Heavy Duty exhaust hangers?

[R60BBA]

Just following up on this.

Appreciate the suggestions chaps but I have discussed this with my mechanic and it was decided to replace the split hanger with a fresh Genuine BMW hanger.

I will monitor it every six months or so and if it splits again within 24 months then it will be a warranty job.

If it splits outside of the 24 month warranty period then I will simply replace the standalone hanger (which is the culprit here) with a poly mount (and retain the two rubber mounts on the other side).

For reference, the back box is standard although it has had the TrueBlue mod. Also all of the hangers were fitted in the correct direction.

It’s gone again…and just outside of the 24 month warranty period…again…

Poly mount it is…

[WBVenom]

You want something soft enough that the exhaust CAN move, if you’re not running solid engine/trans mounts... and maybe even if you are, as thermal expansion of exhaust components is no small thing over the entire length of the car.

I’m running unmodified stock. I’ve replaced them twice in 160,000 miles, the second time pretty recently. Barely an inconvenience...

As per usual, theres a reason stock is designed the way it is.

This! The OE hangers are engineered to allow ample movement horizontally, and to allow very little movement vertically. You can observe this by playing with one off the car. The rubber linkage geometry is cleverly designed to articulate in the right way.

There is large horizontal movement required due to the thermal expansion (and contraction) of the exhaust system. If you constrain it (as every aftermarket mount design does) with a more rigid mount, you will induce significant stress on the exhaust system as it goes to thermally expand at operating temperature and cannot elongate in the way the OE mounts allow. The exhaust system (including the headers) will eventually begin cracking at its weakest points.

OE is the way. The only way. A rigid mount (including filled in) is asking for trouble.

[R60BBA]

This! The OE hangers are engineered to allow ample movement horizontally, and to allow very little movement vertically. You can observe this by playing with one off the car. The rubber linkage geometry is cleverly designed to articulate in the right way.

There is large horizontal movement required due to the thermal expansion (and contraction) of the exhaust system. If you constrain it (as every aftermarket mount design does) with a more rigid mount, you will induce significant stress on the exhaust system as it goes to thermally expand at operating temperature and cannot elongate in the way the OE mounts allow. The exhaust system (including the headers) will eventually begin cracking at its weakest points.

OE is the way. The only way. A rigid mount (including filled in) is asking for trouble.

Aware of that theory but haven’t actually heard of that happening to anyone with poly mounts in practice.

Also aware of folk who have been running poly mounts for years and not had any issues.

To be clear, I’m only replacing the standalone mount with a poly mount, the other two will remain as OE rubber.

[0-60motorsports]

Aware of that theory but haven’t actually heard of that happening to anyone with poly mounts in practice.

Also aware of folk who have been running poly mounts for years and not had any issues.

To be clear, I’m only replacing the standalone mount with a poly mount, the other two will remain as OE rubber.

Let us know how it goes.

[oceansize]

The OE exhaust hanger is now a $130 to $140. I bought the HJS for $28 and its completely fine, little difference in comparison to OE. I ordered two more and I still come out ahead.

[0-60motorsports]

The OE exhaust hanger is now a $130 to $140. I bought the HJS for $28 and its completely fine, little difference in comparison to OE. I ordered two more and I still come out ahead.

Same

[R60BBA]

Let us know how it goes.

My mechanic just sent me these, they’re a bit blurry but you get the gist.





Hopefully I won’t have a problem of this sort in future and therefore won’t have to post on this thread again…

[0-60motorsports]

My mechanic just sent me these, they’re a bit blurry but you get the gist.





Hopefully I won’t have a problem of this sort in future and therefore won’t have to post on this thread again…

Looks good. Yeah let us know once you drive the car if there is any NVH.....

[R60BBA]

Looks good. Yeah let us know once you drive the car if there is any NVH.....

Picked up the car from the garage today.

Drove home (which is ~25 miles) and can confirm there is no new/additional NVH.

[0-60motorsports]

Picked up the car from the garage today.

Drove home (which is ~25 miles) and can confirm there is no new/additional NVH.

Awesome. Thanks for the feedback.

[WBVenom]

Stand back! I am going to try science!

So I measured the exhaust tip protrusion from the diffuser while hot after returning from a drive, and then cool the following morning. The car did not move between measurements. Ambient air temperature approximately 75° F at the time of both measurements. Daily driving intensity, with approximately a few hundred feet cooldown and 1 minute between parking and hot measurement.

Setup:
OE US headers
Rogue Engineering Anti-Rasp V3 Section 1
OE US Section 2
Rogue Engineering El Diablo Section 3
OE exhaust hangers (all 3)

Hot:
Leftmost tip: 26 mm
Rightmost tip: 21 mm



Cool (ambient):
Leftmost tip: 18 mm
Rightmost tip: 13 mm



Difference:
Leftmost tip: 8 mm
Rightmost tip: 8 mm

So there is 8 mm worth of expansion from cool to daily-drive hot. Likely additional expansion at active track driving temperatures. This expansion has to go somewhere. I do not know if the rigid hanger options on the market will allow 8 mm or more of expansion. Likely not. Flexible (OE) motor mounts likely allow the motor to move forward to eat up some expansion, but likely only a very small amount. The rest goes into stressing the pipes.

I would be interested in a rigid hanger design with elongated slots in the polyurethane/rubber that allowed for a small amount of expansion. They likely do not need to accommodate as much expansion as the OE hangers do, but more than zero is likely necessary.

[Obioban]

Yeah, rigid exhaust hangers are just a bad idea.

I bet that expansion doubles with track use.

[Larky7]

I ran 3 Powerflex poly exhaust hangers.

UK car, so Euro OEM set up all the way but Scorpion muffler. Swapped to Powerflex hangers because one of the brand new OEM hangers ripped after a year’s use and before that the muffler used to move and tap/hit the underside on track days - did not experience this with normal road driving.

Powerflex made a difference - more than half the weight savings compared to OEM, no more exhaust movement, no more banging/tappping on track and the exhaust tips did not move or protrude.

As for NVH, there was an ever so small increase, like 5% more exhaust buzz noise.

When I swapped back to the OEM muffler (Scorpion drones when cruising), I also swapped back to OEM hangers as I noticed while there was no cracks, splits or distortion in the exhaust system, the metal O ring gaskets where the muffler joins section 2 were split and broken. I think something had to give during the heat expansion and those metal O rings took the hit.

[Bry5on]

My math says approximately 30mm axial travel at a sort of 'worst case' track hammering (from 0C - 500C average pipe temp for ~11' length = 30mm). If you swap or reinforce a bushing, **something else** will be bending to take up this movement as thermal expansion is an extremely strong force.

My recent 60-70mph highway 2hr road test the exhaust grew 15mm with SSv1 headers+section 1 plus stock section 2 and muffler. This was verified by parts contacting each other during driving, so no cooldown.

Please don't 'upgrade' these

[ac427]

Picked up the car from the garage today.

Drove home (which is ~25 miles) and can confirm there is no new/additional NVH.

It might be worth considering a rubber insert rather than the poly bush.

Where did you get the mount from?