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Downpipe Nut

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Old 07-02-03, 02:25 AM
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Downpipe Nut

During my downpipe installation, I lost one of the four nuts (and the washer) that tightens on the studs. Anbybody know the part number for this nut or a size and place where I can get it replaced?

I tried the dealer, but they do not seem too eager to help me when I called them. I am also trying http://www.mazdaformance.com, but it's hard to tell them what I'm looking for when I don't know the exact part number.
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Old 07-02-03, 02:40 AM
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Take one of the bolts and washer to a hardware store and try to match them up best you can.
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Old 07-02-03, 03:19 AM
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Hmm, not sure how safe just any nut and washer is. I would feel safer if it was made for the car. But I'll try that if I don't find a better solution. Thanks.
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Old 07-02-03, 04:37 AM
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A regular nut will work it's way loose. You don't need a part # with mazdaformance just email him a description of the part (pre-cat stud crush nut). It's about $6. I listed the part numbers for the stud & nut before but on dialup at home and don't wanna search. You need to "replace" the nuts because they smushed like they got stepped on and that clamps them in place. Once you take them off you have rounded them out and they loose that grabbing force. The dealer can also get you the part but it will be special order. You should also replace the metal gasket even thought it's like $40.
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Old 07-02-03, 08:36 AM
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You absolutely don't want to use hardware store materials. This nut/stud sees very high temps and stresses and an inferior part will stretch and come loose.

My downpipe came with all new hardware, which I didn't use because I went with socket head cap screws. If you want, I can drop a couple in an envelope and express mail them to you for a couple bucks. If you're interested.

Dave
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Old 07-02-03, 11:51 AM
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Even with three nuts, my downpipe is holding on pretty tight. No leaks so far. The guys at http://www.mazdaformance.com describe it as a lock nut. I think I will order one from them. That should be fine. The part # was JE10-40-355B. Thanks again for all the help guys.
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Old 07-02-03, 05:11 PM
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Originally posted by dgeesaman
You absolutely don't want to use hardware store materials. This nut/stud sees very high temps and stresses and an inferior part will stretch and come loose.

My downpipe came with all new hardware, which I didn't use because I went with socket head cap screws. If you want, I can drop a couple in an envelope and express mail them to you for a couple bucks. If you're interested.

Dave
where did you get those?

i need 4 of them he he he
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Old 07-20-04, 04:25 PM
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I have some hardware that came with my downpipe, and Im worried that they're not gonna hold, or eventually they will just seize. I have 4 studs, and 4 COPPER nuts that have a cross thread near the top to keep it from coming off. Should I go somewhere and get a different type of screw instead? I don't know whats best to use, I know I need to get at least a grade 8 stainless bolt of some sort, but is the threading different? is using an allenhead bolt better? Ive been reading that many people are using allen head bolts, or allen bolts whatever the difference is I'm not sure. And how do the stock studs come out? Do you use tighten two bolts onto the stud, then try to remove the lower one so the stock stud can twist out?
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Old 07-20-04, 04:33 PM
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If you're not going to reuse the stud just lube it up with PB blast or similar penetrating lube and then grab it with a pipe wrench and start twisting

If you need hardware, esp. stainless socket cap head bolts, I highly recommend Bolt Depot:

http://www.boltdepot.com
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Old 07-20-04, 04:45 PM
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For peace of mind i would replace only with Mazda hardware. Part#'s are:

JE10-40-355B nut $5.94 a piece (you need 4)
NF01-13-708A stud $9.36 a piece (you need 4)

N3B7-13-491A downpipe to turbo gasket i payed like $55.00 for mine

All these parts you can get from Ray Crowe 1(888) 533-3400 and they ship for free.
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Old 07-20-04, 04:46 PM
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well, I have hardware that came with the downpipe, including Brand New studs, which look fine, and the copper nuts which have me guessing how long they will last. Thanks for the suggestions broken93, but I don't even know what to look for. Is getting a better nut the best way to do it? or should I just get a nice stainless bolt to replace the stud and nut combo?
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Old 07-20-04, 04:47 PM
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Hey guys here's the parts I ordered when I installed my Gotham Racing S.S. Downpipe. I used Metric Socket Head Cap Screws (Stainless) from BoltDepot.

Here's the Part Numbers (Qty.of 5 for everything - I wanted an extra set just in case):

P/N: 4519 - Metric Washers, Flat, Stainless A-2 (18-8), 10mm - Total: $0.60
P/N: 4816 - Metric Washers, Lock, Stainless A-2 (18-8), 10mm - Total: $0.60
P/N: 6465 - Metric Socket Head Cap Screw - Stainless A-2 (18-8), 10mm x 1.5, 25mm (length) - Total: $5.00

Total Cost Including Shipping (UPS Second Day Air) was $20.13

Ordered right off their website at www.boltdepot.com

Good Luck!
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Old 07-20-04, 04:51 PM
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[QUOTE=broken93]If you're not going to reuse the stud just lube it up with PB blast or similar penetrating lube and then grab it with a pipe wrench and start twisting

Honestly i wouldnt do that. Once you mess up the treads on that stud and you cant get it out you will be removing your turbos. Get 2 nuts from the hardware store that correctly fit on that stud and double nut them (tighten the 2 of them together). Then put wrench on the one closest to the engine/turbos and back off it. Spay it with penetrating lube first.
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Old 07-20-04, 04:54 PM
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and I got this downpipe for 120 bucks, stainless 304 steel, just don't know the brand. Welds look decent, but what Im perhaps most concerned about is when I finally manage to get the precat off, I don't wanna find out that I need to get another downpipe because this one doesn't fit. I cut a corner that I probably shouldn't have in costs, but if it ends up fitting, the convience of having the Downpipe right here ready to buy from a local store means instant turnover times. Well, theres one way to find out. I could save myself the headache and just go to a muffler shop and have them wrench at it, but driving the car over there means some cooling time and I haven't sprayed the bolts with anything, so any grease monkey would just break those studs right off and then I'd be in deeper ****.
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Old 07-20-04, 04:57 PM
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is this a job I really should be trying on my own? My cat bolts are also fried, and I need to do something about those. I need to drill the studs out of the main cat, as I do have some new bolts and nuts that can go on. same goes for the catback system.
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Old 07-20-04, 05:08 PM
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If your not confident in doing the job yourself then get someone who has done it already to help you. If no one can help then maybe you should see if a rotary shop that deals with RX7's can put it on (this way they have experience with the job).

I would find out what downpipe you have first before removing anything. If its the Ebay "special" you may have a difficult time because that pipe was designed for use with a 3" midpipe and probably will not fit the main cat. Another problem with certain downpipes is it may not fit with the stock studs in place. In other words ALL of the studs will have to come out in order to put the pipe in place.

First see what pipe you have. Then see if you want to tackle the job yourself.
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Old 07-20-04, 06:01 PM
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Stainless steel nuts and bolts should be fine. Stainless steal in itself is resistant to melting up to around or if not more than 2500F. I used stainless steal w/ anti-seize, from the local hardware store and have had no problems with removing or installing said" nut or bolt" or bolt expanding and getting stuck, its just a myth about the bolt expanding or getting stuck or whatever, haven't actually heard it happen.
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Old 07-20-04, 06:43 PM
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Something to consider is the stock studs are very small. I got a replacement stud from Mazdaformance a while back which was a generic replacement from Mazda (started with 9 insted of N) and it was 1/4" longer. The studs I had which I thought were original were also longer and is what gave me fitment problems with my HKS DP. The nuts also are crushed, so they bite on to the stud and keep from backing out.
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Old 07-20-04, 07:08 PM
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ok, I have no idea which manufacturer the pipe is. You bring up a great point about it not being able to fit though, as I have my obvious doubts. and lopedl, the studs that I have use a 10 mm nut with a 1.5 pitched thread. Is this the proper sizing? Does anyone know what size and thread pitch I should get, granted I try to just use a regular bolt instead of a stud and nut? I really dont trust the copper nuts, although they do have the crush or cross thread near the top, I just worry about them melting or fusing to the stud eventually later. I am not sure that the studs that I have now are going to be the right pitch, and am worried that they won't go in. So is a bolt better, or is a stud/nut combo better... *sigh*.

Another thing is that I have stripped out bolts on the cat. I was trying to think of some way to have them tapped out/drilled out and using a bolt and nut to hold things together instead of having a stud threaded into the cat. Is there a method to getting these suckers out? Since I'm gonna be down there, I might as well try to get everything in the exhaust system fixed up. The ground on the exhaust system is also gone, and I don't know where it grounds to. Should I make a new cable and hook it up? I have some beefy copper wiring and fittings, just don't know how long to make the cable and whether or not its even worth it.

I'm really torn as to whether or not I'd take it to a local speed shop here, or try this myself. I know I'm going to run into problems if I try this on my own, and I'd almost rather save myself the headache.

again, thx, I really hope this DP will fit.
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Old 07-20-04, 07:26 PM
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I can't recall the downpipe bolt thread size, but this is how I installed my downpipe. On the top left I used a stainless steel nut didn't bother to take the stud out because it was in there pretty good. The other three studs were removed and replaced with 3 stainless bolts everything anti-seized. On the bottom right the bolt is about an inch smaller because the depth is smaller than the other two. I have had no problems with removing the nut, as I had to do this about 3 times, and reused the bolts no problem. You have several options. Using nuts is the best its easier to get a socket on there, and you won't have to worry about it. One of the easiest probably being getting a bolt that has an allen wrench heads. Or use stainless steel bolts harder to get sockets on but works none the less. Stainless steel is the best to work with because it doesn't strip as easy as copper.

For the cat just drill the suckers out and use a tap and die, or just use a bolt and nut that will fit in the new hole.
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Old 07-20-04, 09:24 PM
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Originally Posted by Stevey629
I have some hardware that came with my downpipe, and Im worried that they're not gonna hold, or eventually they will just seize. I have 4 studs, and 4 COPPER nuts that have a cross thread near the top to keep it from coming off. Should I go somewhere and get a different type of screw instead? I don't know whats best to use, I know I need to get at least a grade 8 stainless bolt of some sort, but is the threading different? is using an allenhead bolt better? Ive been reading that many people are using allen head bolts, or allen bolts whatever the difference is I'm not sure. And how do the stock studs come out? Do you use tighten two bolts onto the stud, then try to remove the lower one so the stock stud can twist out?
- Copper or bronze nuts are no good. You want class 10.9 or 12.9 hardware (grade 8 isn't metric), M10x1.5 x 20mm long. Alloy steel is probably better than stainless steel since it's harder and is still very corrosion resistant. Socket head (allen head) worked fine for me, but I had to get an allen head socket to use with my ratcheting wrench. In fact, I got two and cut one shorter since the socket wrench assembly was too tall to fit in easily. I think a standard hex head cap screw and a lockwasher is probably best since you can use your regular 6-point sockets. Offhand, www.mcmaster.com item 91310A623 and 91190A560 look about right.

- The stock studs should come out with the nut attached since the nuts are staked on real good and tend to stay locked on. If the stud stays in there isn't much room to get the pipe over it.

- Putting in the new ones, USE A TORQUE WRENCH and put anti-seize on the threads. These bolts are of the right size to tempt you into overtorquing and shearing off the heads.

Dave

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Old 07-22-04, 04:12 AM
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OK, its in! Sounds amazing, turbo spool is very audible now. However, there is one problem. One of the studs broke as the nut was getting tightened down on it. Is it best to get the stock studs from mazda? or should I just get a bolt with a hex head on it thats M10x1.5x20mm? Thx for the suggestions, they're just what I needed.
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Old 07-22-04, 06:33 AM
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Since you've got the stock stud/nut in 3 of 4 locations, I say get another stock one.

Lopedl, not all steels are created equal. If you buy just stainless hardware it does not guarantee the strength required for the job - in fact it's hard to find stores that stock 10.9 and 12.9 steel. McMaster-Carr or a place like Bolt Depot are the way to go. Add in the fact that most people don't use a torque wrench and that means overtorquing, and you can expect regular stainless hardware will yield. The tricky thing is that cheap hardware won't break - it will stretch - and you'll end up with an exhaust leak. Once yielded, they look ok but they may as well be made of rubber.

Dave
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Old 07-22-04, 06:35 PM
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actually I have no stock studs in anymore. I pulled all of them out, and used the "new" shitty ones. And the stock ones from mazda are going to be alright correct? Im about to put an order in for 4 new ones.
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Old 07-22-04, 08:59 PM
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If you're going into the CAST IRON exhaust manifold or turbo manifold you don't want to use SS. The difference in values for the coefficient of thermal expansion can cause cracking of the manifolds since the SS screw expands more than the cast iron threads. You're better off using a plain steel (closer too cast iron) and some good anti-sieze.
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