Thread question

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marcofsiny
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Re: Thread question

Post by marcofsiny »

Bill Shields wrote: Mon Jun 13, 2022 6:15 am Or maybe a helicoil could be found..?
I found a helicoil but the hole is too large. I'd have to helicoil a helicoil. Plus I'm still not 100% sure of the thread size
liveaboard wrote: Mon Jun 13, 2022 7:25 am Are other fasteners on the caliper metric or imperialist?

A helicoil would be the best, but finding one for that thread would be a miracle.

So as I understand it, the pin is just the retainer for the pads?
In that case, I would drill oversize, tap with whatever you have, and make a custom pin.
Maybe from a bolt.
Maybe you can get a bolt with the new thread already on it, so you'd only need to turn down the pin section a bit.
Yes other parts are metric. The pin (2) are what the caliper slides back and forth on. When you step on the brake, the piston comes out and the caliper moves the opposite direction causing the other half to squeeze the rotor. So the guide pins not only support the caliper but help it move back and forth.
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liveaboard
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Re: Thread question

Post by liveaboard »

If everything else is metric, the threads in question are surely metric as well.
11mm is rare, but it happens.
Usually there is a heavy casting that the caliper fits into to take the braking load; still you might not want to make your own pins considering that it is somewhat safety critical.
But the same argument can be used for any modification, like welding or drilling oversize.

The only alternative to those options is to find a replacement caliper.
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Bill Shields
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Re: Thread question

Post by Bill Shields »

there was a time when GM care were a mixed bag of Imperial / metric whatnot....NOTHING would surprise me.

I would get a set of thread gauges, or borrow some....
Too many things going on to bother listing them.
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marcofsiny
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Re: Thread question

Post by marcofsiny »

That's this car. Metric and standard all over.
The part is at the welders now. We wil see what happens
earlgo
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Re: Thread question

Post by earlgo »

My error. After a bit more searching, I found that there is indeed a M11x1.25 thread.
11mm = .433" diameter: 7/16 = .4375 " diameter: 11mm is smaller by .004"
1.25mm = .0492" pitch: 20TPI = .05" pitch: 1.25mm is smaller by .0008"
So the two threads should be NEARLY interchangeable.
Why the 7/16-20 die won't go onto the M11x1.25 thread is ?
Amazon and others have M11 x 1.25 taps and dies for sale.
--earlgo
Before you do anything, you must do something else first. - Washington's principle.
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marcofsiny
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Re: Thread question

Post by marcofsiny »

earlgo wrote: Tue Jun 14, 2022 11:07 am My error. After a bit more searching, I found that there is indeed a M11x1.25 thread.
11mm = .433" diameter: 7/16 = .4375 " diameter: 11mm is smaller by .004"
1.25mm = .0492" pitch: 20TPI = .05" pitch: 1.25mm is smaller by .0008"
So the two threads should be NEARLY interchangeable.
Why the 7/16-20 die won't go onto the M11x1.25 thread is ?
Amazon and others have M11 x 1.25 taps and dies for sale.
--earlgo
I dropped the part off at the welders yesterday. I'm waiting for the estimate. He made it sound like it wasn't a problem but if he can't do it,,I will tell him to fill the holes and I'll do it myself. As long as he can verify the threads for me.
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ctwo
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Re: Thread question

Post by ctwo »

Braze the holes?
Standards are so important that everyone must have their own...
To measure is to know - Lord Kelvin
Disclaimer: I'm just a guy with a few machines...
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marcofsiny
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Re: Thread question

Post by marcofsiny »

ctwo wrote: Tue Jun 14, 2022 4:30 pm Braze the holes?
I'm not sure how they will do it but I have some faith in their work. The shop has been around for 70 years, the company I work for uses them.
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marcofsiny
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Re: Thread question

Post by marcofsiny »

I got the part back today. He welded the hole then used a helicoil. I asked the thread size and he said 7/16-20. I unscrewed the guide pin and it felt snug and smooth. If it really isn't 7/16-20 and it is metric then it is too close to see any difference. I guess I have to take his word for it .
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