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Author Topic: Team Go Dog, Go! Modified Partial Streamliners  (Read 1029936 times)

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Offline JimL

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1575 on: February 08, 2014, 11:10:26 AM »
Pretty simple, really.  Clean the bolt with lacquer thinner, first.  If they are galvanized, I throw them in muriatic acid (outdoors, downwind!) to strip the zinc.  After rinse, it can go straight to the phosphoric bath.

I put phosphoric acid in an old glass cake pan or bowl, and leave soak a day or two.  The metal turns brown or purple when you get it right.  Its about like gun bluing, you are just trying to get the phosphorus to slip between the iron crystals and take up valence bonds where water would like to join the party.

Thats the same thing chromium does in stainless steel, and both results are more brittle than good old iron.  The acid method doesnt go that deep, so the bolt keeps its strength better, and can be unscrewed without using anti-seize.

  I dont use stainless bolts where I expect a lot of bending force or chafing, and especilly where there is a long section of thread needed.  It always gets nasty and wont come apart.  Stainless is especially bad where thermal cycling goes on.  Thats why air-fuel ratio sensors almost always require throwing the stainless steel exhaust manifolds away, when the sensor needs replacement on modern vehicles.

On my ocean sailboats, I used bronze hardware instead of stainless, for all underwater or deck mounting (where salt water would pool during long days on the same tack).  Stainless just rusted and snapped off in salt water.

I'm not much on metallurgy, I just learned some things the hard way, sometimes a long way offshore. :-P

Offline manta22

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1576 on: February 08, 2014, 11:26:16 AM »
JimL;

If you have a choice, use a fastener with rolled threads after heat-treat instead of cut threads-- rolled threads are much stronger and have better fatigue strength.

Also.. could you re-thread the hole to 3/8" or 7/16" and then use a standard SAE stud?

Regards, Neil  Tucson, AZ
Regards, Neil  Tucson, AZ

Offline Vinsky

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1577 on: February 08, 2014, 07:22:06 PM »
Any time you can use a roll form tap in aluminum you will have a much stronger thread too.
John

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1578 on: February 09, 2014, 01:42:53 AM »
Tanks for the advice.  These posts and replies show that there are many ways to do the same thing.  The roll thread taps and dies are something I will look into.  The acid method, too.

Stainless and titanium can be tough metals to thread with dies.  There are three methods I use.  One is to cut the threads on the lathe to 80 or 90 percent depth and then to finish the thread with a die.  Another method is to use adjustable dies that can be opened up to cut a set of treads and then closed to recut the threads deeper.

Over the years I bought a whole lot of different sized metric dies including the odd sizes.  This is how I use the odd size dies.  This stud is made from a bolt.  The first pass down this stud was made with a 9mm x 1.25 mm die.  It cut the beginning of the thread.  Then, the final pass was made with the 8mm x 1.25 mm die.  This made the threads much easier to cut.  Anti-sieze was used as a lube during the thread cutting.

Cut threads are weaker than rolled threads.  One way to use cut threads successfully is to use more or larger fasteners to compensate for their lower strength.

Stainless steel screws can seize up in aluminum parts and this is especially bad where salt water is present.  These are three methods I use to prevent this.  One is to install a stainless stud into the aluminum part and to use a use a stainless nut to clamp the two parts together.  This way, there is no need to unscrew anything out of the aluminum part.  The stud stays in place.  Another method is to use blue loctite or anti seize on the threads of the stainless bolt or screw.  This keeps the threads from locking due to corrosion.  The third way is to install a threaded stainless steel, brass, or steel insert in the aluminum part.  The stainless screw or bolt is screwed into the insert rather than the aluminum.   

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1579 on: February 09, 2014, 12:44:14 PM »
The rear brake system on the Triumph has a pressure switch to actuate the brake light.  It is not needed for racing and it will be replaced with a banjo bolt.  A non-corrodible replacement would be nice and I have a rod of 304 stainless somewhere around here.  I cannot find it right now.  I did find a 19mm dia rod of 6-4 titanium and that is what I will use for the banjo bolt.  The freshly made banjo bolt is in the picture next to the old switch.

It is important to know the ti alloy you are using.  Some alloys have much less strength than others.  All of my rod stock is 6-4.  This is often called structural ti and it is alloyed with 6% aluminum and 4% vanadium.  The proof stress of this alloy in the annealed (weakest) state is 827 Newton per square millimeter.  Mild steel, by comparison, has a value of 220.  This allow is plenty strong for the banjo bolt and it is corrosion resistant.  There is a lot of info on Ti in John Bradley's "The Racing Motorcycle, Volume 2."

The ti I buy are cutoffs and scraps.  These purchases are best done in-person with cash in hand.  It does not hurt to mention that you are a land speed racer with limited funds.  It is a good idea to bring a sample of ti with you and to have it handy.  Ti and stainless steel look similar and the stainless weighs more.  It is easy to detect this if you have a piece of ti to pick up at the same time you are handling the piece they are selling you.  I have been burned when I bought a hunk of stainless at ti price.

Galvanized or zinc plated steel have similar ranking on the galvanic scale and they are compatible, corrosion wise.  Ti is very noble and aluminum is not.  There are two things I can do to prevent the bolt from locking up in the aluminum caliper.  One is to use a sealant or marine grade anti-seize to keep water out of the threads.  The other is to install a noble metal threaded insert in the caliper. 

Offline manta22

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1580 on: February 09, 2014, 03:33:12 PM »
It is commonly known as the titanium alloy "6Al-4V". Good stuff.

Regards, Neil  Tucson, AZ
Regards, Neil  Tucson, AZ

Offline tauruck

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1581 on: February 10, 2014, 12:11:02 AM »
I've always wondered about the availability of metric fasteners over there.
We have the opposite problem finding (inches) stuff but not on thread type, more on shank length.

Offline 4-barrel Mike

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1582 on: February 10, 2014, 12:11:32 AM »
Mike Kelly - PROUD owner of the V4F that powered the #1931 VGC to a 82.803 mph record in 2008!

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1583 on: February 10, 2014, 10:16:01 PM »
Mike, stainless fasteners are readily available here cause of the climate.  Almost everything I use is stainless.  Lots of US coarse, US fine, and metric coarse stuff is available in stainless.  Metric fine is hard to find in stainless for some odd reason.  Something like a metric banjo bolt in stainless would be very hard to find.

4-barrel Mike, that was the one motorcycle show I did not want to miss.  It was snowing heavy here and we stayed home all weekend.

These comments apply to 6AL-4V Ti.  The metal does a poor job of conducting heat away from the tool bit during cutting.  This limits cutting speed.  Aqueous cutting fluids do a good job of removing the heat so a steady stream is needed to enable fast cutting.  My tooling is cooled by an old guy dribbling oil out of a can so the heat removal is not optimum.  This limits cutting speed.  The bolt was made with the lathe running at 179 rpm.  That is pretty slow but anything faster overheated the tool bit.

The material is tough.  Deep cuts make the drive belt slip on the lathe or they bog down the motor.  The cut depth for the bolt was 0.010  The back gears were set to advance the bit 0.0046 inches per spindle revolution.  These were about the deepest cuts I could go.  Plan on spending some time when machining 6-4.  The chips tell the story.  Blue chips mean things are too hot and yellow chips also say it is time to slow down.  I use the deepest cut that will not bog down the lathe and produce silver chips.

The banjo bolt has a hole drilled down the center, one drilled in from the side, and a waist cut into the shank where the side hole is.  It is essential to do all of this after the part is threaded.  The force required to thread the part would bend the end if it was threaded after the it was drilled and waisted.  The bolt shown is ready to be threaded.

This is a 10mm x 1.25 mm screw thread.  10mm is 0.394 inches.  It is tempting to turn the shank down to 0.394 before it is threaded.  Don't.  Cut some threads with the die on a scrap part and measure them.  I did and the cut thread OD is 0.385 inches.  The shank was cut to 0.385 inches before it was threaded.  This is a very important step.  It is almost impossible to run a die over an oversize ti shank.

The upper thread on the banjo bolt does not look right.  It is full of anti-seize.  That is what I use for a threading lubricant.   

Note the spiffy finish.  This was "as cut."  This is one good thing about ti.  There should be no surface tearing or chatter marks when everything is set up OK.   

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1584 on: February 15, 2014, 12:19:30 PM »
The lathe does not cut metric threads.  The Armstrong die cutting method is used.  The die and shaft are lubed with anti-seize and the cutting commences.  It takes a lot of brute force to cut the threads.  This metal is very tough.  Do not do it like shown in he first picture.  The force is so great that it bends the end of the shaft.  Use a two handled die wrench or the method in the second pix.  The lathe center, t-handle, and socket keep the die supported and in line  The chuck wrench is used as a key to turn the chuck by hand to make the threads.  This method does not bend the shaft.

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1585 on: February 15, 2014, 12:27:50 PM »
Now the part is drilled and the waist is cut in the shaft for the brake fluid passage.  This weakens the shaft so it is done after the threads are cut.  Drilling works OK with conventional drills.  The speed needs to be kept slow so the bits do not burn up.  Oil is used as a lubricant and coolant.

A couple of nuts are pulled out of the used fasteners can.  They have the same head size as the part being made.  They are drilled out.  The hole size is the major diameter of the threads on the banjo bolt.

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1586 on: February 15, 2014, 12:33:05 PM »
The next step is to file the flats on the bolt head.  The drilled nuts are slipped onto the shaft and they are held in place by a nut with threads that is screwed onto the end of the banjo bolt.  These drilled nuts are a guide to help me file the correct flats.     

Offline wobblywalrus

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1587 on: February 15, 2014, 12:41:34 PM »
The nuts are removed and the bolt is cut from the shaft using a saw.  The bolt is clamped in the chuck with the head end facing out.  The top of the head is faced off.  The turned, cut, and filed finish is shown.  There was no polishing.    There are now two titanium alloy banjo bolts ready for service.  Some folks told me it is impossible to work with ti using my crummy old equipment.   

Offline Koncretekid

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1588 on: February 15, 2014, 01:45:05 PM »
  Some folks told me it is impossible to work with ti using my crummy old equipment.   
But they forgot to tell BSA (nor Triumph & Norton) that they couldn't make motorcycles with the crummy old equipment they had, either! Nice work!
We get too soon oldt, and too late schmart!
Life's uncertain - eat dessert first!

Offline tauruck

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Re: Team Go Dog, Go! Modified Partial Streamliners
« Reply #1589 on: February 15, 2014, 02:57:34 PM »
Bo, that's awesome.

Those Banjo bolts are great.

I guess it's not the old equipment but the guy swinging the handles. :cheers: :cheers: :cheers: