Topic: chasing threads

[wannabridin]

hey guys!  just wondering if anyone had a list or could tell me the thread sizes on the cases so i can confirm i have the right size chases.

i had my cases blasted recently so i'd like to chase everything before i go any farther!  thanks

[markb]

I'm assuming you mean taps, to clean out the tapped holes.  (Chasing threads, like with a die, would be for external threads).
The three sizes you should have are:
M5 x 0.8
M6 x 1.0
M8 x 1.25
I would blow the holes out real good before running the tap in.
Good luck,
Mark

[wannabridin]

i'm going to run a thread chaser in after them, because i don't want to do anything to the threads, just clean the gunk out, and a BUNCH of people told me to get thread chasers, not taps...  here's the kit i bought:

http://www.mysears.com/Craftsman-48-pc-SAE-amp-Metric-Thread-Restorer-Kit-reviews

i'm pretty sure it includes those sizes as they're quite common, i just wanted to make sure.  thanks Mark!

[Terry in Australia]

Like Mark suggests, if you properly clean all the grit out of your cases (wash the cases in a big tub of hot soapy water and run pipe cleaners and bore brushes through every orifice, and a dish brush for every other surface, then flush with your garden hose, then blow out every orifice with a high pressure air hose or you'll be sorry, and I mean, really really sorry...........) you don't need to chase the threads, you certainly need to after getting your frame powder coated, but I suppose it wouldn't hurt to loosen any grit still stuck in your threads after a thorough clean as described above, not that there should be any grit present at all, just a tiny amount of grit will destroy your engine. How do I know? I've done it, of course...............  

[TwoTired]

FYI:  A chaser is different from a tap.  A tap cuts metal away.  A good chaser pushes the metal threads back into proper place.  Better to have the threads where they belong rather than just cut away the ones that aren't in the proper place.

You still have to clean the threads of swarf or other debris in either case.

Cheers,

[wannabridin]

ya, i wanted to restore the threads, not cut anything away!  thanks TT!

and thanks Terry for the cleaning advice.  pipe cleaners are a good tip!

[markb]

It looks like that will do it for you.  It appears it's a set of taps and dies.  Even when I had a job as a machinist I never heard of a "thread chaser" pertaining to a tapped hole.  But this might be specifically designed for restoring threads.  I'll have to check it out.  I've always just used taps and it works fine.  If you run a tap in a tapped hole it won't hurt the threads if you're careful starting it.  Even squirting some solvent in the holes and blowing them out would be a good idea before running anything in the hole and I think it's a good idea to run a tap (or whatever) in each hole.  It will make your reassembly so much easier and you will get consistent torquing.
Mark    

[Terry in Australia]

I've got a set of "chasers" here Mark theyre basically just a bolt with a vertical trench cut down one side, we used to make them ourselves when the hardware store was closed and we wanted to fix our bikes and ride. You can do the same with any nut, just hacksaw a trench on an angle across one of the flats. Cheers, Terry.

[wannabridin]

awesome terry!!  good tip!  i figured the price was right on this set, and i had a gift card, so why not!  it's a nice selection and should help out with the holes.  but a GOOD thorough cleaning will be mandatory before anything is screwed into any hole.  also a good scrubbing of the cases AFTER the threads are cleaning to make sure the engine is SQUEAKY clean before final assembly!!

[markb]

Terry and TwoTired,
Good info and good tips!  I always learn something around here.
Mark

[fmctm1sw]

I had good success blasting the holes with my air compressor.  Just don't be looking right at the hole if you're not wearing goggles....   

[Steve_K]

After bead blasting my fork lowers (the holes were coverd with masking tape) I washed them in hot water several times and I still found glass beads inside the forks!  Be very careful to be sure it is all clean.  Nice finish and I like it.
Steve

[turboguzzi]

if you prepare your stuff well for blasting, i.e. put bolts in EVERY hole with threads, you shouldnt need these "restoration" steps. when grit gets into any taped hole it becomes very very difficult to get it all out, even with "chasers", taps, whatever.

so next time you invest all that time and money into blasting, dotn cut corners and shut off with bolts or putty every possible hole or thread.

[MRieck]

I have that exact set and use it all the time. It works very well. And TG is very correct about putting bolts in all the threaded holes.

[Steve F]

This might sound a little too dangerous for some, but it works for me.  I adapted a small 1/8" diameter stainless tube, similar to brake line, to my pressure washer, and would use it to reach down into tapped threaded holes to really REALLY clean them of all crap.  If you do this, remember to wear a face shield and gloves.  This is especially useful after anything has been sand blasted or glass bead blasted and nothing else would work.  Works really fast too, and takes about 3 seconds per hole.

[wannabridin]

The shop I took the parts to said they covered the holes, this is just added insurance for piece of mine and to be thorough...  Thanks for the help guys!! I might have to try to do something with my pressure washer as well!!

[turboguzzi]

The shop I took the parts to said they covered the holes, this is just added insurance for piece of mine and to be thorough...  Thanks for the help guys!! I might have to try to do something with my pressure washer as well!!

do it yourself ext time and you'll be sure it was done and done well.... and you'll pay less too. at least that's how it is around here

TG

[Terry in Australia]

awesome terry!!  good tip!  i figured the price was right on this set, and i had a gift card, so why not!  it's a nice selection and should help out with the holes.  but a GOOD thorough cleaning will be mandatory before anything is screwed into any hole.  also a good scrubbing of the cases AFTER the threads are cleaning to make sure the engine is SQUEAKY clean before final assembly!!

That's a good looking kit mate, I might buy one myself! And like everyone has said, put the maximum effort into cleaning those cases before reassembly, grit blasting is a great way to remove old paint and corrosion etc, but it's totally evil, and will screw you if you give it a chance!