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Old 05-25-2016, 12:37 PM   #1
NJ C10 Guy
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Bleeder bolt size

I've been trying to search to find out what size bleeder bolts I need. My system is stock, rotors in the front drums in the back. 86 custom deluxe. I want to pick up a set of speed bleeders but I'm getting different sizes when I look on summit. Are the front and rear different sizes? Here's what I'm looking to get:

http://www.summitracing.com/parts/ru...olet/model/c10

http://www.summitracing.com/parts/ru...olet/model/c10

Thanks for the help!
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Old 05-25-2016, 06:56 PM   #2
MikeB
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Re: Bleeder bolt size

What size wrench do your current bleeder valves take? GM couldn't decide if they wanted to go metric or SAE in the 80s, so there's a little of both on our trucks.

As I recall, the metric version has 10 mm threads and takes a 10 mm wrench. The SAE version is 3/8"-24 and takes a 3/8" wrench.

3/8" = .375"
10 mm = .394"

So if a 3/8" wrench is too small and a 7/16" too big, you probably have 10 mm bleeder valves.
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1969 C10 LWB -- owned for 35 years. 350/TH350, 3.08 posi, 1st Gen Vintage Air, recent AAW wiring harness, 5-lug conversion, 1985 spindles and brakes.
1982 C10 SWB -- sold
1981 C10 Silverado LWB -- sold, but wish I still had it!
1969 C10 (not the current one) that I bought in the early 1980s. Paid $1200; sold for $1500 a few years later. Just a hint at the appreciation that was coming.
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Old 05-25-2016, 07:02 PM   #3
NJ C10 Guy
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Re: Bleeder bolt size

Ok, so it's one or the other, not both. Makes sense but it wouldn't surprise me if it was both. I'll double check but i think they're standard. Thank you.
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Old 05-26-2016, 09:29 AM   #4
NJ C10 Guy
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Re: Bleeder bolt size

I just went out and checked. The rear is 3/8, but the front is definitely smaller. 3/8 didn't fit and neither did 10mm. I went down to 8mm and 5/16 and the 8mm seemed to do the job. 1/4 was too small. I just want 1 thing to be relatively easy. I hate ordering the wrong parts, especially when they are only a couple bucks. It's a waste and sending them back is a hassle.
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Old 05-26-2016, 03:28 PM   #5
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Re: Bleeder bolt size

Quote:
Originally Posted by NJ C10 Guy View Post
I just went out and checked. The rear is 3/8, but the front is definitely smaller. 3/8 didn't fit and neither did 10mm. I went down to 8mm and 5/16 and the 8mm seemed to do the job. 1/4 was too small. I just want 1 thing to be relatively easy. I hate ordering the wrong parts, especially when they are only a couple bucks. It's a waste and sending them back is a hassle.
But there is more! Make sure you have the correct thread size. On my '82 K20 the front thread are 1.5 mm coarse, and an after market slave cylinders for the rear use 1 mm, fine thread.
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