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Joe

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dnalot sounds like a very clever fella. I would suggest that you don't dickle around and get an oxy acetylene unit ( rental, stolen ) leave your bolts loose and start heating as long a section as possible and work it up to where 4 to 6 inches is cherry and then snug your bolts up. Let it cool but remove the bolts before the pipe cools all the way and then replace them. Brass nuts are a good idea on exhaust if you can find them.
If this doesn't work I could whip you up a couple of taper shims but I think dnalots idea is better on several levels.
 

Steamchick

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Hi Rag n Anorak.
Safety First: Just be sure you do not "Torch" the whole car when doing that! Remember there are brake pipes and fuel lines underfloor. Brake fluid is responsible for starting more fires than fuel due to its low flash-point. (Typically in crashes where a broken brake or clutch or power-steering hydraulic pipe fails and slashes fluid onto the hot exhaust. It will flash into a conflagration at a much lower temperature than fuel).
A "Quick" - almost momentary flash with a Mapp-gas torch could cause a fluid vapour explosion in the pipe. (Like a steam bubble, but with hydrocarbon vapour). If the pressure finds a weak spot, fluid may burst out and the vapour explode in a ball of very nasty flame. Not good if you are under the car. Good practice to have a competent companion with a fire extinguisher to hand while you are working under the car with a torch... and proper flame protection around the zone so you cannot cook the wrong thing. (sheet steel - tin cans are OK - or aluminium - beer cans (after enjoying the beer!) - with insulation behind it).
The job - second:
Even if you can only create a dull red hot spot on the stainless exhaust tube, worked around with the flame, that should permit the stresses to relieve and allow the flanges to align together. Then you just have to fit the proper gasket when "straight enough".
Take care.
K2
 

packrat

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You could get your steel supply house to cut you slice of round stock at a angle and then use your grinder to make the final fit,
then drill the holes, or weld two 1/4 inch plates in a off set sandwich and use grinder to make the angle you need..
 
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stevehuckss396

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There is an episode of "engine masters" where they progressively crushed exhaust tube and then dyno tested. There were tubes that were 80 percent closed and still didn't see any notable loss in hp and tq. Moral of the short story is go have those tubes bent into alignment unless you like replacing exhaust gaskets. Trust me when I say, you want that to be the least of your problems.

I'm not just blowing internet smoke
 

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Steamchick

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Hi Ragnarok (sorry I mis-interpreted your handle in an earlier post).
Stever Hucks says it all. Get the "wrong" part corrected.
Incidentally, how did the parts become mis-aligned? - Is one a new part and not correct? Or were they off the car and one got bent? - Or something?
K2
 

ragnarok

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I was thinking about some sort of extra shielding, for safety's sake. So i will do that, I appreciate the advice. I will ask a friend if I can borrow his oxy-acetylene setup, otherwise I will go get a 2nd MAPP gas torch and have at it that way.

If this doesn't work I could whip you up a couple of taper shims but I think dnalots idea is better on several levels.
Thanks for your offer, Joe. If this doesn't work I will ask you about it.

These parts are misaligned because the headers are cheapo Chinese stainless headers off e.B.a.y, and for ~$100 their construction and build quality seems pretty good in every way except this one. The flanges line up fine in other ways (the bolt holes are clocked at the correct angle, for example). It seems to me that this heat treatment solution will work better on the factory side of the exhaust, and considering the small angle that needs to be corrected, I'm ok with that.
 

Drawfiler

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I Hope you are happy with using heat under the vehicle because of the fire risk. I can make you the spacer you need in the material of your choice, if the bolts are the made from the same stuff they will expand the same as the spacer so maintaining tension.
dont over complicate things.
peter
 

kulk_sd

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I am looking for jobwork. Located in India, pin code 416410.
Have CNC turning and Ruhls milling machine. Have experiance with electronics and other stuff.
Please mail to [email protected]
 

terryd

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I have no idea if this would be the proper forum for my request, but here goes. I have an odd problem with my sports car; the aftermarket and factory exhaust flanges don't line up quite correctly. They are not parallel to each other. The bolts and pipe line up fine, but the gap between the flanges is wedge shaped. So what I want is an exhaust gasket made with the wedge shape built in. (I figure this solves the issue without removing anything from the car.)

I have attached a quick schematic of the dimensions of the gasket. I don't care what material is used, as long as it can stand up to the heat of a non-turbo exhaust header and the environment of the underside of a car. IF more dimensions are needed, I assume someone will let me know.

The "wedge" part: The tricky part is building the wedge shape into the gasket. In the drawing, Edge A needs to be 1/16", and then thicken in a direction perpendicular to that edge, across the part to Edge B, which needs to be 1/8".

I am willing to pay whatever for your time and material, of course.

Edit: I need two of these. Dual exhaust, both flanges have this issue.


View attachment 136140
Hi,
Not a difficult part to make. I could make a couple but am on the wrong side of the big waters of the Atlantic. I think that a better name for your part is a 'tapered spacer'. The use of the term wedge bring up all sorts of images.

I can see several quite straightforward ways of making them using a lathe or a milling machine (I don't like to use the verb 'mill' to describe the machine - give it it's proper name). I would prepare oversize rectangular blanks (76mm wide) with plenty of excess for clamping, bolting down etc which can be tapered and the final form created from the blank after tapering.

If aluminium they could also be made quite simply by forming a suitably tapered blank on a belt linisher then cutting and shaping the outlines with hand tools.

as for thermal expansion the effect would be negligible the combined expansion of the two flanges plus the aluminium spacer would be compensated for by the expansion of the (mild) steel bolts which are already stressed during the tightening process and any minor stressesinduced by heating certainly would not be anywhere close to the uts of the bolts.

TerryD
 
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terryd

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That's an interesting thought. I would be afraid the tube would fold/tear in ways I don't want it to. Have you done something like this before? Would a MAPP gas torch be sufficient for that?
I doubt that heating with mapp gas would provide sufficient heat/temperature to allow stainless steel tube to deform even that relatively small amount - It may work but I think that you are better off with your spacer idea, especially if you are working on the vehicle and possibly in a restricted space. Is it worth the risk of a fire?

TerryD
 

ragnarok

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a friend of mine had an oxy-acetylene torch, but arranging a time to get the Z3 over there is becoming an issue. for me, the easiest solution is having these tapered shims made so i can just slide under, bolt them in, and be done. the other plus is that it leaves the factory parts completely stock. Hm.
 

Joe

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I can do these out of steel for you. My one question is, in the drawing in your first post you show side a and b and a 1/16" difference in thickness. Can you confirm the angle of the taper is parallel to these sides as opposed to the line of the mounting holes ? Oh yeh, is the taper all on one side OK, or would 1/2 on each side be better ? Might be easier with direct email, mine is jorogi( dot ) shaw ( at ) gmail ( dot ) com I'm sure you can figure out my cunning bot spoofing code there.
John
 

geo

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This article is nonsense can’t understand why the moderators haven’t shut it down
 
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