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      09-18-2016, 02:12 PM   #1
inTgr8r
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Melted rear bumper cutouts? - Hanger fix

I've had an issue with the exhaust tips shifting and melting the rear bumper cutouts.
This is primarily an issue for tracked cars and the bigger the tips, the bigger the problem.



I ran DKF hangars for a while and they were better than OE for this but not perfect either.
I switched back to OE hangers because I had too many failed isolators with the DKF. I'm no sure if the larger isolators on DKF solved this or not.

The OE hangers allow too much lateral movement under track loads which puts the tips in contact with the bumper.
(center portion mushrooms out)

I found a solution that has worked for me.
I added two flat bars on each side of the hanger, held in place by the muffler hanger bolt.
I used 1" aluminum flat stock for this. (green arrows in pics)





The damage in pic #1 occurred before the fix.
I haven't refinished the damage yet but I have run 6 track days since the fix with no further damage.

These restrictor plates only limit horizontal movement, the hanger can still function fore/aft as well as vertically.

Also of note (blue arrow) I added a rubber isolator between the hanger and car frame which helps isolate drone from being transmitted to the car.



.
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      09-18-2016, 02:39 PM   #2
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Wow, impressed on the ingenuity! Great idea for those who may run into this same situation. Thanks for sharing
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      09-18-2016, 04:04 PM   #3
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Excellent Fix! Adding this to the list
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      09-18-2016, 04:23 PM   #4
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You've been busy.
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      09-18-2016, 04:32 PM   #5
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Quote:
Originally Posted by crfine88 View Post
Excellent Fix! Adding this to the list
With the size of your custom Stromung tips, even this fix will be pushed to the limit to keep things contained.
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      09-18-2016, 04:34 PM   #6
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Quote:
Originally Posted by Finnegan View Post
You've been busy.
LOL, I don't know how I ever found time to work
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      09-21-2016, 10:59 PM   #7
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I have the same paint damage on my left side tip. Annoys the he'll out of me but not worth paying to fix since it's so hard to see. Being a Z4 owner only makes my OCDness worse.
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      09-22-2016, 11:42 PM   #8
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Thanks for the information! Will be very helpful to all members!
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      09-24-2016, 10:59 AM   #9
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Lol i did too, however have since gutted that whole bit. Great ingenuity again Ian, good stuff mate. I have the latest isolators, and will let you know how they go after this season.
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      03-23-2017, 01:19 PM   #10
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inTgr8r, how did your fix end up working out? I think it's simple and ingenious and I intend to copy it!

I am having the same issue on my MZ3 with my new 80mm-tipped Supersprint. No issues on my MZ3 with Supersprint DTM tips, but the 80s can touch the bumper cutout on one side because the hangers can move horizontally a little bit.
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      03-28-2017, 08:01 AM   #11
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Quote:
Originally Posted by JonM View Post
inTgr8r, how did your fix end up working out? I think it's simple and ingenious and I intend to copy it!

I am having the same issue on my MZ3 with my new 80mm-tipped Supersprint. No issues on my MZ3 with Supersprint DTM tips, but the 80s can touch the bumper cutout on one side because the hangers can move horizontally a little bit.
Thanks Jon, it has gone well, no further damage.

I had the exhaust off recently and was looking at this.
I think it could be made slightly better with more dimension at the mid-point where the bolt goes through.
More of a shaped piece instead of just flat bar.

The key thing is to allow enough clearance for, for/aft movement when the pipes elongate with heat.
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      03-28-2017, 12:49 PM   #12
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I will post pics of the ones I am making for my MZ3. I am copying the profile shape of the hanger itself to do exactly what you said. And, I am coming down about 1/4" from the top of the hanger, just so there is no way my side brackets hit the body when the exhaust moves up and down (over bumps). I agree on leaving the hanger open to move fore/aft and also up/down.
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