I realized that this is the wrong section, but I can't delete it now.. I bought an KHS downpipe. This is my first downpipe, so I figured it would probably be best to get new gaskets and nuts. I went to the dealer to get the cat nuts and gasket, and the turbo nuts, gasket, and studs. Dealer wanted almost $300 for this. Any suggestions on what I actually need, and where I can get it, before I take out the pre-cat?

Down Pipe I bought
http://www.rx7store.net/product_p/hksdpfd3s.htm

 

I have all of the hardware in stock

 

http://www.rx7.com/store/rx7/fdexhaust.html

 

Also at Mazdatrix or through Ray Crowe at Malloy (888-533-3400).

 

I would just use the old hardware and check the gasket out once you have it off. It's metal so you can reuse it if its not trashed.

 

^ how safe is re-using everything? and how would a metal gasket get trashed? just so much heat over time?

 

I don't like to re-use any of the studs or nuts. They tend to gall when removed. The next time you take it apart you can end up with a broken stud. You can look at the gasket face and see if there is any evidence of carbon making its way part the edges, but I would just replace it. The gasket is meant to be crushed down to make a seal. Once it is crushed, it won't seal as good again.

 

As usual Ihor hit all the important stuff.

The gaskets can be re-used but really only when you are bolting the exact same parts together again. In this case the downpipe is a new part and you should replace it. It's an expensive gasket but it's important.

The hardware is a sticking point - they are really expensive from Mazda ($10/ea stud or nut) but they are superior to anything else out there. I would caution against using hardware store hardware since it is not a high grade steel and will rust very fast if the heads even fit in the tight space there. ATP turbo sells similar hardware that's not bad. Just be sure to torque to spec and NO MORE.

Dave

 

Just reuse the stock hardware and gasket on the downpipe. The studs will probably backout with the nut, but that makes things easier. The gasket is metal and not worth replacing unless its blown out.

 

^ hmmm, thats completly opposite of what everyone just said. I was convinced i needed one...now im not sure again.

 

Well either the used gasket will leak or it won't. They don't go bad unless there is obvious damage, and it's up to you whether you'll accept going in and removing it again to change a gasket later.

 

i've reused (almost) everything many times:

1. from stock to ebay dp:
broke a stud while removing stock dp, reused all other studs, nuts and gasket and added an allen bolt for the tight bend.

2. from ebay to bonez dp:
reused everything

3. from bonez to hks:
reused everything

4. from hks to SMB 4"-3.5" monster:
new studs and nuts, reused the gasket.

I've never had it leak. Make sure you torque to spec and retorque after driving a few miles (~500). Generous use of high temp anti seize compound made my life real easy when I removed everything after the 1st time.

and why did I change so many times? i guess i was bored lol! I was never really satisfied until the smb.

 

comes a time when you just have to experiment on your own, not everyone has the same opinion on things...

 

We have probably installed 100 downpipes and always reuse the stock hardware.

 

not to change the subject, but what were you not satified with the other 3 DP's. Im about to buy one, and im still not sure which i want. The ebay one is frickin cheap, and comes with a "gasket". of course, im sure the quality is lower, but hey, if it works......

 

I am sure the "ebay" gasket will melt within 1,000mi of operation.

I would go with all new hardware and use hightemp antiseize on the threads. For the gasket I haven't heard any feedback yet on Pineapple Racing's graphite gaskets, anyone have a feedback?

 

the ebay one i bought didn't include a gasket, it was from ssautochrome. I had it Jethot2000 ceramic coated and installed it with minor hassle. Fitment was excellent.

the Bonez I bought because I got it for a good price and it included a 2nd o2 bung. I had it jethotted also and thermo wrapped as well. Fitment was better at the tight bend, i.e., easier to tighten the bolt.

the hks i bought just because i found a good deal and ive never seen one in person and was bored! lol

the smb i just decided to do it because i didn't like the crushed area in the hks and i plan to max out the twins so i need the least restriction possible! (smb has a 5" expansion chamber down to 4" pipe and then tapers to 3.5" before it mates to the 3.5" resonated high flow midpipe.) Plus it's a thing of beauty!

and again, i like working on the car and when i get bored i buy parts to change!

 

I am interested in this aswell.. I will be swapping out my existing DP for the M2 one I have that I welded a secondary bung on.

Couple things I would be interested in knowing... What torque does the piping need to be fastened to? Also, is there a trick or anything to get that 4th bolt (upper rear) off without breaking things? I'll be doing mine in a shop, on a lift, with a full array of tools and whatnot.

I dropped the request to order parts with Malloy earlier today, so will probably start the swap once the gasket and hardware comes in.