Exhaust Y-pipe flange anyone? (1 Viewer)

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I have a pathetic situation. My truck is my only vehicle and I am about to tear it down for exhaust repair, EGR removal, new spark plugs, bumper etc... But when I tear it down I won't be able to drive it in order to buy the needed parts, so I need t complete some parts in advance. My main problem is the shape and dimensions of the flange which connects the Y-pipe to the cast manifold.

Thanks a lot :)
 
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That's probably it but I was looking for some kind of template which would have all the dimensions drawn. I just need to have it cut and ready to weld before I disassemble the truck. Probably someone who has ever done a custom exhaust will give some info.
 

little_joe

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Please let me know if you still need measurements, I have exhaust manifolds in the garage and can get whatever dimension you need. Best to PM or email via the board.
 
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I wanted to officially thank little_joe for taking the time and making detailed measurements (in milimeters :)) along with photos. Thanks for helping a fellow mudder.
 
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As soon as I make those flanges and make sure they are 100% OK, I will post here the drawings for anyone to use.
 
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Thanks Joe for those measurements.

Mike, what inner diameter are you using for the flanges? I imagine there has to be some material there for the dounut gasket to be pressed against.


As soon as I make those flanges and make sure they are 100% OK, I will post here the drawings for anyone to use.
 
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I will update the thread within a day or two with some details and drawings. Joe really made great measurements with the exception of bolt size. It is 10mm instead of 8mm, so the bolt holes should be around 12mm prevent stress from heat expansion. Anyway, details will be posted soon.
 
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I used the dimensions that Joe sent to Mike and me to draw this up in sketchup. I have some questions:

- Can you guys double check my dimensions?
- What thickness should I use? Anyone know how thick the EMS flanges are? I was thinking 3/8"
- What type of gaskets are you guys going to use? There seem to be 2 types, one the is like a doughnut, the other is the same shape as the flange and is posted in a post above via a link to summitracing.com

I am going to try and figure out how to export this in a dwg file and get a quote from the local water jet guy for stainless steel flanges.


 
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Hey guys, does anyone have a hook up at a machine shop or a water jet place?

I have a DWG file. We would have to double check my dimensions but if anyone needs the file I can send it.
 
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Hey guys, does anyone have a hook up at a machine shop or a water jet place?

I have a DWG file. We would have to double check my dimensions but if anyone needs the file I can send it.
You need just the flanges? I can have them cut for you at the local water jet / laser cutting facility here in Austin. Shouldnt be much. Just make sure that your drawings are correct. Worst thing would be having a bunch of flanges cut and they're not correct
 
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jmvar, adjust the bolt holes to 12mm. The bolt is indeed 10mm, but ther needs to be some play to compensate for heat expansion and to simply make things easier. The OEM flanges have some play. I just redrilled my too-small holes but you can do it right from the beginning.

If you need a water jet, just google for 'water jet' and the name of your city. Worked for me :)
 
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Here go my drawings. I used an 8mm thick '304' stainless steel. All the flanges seem really really sturdy.

The o2 sensor flange is proper as it is but one of my sensors had a few weld burrs around the drilled 'cap' and it wasn't a perfect fit. I had to take a file and scrub the welds down a bit. Really no big deal, but the perfectionist types can make a 16 or maybe even 17mm center hole.

The manifold flange (medium size one) needs 12mm bolt holes. The spacing is right but just the holes need to be 12mm. I used those flanges today and the fit is perfect.

The biggest flanges will connect sections of the exhaust. It all seems OK with them. They are for 70mm tubing (2,7") so people who need a typical 2.5" exhaust will need to make modifications.

I just gave the drawings as JPG and the waterjet company didn't complain or impose any extra charge. Your mileage may vary, though.

Jmvar, I am going to use the OEM dougnut gaskets. The headers have a recess which allows the tubing to slide inside with the gasket around it. See next post.
manifold-flange.jpg
o2flange.jpg
exhaust-flange.jpg
 
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Here is the diagram of the header to exhaust area. The tubes go a little bit past the flange and a 50mm tube is an almost tight fit into the header. This is a first heat barrier that will protect te gasket from direct exposure to very hot exhaust gases. The gasket (red) works as a second barrier. I will even reuse the old gaskets. They are just rings of thin metal which has a shape similar to a differential crush sleeve. This acts as a spring and gasket in one. I am almost sure that the FSM will state that it is a non-reusable part, but I have unbolted the exhaust 2 years ago (to have it welded) and there were no problems after reinstalling the used doughnuts. I will do it once again. My 50mm tubes are a tiny bit larger than stock so they will protect the doughnuts even more. I don't expect any problems.
manifold-diagram.jpg
 
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Mike thanks for the tip on the studs. I have changed my drawing to 12mm holes for the studs and 49.5 mm (~1.95 inches) for the opening. I chose this size to ensure the flange crushes the Bosal brand gaskets which have an inner diameter of 50.2 mm.

I spoke with my exhaust guy today and he said he is going to use 2.25" pipe for the down pipe and 2.5" pipe for the rest of the exhaust.

I found a local water jet guy that will cut me 2 flanges for $80 so unless someone here has a better hook up I will shoot him the DWG file tomorrow. Any help here is appreciated.


Here is a screen shot with dimensions:


 

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