CGLockRacer GRM+ Memberand Reader
8/13/11 6:19 p.m.

So I finally got around to installing my FM butterfly brace today. As said on their website, it does not really fit with the stock downpipe of a 1.6L Miata without modification. My downpipe heat shield was rusted and rattling anyway, so I removed that. The butterfly brace now fits...with about 1/16" clearance to the downpipe. Any turns or bumps and it bangs on the brace. I knew it was a risk, but the car feels great now! It's like I put the hardtop on.

Anyway, onto my question. I need to move the downpipe over about a half inch. There is enough room around the rest of the exhaust system that I can do this. However, I really don't want to remove the downpipe (one of the mounting studs is already stripped). Can I heat up a 360 deg. section of the pipe to red hot, and then ice one side to bend it? Repeat until desired clearance is achieved. Next question is can I do this with a map gas torch?

I have header wrap to replace the removed heat shield once I get the fit how I want it.


motomoron HalfDork
8/13/11 6:36 p.m.

Raceland header?

CGLockRacer GRM+ Memberand Reader
8/13/11 6:45 p.m.

In reply to motomoron: I'm avoiding a header at the moment. I'm too cheap. And not enough gain for the $$. I'm trying to do this the GRM way. Make what I have work.

mad_machine GRM+ Memberand SuperDork
8/13/11 7:13 p.m.

I have seen headers get redhot without deforming... just saying

Chas_H New Reader
8/13/11 7:45 p.m.

Put a dimple in the pipe for added clearance. You're not gonna bend it.

Keith GRM+ Memberand SuperDork
8/13/11 8:31 p.m.

You can, actually. Never tried this with the downpipe on the car, but if you heat one side of the pipe, using a diamond shaped pattern, it'll pull to that side when it cools.

On your car, you can either remove the downpipe from the manifold or the manifold from the head. If it's stripped at the bottom end, take the cat off with the downpipe.

CGLockRacer GRM+ Memberand Reader
8/13/11 8:59 p.m.

The stripped stud is at the manifold to downpipe. The cat is 20 years rusted to the downpipe also. I don't want to remove anything since I don't have gaskets, hence the question if I can do this on the car. I figure I'll heat the pipe, use some leverage and wood blocks to hold position and apply pressure while it cools. I'm going to give this a shot tomorrow and report back.

CGLockRacer GRM+ Memberand Reader
8/14/11 12:57 p.m.

OK, I ended up having to do it the hard way. I didn't try heat at all after looking closer at the problem, it wouldn't have worked in this case; plus I didn't want anything inside the car melting. So I ended up doing a small pie cut in one area and a through cut in another to move the downpipe over. Then when welding it up, i realized I couldn't get all the way around it. Arrgghh... Out comes the butterfly brace (not too hard actually), off comes the down pipe, clean up the welds and reweld a few areas. Put it back on the car, only to find out that it didn't quite line up as it did previously, but still had clearance all the way around. Phew. No more rattles and cheaper than a header.

mad_machine GRM+ Memberand SuperDork
8/14/11 3:29 p.m.

time to save up for the header?

CGLockRacer GRM+ Memberand Reader
8/14/11 3:39 p.m.

In reply to mad_machine:

or some other power booster :) one reason I didn't want a header if I'd be replacing it eventually.

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