Author Topic: 750 K3 - Right mirror threads (Read 1828 times)

Gene · « **on:** February 21, 2018, 03:05:05 PM »

This is silly, I'm sure - and not nearly as interesting as carb work. However, I may or may not have accidentally clipped the side mirror of a white Ford econo-line with my right mirror negotiating a narrow passageway. It spun the mirror around - no big, but when I tried to re-attach I found it was basically stripped in the holder. It just sits in the hole now.

I tried a new mirror and it won't grab. I'll try to take a pic later today. I was working in the dark last night.

My question is, do I just need to re-thread this? Seems like it would be crazy to have to attach a new MC just to get the mirror situated. IIRC in CA you only need 1, so I'm legal, just wondering if there is a solution I'm not thinking about.

madmtnmotors · « **Reply #1 on:** February 21, 2018, 03:20:50 PM »

Drill and tap for a heli-coil repair to restore stock thread diameter and pitch. Simply rethreading would require tapping out to a larger diameter while the heli-coil repair would restore the original size. Sounds like a good part to learn on so you will have some experience when it comes time to do a more critical repair...

and that time will come!

If you're not comfortable making the repair then ship it to me and I'll make the repair for free if you pay round trip shipping.

Gene · « **Reply #2 on:** February 21, 2018, 03:29:46 PM »

Thank you - yes, I've not had to do this particular type of repair. I'll do some reading and if it's over my head I'll send it off.

madmtnmotors · « **Reply #3 on:** February 21, 2018, 04:01:34 PM »

Sounds good. The tough part is that the mirror mounting hole is a "blind bore" in that the hole does not go all the way through, so it may require two taps to be able to get the threaded insert installed properly. The first tap to get the threads started as far down as possible which are typically tapered at the leading edge. This may not get far enough down to get the repair threads inserted far enough so the first tap can be followed up with a "bottoming tap" that is squared up on the leading edge in order to cut threads all the way down to the bottom of the hole so the repair threads can be inserted fully.

Not sure what the threads are off the top of my head, let me know if you need me to verify the diameter and thread pitch before ordering a repair kit if you decide to give it a go. I have most of the common repair threads on hand since I order extras any time I have to order any.

madmtnmotors · « **Reply #4 on:** February 21, 2018, 04:04:16 PM »

Just went and checked. The mirror threads are 10mmx1.25

Gene · « **Reply #5 on:** February 21, 2018, 04:25:30 PM »

Good info - thank you. Doing some research.

madmtnmotors · « **Reply #6 on:** February 21, 2018, 05:24:17 PM »

The threaded hole in the master cylinder casting is pretty deep, and the heli-coil taps are semi-squared at the end, so the standard length repair coil (13.5mm long, just over 1/2" long) should not require any type of special "bottoming tap". The designation on the repair kit will likely read: M10x1.25

For a quick turnaround you might find a local machine shop that may do the repair for close to the cost of round trip shipping to and from Florida. Just let me know and I'll PM you my address if you need it.

Gene · « **Reply #7 on:** February 21, 2018, 05:56:55 PM »

Very cool. I do have a couple of local garages I could check with. WTH - they prolly already have the stuff and the knowledge.

Or - I learn something.

madmtnmotors · « **Reply #8 on:** February 21, 2018, 06:57:17 PM »

Quote from: Gene on February 21, 2018, 05:56:55 PM

Or - I learn something.

I find that part quite rewarding. The accomplishment of saving a perfectly good part (the master cylinder in your case) and being able to reuse the original mirror instead of having to find one with a larger base or having to cobble together some kind of adapter. Helicoils are pretty easy to do and only require the kit and a drill and some patience. The mounting boss for the mirror is large enough that even if the helicoil repair was wrecked badly there should be enough material to repair that with what is called a "Big Sert" for terribly oversized holes.

Here's some I found:

https://www.amazon.com/gp/product/B0182N26Z8/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

https://www.amazon.com/Harpow-Professional-Helicoil-Thread-Rethread/dp/B00V839CFM/ref=sr_1_12?ie=UTF8&qid=1519266846&sr=8-12&keywords=m10+helicoil

Although shipping time on the 2nd one is 2 to 3 weeks.

I will usually add red locktight sparingly to the repair threads within the part that will be receiving the repair coil prior to inserting the repair coil. Once the repair coil is in place I'll usually allow it to cure for a couple days. A little goes a long way here since the coils are like a spring and will allow the locktight to flow through to the inner threads. I'll slather up the fastener (or mirror threads in your case) and the inner threads of the repair coil with anti-seize as extra insurance to keep any of the red locktight from grabbing the fastener, it's only there to keep the repair coil in place. You'll get a stronger repair if you make sure to turn the repair threads 1 to 1-1/2 turns below the surface of the part.

Don't forget to knock off and retrieve the insertion tang!

EZPZ

Acceptable results could likely be achieved with blue locktight as well if the image of your mirror and master cylinder housing becoming fused together as one by the red locktight gives you nightmares....

Gene · « **Reply #9 on:** February 21, 2018, 09:05:29 PM »

Thanks. I'm leaning on the idea of trying it. Cracks me up though - I thought "Yeah, grab the freeway home, not that bad and you can share the lane." The one tight spot ends up costing me a mirror, kit, and a lot of learning I wasn't planning on. But hey, them's the breaks, yeah?

spotty · « **Reply #10 on:** February 21, 2018, 09:17:50 PM »

or....have you thought about bar end mirrors?

Gene · « **Reply #11 on:** February 21, 2018, 10:22:15 PM »

Quote from: spotty on February 21, 2018, 09:17:50 PM

or....have you thought about bar end mirrors?

Not really, I see the appeal but I'm a stocker guy. I'm used to looking in one place for what's behind me. I know, that makes me old, but I like the Bug-Eye mirrors. And I'm comfortable with them. To train my eyes to look for a new point of reference may be harder than heli-coiling a new thread.

spotty · « **Reply #12 on:** February 22, 2018, 02:35:58 AM »

I know what you mean, took me a while to get used to bar ends but I had no other choice, I put hayabusa master cylinders on the vmax and they have no facility for mirrors ( they're attached to the bodywork on a 'busa)
I have also gotten used to none at all in the past as well as using a micro bicycle mirror after I got busted for none at all

And of course at the other extreme I started off on scooters with at least a dozen mirrors and at least as many spotlights

ekpent · « **Reply #13 on:** February 22, 2018, 04:38:44 AM »

Gee whiz Gene just do what any good shade tree mechanic- crappy previous owner would do. Fill that hole with a huge ole' glob of JBweld and plop that sucka in there !!

Hopefully you know I'm just kidding.

Stev-o · « **Reply #14 on:** February 22, 2018, 06:47:34 AM »

+1 on the JB Weld! Ha. Very generous offer from Wilbur but I think you got this, Gene.

Gene · « **Reply #15 on:** February 22, 2018, 10:24:19 AM »

Quote from: spotty on February 22, 2018, 02:35:58 AM

And of course at the other extreme I started off on scooters with at least a dozen mirrors and at least as many spotlights

I have to admit - I've always liked the look of those.

Gene · « **Reply #16 on:** February 22, 2018, 10:25:10 AM »

Quote from: ekpent on February 22, 2018, 04:38:44 AM

Gee whiz Gene just do what any good shade tree mechanic- crappy previous owner would do. Fill that hole with a huge ole' glob of JBweld and plop that sucka in there !! Hopefully you know I'm just kidding.

Don't think for a second it didn't cross my mind. That and some duct tape. Good to go

Gene · « **Reply #17 on:** February 22, 2018, 02:25:18 PM »

Ordered a kit. I'll give it a shot this weekend. Thank you all.

Gene · « **Reply #18 on:** February 24, 2018, 01:46:04 PM »

Holy s*^t. That's the easiest thing I've ever done on a bike. I'm sure my tolerances aren't "spec" but that f***in mirror is in and it took 10 minutes.

Wilbur and everyone else, thank you. For those of you trying this at home, the most important part is drilling straight. Take it slowly, blow out the shavings as you go, and dammit, clean up after yourselves.

madmtnmotors · « **Reply #19 on:** February 24, 2018, 03:28:45 PM »

Quote from: Gene on February 24, 2018, 01:46:04 PM

Holy s*^t. That's the easiest thing I've ever done on a bike. I'm sure my tolerances aren't "spec" but that f***in mirror is in and it took 10 minutes.

Wilbur and everyone else, thank you. For those of you trying this at home, the most important part is drilling straight. Take it slowly, blow out the shavings as you go, and dammit, clean up after yourselves.

The feeling of accomplishment and satisfaction is very rewarding, and I had a feeling you were up to it! Glad it worked well for you, and your observations are spot on:

>Take your time
>Drill it straight
>Enjoy the fact that you have returned a broken piece back to fully functional service!

The repair does often go very quickly. Broken bolts and/or stripped threads used to inspire rage, now my first thought is what the first step will be to either extract the broken piece (left hand drill bit is often the first choice) or which thread repair method will be the most appropriate. Now you understand why I had no reservations about making the repair for you... it's too easy!

Gene · « **Reply #20 on:** February 24, 2018, 03:56:07 PM »

Love it. Now, of course, I have a leak to deal with. Moving on as soon as my pics make it to the computer. Thanks again - NEW THREAD TIME!

Stev-o · « **Reply #21 on:** February 24, 2018, 04:24:12 PM »

Good to hear, Gene, we knew you could do it!

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Author Topic: 750 K3 - Right mirror threads (Read 1828 times)