kosoku

I'm going to buy 4 allen bolts to install the dp. should I buy stainless steel bolts or grade 12.9 heat treated alloy steel bolts?
http://www.boltdepot.com/metric-socket-products.aspx

ManGaZeRo

iTrader: (1)

Go with the stainless 93silverbullet went with it along with me.

HobbeZ

why not go with the 10.9 grade hex bolts?

TT_Rex_7

I never thought about using allen bolts, but he's probably wanting to use them to make it easier to tighten/loosen the bolts. Alot easier fitting an allen wrench up there than a wrench/socket.

I would go with S.S. I thought I could get away using coated steel bolts, and went I went to remove all my turbo stuff, they was rusted all to hell and were a PITA to remove. I only had the stupid things on for maybe 2 months.

-Alex

HobbeZ

the only thing i'd worry about with allen bolts is to get the adiquate amount of torque.

TT_Rex_7

Take a 1-2 foot pipe and slide it over the allen wrench to get more leverage.

-Alex

dgeesaman

iTrader: (7)

Hex head bolts will arrive at 17mm head, or 16mm if you get JIS somehow. They'll be a tough fit.

Allen head bolts (socket head cap screw) will give more headroom, but I had to cut the allen head socket down to get my wrench into them. But they are available in 12.9, unlike the other options.

Any kind of black oxide, zinc coated, blue ultra coat alloy steel will corrode after a short time. Just use anti-seize, that's life.

Stainless does not come in the strength of 12.9 alloy steel.

Currently, I have Mazda OEM hardware - I don't think it's even steel - it looks like a Monel or Inconel. You won't get anything comparable except from Mazda at that price.

Dave

dgeesaman

iTrader: (7)

No, that will make it very easy to overtorque them. Once overtorqued, you'll either shear off the head or stretch the bolt. Once it's stretched, it will lose it's clamping ability.

TT_Rex_7

As long as your careful and don't apply all the force you possibly can it shouldn't be a problem.

As far as the factory studs, they're made from inconel.

-Alex

GQMRacerX7

You don't want SS. It will probably crack your cast iron manifold by the SS expanding more than cast iron. I also used steel cap screws from http://www.boltdepot.com/product.asp...&cm=23&cd=1325
I'd have to go home to get the correct length. Use a good anti-sieze and you should be fine as long as you don't overtorque them. I used a 3/8 In. Drive Metric Hex Bit Socket so I could use my torque wrench. I actually needed to buy an extra hex bit that I cut to a shorter length so I could get my torque wrench on one of them. One last thing you probably want to retorque them after a couple hours of driving since they have no locking function like the stock stud/nut combo.

ManGaZeRo

iTrader: (1)

What are the torque specs on the dp nuts.

dgeesaman

iTrader: (7)

That's not obvious to everyone. Many people instinctively tighten a bolt as much as they can.

I think it's supposed to be 25-40ft-lb or close to that. Look it up for yourself.

Stainless steel at 10mm diameter will expand .002" more than the cast iron hole. Given the clearances in the threads I don't think it's a problem at all. The reason I like alloy is because it's available in 10.9 or 12.9 which is much stronger than A2 or A4 stainless.

Dave

GQMRacerX7

You need a shop manual - www.iluvmyrx7.com

28-38 ft-lbs

a3dcadman

iTrader: (1)

I used stainless socket head bolts. If memory serves me, there are a couple of the holes your bolt will bottom out on if too long. I think the max length on the threaded portion was about 1.00". I used a modified long handled allen wrench with a cheater bar (steel tubing) to torque the bolts. To install and get them started, I removed the allen wrench portion of a 3/8" drive allen head socket and turned it with a flat rachet since there wasnt enough room for a standard rachet. With stainless its important to use hi heat anti-seize compound to prevent galling. Ran the car for a test drive and then retorqued the bolts. Havent had any problems with leaks at the downpipe. I have a leak somewhere else in that vicinity as yet undetermined. You might also want to check the shoulder of the bolt for a flush contact with the downpipe flange and if necessary grind any excess weld bead away to allow good contact. I lightly block sanded the faces and gasket of the mating surfaces and cleaned it with lacquer thinner to remove residue and oils. Use fine baling wire to hold the gasket in place while installing the bolts. Getting the bolts started was a major pain in the ***. Have fun and good luck.
chuck

93silverbullet

iTrader: (7)

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. After one year no problems at all!I agree with using a good anti-sieze compound.

Good Luck!

kosoku

So do I need lock washers AND flat washers?

93silverbullet

iTrader: (7)

That's what I used. No problems so far .

lopedl

iTrader: (1)

I have used stainless steel bolts and haven't had much problems with them yet, and have had them on and off several time. I also made sure to put anti-seize on the threads. The odd bolt is the bottom right the rest you can use the same length.

ManGaZeRo

iTrader: (1)

What did you have to to the bottom right bolt to make it fit?

a3dcadman

iTrader: (1)

I think I used all 1.00" long bolts - 25mm. Put the bolts in the holes prior to installing the down pipe to see how deep they go and how much of a gap there is when in all the way.

chuck

eyecandy

iTrader: (19)

I assume by using the bolts rather than the studs and nuts this allows you to remove the downpipe pains free, and no more removing the studs....

dgeesaman

iTrader: (7)

Well yes removing it is easier, but putting it back on is still annoying. With bolts you need to get it aligned with the gasket in the proper place and thread them in. That can still get on my nerves.

Dave

sevensheaven

iTrader: (1)

I have used both, I liked the bolts (allen head) better. However I went back to studs. The lock washwers are toast after all the heat and I'm not real sure they even were any use after that. When I removed my pipe the washers stayed flat as paper. I went back to the studs and nuts. They're a special metal and thats part of why they cost so much. As much as they are a pain in the &^#%, Mazda got that part right.

Terry7

dgeesaman

iTrader: (7)

Plus, the stock studs tend to behave like bolts. If you used anti-seize they will tend to come out with the nut. I too now have stock hardware installed.

spiffy9999

iTrader: (1)

I know this thread is rather old and dead...but what size allen wrench do these bolts take?