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Fix for seized down pipe nuts

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#1
JNJ

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 After drilling many seized/broken down pipe studs out of exhaust manifolds for friends, I went looking for a solution.  There really isn't any good ones that I could find so I made some and after a few changes, came up with a 10 X 1.5 mm 360 flanged brass nut that that is 19mm long and have a 14mm hex.   The 360 brass will not seize to the stud and the longer length covers all of the threads and makes them really easy to access for removal.  The down pipe nut is the only 14mm hex that is 1.5mm thread so if you use a nut for the manifold on the down pipe stud it will cause you some problems.  JIS (Japanese Industry Standard) 14mm hex is always 10 X 1.25 mm.  Nice to know when you have to pull a trans at the track that these nuts will come of, and easily too.  No chance of mixing them up either. 

 

https://www.ebay.com...4.c100667.m2042

 

 

 

 

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#2
Steve Scheifler

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I like it, but... Not sure about 360 brass but generally brass takes even less torque than bronze, roughy equal to a grade 2 steel thread. The extra length makes me feel better about that but I’d still probably wince a bit each time. Plus it probably has a significantly higher coefficient of thermal expansion which may or may not be an issue at those temps.

Bottom line, let us know how it works!
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#3
JNJ

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My BMW E39 M5 comes stock with 360 brass nuts, standard length and no flange.  I reused them when I put in the new clutch now they are almost 20 years old.  Most private aircraft use them too.  Cat uses them on their turbos and some silver plated nuts .  The longer grip length and the flange make them far better than anything else out there, period.   They worked on my car at several Majors and Super Tours as well as many club races.  Other racers have them too, all of them with positive feedback.   Most OE don't use brass nuts because of cost, (I know this because I worked for one) the really should on high output and Turbo applications.  They will up for copper washed nuts on some Turbo apps. they are at best a one time use. The extra length allows for a short ball socket (14MM) make it super easy to remove, especially the one behind the bend.  BTW, the stock Mazda nut is Moly coated and should be replaced after every removal and even then it is a little scary with an impact.



#4
Steve Scheifler

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Fair enough. But $15 EACH plus $5 shipping??? Talk about specialty limited production pricing, ouch!! Does he at least drop the shipping for additional pieces?
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#5
Dave D.

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Most of the old Chevy small blocks had brass exhaust flange nuts. I'd jump on these but not at that price.  Even at a couple bucks each ( I'm sure the OEM Mazdas are going to be at least a buck or so a peace), I would buy a bunch. With a CNC mill or lathe spitting these out, he can't get the prices any more competitive? Or just looking for max profit?



#6
JNJ

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CNC prices are $16 each for a run of 300.  The price goes down after 500 pieces as the set up time is the same 300/set up or 500/set up.  I am making these manually.  The material is $1, there is a cutting operation (cold saw) lathe operation facing, counter sink, drilling and tapping.  Then in the mill on an indexing head and six sides machined for the hex.  Then back on the lathe for facing the small side hex on a special fixture.  Every surface has been touched by a machine.  I am making about 10 bucks an hour (could make more flipping burgers)  and have the machinery and skills to do this. I also have the contacts to CNC them but the price would only come down slightly unless the run was over 500 nuts.  Even at that, I would have to write a big check and own the inventory while I tried to convince people that it is really what it costs to make them.  

 

The cost effective way to make these is to cold head them but they would need to be a made in huge scale.  Try to find a flanged brass nut, try to find a long brass nut and now try to find it in 10 X 1.5 and with a 14 hex.  The only one I know of is one Ebay. This is a good deal and please don't buy any if you think they cost too much as I not interested in making more than one or two runs of these.  This run was to finish off the 12 foot, 3/4 brass rod I had to buy.  I will ship 9 for the same price. 

 

Take the stock nut and run a tap through it to remove the locking and coat the stud with antiseize.  It will reduce the possibility of it seizing but it is messy and still hard to get at.



#7
Steve Scheifler

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Sorry, I missed on first read that you made them, hence my reference to whether “he” drops the cost of shipping on multiple. As I stated, I get the issue of limited production, but ultimately that doesn’t change the value equation for most potential buyers any more than their idea of value changes the cost of production. It’s why countless great ideas never come to market. So, I commend the effort and the execution, I might even be tempted, but first I’d probably explore an alternate stud & nut combination using more readily available parts.
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#8
Alberto

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That's kinda cool.  I have yet to separate a downpipe from the header without breaking the stud trying to remove the nut.


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#9
Dave D.

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I would most likely buy a set or two for my own car as I can appreciate the work that goes into one off special parts( that no one else would), but most customers would look at me like I was crazy adding $45 to their clutch job for 3 exhaust flange nuts. Now that price built into a full SM build that is gonna be in the $20k to $30k budget, then there's no issue..................If these could be brought down to even $5 each, I would stock a bunch for engine and clutch jobs.   


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#10
LarryKing

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"Almost" any rusted nut will loosen if you plan ahead. When I know I'll have a "problem child" I start about a month in advance spraying the nut(s) with PB Blaster or equivalent, then repeat every day or two for several weeks. Usually works.
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#11
JNJ

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It is a stainless nut (new it is moly coated but after one use it wears off) and stainless stud, they actually weld together  and then the stud breaks.  This is a real PIA but more so at the track while changing a trans.  The extra length makes it easy to get to with a 14 ball socket and you can use an impact to remove.  This is a real plus if you work on your own car.  If you replace the stock nuts every time you remove them then you will be ok but these nut can be reused, are easier to get to and won't get mixed up with the all the rest of the 14mm nuts that are 10 X 1.25mm, the JIS Standard.  Every person that has them wants more.






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