Wanted I need a part made...

[Joe]

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.

 

[SmithDoor]

Hmm. I may pick up a 2nd torch and try that out.

A photo problem would helpful at this point. It sounds something else is going on.

Dave

 

[Steamchick]

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]

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..

 

[stevehuckss396]

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

 

[Steamchick]

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]

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]

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]

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]

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

 

[terryd]

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]

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]

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]

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

 

[Joe]

Sorry to hear you find this thread to be " nonsense ". I would just suggest that there are a few members whom have taken the time to constructively comment and whilst the " project " in this case is at 100% scale it is still both engine and machining in nature. Myself, I get the update email each day and I read perhaps two of the threads, sometimes more and sometimes less. I don't see the content that doesn't interest me as anything bad or inappropriate, it is simply of interest to others and I find it easier to moderate it myself and not click on it than expect someone else to remove it for everyone. If all the posts were such as to perfectly please one individual then I would suggest the site would be very boring and narrow and the experience of saying to oneself " huh, that's interesting " would be a rare occurrence.
John

 

[terryd]

Sorry to hear you find this thread to be " nonsense ". I would just suggest that there are a few members whom have taken the time to constructively comment and whilst the " project " in this case is at 100% scale it is still both engine and machining in nature. Myself, I get the update email each day and I read perhaps two of the threads, sometimes more and sometimes less. I don't see the content that doesn't interest me as anything bad or inappropriate, it is simply of interest to others and I find it easier to moderate it myself and not click on it than expect someone else to remove it for everyone. If all the posts were such as to perfectly please one individual then I would suggest the site would be very boring and narrow and the experience of saying to oneself " huh, that's interesting " would be a rare occurrence.
John

Hear Hear, I agree entirely after all we can have 12" to the foot models

 

[ragnarok]

Hear Hear, I agree entirely after all we can have 12" to the foot models

I had a specific moment in my early 20s when I realized I had over $1,000 in each of several RC cars (my favorite hobby), and for that kind of money I could be working on a full size machine I could ride in myself...so I gritted my teeth and made the transition. Fast forward 25 years or so and here I am on HMEM. It's all just a matter of scale.

I will admit, however, that I didn't intend for this to become such an involved discussion on the proper solution to my issue, in the For Sale/Wanted forum...I half expect a mod to put it in a more appropriate place at any moment...

Still have a few RC cars, though...

 

[william_b_noble]

1. do NOT use aluminum, please don't do that
2. okay to heat red hot, if you are running the engine hard they will get that hot anyway
3. usually there is some flex in the exhaust, it may mate up just fine once you tighten it.
4. remember to allow for expansion and contraction -that's why the holes where the manifold bolts to the studs in the cylinder head are enlongated. if you don't allow for expansion the thing will rip itself apart.

 

[Steamchick]

Hi Bill, considering that aluminium cylinder heads do not melt, I suggest that aluminium for these tapered spacers would probably be OK, as long as a large surface contact with the cylinder head exists. BUT (Having melted pistons when the cylinder head wasn't melted) it is a balance between engine performance, heat flow, customer use of the engine, etc. What works for drag racing, doesn't necessarily work for 200 mile races, or going to the shops!
(Aside - the un-interesting anecdote! - please ignore if you wish.)
- I had a 350LC race tuned Yamaha that repeatedly blew a piston when idly cruising in traffic just between 55 and 56 mph on the clock. This proves that exhaust gases are hot enough to melt aluminium. But adequate cooling (as per the cylinder head on your car) can prevent this. I cured my problem with a de-compression plate... (for road octane fuel), but suspected it was due to a resonance with the exhaust cans that partially blocked the exhaust with a shock wave, thus heating the exhaust port (and piston) to overheat the piston at the port. You could hear a change of note (loudness) just at that point in the revs. In any other gear it was OK at that speed. So maybe it could happen again? - I sold the bike to someone who wanted to race it! -

(Back to main plot) - Steel is a better option than aluminium.

Cheers!
K2

 

[william_b_noble]

I'm not going to argue, it's not my car. I have seen the manifolds on one of my cars turn bright orange. if there had been aluminum in that area it most assuredly would have melted. I would not put aluminum in the exhaust headers. The reason the head doesn't melt is that it is water cooled, the manifolds a few inches from the head are much much hotter becasue the combustion products keep burning. orange hot headers 1 orange hot headers 2 waaay hot headers 3