legendr35

Sup,

The four bolts that go from the exhaust manifold and the pre-cat are borken, so i was wondering which specific bolt sizes I need that I can either purchase from home depot or pep boys? Thanks! I heard mazda dealers charge a lot for the bolts

Dr Wankel

They probably do charge a lot but at least you will know it is the right one.

pweizman

They are metric studs. I cannot remember the size.

Just take one with you, and compare sizes. I believe Pep boys has them.

How did you break them? What did you break, the bolt, or did you strip the nut?

Patrick

legendr35

Thanks, the stud broke in half while trying to take it off...

Brad

The metric size is M10. The lengths actually will vary depending on the downpipe. Home Depot does not carry the right studs. Some Lowe's in my area carry metric studs, but it is a very limited selection. I would also recommend not buying them from a Lowe's/Depot/Ace or whatever. Try to go to a specialty fastener shop, so you can get the higher grade studs.

legendr35

Thanks, i'll give it a shot !

thatoneguy

You should never buy bolts, studs, etc. from a home improvement store. They grade of the products aren't suitable for using on an automobile. Especially out of an exhaust manifold.

MeLoN350

iTrader: (2)

Go to your local mom and pop hardware store, they usually have an isle with those little pull out bins that have all those bolts you can never find. They should have SS allen key bolts, just bring the DP in with you so you can see what length you need. The SS ones seem to come out the best for me the many times I have removed my DP, the original bolts that came with my DP were much harder to get out untill I switched to SS.

Nick

atpeak23

Stud sizes for the Exhaust Manifold? does anyone know? thanks

Brad

M12

atpeak23

ok...I picked up a 12m 1.25 and it won't go...
I see other ones at the Auto PArts store that are 1.50 Isn't is a certain type of 12M? thanks for your help

Brad

Oh yeah, forgot about the thread size. It's M12 x 1.5. Also, make sure they are grade 8.

Flybye

Being SS is VERY important...

the_saint

I can only get M10 x 1.5 bolts to fit.

The M12 are too large.

thesaint

RonKMiller

Bite the bullet and go with OEM. The flange on the bottom of the nut is designed to distribute torque properly. Put some high temp anti-sieze on the studs and use a good quality torque wrench. Tighten them down gradually and in a criss cross pattern.

911GT2

I agree, but if you really want bolts instead, find a True Value hardware store. They have a room the size of my house dedicated to nuts and bolts. Bring one and compare sizes, and def. get SS.

dgeesaman

iTrader: (7)

I've got some replacement studs that came with my Pettit DP, as well as a few of the used stock studs (52k on them). I'm using some 316 SS M10 Socket Head Cap Screws on mine. Measure the studs you've got to figure out how long the thread needs to be. Don't waste your time (and risk your equipment) with fasteners from anywhere other than an automotive supply. It has to be the right kind of stainless steel or else it will corrode under the heat + elements on that exhaust manifold.

Anyone interested I can send/sell for a few bucks. You'll be sure to get the right stuff.

Dave

Dave

apneablue

I dunno, but I wouldn't use a home depot stud to hold my DP in place...Go with the mazda part, it's safer that way considering that's one of the hottest parts...these things are such a bitch to get off when they break in there it's better to just be safe than sorry...afterall, we are talking about probably $6-8 for each stud from mazda...when you are talking FD, in the grand scheme of things, that's nothing.

spurvo

Absolutely. BUT: I would go for the slightly shorter studs that are used to attach the turbos to the exhaust manifold. Makes getting the DP on a piece of cake. They are part number NF01-13-708A, and were in the $4.00 range from Malloy.

vudoodoodoo

Those ******* are expensive from the dealer. I broke 2 I think.
Use anti-seize.

James Paventi

iTrader: (34)

I've got to agree ... get the studs from www.mazdaformance.com.

potatochobit

iTrader: (1)

dont go oem. there is an aftermarket set available. they are pricey 20$ but they are half the size nuts and are way easy to get on and off. cuts the bolting time in half.

RonKMiller

I've owned my FD3S for over 10 years, and I just have to say that almost EVERY time I've gone with an aftermarket part I wish I stayed with stock.

Just what exactly is a "half the size nut"? ....and why does this make it easier to get on/off?

If it is "half the size" you are compromising clamping strength.....and focusing torque on a MUCH smaller surface area - that's why God invented flanges.

I'm always willing to learn new stuff but I think you are pissin' in the chilies on this one.

spurvo

He's probably talking about the type of nuts Pettit sends with their DP's. They have the M10x1.5 threading, but are only a 13 mm outer size, and very thin-walled. When I pulled my DP for the engine repop, I noticed these thin nuts weren't holding the DP very well, so I went with flange nuts on the upper studs, and regular 10Mx1.5 nuts on the bottom with a lock washer for mating to the surface that is too crowded on the lower flange locations. Seals much better than what I was leaking with before (leaking nuts? TOO CLOSE!!)

RonKMiller

Lock washers will dramatically distort the torque settings........not to mention they will fracture over time from expansion/contraction. But WTF do I know...

The ONLY way to get constant clamping pressure across the manifold is to use the same size fasteners at all four points and install them as I described. Not to mention NOBODY pops for the $46.00 metal gasket that is required when re-installing.

I've said it hundreds of times: metal gaskets are one time use ONLY.

Otherwise, you have (and are) an exhaust leak!