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Front Handbrake Cable Rubber Seal

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Bpt70gt Avatar
Bpt70gt Brian T
Westmoreland, NH, USA   USA
My GT6+ has a different set up than the Spitfire. No grommet like yours. Pictures of your grommet is the next step.

BT

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cmfisher4 Avatar
cmfisher4 Gold Member Chris Fisher
Mystic, CT, USA   USA
For those that are curious, here's what that rubber grommet looks like. Pretty much can't get more complicated than it is for what it does.

Brian, I blew up your email inbox with you pics with measurements, if you haven't seen them yet.

Cheers,
Chris



I learn something new every day...especially if I am working on my LBC!
Please visit my blog and website at http://www.roundtailrestoration.com
and my YouTube Channel at https://www.youtube.com/channel/UC8LASST0WuNG0-po4hK0Maw


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Bpt70gt Avatar
Bpt70gt Brian T
Westmoreland, NH, USA   USA
Chris, I'm on it. Should have a CAD rendering in a few minutes. Stay tuned.

BT

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Bpt70gt Avatar
Bpt70gt Brian T
Westmoreland, NH, USA   USA
Here we are. I'll have a first prototype off the printer tonight. Chris---what is the diameter of the hole in the sheet metal of the car body and the thickness of the sheet metal at the hole?

BT


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Bpt70gt Avatar
Bpt70gt Brian T
Westmoreland, NH, USA   USA
Chris, is there an actual Triumph part number for this grommet? Or it will be called the Chris grommet.

BT

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cmfisher4 Avatar
cmfisher4 Gold Member Chris Fisher
Mystic, CT, USA   USA
Man, you're fast. The P/N is 133913 - GROMMET - HANDBRAKE CABLE TO FLOOR (this according to Canley's).

The sheetmetal is the typical body sheetmetal, so 20-ga I think, which is 0.032" or 0.81mm from a chart I found.

The hole <edit: in the rubber grommet>, from a picture I forgot to send you, is about 9.61mm. This is quite a bit bigger than the cable that runs through it, but I'm not so sure it's supposed to be a water seal.

Thanks, Brian. You rock!



I learn something new every day...especially if I am working on my LBC!
Please visit my blog and website at http://www.roundtailrestoration.com
and my YouTube Channel at https://www.youtube.com/channel/UC8LASST0WuNG0-po4hK0Maw



Edited 2 time(s). Last edit at 2019-03-14 08:17 PM by cmfisher4.

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cmfisher4 Avatar
cmfisher4 Gold Member Chris Fisher
Mystic, CT, USA   USA
Sorry, re-read your post...I don't think I measured the size of the hole in the sheet metal itself, just the hole in the rubber. I can run over there after work tomorrow and get you that number, though. If I had to guess I'd say it was 1/2".

The outer diameter of the grommet that goes through the hole is 16.2mm, which is about 0.64", so that would make sense, I guess.

Chris



I learn something new every day...especially if I am working on my LBC!
Please visit my blog and website at http://www.roundtailrestoration.com
and my YouTube Channel at https://www.youtube.com/channel/UC8LASST0WuNG0-po4hK0Maw

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Bpt70gt Avatar
Bpt70gt Brian T
Westmoreland, NH, USA   USA
OK, good-I'll need the hole diameter in the sheet metal because that's the "neck" of the grommet. It's on the printer now so we'll have a first look of the prototype tonight--shortly. If you can get a mike in the hole to measure thickness would be good. .032 sounds a little thick for our cars.
I've taken into account the hole up through the center of the grommet may be slightly oversize from 50 years of life. So I plan on the grommet grabbing the cable. If you can--measure the diameter of the cable that goes through the grommet.

BT

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Bpt70gt Brian T
Westmoreland, NH, USA   USA
Forgot to ask, just one of these per car?


BT

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cmfisher4 Avatar
cmfisher4 Gold Member Chris Fisher
Mystic, CT, USA   USA
Yup, just one. I'll grab those numbers for you tomorrow.

Thanks, Brian.

Chris



I learn something new every day...especially if I am working on my LBC!
Please visit my blog and website at http://www.roundtailrestoration.com
and my YouTube Channel at https://www.youtube.com/channel/UC8LASST0WuNG0-po4hK0Maw

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Bpt70gt Brian T
Westmoreland, NH, USA   USA
First prototype grommet. 95A durometer polyurethane. May go to a 85A durometer.

BT


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cmfisher4 Avatar
cmfisher4 Gold Member Chris Fisher
Mystic, CT, USA   USA
That's awesome, Brian. I was thinking a bit and I think the forward cable, which is sprung, presses against this grommet when the brake is set, so it may be a hard rubber anyway and just not 50 years of embrittlement. Hard to explain, but it doesn't feel the same as the old "regular" rubber grommets that I pulled off the floors and the like.
I don't know what your numbers mean, but maybe that's part of that.

I'll get you those numbers this afternoon.

Chris



I learn something new every day...especially if I am working on my LBC!
Please visit my blog and website at http://www.roundtailrestoration.com
and my YouTube Channel at https://www.youtube.com/channel/UC8LASST0WuNG0-po4hK0Maw

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Bpt70gt Brian T
Westmoreland, NH, USA   USA
OK Chris. There are several "adjustments" I can make on the part to make it more compliant if need be. The first one I printed was at 100% infill which basically means it's solid. I have a second one on the printer now that will have a 20% infill which means it has a honeycomb structure inside. Once we are dimensionally good, then I can send you several "variants" for you to test. It's just part of the R&D that comes along with developing NLA parts. This is what the 3D printing process shines on. Also with the thermoplastic polyurethane, it can be boiled in water to temper its hardness. This little project will definitely be one of the easier projects I've dealt with in the past year. I've got one project/part for the GT6 than I've been struggling with for over a year.

BT

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Bpt70gt Brian T
Westmoreland, NH, USA   USA
Here is a third version. I segmented the "mushroom" to make it easier to install in the hole of the car body. Chris, I had previously guessed that the hole in the car body was 1/2" but I can easily change that.

One more question: Is this part inserted from inside the car or from the underside?

BT


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cmfisher4 Gold Member Chris Fisher
Mystic, CT, USA   USA
I can only imagine it is installed from the outside of the car. The thicker part sort of floats on the cable until pressure is applied, then the spring compresses against the whole thing as the handbrake is applied.



I learn something new every day...especially if I am working on my LBC!
Please visit my blog and website at http://www.roundtailrestoration.com
and my YouTube Channel at https://www.youtube.com/channel/UC8LASST0WuNG0-po4hK0Maw

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