AA EL Mid Pipe Rattle Thread

[biggripper]

I think this may become helpful thread in the future with more users getting their AA EL Mid Pipes installed.

I still have some intermittent rattling even after identifying/eliminating two. Also before I continue let me state that I did install new gaskets at the down-pipe outlets. I don't know how anyone could get away with reusing the old ones. Mine were badly deformed and shredded. Do yourself a favor and just replace these. Consequently this is the only part of the system that doesn't leak any water.

Here's what I've found and fixed followed by what I haven't found.

What I Have Found/Fixed
1) heat shield contacting midpipe on passenger side more towards the front (between down pipes and cross brace). The degree of contact with the midpipe here was quite surprising but only required a long screw driver to bend the shielding back a bit in select spots.

2) Cross brace contact. Even with the Active Autowerke cross brace it's still possible to contact. To remedy this I simple loosened the ball clamps and inserted a temporary spacer between the cross brace and mode pipe, then re-tightened the ball clams prior to removing my spacer block. If the problem reoccurs I may use the "ol' washer method" to provide some extra spacing for the cross brace.

What I haven't Found:
1) Cold start rattle. This rattle only seems to occur in the morning after I start the car. It self-resolves after less than a minute of engine idling. It sounds like it's coming from the back muffler area. My suspicion Is that it may possible be contact at the cut point between the stock exhaust pipes and the mid pipes. Per the installation manual there is supposed to be a slight gap between the cut pipes and the mid pipes. Although I did measure 1.5" from the weld I feel like my gap didn't quite look like the gap in the install manual.

UPDATE—after speaking to someone at active this cold start rattle is likely my exhaust flaps. Which are known to rattle a bit when cold. It's probably more obvious in my case because I used my VSC-2 valve controller to close them prior to early morning cold starts in order to save my neighbors.

2) My last rattle seems to emanate from what seems to rift underneath the DCT shifter. It's a very low rattle that I might describe as a shudder rather than a rattle. It seems to occur only at very low speeds. I notice it most frequently when the car is on a slight angle driving out or backing into my driveway. My though is that something about the angle of the car is affecting the angle of the engine/exhaust components enough that the mid pipe is making contact somewhere—probably somewhere in the tighter portion of the tunnel.

UPDATE— after talking to Active, it sounds like this is most likely a symptom of how I tightened the connections with the down pipes. With the OE downpipes the right downpipe has a fixed flange where as the left has a floating flange. By tightening the fixed flange first the midpipe will naturally crowd the left side of the car. The tech I spoke to recommended securing the left (floating) side first and making sure the tunnel spacing left-to-right looks good prior to tightening the right side.


Anyway I suspect others will have some minor rattles with this product also, so I thought it would be helpful if people could share there findings and remedies.

[mike@x-ph.com]

We have the Active Equal length on the shop's car, no rattle.

The non-res do not match well with catless or high-flow catted downpipes, especially if you have an aftermarket axle-back.

We got a metallic (rattle-like sound) with this setup as well, once we switched to resonated it fixed the issue.

From my experience, if installed correctly the exhaust does not come in contact with any other car component.

[biggripper]

Originally Posted by mike@x-ph.com

We have the Active Equal length on the shop's car, no rattle.

The non-res do not match well with catless or high-flow catted downpipes, especially if you have an aftermarket axle-back.

We got a metallic (rattle-like sound) with this setup as well, once we switched to resonated it fixed the issue.

From my experience, if installed correctly the exhaust does not come in contact with any other car component.

Thanks Mike. I'm running stock downpipes.

I'm curious about the included clamps. There were no torque specs for either set of clamps. How tight should the be? I feel like they're as thighs as they should be but there wasn't really any information to that end.

[mike@x-ph.com]

Originally Posted by biggripper

Thanks Mike. I'm running stock downpipes.

I'm curious about the included clamps. There were no torque specs for either set of clamps. How tight should the be? I feel like they're as thighs as they should be but there wasn't really any information to that end.

I recommend you check the install again, it's not easy.

My installer went back a few times, untightened the midpipe, and adjusted it until he was happy with the clearance. In the end, if it was a perfect fitment.

[biggripper]

Original post updated after phone call to Active. I'd like to thank them for taking the time to talk through things with me.

[biggripper]

I took my car to a local muffler shop and had them take a look. The last remaining rattle which seemed to be coming from under the transmission turned out to be some other pieces of heat shielding. The technician bent those portions to gain clearance and the rattle is gone.

[bmwmdistrict]

I really appreciate all the detailed notes in this thread. About to have the AA midpipe installed later this month once it arrives and I'll be sure to pass along these findings to the installer. Thank you!

[biggripper]

Originally Posted by bsm.m4

I really appreciate all the detailed notes in this thread. About to have the AA midpipe installed later this month once it arrives and I'll be sure to pass along these findings to the installer. Thank you!

Chances are yours will go off without a hitch. It's a little more difficult to get everything just right when your car is on jack stands. 🤣

[RugbyBro]

Originally Posted by biggripper

Chances are yours will go off without a hitch. It's a little more difficult to get everything just right when your car is on jack stands. 🤣

Oh yeah, out of laziness and time constraints I did mine with the car only on jacks at the rear... and I'm lowered too. Let's just say that clearance was unsettlingly tight

[DefinitelyNot]

How many miles on the car? It's possible that your valves are just experiencing too much pressure causing them to "bounce"/rattle

If your car is tuned test it with cold start off and see if it rattles less

[horsepower_and_hounds]

Make sure you check it when the car & exhaust is hot. The OEM downpipes expand a lot when the warm up. It can move between 1/4-1/2 rearwards between cold/hot. I installed AA & MPE assembled from another owners car and when it warms up one of the pipes rub the diff carrier. it is the way their shop cut and installed it. Can't change it so I have moved it around the bet I could but still rubs when it gets real hot.

Just something else to double check

[biggripper]

Originally Posted by BruiserM3

How many miles on the car? It's possible that your valves are just experiencing too much pressure causing them to "bounce"/rattle

If your car is tuned test it with cold start off and see if it rattles less

I purchased the car with 9300 on the odometer and I've only put another 200 on it so far. I'm going to try starting today with valves full open. I don't have a tune as yet.

[biggripper]

Originally Posted by horsepower_and_hounds

Make sure you check it when the car & exhaust is hot. The OEM downpipes expand a lot when the warm up. It can move between 1/4-1/2 rearwards between cold/hot. I installed AA & MPE assembled from another owners car and when it warms up one of the pipes rub the diff carrier. it is the way their shop cut and installed it. Can't change it so I have moved it around the bet I could but still rubs when it gets real hot.

Just something else to double check

Thanks. I'll keep an eye out for that.

[jimmydick]

Someone had a diy where the lifted one side for access instead of the rear.

[mike@x-ph.com]

Here is a video we posted a while back where we show how we replaced the single midpipe with the equal length

[300tour]

Had a similar issue after installing the AA non-res EL and Madd Maxx rear so I called AA and spoke to a tech. I'd advise on reaching out as they were super helpful in resolving my issue.

[biggripper]

Originally Posted by 300tour

Had a similar issue after installing the AA non-res EL and Madd Maxx rear so I called AA and spoke to a tech. I'd advise on reaching out as they were super helpful in resolving my issue.

I did as well and they were very helpful.

[slaughter.mode]

Just want to chime in here. Mike is 100% right. The resonated AA EL mid-pipe, when paired with cat-less downpipes and an aftermarket muffler, has a metallic buzz that you simply cannot get rid of.

Period.

I had swapped all the gaskets, adjusted multiple times, swapped the pricey muffler and pipe hangers and I am confident without a doubt that there's no contact anywhere. I can even put my hand between the F brace and the pipes. The moment I put back in my AA single mid pipe: Smooth, no rattles, really nice with valves closed but it just sounds 'ugly' loud when I open it up.

[horsepower_and_hounds]

That is why the single mid with the MPE is the best....and the way BMW designed the car to sound just slightly deeper and meaner. Would not want it any other way except maybe the M4 GT4 straight pipe set up

[hurricane56]

I did the install myself this weekend and noticed a few things. Did anyone feel centering the pipes left to right was a bit difficult? My pipes seems to be closer to the passenger side. This was close enough to have the pipes touch the heat shield. I did a little pushing and bending to make clearance. It makes a a lot more sense now to start tightening the driver's side pipe before the passenger. I might go back down there and tighten everything again.

The question that I had, maybe you all can help with this, I ended up with two extra bolts and I do not recall ever removing these bolts. Can anyone help me identify the location of these bolts?

[Xer0449]

Just had mine installed. The only rattle I've really noticed is what sounds like the exhaust banging against _something_ under the rear of the car. I'm going to let it heat cycle a few times before trying to adjust.

[hurricane56]

Originally Posted by hurricane56

I did the install myself this weekend and noticed a few things. Did anyone feel centering the pipes left to right was a bit difficult? My pipes seems to be closer to the passenger side. This was close enough to have the pipes touch the heat shield. I did a little pushing and bending to make clearance. It makes a a lot more sense now to start tightening the driver's side pipe before the passenger. I might go back down there and tighten everything again.

The question that I had, maybe you all can help with this, I ended up with two extra bolts and I do not recall ever removing these bolts. Can anyone help me identify the location of these bolts?

I removed the transmission mount bolts above the front exhaust isolator. luckily I put them back on before driving!