Arm Motorsports Downpipes

[e46m3to335i]

I had the same rattling sound most are experiencing. The only thing that fully cured it was to put a spot weld between the flange and the DP on the longer bank 1 pipe.

Being that the flange doesn't actually connect to the DP, that's what was causing the rattle to occur. Ever since the spot weld was done, it's been dead silent.

I still don't understand the design logic of the leaving one DP without the flange being welded to it as the shorter bank 2 pipe is.

[hellokitty]

Just got this unit installed paired up with an Akrapovic Evolution full cat back. No rattling or fitment issues to report.

In terms of sound, it’s not as loud as my old N54 with essentially a straight xpipe pipe and full catless. The N54 setup was 10/10 stupid loud. I would say this setup is 7/10 loudness.

With only the Evolution exhaust and stock downpipes, I would rate that as 5/10 loudness so only slightly louder than before.

I need to do more driving to determine rasp levels which appear to be mild since there are resonators on the cats as well as on the Akra midpipe plus the Akra mufflers help.

With valves closed, the car is essentially silent/stock. Great setup with a valved exhaust system.

In terms of smell, it is noticeable but not terrible. If you want zero smell, you need a quality catted exhaust such as ESS.

[ssgm1x]

Originally Posted by e46m3to335i

I had the same rattling sound most are experiencing. The only thing that fully cured it was to put a spot weld between the flange and the DP on the longer bank 1 pipe.

Being that the flange doesn't actually connect to the DP, that's what was causing the rattle to occur. Ever since the spot weld was done, it's been dead silent.

I still don't understand the design logic of the leaving one DP without the flange being welded to it as the shorter bank 2 pipe is.

Yeah i don't quite understand why that flange is not welded to the downpipe like the other side is. It does not make any sense to me. Unfortunately my Arm downpipe's were rattling very bad and I had to remove them, and now I've been waiting 10 weeks for Arm Motorsport to send me a new flange so that I can install these down pipes without the rattling.

[e46m3to335i]

Originally Posted by ssgm1x

Yeah i don't quite understand why that flange is not welded to the downpipe like the other side is. It does not make any sense to me. Unfortunately my Arm downpipe's were rattling very bad and I had to remove them, and now I've been waiting 10 weeks for Arm Motorsport to send me a new flange so that I can install these down pipes without the rattling.

If the new ones rattle. Just have an exhaust shop put a tack weld between the flange and the DP. Mine have been dead silent after putting the tack weld.

[ssgm1x]

For those of you with defective ARM Downpipes due to the Flange being too big. What you can do to resolve the rattling noise is to wrap the downpipe in a heat resistant adhesive foil tape to make the downpipe slightly thicker so that the flange is not loose and does not move causing the rattling noise.
Or....you could also tac weld the flange to stop the rattling.

[fabulousprofound]

I just installed catted ARM downpipes on my F80, and about 5 minutes after leaving the shop it started rattling. The only time it dosen't rattle is anything over 4th gear above 2k rpm.

I went back to ask the shop thinking it was making contact with the under tray, but the shop said no and suspects it's the flange.

I wrote an email to ARM but haven't heard back. The shop can weld it but I don't want to do anything that might void the warranty on the product if it does turn out to be defective.

Does anyone have a pic of how it looks when welding the flange to the downpipe? why is it loose to begin with?

[hellokitty]

Originally Posted by fabulousprofound

I just installed catted ARM downpipes on my F80, and about 5 minutes after leaving the shop it started rattling. The only time it dosen't rattle is anything over 4th gear above 2k rpm.

I went back to the shop this morning thinking it was making contact with the under tray, but upon inspection it was not, and the shop now suspects it's the flange.

I wrote an email to ARM but haven't heard back. The shop can weld it but I don't want to do anything that might void the warranty on the product if it does turn out to be defective.

Does anyone have a pic of how it looks when welding the flange to the downpipe? why is it loose to begin with?

Anyone know what the little O ring is for? It seems it's meant to fit between the flange and the pipe but wasn't sure…

[fabulousprofound]

I thought the o ring was meant to be an isolator between the flange and the downpipe… but in my case it did little to stop the flange from rattling.

[fabulousprofound]

ARM replied back to my email. They said they would send me a new flange and gasket, But when I told them mine came with a gasket, it meant I already have the revised one, but for me it's still rattling.

I asked them what is this gasket made of, and they said it is made out of hi-temp silicone and it has proven not to fail under testing.

What should I do? Because I don't live in the US shipping takes forever and the car is undriveable because the rattling is louder than my exhaust believe it or not... Should I just get the flange welded? Will this cause issues for me in the future if I have to do exhaust work?

[marauder1]

Originally Posted by fabulousprofound

ARM replied back to my email. They said they would send me a new flange and gasket, But when I told them mine came with a gasket, it meant I already have the revised one and it's still rattling.

I asked them what is this gasket made of, and they said it is made out of hi-temp silicone and it has proven not to fail under testing.

What should I do? Because I don't live in the US shipping takes forever and the car is undriveable because the rattling is louder than my exhaust believe it or not... Should I just get the flange welded? Will this cause issues for me in the future if I have to do exhaust work?

I don't see adding a few tack welds as causing any issues down the road.

Did they state where the o-ring should be placed? Before the flange or after? like between flange and oem exhaust gasket?

[fabulousprofound]

Originally Posted by marauder1

I don't see adding a few tack welds as causing any issues down the road.

Did they state where the o-ring should be placed? Before the flange or after? like between flange and oem exhaust gasket?

Someone above posted a pic from ARM on where the gasket is supposed to be installed. It was the same picture they sent me.

[hellokitty]

Originally Posted by fabulousprofound

Someone above posted a pic from ARM on where the gasket is supposed to be installed. It was the same picture they sent me.

I placed the O ring in that exact spot and I have no rattles.

[fabulousprofound]

ARM sent this video:

[fabulousprofound]

Dammit, I had to get the flange welded. No amount of magic tricks with the gasket would make it stop rattling and the shop had other appointments waiting. I hope I never have to take this off.

[hellokitty]

Originally Posted by fabulousprofound

Dammit, I had to get the flange welded. No magic tricks with the gasket would make it stop rattling. I hope I never have to take this off.

How much did that run you?

[fabulousprofound]

I was charged 2.5 hours shop time, including this welding. I had CTS catless downpipes replaced with this. It got too raspy after I got my Akrapovic and this catted ARM seems to have fixed that. Gonna find an early morning on an empty highway soon and just send it to see how it sounds. Cops in my area are on a witch hunt for noise violations so I have to get out of the city limits to try it out.

[Rokoz]

Originally Posted by fabulousprofound

Dammit, I had to get the flange welded. No magic tricks with the gasket would make it stop rattling. I hope I never have to take this off.

What would make this difficult to remove? Didn't they just weld the flange to the pipe and then bolt it in as one piece?

[TopJimmy]

The OEM flanges are welded on, and the bolts are welded into the flange. Not having the flange attached makes adjusting and rotating easier to tweak fitment.

If your flange isn't snug on the pipe you can wrap a thin strip of aluminum foil around the pipe first (right under the flange) to make a crush-gasket. My ARMs fit fine without any modification.

[marauder1]

I don't get why arm is still trying to stick with this o-ring instead of just updating the flange to have a slightly smaller opening.

I don't see any issues if you just tac weld the flange on after it's been installed.

[hellokitty]

Stupid question here but do you notice that these downpipes get louder over time?

The only thing I could attribute it to is carbon lining the downpipe and perhaps some material is coming out of the perforations in the resonators (or perhaps clogging them in carbon).

After 1,000 miles, definitely seems louder compared to the first day I put them on.

I'm also starting to get a tiny bit of rattle on cold start which goes away after things heat up. Going to tack weld it like others mentioned.

[E92Roni]

I've put about 100 miles since installing the catless, resonated DP's. I ordered new from ARM with the O ring that's apparently suppose to fix the rattling. Had one of the most reputable shops in LA install but the rattle is SO LOUD that anywhere I drive people ask what's wrong with the car. Is the tack weld the only solution at this point?

[Wanted_M]

^^Yes, two small tacks (6&3 o clock) will solve your headache.