flange. Tightening them is a bit a pain, but a ratcheting box wrench really helps.

Originally Posted by 1000hp

The flange for the longer downpipe (bank-1) is pretty cheap from the dealer. I got a new one when I put my midpipe on just in case of issues with the stock studs and nuts. I think it was $45ish.

Part number: 18 32 7 850 430

BMW only sells a replacement flange for the long downpipe. I was worried about the flange mounted to the shorter stock downpipe. If I ever need to reinstall the stock DP's I needed a way to replace the stud I cut off. I wish BMW sold the studs separately like they did for the non-M E46's back in the day.

[1000hp]

Originally Posted by Niart906

BMW only sells a replacement flange for the long downpipe. I was worried about the flange mounted to the shorter stock downpipe. If I ever need to reinstall the stock DP's I needed a way to replace the stud I cut off. I wish BMW sold the studs separately like they did for the non-M E46's back in the day.

Ah, I see. You can also clean the threads up with a thread chaser or die, if you haven't broken them off already. Either way you should be alright if they can be pressed-out.

[Niart906]

Originally Posted by 1000hp

Ah, I see. You can also clean the threads up with a thread chaser or die, if you haven't broken them off already. Either way you should be alright if they can be pressed-out.

I already cut them off with a grinder. The nuts were so corroded that I couldn't even get an extractor socket to grab. I'm sure the threads were toast. Plus I'd rather know I have new hardware for the next time I need to drop the exhaust.