Artech Downpipe crack. Will a repair hold up? - Page 4 - Miata Turbo Forum - Boost cars, acquire cats.

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Old 04-08-2015, 01:07 PM   #61
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Originally Posted by BTMiata View Post
The only thing I noticed when removing the downpipe yesterday was that the exhaust seemed to be pulling down on the back side of the downpipe. I'm assuming that was putting stress on the weld that cracked and thats why it split. I fully plan to add a brace and see what happens this time.
that's exactly what the split is suggesting to me.

like the DP should be welded back up exactly as pictured.
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Old 04-08-2015, 01:09 PM   #62
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I'd be more worried about the stress thats being put on the manifold. Once you strengthen that failure point whats next.

Also major props to Abe for standing behind his work like this. It's really comforting for people who are looking to purchase from him.
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Old 04-08-2015, 01:10 PM   #63
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Quote:
Originally Posted by BTMiata View Post
The only thing I noticed when removing the downpipe yesterday was that the exhaust seemed to be pulling down on the back side of the downpipe. I'm assuming that was putting stress on the weld that cracked and thats why it split. I fully plan to add a brace and see what happens this time.
That is likely your problem. My suggestion is to first fix the hangers so that the exhaust system is holding itself up, and it's basically nuetral, the downpipe and the exhaust, then you bolt them together/clamp/however they attach. You don't want any load on the downpipe if possible. I admitedly need to add a hanger on the front of my exhaust system, but it's .065 mild steel so it probably won't fail regardless but still better to not have a huge load there.
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Old 04-08-2015, 01:15 PM   #64
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I don't know. In one of his pics (this one: http://i119.photobucket.com/albums/o...pszeiucefg.jpg ), it looks like the 2nd weld was not all the way around, there is a spot (that failed) that is still undercut in the pics. Perhaps (again, I don't TIG much so don't know much about TIG) this spot failed and then the crack propegated.

But I dunno. Seems to me something is putting really high stress in that spot. Hence why I recommended a brace.

Random thought, but if his EGT's were really high for some reason, would that contribute to this failure?

I actually took it back to the guy who repaired it before re-installing it the first time because I noticed that he didn't weld all the way around. He inspected it with a magnifying glass and welded the missed spot.... I guess there is a chance that he still didn't get the new weld all the way around... I dont know, I'm at a loss... Blah
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Old 04-10-2015, 09:30 AM   #65
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What do you guys think about adding an extra exhaust hanger to the rear section of the downpipe and using all poly hangers?

I still have all original hangers from 1991 so they probably need to be replaced anyway.
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Old 04-10-2015, 09:39 AM   #66
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Quote:
Originally Posted by BTMiata View Post
What do you guys think about adding an extra exhaust hanger to the rear section of the downpipe and using all poly hangers?

I still have all original hangers from 1991 so they probably need to be replaced anyway.
Poly hangers will probably be a good idea. I am not sure where you would mount an additional hanger around where the downpipe comes ends. There are not many bolt holes around there, unless you want to drill into the trans tunnel and fab something yourself.
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Old 04-10-2015, 10:00 AM   #67
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I have an ARTech downpipe with a flex joint in the same location and have not had problems.

I do also have MSM comp mounts, poly diff mounts, and poly exhaust hangers, so maybe that's helping. Hope you get it back in time for the meet!
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Old 04-10-2015, 10:12 AM   #68
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Originally Posted by Mazdaspeeder View Post
I have an ARTech downpipe with a flex joint in the same location and have not had problems.

I do also have MSM comp mounts, poly diff mounts, and poly exhaust hangers, so maybe that's helping. Hope you get it back in time for the meet!
I have brand new MSM mounts installed when I swapped in the 1.8 and turbo parts back in October, and just added Poly diff mounts when I swapped in the 3.9 torsen. Definitely ordering up the poly exhaust hangers.

I'll probably just end up fabbing up some kind of bracket to take weight off the back of the downpipe and hoping it holds up. All this has me up at night hahaha
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Old 04-10-2015, 10:21 AM   #69
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Originally Posted by BTMiata View Post
I have brand new MSM mounts installed when I swapped in the 1.8 and turbo parts back in October, and just added Poly diff mounts when I swapped in the 3.9 torsen. Definitely ordering up the poly exhaust hangers.

I'll probably just end up fabbing up some kind of bracket to take weight off the back of the downpipe and hoping it holds up. All this has me up at night hahaha
Those poly exhaust hangers are a bitch to install but I really think they will help you. I got mine from Corksport when I ordered my catback. I would probably loosen all your exhaust bolts when you put them in because chances are your OEM ones are stretched and you'll want to re-align the exhaust system as you install.
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Old 04-13-2015, 02:03 PM   #70
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Got a pic from Abe! Now just a matter of waiting for it to come back to me and then developing some kind of bracket to take the weight off the back end of it. Also have to order some poly hangers ...

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Artech Downpipe crack. Will a repair hold up?-20150412_224517_zps3ksjsmak.jpg  
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Old 04-18-2015, 09:36 AM   #71
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Ok so downpipe is back in the car.

I picked up a 3" clamp and some steel for a bracket but i'd trying to decide the best place to run the bracket to.

First thought was one of the bell housing bolts, but space is limited...

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Maybe after the flex pipe and run the steel from the end of the downpipe on the clamp, to one of the ppf bolts?

Attached Thumbnails
Artech Downpipe crack. Will a repair hold up?-20150418_082313_zpsaxn3gf2b.jpg   Artech Downpipe crack. Will a repair hold up?-20150418_082322_zpsxc0pvl4l.jpg   Artech Downpipe crack. Will a repair hold up?-20150418_082330_zps1cu5u5p7.jpg  
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Old 04-18-2015, 10:15 AM   #72
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The stock MSM downpipe is connected to the transmission right around where you have that clamp (not the v-band but the one up front). Do you see anything there? It was a 2 bolt bracket I remember. It's been out of my car for years now and I don't know if the other Miata trannies would have those holes3


You can see how its connected up here. It looks like its to the bellhousing bolts that are tight lol. Look in front of the cat and in front of the silver "sleeve" on the pipe and you'll see the connection.
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Artech Downpipe crack. Will a repair hold up?-114016d1400938040-flyin-miata-msm-downpipe-005_zpsab99ac7f.jpg   Artech Downpipe crack. Will a repair hold up?-naked_mazdaspeed_drivetrain.sized.jpg  
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Old 04-18-2015, 10:38 AM   #73
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Yeah my stock exhaust did have that bracket but unfortunately I believe I trashed it when my car was bone stock trying to eliminate a deceleration rattle.
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Old 04-18-2015, 10:39 AM   #74
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Should still be able to use the holes it leaves behind no?
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Old 04-18-2015, 10:46 AM   #75
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Quote:
Originally Posted by Mazdaspeeder View Post
Should still be able to use the holes it leaves behind no?
Well the bracket on mine was just held on by the bell housing bolts, which is why I was thinking of using one of those to run that bracket to
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Old 04-18-2015, 12:58 PM   #76
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Support should go before the flex.
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Old 04-18-2015, 02:16 PM   #77
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Also you should use a band clamp instead of one of those kind of exhaust clamps.
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Old 04-18-2015, 02:49 PM   #78
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Also you should use a band clamp instead of one of those kind of exhaust clamps.
FM uses the type BT shows. What advantage do you see in the band?
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Old 04-18-2015, 02:49 PM   #79
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Does anyone know where my motor mounts should be in those adjustable slots... I just noticed that mine are bottomed out... Would that cause any issues?

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Old 04-18-2015, 02:50 PM   #80
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Bob Bundy had issues with it causing cracking and extra stress. I need to find the thread where we talked about it. hi_im_sean might remember, he was there too.
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