What size are the threads on my DP screws?
 

My boys stripped them trying to install a Gotham DP. What size are these screws so I can find them at Home Depo or OSH? I'm thinking of getting threaded studs and just getting bolts to make this job easier. The Gotham DP didn't really like the stock screws. Help me out please!

Justin

I have the perfect set of screws for the job just send me a email and they are on the way!!!

They are M10x1.5mm. I wouldn't use anything but the stock mazda hardware - or at least a class 10.9 bolt. Unfortunately, bolts have much bigger heads than the mazda nuts, so they are a bear to work with. Socket head cap screws are a good fit for head size, but I had to cut down a 3/8" socket allen drive to tighten them.

Dave

M10x1.5 I could get some allen head, 20 or 25 mm long, grade 12.8 from work and mail them to you if you pay shipping (about $4 Priority Mail)

No need to cut down anything. You just need the right bolt with the right head at the right length;)

Maybe I wasn't clear. The holes on a 3" downpipe flange are nearly against the weld.

If you put a 17mm headed bolt in, you won't have any room for even a socket to fit over. It becomes a bear and impossible to torque correctly. Only socket head cap screws and Mazda stud+nut (which is 14mm btw) have a chance of fitting consistently.

And I agree, 25mm is the right length for the bolt.

Dave

I used allen head cap screws and had insufficient clearance to use a conventional allen head socket wrench on one of the screws (same as dgeesaman). Rather than cut or grind down the allen socket wrench, I bought a ball-head allen socket wrench. With the slight offset angle it allowed, I was able to still get my torque wrench in there to get the screw to spec torque. The ball-head allen socket wrench was a special order item at an auto supply store and cost about $15, but did the job.

Let us get this straight!

There are no SCREWS hold the DP to anything. The corrrect fastener terms are
"studs", "bolts", and "nuts".


The next thing you-all will be doing is renaming them with some getto/ricer terminology.

If you check a few hardware supply catalogues online, you will see what are called socket head cap SCREWS like those supplied to me by Pettit, to hold the downpipe instead of using the factory studs and nuts. :D

PM Sent! Thank you so much :)

Sorry? I'll make sure I call the screw a "bolt" next time. It was late and I was exhausted from working on the 7 when I posted and I knew the board members are smart enough to figure out exactly what I was talking about so I didn't bother proof reading my post.

Thanks for all the info. Sounds like you guys had a hard time with it at one point too :p:

Bolt vs. Screw - now THAT's getting anal retentive. For anyone who's following along, a bolt works with a nut, and a screw doesn't. Bolts have a specific untapered thread form that fits with a nut but screws can be anything. Of course, industry got smart and made a whole bunch of screws that match bolt thread specs (improves interchangability), and ever since engineers are lost and argue about it. It doesn't help that our major reference texts don't agree on this either, and that fastener suppliers stock both screws and bolts in identical sizes.

No need to bust my balls - they're practically the same in this case. If there is a significant difference between an M10x1.5 Hex Head Cap Screw and an M10x1.5 Hex Head Bolt, I'd like to know the difference. My suppliers interchange them.

(Or is it 'bust my nuts'?) :cool:

Dave

"bust my nuts and bolts" :D

Screw you guys! ;)

(it must be Friday...)

-Rob

Always someone fuccking things up does not make it correct. I expect more of these forums than most.

An install trick I learned makes it far easier. When installing the downpipe put the lower rear nut on first. Doing it first let's you pull the pipe away from the turbos as you run the nut down the stud. Once it's snug assemble the other 3. I use a wrench on the lower rear nut and a socket for the rest.

If you install a different nut first the downpipe ends up snug against the turbos and gives you much less room to get the nut on the lower rear started since the downpipe curves down so closely to the end of that stud.

how about the real names Hex Head Bolt and Hex Cap Screw

Not the fastener, but the socket. I remember cutting down an allen head socket too, those things are hard steel. My tool box is filling with "custom" FD tools

Oops, wouldn't want anyone mixing a Hex Head Cap Screw with a Hex Cap Screw. We'd all die!!

Dave

That was not focused on your comment but on the fact that there ARE screws that hold DP's not just bolts, nuts and studs. A Cap Screw is a screw not a bolt; hell hex, allen socket or whatever

It must have been a long week for all of use.

Anybody know the part #'s for studs bolts and gasket off hand, or better yet is quicker with the manual than me!

Nut: 9YB10-1001
Stud: 9YA10-1008

Dave

Damn you always have the numbers. A few of you guys really stand out on this forum!
Thanks

Brad

I just have a spreadsheet with part numbers and prices. Every time I call Ray I put them on the list.

I left out the cruel part: the nut was $4.00/ea and the stud was $5.25/ea.

Dave

this is for all the SCREW balls and NUT cases that never get any HEAD, contemplate all the head you may be missing: fillister head, button head, flat head, oval head, round head, truss head, binder head, pan head (save this one for all the knuckle heads), and finally for those less endowed pin head

this is all about getting head right. so if youre getting good head and it works, who cares about the rest just as long as it fits.
m10x1.5 socket head screw = m10x1.5 hex head bolt

pass this on to ten people or you may never get screwed or head again. after sending each one - say tap or die.

chuck

I hate to "screw" up this thread with a "nutty" response but Ray sold me Part #NF01-13-708a for the stud and #JE10-40-355 for the nut.
Does anyone know what the alloy is for these things, 'cause they're not something you could buy at Home Depot?
My guess is some kind of nickel alloy to deal with the heat.

I think they're inconel or monel.

Dave

Who's Ray and where can I find these? The nuts I keep finding at Home Depo and OSH are the same size as the heads on the bolts that fit. I really need nuts that are small enough to screw onto the stud without hitting the bend on the DP. Would this be my solution? I couldn't even find metric studs at Home Depo or OSH. My best shot so far is Allen head bolts.

Ray Crowe is the parts manager at Malloy Mazda. He gives club members a very good price on Mazda RX-7 parts. 888-533-3400. The only issue is he's in Virginia - you might have better luck with Mazdatrix (http://www.mazdatrix.com/e7.htm is the page with exhaust hardware) since they're on the west coast and shipping will be faster.

As for hardware at this joint - I've literally tried them all. Mazda hardware is clearly the best. 2nd best might be a class 10.9 or 12.9 socket head cap screw with a split lock washer or other small washer under the head. You might need to grind the weld of the downpipe a little bit to give enough flat space for the nut or screw head to clamp well. Naturally don't overdo it or you'll break thru and cause a leak, but it's stainless and it takes a little while to dig just 1mm like I did.

Dave

Wow it's almost 10 bucks a stud from MazdaTrix! Unreal.

Why would anybody use a low spec Home Depot bolt/screw/nut. All bolts on a car are HS alloy steel. Also ASTM and SAE nuts are a larger size for a given bolt than japanese JIC nuts. The Japanese car companies pushed for weight reduction, just as the US aviation consortium did, thus nuts are smaller but of higher strength material.

Rather than comprimise the weld in the DP, why not just use socket head bolt/screws at least for that one though position. then to keep tools the same use the same for all. Also why risk getting studs stuck/broken by using then again. Just my pennys worth of thoughts

Let's get this terminology straight once and for all. All words refering to screws, nuts, bolts and studs must be preceded by the word "fucking."

I think this thread is stripped.

Bringing This From The Dead.

If there is clearence issues, Why Not Go With a Low Head Socket Head Cap Screw

McMaster Car Part Number

93070A215