Roadstersport midpipe installation

[hsiungfucius]

Does anyone have instructions for installation of the Roadstersport midpipe (not the racing one)? I just ordered it (along with the exhaust), but want to make sure it's something I can handle in my garage.

Thanks!

[slartibartfast]

Two bolts at the muffler, two studs at the header and wriggle it out of the hangers. That's it regarding removal of the OE pipe.

The Goodwin mid-pipe is two-piece and I believe I installed the front portion first. Whichever half has the hanger hooks is the one you want to install first. Don't tighten anything until both pieces are in place. An easy one-person job. Don't forget to slide the U-clamp onto a pipe BEFORE connecting the two halves!

[Brian]

Excellent summation above. Will belabor the points with lots more wordiness below....


Much the same easy install as the muffler. Note that install of our NC and NB midpipes is much the same...the only distinction being at the header connection point. Both NB and NC connection points from the header dump tube are TWO BOLT flanges....but the NC has sprung connectors as shown in additional posts below.

1. Unbolt braces blocking your access to the midpipe.
2. Unbolt the flange at both ends of factory midpipe (two bolts each).
3. Lower and remove factory midpipe.

4. Notice that replacement midpipe has a slip joint in the middle. The only mistake that folks sometimes make is that they shove the slip joint all the way together. Instead of doing that, realize that the slip joint is there as your friend so you can adjust length as you need it to match the flange of the stock header, aftermarket headers, and any muffler on the back end. The slip joint also allows you to adjust height that the midpipe hangs at. Make it short to raise the midpipe. Make it longer to lower the midpipe. And move it right or left by twisting at the slip joint. With these thoughts in mind, lube up the joint with dish soap and connect two halfs of the midpipe but keep the clamp in the middle just barely snug for now. Match the new midpipe to the rough length and orientation of the factory midpipe that you already removed by laying them side by side on the garage floor.

5. Now raise the new midpipe into the car, bolt the front half to the header exit, connect the single midpipe hanger, and thread the bolts for the rear flange connecting midpipe to muffler (open and slide the slip joint as needed to make this happen).

6. Now look at how it hangs. Adjust the slip flange so that the midpipe hangs where you want it. To tighten your bolts start at the front flange which connects to the header and get the flanges all nicely lined up evenly and then bolt those down first. Then head back and adjust slip joint until you get the flange that connects to the muffler nicely lined up and flat and bolt that flange down. Torque to about 25 foot pounds (if you don't have a torque wrench the Harbor Freight $15 torque wrench works really well for the price).

7. Lastly, torque the clamp that holds the slip joint and reinstall braces that you pulled for access. Slip joint bolt just 10 to 15 foot pounds and the same for the relatively small brace bolts.

[hsiungfucius]

Thanks for the detailed instructions, guys. I'm looking forward to getting the midpipe and the exhaust in the mail soon. Now if I can only work up enough courage to do the header myself...

[mx-5-06]

[if you don't have a torque wrench the Harbor Freight $15 torque wrench works really well for the price]

Do you sell the torque wrench Brian?

[Brian]

[if you don't have a torque wrench the Harbor Freight $15 torque wrench works really well for the price]

Do you sell the torque wrench Brian?

We don't. But I do have a few of these cheap harbor freight choices. These are the torque wrenches I take to track events. They are reasonably repeatable, take some abuse, and when they get loaned out and don't make it back it is no big deal.

[slartibartfast]

Dang, forgot about the [flimsy] X-brace. I didn't occur to me to pre-assemble the pipe first. It weren't nuthin' to do it my way, but then I'm no stranger to the dirty side of a car. Wait, that would be the top of my car at the moment!

[Brian]

Dang, forgot about the [flimsy] X-brace. I didn't occur to me to pre-assemble the pipe first. It weren't nuthin' to do it my way, but then I'm no stranger to the dirty side of a car. Wait, that would be the top of my car at the moment!

I had not thought of doing it that way (leaving X brace in place and threading front of midpipe up first, and then assembling the midpipe on the car). I agree that saves some steps of my method (removing the X brace).

[slartibartfast]

Oh, I did remove the X-brace, I didn't pre-assemble the pipe. Seems there's always more than one way to skin the proverbial cat.

[hsiungfucius]

Is there a trick to removing the bolts connecting the midpipe to the header? At first, I thought mine were just stuck on really tight because I could not remove it despite letting the WD-40 soak in overnight. I even tried using a breaker bar, but felt that I would be bending the bolt rather than turning it if I applied much more force.

Is this a regular bolt (i.e., counterclockwise to loosen)? I am trying to unscrew it from the rearward facing side...should I be loosening it from the header side?

Or, do I just have a really stubborn bolt that'll require an air gun?

Thanks.

[slartibartfast]

If you're looking at the header side of the flange, you're NOT looking at nuts, you're looking studs. The nuts are permanently attached and the studs comes out with the nuts. The nut is both to provide a wrenching surface and to trap a tensioning spring.

That's to what I was alluding earlier in this thread. It caught me by suprise, too.

[hsiungfucius]

Thanks.

So just to be sure, the part on which I should be applying the torque is on the side of the flange facing AWAY from the header (toward the rear)? It's a spring bolt, right?

[slartibartfast]

I'm going to say no. I want to say either the mid-pipe flange is threaded or has a nut welded to it. I removed the nut/stud combo from the header side.

This is where Brian steps in and corrects me. I did my install several months ago and some details are fading.

[Brian]

The NC header flange is threaded. The midpipe flange is not. It feels a little strange when unscrewing because it is a sprung connection (two springs are in there to keep constant tension...yet actually allow the header outlet to move a little like a ball in the socket of the midpipe receiving piece. Very cool bit of design. Anyway, those springs make removing the nuts feel odd...feels like you are not making progress even when you are. Whole assembly looks like this:




Also, it can be tough to get the nuts off the stud....very common the entire part unscrews from the header flange as you see above. You can soak them real good and use an impact gun (harbor freight sells cheap impact guns that run off your battery as emergency tire changing items for about $20). Anyway, common that the entire nut and stud will come out of the header flange rather than just the nut. If the nut is stuck to the stud as you see in this shot....then you likely will not get it back in. In that case, take these to local autoparts store and replace with simple bolt of same length and use that with the spring.

[Brian]

ABOVE install is for the NC generation Miata.....but the NB generation RoadsterSport Midpipe is much the same. The NB version does NOT have the unusual header connection studs with springs. Instead, the NB version has a standard TWO BOLT flange. Customers regularly call and say we sent the wrong pipe because their car has THREE BOLT flange at header exit. That's NOT where the NB midpipe bolts. Look for the TWO BOLT flange connection point. The other tips here regarding length and using the slip joint are the same.

Note we locate the O2 sensor AFTER the converter instead of IN the converter. Why? Because with a highflow converter there is a good chance of a code if you leave the sensor between the two internal "biscuits" of the higher flowing unit. Thus, we locate the sensor connection a few inches BEHIND the converter to best avoid codes. Yes, the wires will reach (pinch the boot where it meets the body if you need to pull a little more wire as needed).