front and rear wheel cylinder mounting bolt sizes?

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bloodysalmon
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front and rear wheel cylinder mounting bolt sizes?

Post by bloodysalmon » Sun Aug 04, 2019 5:34 am

I don't appear to have any bolts that fit the front nor rear brake cylinders to the back plates; what are the sizes and threads please?
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frenchblatter
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Re: front and rear wheel cylinder mounting bolt sizes?

Post by frenchblatter » Sun Aug 04, 2019 1:45 pm

They may be UNF, try it.
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Steve Simmons
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Re: front and rear wheel cylinder mounting bolt sizes?

Post by Steve Simmons » Sun Aug 04, 2019 1:50 pm

1/4" UNF.
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Duncan M
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Re: front and rear wheel cylinder mounting bolt sizes?

Post by Duncan M » Sun Aug 04, 2019 8:16 pm

I seem to recall one size for front, and smaller in back.

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Marv
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Re: front and rear wheel cylinder mounting bolt sizes?

Post by Marv » Sun Aug 04, 2019 9:10 pm

Brake component were supplied by Lockheed (Now Delphi) Lockheed was all SAE threads try 1/4" and 5/16" fasteners, I believe they were fine thread 1/4-28 and 5/16-24. I think...

bloodysalmon
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Re: front and rear wheel cylinder mounting bolt sizes?

Post by bloodysalmon » Sun Aug 04, 2019 11:28 pm

cheers for this, I didn't think of UNF ... doh! Now ordered 10 of each 1/4" & 5/16", both 1/2" and 5/16" long too
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Re: front and rear wheel cylinder mounting bolt sizes?

Post by frenchblatter » Mon Aug 05, 2019 9:01 am

Chris, kindly remember that I'm not far away and have stocks of UNF, UNC, Metric, Whitworth and BSF screws, bolts and nuts as well as washers. If you need anything just pop up and get it.
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Steve Simmons
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Re: front and rear wheel cylinder mounting bolt sizes?

Post by Steve Simmons » Mon Aug 05, 2019 10:00 am

Oops, reading too fast and thought it was a question about fronts. I should stop browsing the web on a mobile phone. I agree rear are different and 5/16-24 sounds familiar.
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bloodysalmon
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Re: front and rear wheel cylinder mounting bolt sizes?

Post by bloodysalmon » Fri Aug 09, 2019 10:04 am

Having bought 20x 1/4" UNF and 20x 5/16"UNF bolts I can confirm the 1/4" work fine but ... the 5/16" UNF bolts dont ... if fact they are not as good as the BSF 5/16 nor the M8 bolts ... whats going on?
Is it because the 5/16 UNF has the incorrect tpi ! I've looked around and I cant determine if there are any other 5/16" UNF that dont have 24tpi ... do you?
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Marv
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Re: front and rear wheel cylinder mounting bolt sizes?

Post by Marv » Fri Aug 09, 2019 12:19 pm

Chris: you say the 5/16 BSF seems better than the UNF 5/16 24. BSF is 22tpi Does it thread in all the way or hang up. The M8 x1.25 has 20.32tpi. The SAE size you may want is 5/16 - 18 UNC. There are other 5/16 SAE tpi's of 28 and 32 but these are highly specialized and fasteners are very expensive.

I'll pull one of mine and check the threads, will get back to you shortly.

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Marv
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Re: front and rear wheel cylinder mounting bolt sizes?

Post by Marv » Fri Aug 09, 2019 12:48 pm

OK Chris: I've verified it with mine. They are 5/16-18UNC not UNF Mine are fully threaded 3/4" length under the head with a flat and lock washer in tow. If your source is slow or unavailable, I can pop 8 or 10 in a packet and send them across the puddle for you.
brake cylinder bolt-front.png
brake cylinder bolt-front.png (292.64 KiB) Viewed 2360 times

bloodysalmon
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Re: front and rear wheel cylinder mounting bolt sizes?

Post by bloodysalmon » Fri Aug 09, 2019 12:50 pm

Hi Marv, appreciate your input. I'm assuming 5/16"UNF default tpi is 24. If this is the case I suspect this is what I have bought ... but this was based upon assumption and no other obvious alternative.
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Marv
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Re: front and rear wheel cylinder mounting bolt sizes?

Post by Marv » Fri Aug 09, 2019 1:06 pm

Yes Chris, 24tpi is the standard UNF for 5/16" SAE. 18tpi is the standard for UNC SAE.
I am surprised that the fronts are 18tpi as most Lockheed brake components I'm familiar with use the fine thread pitch. They must have had a reason. Another thought is that BSW is almost a direct match in the 5/16"-18 size. Can't imagine that to be the reason but it may be. I did use my Whitworth socket to remove that bolt in the picture. But only because it was handy. If you can source 5/16" BSW, try it, I'll bet it works... otherwise, if I can help source SAE, let me know.


bloodysalmon
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Re: front and rear wheel cylinder mounting bolt sizes?

Post by bloodysalmon » Sat Aug 10, 2019 3:27 am

cheers for the update Marv, I did wonder what they were going to be. Crazy what ... rears 1/4"UNF and the fronts 5/16"UNC !!
I've just ordered a dozen 5/16" UNC bolts at 3/4" long which should be with me Mon/Tuesday, but thank you for the offer Marv
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