Fine or Coarse Metric Threads??

[Yamahafan]

Probably a stupid question, but the search function is down. Does my 2002 WRF have fine or coarse metric threads? I am looking to buy a helicoil to fix a stripped thread in the swingarm.

[aschultz91]

metric doesnt really use fine and coarse like standard. They use thread pitch numbers like 1, 1.25, 1.75 stuff like that. But sorry im not sure what it is i would have to go outside and look at it

[huffster]

The pitch on metric fastener threads also varies by the torque needed on the particular fastener...So, there is not a single answer to your question.

[Yamahafan]

There are two kinds of ISO metric threads: coarse and fine.

http://www.metrication.com/engineering/threads.htm

I am thinking coarse, since the screws holding the chain guard on the top of the swingarm behind the countersocket are M5 and they don't make them in fine.

[aschultz91]

are you trying to fix the chain adjuster or something else?

[Yamahafan]

The top rear screw holding the chain slider stripped out of the aluminum swing arm. I am going to buy and install an M5 helicoil so it won't strip out again and I can use the stock screw I just ordered.

[SUnruh]

tap it and use an M6. been there done that. ?

[Yamahafan]

Is the original M5 hole small enough to tap it with an M6? Did you drill it first or just use an M6 tap?

[SUnruh]

that was 3 or 4 years ago. way too much leaded race fuel inhaled since then to remember. i'm sure i used an sae drill bit to clean it up and just tapped it bigger. heck, i might not even be remembering this correctly! ?

[Yamahafan]

Answering my own question - After I got home I checked the maintenance specs in the manual. Yamaha uses both coarse and fine threads.

8mm Head = M6 x 1.0 thread size (coarse)

10mm head = M8 x1.25 thread size (coarse)

12mm head = M10 x 1.25 thread size (fine)

[chrisbradley44]

There are two kinds of ISO metric threads: coarse and fine.

http://www.metrication.com/engineering/threads.htm

I am thinking coarse, since the screws holding the chain guard on the top of the swingarm behind the countersocket are M5 and they don't make them in fine.

BAmmm!!!! you just made them guys at the top look like dummies...Kepp on truckin

[BazookaJoe]

There are two kinds of ISO metric threads: coarse and fine.

http://www.metrication.com/engineering/threads.htm

I am thinking coarse, since the screws holding the chain guard on the top of the swingarm behind the countersocket are M5 and they don't make them in fine.

Well, actually, there are metric threads in more than just plain old coarse and fine. There are many sizes with an extra fine pitch as well, and then some even finer than that (once you get larger diameter).

If you go to a site like www.mcmaster-carr.com and snoop around the pages with taps, you'll see a whole bunch of varieties.

Back to the question at hand, most of the M5 and M6 threads on the Yam is a coarse thread. There are some fine threads lurking here and there, like within the shock and forks.

Engineeering class is over, time to go riding instead. ?

[huffster]

BAmmm!!!! you just made them guys at the top look like dummies...Kepp on truckin

I be thinking you the one that looks like a dummy.....Your post was not constructive and offers nothing to help the original poster with his question....If you can't offer actual information, perhaps you should be a lurker.... ?