Exhaust pipes material

  • Thread starter Thread starter Erivaj
  • Start date Start date
E

Erivaj

Guest
Hi,

I have the original (even It is possible to read the Laverda part number) 3 exhaust pipes of my Jota 1980 in not nice conditions. It looks rough and rusty, and I am thinking in polish (stainless steel) or paint (steel chromed) them.

Which one is the material of these pipes ... Stainless steel, steel chromed?

Regards
 
Erivaj

Having numbers stamped is no guarantee that they are factory originals, several of the replica manufacturers quite openly stamp their exhausts with Laverda part numbers.  Is Pierro going to sue them? I don't think so.
But you can find out easily with a simple test, using a magnet. Put the magnet on the pipe. If it sticks, it's chromed steel, if it doesn't, it's stainless steel. You might have a system with stainless headers, but the collector could be mild steel, and the mufflers could also be mild steel or stainless. The magnet will tell you.

Ken
 
Hi Ken

a magnet does stick to 400 series stainless steel, which is what my ZX 14 header is made of.....

Hi Erivaj

if the header pies are original, they are chromed steel

if the header pipes are not original, but are rusty, then they are steel.

if the header pipes have turned sort of yellow, they are stainless, and should polish up well.

whatever they are made of, if you don't want to buy new header pipes, wrap them in exhaust heat tape.....  http://www.thermotec.com/  problem solved!

Paul LeClair
 
Magnetism is a fascinating area of metallurgy.

It's only the austenitic stainless steels (3XX series) that are non-magnetic. All other grades of stainless (like the 400 of Paul's headers) are strongly magnetic.

The interesting thing about the non-magnetic grades is that they become magnetic with work-hardening (which changes the austenite to martensite). So if you have a 304 or 316 stainless exhaust system that has become responsive to a magnet, chances are it's well into the work-hardening process and not far off developing cracks.

If that's not enough boring trivia, here's some more: It's not the chromium content of stainless steel that changes its magnetic properties, it's the nickel. A high nickel content is what makes the crystal structure austenitic. Paradoxically, nickel is a ferromagnetic metal like iron (chromium is non-magnetic), but when iron and nickel are alloyed together they become non-magnetic.

Cheers,
Cam
 
Javi,
I have had chromed and stainless systems on my triples over the years.Stainless is much less trouble as it does not rust, but it does tarnish to a dull yellow/brown colour and can suffer dark spots as well. These can be removed by a good polish with a polishing wheel on a drill.
Chrome looks better, in my view, but needs more attention to keep looking smart for a long time. Plus the bends at exits from the head can turn blue if it is running lean.

I usually go with a stainless system, but with chromed steel downpipes to try to get the best of both worlds.
 
Dellortoman said:
Magnetism is a fascinating area of metallurgy.

It's only the austenitic stainless steels (3XX series) that are non-magnetic. All other grades of stainless (like the 400 of Paul's headers) are strongly magnetic.

The interesting thing about the non-magnetic grades is that they become magnetic with work-hardening (which changes the austenite to martensite). So if you have a 304 or 316 stainless exhaust system that has become responsive to a magnet, chances are it's well into the work-hardening process and not far off developing cracks.

If that's not enough boring trivia, here's some more: It's not the chromium content of stainless steel that changes its magnetic properties, it's the nickel. A high nickel content is what makes the crystal structure austenitic. Paradoxically, nickel is a ferromagnetic metal like iron (chromium is non-magnetic), but when iron and nickel are alloyed together they become non-magnetic.

Cheers,
Cam
Click to expand...

Bloody hell Cam. is there anything you missed out  :D
 
Austenitic grades also become 'magnetic' with age hardening (slooooooowly though).

To double check for suspected austenitic grades with a magnet - compare the bent (worked) areas of the pipe to the straights (relatively unworked). You should feel a slight difference.
 
304 (the most likely grade for a non-specialst SS exhaust system) can be successfully chrome plated, but that has nothing to do with it's 'magnetism'.

It takes quite a lot of process development by the plater - you can't just stick it in with all the other stuff.

I worked on a tailpipe trim for Audi R8 V10 and we defeated 3 top-grade plating shops, who had to give up due to quality issues. The 4th got it right - after 6 weeks of continuous process experimentation development. Any plater that tells you it is easy has only consulted his reference books and not done it for real (and certainly not on exhaust parts which have the thermomechanical cycle to contend with).

P
 
Robjota said:
Bloody hell Cam. is there anything you missed out  :D
Click to expand...

Yeah, heaps... 

How about transcrystalline caustic embrittlement, or oxygen concentration cell corrosion?

Stainless steel isn't as durable as most people think. In fact, it's downright sneaky stuff. It can look 100% normal and then fail without warning. There would be more than a few yachts that have lost masts because the stainless rigging wire has suddenly let go without showing any evidence that it's on the way out. There are ways to minimise risks with stainless yacht rigging, but to go there would be a serious thread hijack.

For exhausts, I reckon ceramic coated mild steel is the way to go.

Cheers,
Cam
 
Dellortoman said:
Robjota said:
Bloody hell Cam. is there anything you missed out  :D
Click to expand...

Yeah, heaps... 

How about transcrystalline caustic embrittlement, or oxygen concentration cell corrosion?

Stainless steel isn't as durable as most people think. In fact, it's downright sneaky stuff. It can look 100% normal and then fail without warning. There would be more than a few yachts that have lost masts because the stainless rigging wire has suddenly let go without showing any evidence that it's on the way out. There are ways to minimise risks with stainless yacht rigging, but to go there would be a serious thread hijack.

For exhausts, I reckon ceramic coated mild steel is the way to go.

Cheers,
Cam
Click to expand...

Ah well, Im already committed to 304 and never even thought about that ! Spring loaded joints work much better than hard clamped, for me anyway..
 
Well it's going to be 3.2kg lighter in s/steel !!

Because I'm only going to run one silencer......Fed up being the quietest bike on the track, when everyone looks at the slow noisy ones  :D :D
 
You must log in or register to reply here.
Back
Top