Redleg Posted May 15, 2012 Share Posted May 15, 2012 I love the new gravely engine tone that comes from my car. A while after having a 3" downpipe installed then hearing my exhaust suddenly get real loud, my mechanic said I lost the bolts holding the downpipe to the next pipe downstream. He put in new nuts/bolts and some gasket material between the metal flanges. The stuff is crumbling away 1 year later. I can feel exhaust shooting out of the interface. Will a stock gasket from Subaru work to fix this? Is it a donut shape or a flat gasket? How do I describe it to the parts dept? Thanks Link to comment Share on other sites More sharing options...
Moderators BarManBean Posted May 15, 2012 Moderators Share Posted May 15, 2012 what kind of downpipe and CBE? Donut gasket: http://www.fredbeansparts.com/index.php/subaru-downpipe-to-intermediate-pipe-gasket.html "Bullet-proof" your OEM TMIC! <<Buy your kit here>> Not currently in stock Link to comment Share on other sites More sharing options...
Max Capacity Posted May 15, 2012 Share Posted May 15, 2012 You need something like this and stop using the donut. Thats the style I use on my Invidia DP to oem midpipe. Just get to 3/8 bolts with washers and lock washers and nuts and you should be fine. http://www.fredbeansparts.com/index.php/grimmspeed-header-to-uppipe-2x-thick-gasket.html Most auto parts stores should carry something like it. 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
Redleg Posted May 16, 2012 Author Share Posted May 16, 2012 The downpipe is aftermarket, I believe it is by CNT. It connect to the OEM CBE. From what I gather there are options being recommended here: - donut - flat gasket I like the idea of a donut making the air seal and allowing flange to flange contact seems more structural. In general I'm willing to spend a little more for better reliability, are you saying that the flat metal gasket stacks you use are better from a reliability standpoint? Thanks for the links Link to comment Share on other sites More sharing options...
Max Capacity Posted May 16, 2012 Share Posted May 16, 2012 I have tried a oem donut on my oem mid pipe and my Invidia catless dp. Didn't work very well. I just use a 3" flat gasket now. The DP has long holes in the flange so there's plenty of room to center the gasket. 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
bmx045 Posted May 16, 2012 Share Posted May 16, 2012 the cnt downpipe is not bellmouth design, it's a flat flange. you need to buy a 3" adapter in order for it to mate and seal properly. http://www.fredbeansparts.com/index.php/grimmspeed-3-inch-subaru-downpipe-adapter.html been there done that, no real way around it...i've tried sealing it without the adapter with massive amounts of rtv and double gaskets, no go. the way the midpipe is designed, there isn't enough flat surface area to properly seal. you may get a visual seal but it will leak and blow out, there also needs to be flex there because downpipe mounting angle is sometimes askew compared to the direction of the midpipe. thus sometimes mates crooked, which is another reason an adapter is needed Link to comment Share on other sites More sharing options...
MatsuDano Posted May 16, 2012 Share Posted May 16, 2012 So here's what it sounds like, stop me if I'm wrong. - Your stock spring bolts broke, but got replaced. - You are mating a 3" DP flange to the 2.5" OEM midpipe - You didn't replace any of the original gaskets in the install of the downpipe If so, you need all of the above. I'm assuming you already have a 3" to 2.5" adapter, but if you don't, the entire assembly looks like this http://www.fredbeansparts.com/index.php/3-inch-downpipe-to-2-5-inch-cat-back-exhaust-adaptor-1.html The adaptor should be in good shape, assuming it's not rusted to hell from NE winters. Link to comment Share on other sites More sharing options...
MatsuDano Posted May 16, 2012 Share Posted May 16, 2012 You beat me by two minutes ya limey bastard! Link to comment Share on other sites More sharing options...
planelazy Posted May 16, 2012 Share Posted May 16, 2012 You need something like this and stop using the donut. Thats the style I use on my Invidia DP to oem midpipe. Just get to 3/8 bolts with washers and lock washers and nuts and you should be fine. http://www.fredbeansparts.com/index.php/grimmspeed-header-to-uppipe-2x-thick-gasket.html Most auto parts stores should carry something like it. Yes and no.. I have a slight leak from my CBE/DP flanges even with that 2x thick gasket.. I'm not running a donut gasket. Link to comment Share on other sites More sharing options...
Max Capacity Posted May 16, 2012 Share Posted May 16, 2012 plane, have you tried larger outside diameter washers on the flange. BTW, I don't use the springs either. Just some 10 or 12mm bolts, nut's, large washers and lock washers. Take's a 17mm socket. 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
Moderators BarManBean Posted May 16, 2012 Moderators Share Posted May 16, 2012 Ok, I just had the same exact setup and ran it for a month with no issues before changing it because I felt like it. This should be your setup: Downpipe-->3" flat gasket-->3"-to-2.5" adapter with donut gasket slipped on with the smaller end facing towards the back of the car-->CBE. Done. It works. Use regular bolts, washers, nuts, and lockwashers like Max said--I used the same style hardware and picked it up from CarQuest (grade 8). If you don't have all of the above buy whatever you need form Fredbeans parts, AZP, or Infamous (m sprank). "Bullet-proof" your OEM TMIC! <<Buy your kit here>> Not currently in stock Link to comment Share on other sites More sharing options...
planelazy Posted May 16, 2012 Share Posted May 16, 2012 plane, have you tried larger outside diameter washers on the flange. BTW, I don't use the springs either. Just some 10 or 12mm bolts, nut's, large washers and lock washers. Take's a 17mm socket. I've gone with as big as I can get, but the problem is the SPTv2 CBE I have is a POS, not just in build quality, but... ok yeah all in build quality. The flange has a lip that prevents you from using a huge washer. I also have the CNT DP. I'm not going to fix my leak anytime soon since I'm going to end up getting a custom magnaflow CBE. Link to comment Share on other sites More sharing options...
bmx045 Posted May 16, 2012 Share Posted May 16, 2012 WTF are you talking about? The SPT is one of the nicest quality CBE you can get. It, just like the magnaflow, was designed to mate up to the stock dp and/or a bellmouth design. Blame your POS CNT, not the catback. Link to comment Share on other sites More sharing options...
MatsuDano Posted May 16, 2012 Share Posted May 16, 2012 I've gone with as big as I can get, but the problem is the SPTv2 CBE I have is a POS, not just in build quality, but... ok yeah all in build quality. The flange has a lip that prevents you from using a huge washer. I also have the CNT DP. I'm not going to fix my leak anytime soon since I'm going to end up getting a custom magnaflow CBE. I also have the SPTv2 and the CNT DP but have had no problem. I stacked my washers though, smaller to larger to avoid the lip. Link to comment Share on other sites More sharing options...
Max Capacity Posted May 16, 2012 Share Posted May 16, 2012 Here's my set up that I have been using for a couple of years. http://i185.photobucket.com/albums/x40/92Si/DSCN4781.jpg 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
Moderators BarManBean Posted May 16, 2012 Moderators Share Posted May 16, 2012 Why so many washers?!? "Bullet-proof" your OEM TMIC! <<Buy your kit here>> Not currently in stock Link to comment Share on other sites More sharing options...
bmx045 Posted May 16, 2012 Share Posted May 16, 2012 Because his screws are too long Link to comment Share on other sites More sharing options...
Max Capacity Posted May 16, 2012 Share Posted May 16, 2012 Yep. 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
No DRFT Posted May 17, 2012 Share Posted May 17, 2012 Can i still use the oem spring/bolt for the downpipe to catback? I have no control over drippie. Link to comment Share on other sites More sharing options...
bmx045 Posted May 17, 2012 Share Posted May 17, 2012 They wont reach if you use an adapter in between Link to comment Share on other sites More sharing options...
No DRFT Posted May 17, 2012 Share Posted May 17, 2012 What length bolt/size nut do i need then? I have no control over drippie. Link to comment Share on other sites More sharing options...
Moderators BarManBean Posted May 17, 2012 Moderators Share Posted May 17, 2012 m12 for most downpipes, m10 for a cobb downpipe. 60mm length usually comes full threaded (i think) and should be long enough "Bullet-proof" your OEM TMIC! <<Buy your kit here>> Not currently in stock Link to comment Share on other sites More sharing options...
No DRFT Posted May 17, 2012 Share Posted May 17, 2012 Excellent, thanks. I have no control over drippie. Link to comment Share on other sites More sharing options...
Redleg Posted May 17, 2012 Author Share Posted May 17, 2012 I don't know what hardware was used when the aftermarket DP went in. The work was not done locally. I'm guessing the DP was installed with the gasket/adapter/donut and when the bolts loosened and fell out I lost these parts, too. So when my local mechanic took a look he didn't realize what I had lost on the road, he just got it back together with what he had lying around (at no charge to me!). I'm going to have to get under the car and disassemble the existing joint to make sure I have what we think I have. Then likely order that kit you guys pointed out. Link to comment Share on other sites More sharing options...
SCHM1AN Posted May 18, 2012 Share Posted May 18, 2012 Why so many washers?!? Because Hogzaust. Link to comment Share on other sites More sharing options...
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